Introduction:
When performing hip arthroplasty to manage femoral neck fracture (FNF) in the elderly patients, the optimal choice between total hip arthroplasty (THA) or hemiarthroplasty (HA) is still controversial. In addition, dual mobility cups (DM) have been shown to prevent instability that remains a concern in these patients with conventional THA. This study compared the outcomes of HA, DM and conventional THA to manage FNF across a nationwide observation issued from the Swiss National Joint Registry (SIRIS).

Method:
From 2012 and 2022 in Switzerland, 37,169 patients who were managed with hip arthroplasty for FNF were exhaustively and prospectively included in the SIRIS registry. There were 22,053 HA, 3,263 DM THA and 11,853 conventional THA included. The revision rates and survivorship for septic and aseptic failures were compared between HA, DM and conventional THA. Hazard ratios (HR) for revisions were used to compare HA, DM and conventional THA. Subgroups analyses with adjustments for age, gender, BMI and ASA score were performed.

Results:
At 10-year follow-up, the cumulative revision rates for HA were 7.8% [6.4-9,4], for DM THA 8.1% [7.6-10] and conventional THA 8.7% [7,7-9,9]. HA tended towards a lower revision risk than DM and conventional THA (HR=0.86 [95%-CI: 0.72-1.02]) without reaching significance. However, in patients < 65 years, the revision rate after HA was as high as 20.7% [13.5-31.1] with 56,1% of the revisions being for conversion to THA. In addition, HA performed with cementless femoral stem were characterized by significantly higher revision rate than HA performed with cemented femoral stem regarding the risk of femoral periprosthetic fracture (HR=1.81 [95%- CI: 1.39 to 2.38]). Moreover, the revision rate due to dislocation was significantly higher for HA performed through a posterior approach compared to anterior approaches (Hueter or Hardinge) (HR=1.64 [95%-CI: 1.268 – 2.113]).

Conclusions:
When considering arthroplasty options to manage FNF, no significant difference was observed in terms of revision rate and survivorship between HA, DM THA and conventional THA. However, a 20% revision rate at 10 years follow-up was observed after HA in patients < 65 years. Therefore, THA is recommended in younger patients and/or when life expectancy is > 10 years. Importantly for HA, a cemented femoral stem should be considered to limit the risk of femoral periprosthetic fracture as well as anterior approaches to avoid dislocation.

Background:
Despite many advantages, the direct anterior approach (DAA) is associated with a risk of lateral cutaneous femoral nerve (LCFN) injury. This may lead to numbness of the antero-lateral thigh, which is only temporary in most cases, but can sometimes cause persistent neuropathic symptoms with pain, numbness, and tingling, impairing mobility and daily activities. This study aims to evaluate the effect of LCFN lesions after primary THA using the DAA on long-term clinical outcome and function.
Methods:
Our institutional database of primary THA patients (2015-2022) was searched for patients with LCFN lesions after DAA. Only patients with a consultation by a neurologist for LCFN symptoms were included. Prospective clinical assessment (Ethical approval 2023-01287) included Visual Analog Scale (VAS), incision length, distance to anterior superior iliac spine (ASIS), size of the area of symptoms, Tinel sign, range of motion (ROM). Patient-reported outcomes (OHS, COMI Hip, UCLA) were obtained.
Results:
Out of 1418 patients screened, only 29/2.0% (female: 19, 65.6%) met the criteria (7 surgeons). Mean age 64y±12, BMI 26.8kg/m²±4.3, surgical time 77min±25, 20.7% smokers (n=6), 55.2% bikini incision (n=16). 22 patients (75.9%) had ultrasound, 18 (62.1%) received nerve infiltration (13/ 18 (72.2%) showed long-term LCFN symptom improvement), and 2 (6.9%) had surgical neurolysis. Preliminary clinical data of 12 patients with a mean f-up of 4.8±2.0 (2.3 – 8.6) years. Mean VAS 1.9±2.2, incision length 9.2cm±1.1, distance to ASIS 4.3cm±1.3. 10 hypesthesia, 5 dysesthesia, 2 tingling, area size 287cm²±269. Tinel sign positive (n=2, 16.6%). Mean hip flexion 100°±6, internal 23.8°±6.8/external 37.9°±3.3 rotation. Mean OHS 38.5±7.2, COMI Hip 3.03±2.24, UCLA 5.9±2.2.
Conclusion:
Painful LCFN lesions after primary THA using DAA are rare in a high-volume orthopedic setting (>200 THA/surgeon/year), with an overall higher occurrence in women. However, persistent LCFN symptoms after intraoperative nerve injury appear to have a relevant impact on long-term clinical outcomes. The bikini incision did not increase the risk for LCFN symptoms. Ultrasound-guided nerve infiltration led to favorable long-term therapeutic results.

Introduction
Effective perioperative pain management and early mobilization after surgery are crucial to optimize recovery. In addition to routine pain medication, peripheral anaesthetic blocks are reportedly effective. The aim of this study was to determine the effect of the the PEricapsular Nerve Group (PENG) block on postoperative (1) patient-reported pain, (2) total consumption of morphine and (3) length of stay (LOS) after surgical hip dislocation (SHD).

Methods
IRB-approved, single-center, multidisciplinary, prospective, randomized, double-blind controlled trial of patients undergoing SHD for femoro-acetabular impingement between June 2022 and November 2023. Preoperatively, patients were randomly assigned to either the study group (39 patients) or the control group (33 patients). Both groups underwent an ultrasound-guided injection of a 20 mL solution, the study group received 0.5% ropivacaine and the control group 0.9% NaCl. Each patient, anesthesiologist and surgeon were blinded to the solution injected. Nine patients who required additional procedures or did not receive the standard analgesia protocol were excluded from the study, resulting in a total of 71 patients (72 hips). The demographics of the two groups did not significantly differ. Overall the study population was 38% female, mean age was 29 ± 6 (19 to 46) years and mean body-mass-index was 23 ± 3 (19 to 30) kg/m2. We assessed (1) postoperative pain at 1h, 6h, 12h and 24h postoperatively via the Visual Analogue Scale (VAS) ranging from 0 (no pain) to 10 (maximal pain), (2) total morphine consumption in Morphine Equivalent Dose (MED) during the first 24 hours after surgery and (3) the LOS in days. Differences between the study group and the control group were analyzed using the Mann-Whitney test. The significance level was set at α < .05.

Results
VAS differs slightly and significantly at 1hour in the study group (4 ± 2 [0 to 8] VAS) compared to the control group (5 ± 2 [1 to 10] VAS) (P < .05). There were no significant difference at any of the three other time points, for the 24-hour morphine consumption and the LOS between the two groups (all P > .05). No femoral motor nerve block or injection site infection were observed in either group.

Conclusion
In this prospective randomized controlled trial, the PENG block showed a slight difference in terms of reported VAS at 1 hour postoperatively only, but no difference in morphine consumption and LOS after SHD when compared to a placebo.

Background
Previous studies have indicated poor outcomes in patients having revision of metal-on-metal (MoM) total hip arthroplasty (THA) resulting from Adverse Local Tissue Reaction (ALTR). We reviewed all patients who had a MoM THA revision to determine (1) the rate of complications; (2) the clinical and radiological outcomes; and (3) the influence of the index revision on the serum metal ions levels; and to compare the results (1) to (3) in cases with isolated revision of the acetabular component to those after revision of both acetabular and femoral components.

Methods
We identified 79 patients who underwent a revision of a MoM THA and did not show any sign of loosening of the femoral stem. Among these, 62 had an isolated revision of the acetabular component (Gp1) and 17 had a revision of both components (Gp2). Mean age at revision surgery was 61.8 years. The mean time from the index MoM THA was 93.1 months and mean followup after revision was 57.7 months. Major complications (instability, infection, aseptic loosening, and periprothetic fracture within one year) were documented and included in the analyses. The PMA and the Harris Hip score (HHS) were determined, and Patient-reported outcome measures (PROMs) were collected. Serum samples were analyzed to assess serum Cobalt (Co) and Chromium (Cr), before and within 12 months of revision.

Results
Revision diagnoses were ALTR (66%), aseptic loosening of the cup (7.6%), iliopsoas impingement (3.8%), recurrent dislocation (2.5%), chronic pain (1.3%) and heterotopic ossification (1.3%). Five major complications occurred in five different patients (6.3%). There were two acetabular component loosenings (both in Gp1)) and three dislocations (2 in Gp1 and 1 in Gp2). Smoking appeared as a statistically significant predictive factor of complication (p=0.027). Intraoperative blood loss and operation time were significantly lower in Gp1. Similar improvements in PMA, HHS, SF-12 and Womac scores were observed in both groups. Metal ion levels decreased after revision and this difference was not significant between Gp1 and 2.

Conclusion
In comparison to the current literature, our study shows a low complication rate after MoM revision THA. Our data suggest that isolated revision of the acetabular component of failed MoM THA can be performed without revising a stable femoral component and results in similar complication rate, clinical improvement, and metal ion decrease as compared to both components revision.

Introduction: Malpositioned cups with an uncovered anterolateral rim can irritate the iliopsoas tendon causing pain. However, early revision of a stable implant with slight protrusion should be avoided. Iliopsoas (IP) tenotomy has demonstrated effectiveness in alleviating pain even in these cases. This study assesses the clinical outcome, the impact on hip flexion strength and the morphological changes of the IP muscle in magnetic resonance imaging (MRI) following labral-level tenotomy.

Methods: All patients undergoing arthroscopic labral-level IP tenotomy for tendinopathy after hip arthroplasty between 2013 and 2020 with at least 12 months follow-up were included. Pre- and post-operative cross-sectional areas of the iliopsoas muscle were measured at 2 different levels in the MRI. Muscle atrophy according to Goutallier, tendon irregularities, muscle edema and compensatory hypertrophy were assessed. Hip flexion strength was measured in seated and supine position using a dynamometer. Analysis was performed using Mann-Whitney U and Kruskal-Wallis tests.

Results: The study evaluated 22 patients of whom 17 met the inclusion criteria. Median follow-up was 51 months (range 12 - 105). Post-operative MRIs revealed a reduction of the iliopsoas cross-sectional area by 36% (±33.85%) at the anterior superior iliac spine (ASIS) and 31% (±30.02%) at the anterior inferior iliac spine (AIIS) as compared to the unaffected side. When comparing pre- and post-operative MRIs of the affected side, a reduction of 34% (±27.53%) at the ASIS and of 25 % (±15.69%) at the AIIS was observed. Using the Goutallier classification, we observed atrophy (psoas/iliacus) as followed: grade 0 (1/4), grade 1 (6/7), grade 2 (9/5), grade 3 (1/1) and grade 4 (0/0). Hip flexion showed a reduction of strength of 12% in seated and 18% in supine position when comparing the affected with the non-affected side. All patients reported a complete reduction of their symptoms and were satisfied with the procedure.

Conclusion: The study confirms that IP muscle atrophy occurs in most patients after IP tenotomy, on average reducing the cross-sectional area of the IP muscle by about one-third. Despite this reduction, hip flexion strength remains virtually unaffected. These findings align with existing research, highlighting the absence of severe atrophy after labral-level tenotomies compared to lesser trochanteric ones. In this study all patients reported satisfaction after tenotomy.

Introduction: Previous studies have shown that dexamethasone has a positive effect on postoperative pain control, opioid consumption, postoperative nausea, vomiting and length of hospital stay after arthroplasty surgery. The study assessed if adding perioperative dexamethasone to our current pain regimen after hip arthroscopy is more effective than a placebo. It was hypothesized that dexamethasone can reduce postoperative pain, reduce opioid consumption, improve subjective pain and nausea scores and reduce the number of vomiting events.
Study Design: Double-blinded randomized controlled trial; level of evidence 1.
Methods: Fifty patients requiring an unilateral elective hip arthroscopy were randomized to receive perioperative intravenous dexamethasone (2x12mg) or a placebo (NaCl 0.9%). The patient, the surgeons, the treating anesthesiologist as well as the involved nursing and physiotherapy personnel were blinded. Primary outcome included postoperative pain, secondary outcomes opioid consumption and nausea scores as assessed with a translated revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) six hours postoperatively, on day 1 and 2 and vomiting events. A clinical follow-up was performed 12 weeks postoperatively to assess for adverse events.
Results: The mean age at inclusion was 29 years in both groups. Postoperative pain levels did not differ significantly in the majority of instances. The opioid requirements during the hospitalisation in the dexamethasone group were significantly lower than in the placebo group 31.96 ±20.56 mg vs. 51.43 ±38.00mg (P=0.0139). Significantly fewer vomiting events were noted in the dexamethasone group 0.15 ±0.59 vs 0.65 ±0.91 (P=0.034). Demographics and surgical parameters did not differ significantly.
Conclusion: Perioperative intravenous dexamethasone significantly reduced postoperative opioid consumption by 40% without compromising pain level and safety, as no corticosteroid-related side effects were observed. Dexamethasone may be a valuable adjuvant to a multimodal systemic pain regimen after hip arthroscopy.

Background
Intraarticular hip pain is a significant clinical challenge, with recent literature implicating lesions in the ligamentum teres (LT) as potential contributors. Damage to the LT is prevalent among young patients undergoing joint-preserving surgery. There is a significant lack of research examining LT biomechanics specifically within the relevant patient cohort—individuals who qualify for joint-preserving surgical interventions. Aims: to determine (1) the biomechanical properties (ultimate load to failure, tensile strength, stiffness, and elastic modulus) of fresh frozen ligaments from patients undergoing surgical hip dislocation and (2) to identify patient-specific factors that are associated with them.
Methods
IRB-approved study on intraoperatively harvested LTs of 74 consecutive patients undergoing surgical hip dislocation for joint preservation (August 2021 to September 2022). After exclusion of patients with previous surgery, posttraumatic deformities, avascular necrosis, slipped capital femoral epiphysis and Perthes disease, 31 ligaments analyzed. Main indication for surgery was femoroacetabular impingement. Standardized AP pelvic- and axial radiographs and CT scans performed to identify associated radiological factors. Thorough transection of the LT at its origin and insertion area. Documentation of intraarticular damage to the ligamentous-fossa-foveolar complex. Storage at -20° C. Specimens were mounted to a materials testing machine (Instron Electropuls 10,000, Norwood, MA, USA) via custom clamps. Ultimate failure load, tensile strength, stiffness and elastic modulus were determined.
Results
Ultimate load to failure was 126 ± 92 N while tensile strength was 1 ± 0.8 MPa. Stiffness was 24 ± 15 N/mm, the elastic modulus 7 ± 5 MPa. Multiple regression showed that age < 20 years old, female sex and excessive femoral torsion were associated with higher values, while underlying lesions of the acetabular fossa and fovea seen intraoperatively were predictors for decreased structural properties.
Conclusion
In comparison to other stabilizing ligaments in the body such as the anterior cruciate ligament (ACL) of the knee, the LT seems to be substantially weaker. It is therefore questionable if the LT provides considerable stability to the hip joint. Younger, female patients with high femoral torsion exhibited higher ligament properties.

Background: Stair climbing is important for maintaining mobility, high quality of life, and independence. Although healthy persons can climb stairs quite easily, this strenuous task might be quite demanding when motor functions are reduced. A detailed biomechanical analysis of stair climbing in patients with muscle weakness could provide insight into the diverse and complicated processes involved in human locomotion and may be useful in the field of rehabilitation
Purpose: To investigate the effects of an experimentally induced weakness of the gluteal muscles, through sequential nerve blocks of the superior gluteal nerve to the fascia lata (SGNtfl), superior (SGN), and inferior gluteal nerve (IGN), on joint kinematics, reactions forces (JRFs), and dynamic balance performance during stair climbing in healthy young adults.

Methods: Ten healthy adult volunteers received sequential blocks of the SGNtfl, SGN, and IGN on their dominant right leg. At the control condition and following each block, the participants were instructed to perform stair-ascent and descent activities. A full-body movement analysis was then performed and joint kinematics, JRFs, and dynamic balance performance were recorded. 

Results: Following the SGN block, five out of ten of the healthy participants couldn’t complete the task. In participants who completed the task, their joint kinematics were significantly different compared to the control condition, demonstrating more hip flexion and internal rotation during both stair-ascent and descent activity under the SGN block. Significantly lower JRFs were observed following SGN and IGN blocks at the hip, knee, and ankle compared to the control condition. The participants demonstrated also an increased center of mass (CoM) mean and standard deviation in the mediolateral direction during both stair-ascent and descent under the SGN and IGN block.

Conclusion: Stair climbing was mostly affected by a weakness of the hip abductors, with 50% of the healthy volunteers not being able to complete the task. In patients who did complete the task, the compensation was insufficient as reflected in the abnormal joint kinematics, reduced JRFs, and worst dynamic balance performance.

Introduction: Accurate component placement plays a critical role in the outcome of total hip arthroplasty (THA). Robotic-assisted THA (R-THA) has emerged as an option to optimize this aspect compared to the conventional manual THA (C-THA). The aim of this meta-analysis was to analyse the studies comparing R-THA and C-THA in terms of radiological results, clinical outcomes, perioperative parameters, complications, and revisions.
Methods: The literature search was conducted on three databases (PubMed, Cochrane Library, and Web of Science) on January 25, 2024 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria were: comparative studies, written in English language, with no time limitation, focusing on the comparison of R-THA and C-THA. The quality of each article was assessed using the “Downs and Black’s Checklist for Measuring Quality”.
Results: Among the 1883 articles retrieved, 38 studies (9537 patients) were included. R-THA provided superior radiological results compared to C-THA in terms of acetabular cup placement within the Lewinnek safe zone (p < 0.01) and horizontal change of the rotation centre (p = 0.05). No statistically significant difference was obtained in terms of clinical scores between the two approaches, including Harris Hip Score, Western Ontario and McMaster Universities Arthritis Index, Forgotten Joint Score, and Merle d’Aubigné Hip Score. R-THA showed longer operative time (p < 0.01) compared to C-THA but shorter length of hospital stay (p = 0.05) and lower complication rates (p = 0.04). No difference was obtained in terms of intra-operative bleeding and revision rates.
Conclusion: The results of this meta-analysis suggest that R-THA could provide more precise cup placement and better restoration of the native hip anatomy while reducing complication rates and hospital stay compared to C-THA. However, these benefits did not translate into clinical differences in terms of patient-reported outcome measures between the two approaches and R-THA required longer operative time compared to C-THA. While the overall results do not suggest decisive benefits from the use of robotic technology, future studies should investigate if further technical improvements will translate into clinically relevant benefits for patients undergoing THA.

Introduction
Questions remain concerning the long-term surveillance needs of MoM THAs. Objectives were to assess blood cobalt levels over time in MoM THA and the relation with clinical outcomes in small heads.

Methods
We included all primary MoM THAs with postoperative blood cobalt concentrations. These THAs were performed between 11/1998 and 03/2011. We stratified the MoM THAs in 2 groups, small (≤ 36mm) vs. large (> 36mm) head. To assess the pattern of blood cobalt levels over time only unilateral MoM THAs with at least two cobalt measurements were included. Linear mixed effects models were used for analysis.

Results
Overall, 526 MoM THAs were included, 427 with small heads (199 females) and 99 with large heads (31 females). Mean time of serologies for metal ion levels was 10.5 years. Revision for any reason was performed in 51 of these patients. Considering patients with at least two serologies before revision (n = 205), cobalt ion levels were higher for patients with large compared to small heads (median ±interquartile range: 3.5 ±5.3 vs. 1.3 ±1.4, p < 0.001). We did not find any effect of time on cobalt ion levels (ps > 0.42).
Cobalt levels before and after MoM prosthesis removal for large (medians 7.8 vs. 1.8) and small heads (medians 1.9 vs. 0.9) indicated a reduction to values in the normal range for large heads.
We did not find any significant correlation between cobalt ion levels and clinical outcomes (WOMAC pain and function scores, and Harris hip and limp scores; Spearman’s rs < 0.8, ps > 0.15).

Conclusion
We observed stable cobalt levels over time. Repeat laboratory workups seem unnecessary given that cobalt values remained stable. Removal of the MoM prosthesis largely reduced cobalt blood concentrations to normal levels in the months after the intervention. Clinical outcomes in small head MoM THAs were not associated with cobalt levels.

Introduction
One-stage bilateral total hip arthroplasty (bTHA) in selected patients with bilateral hip OA may expedite rehabilitation particularly when using a direct anterior approach (DAA). While previous studies using other approaches indicate that bTHA may have increased complication rates, advancements in surgical and anesthetic techniques have improved outcomes of bTHA. Postulated benefits of bTHA include a single anesthesia, reduced total hospital stay, and shorter overall rehab. However, data on long-term patient-reported outcomes (PROMs) following bTHA/DAA is scarce. This study aims to compare long-term PROMs between bTHA and unilateral THA (uTHA), both through a DAA.

Methods
In this retrospective case series, patients were selected from our THA registry. PROMs: OHS, COMI, UCLA, EQ5D, Global treatment outcome (GTO) were completed at home before surgery, and at 6, 12, 24, 48, and 60 months postoperatively. To minimize selection bias, propensity score-matching distributed patient characteristics evenly between two treatment groups. Of 11’031 cases in the registry, 357 bilateral cases were matched 1:2 within 4’098 cases having complete 2-year data. The final groups comprised 357 bTHAs and 714 uTHAs.

Results
The baseline characteristics of the two groups, including sex, age, BMI, ASA classification, smoking status, and other sociodemographic factors, were comparable. As expected, bTHA showed longer surgical time (but 4 min less than double that of uTHA), more blood loss, and longer hospital stay (p < 0.01). Intra-operative complications were more frequent in the bTHA group (27% vs 16%, p < 0.05), e.g. calcar cracks occurred in 12 and 10 hips, respectively, ie. below 1.7% for both groups once adjusted for the number of hips operated. Regarding PROMs, there was no significant difference between the two groups for COMI, OHS, or EQ5D at any follow-up interval. Interestingly, the UCLA activity score was higher in the bTHA group at 6, 12, and 24 months and GTO were also rated more favorably in bTHA at 2-year postoperative (p < 0.05).

Conclusion
This retrospective comparative matched cohort study suggests that bTHA yields equivalent or superior mid-term PROMs compared to uTHA, with comparable complication rates when adjusted for the number of hips. One-stage bilateral approach might offer significant economic benefits, warranting a detailed cost analysis against staged THA/DAA procedures.

During total hip arthroplasty (THA), surgeons have control over the structure of the operated limb, specifically on femoral, acetabular and global offsets. The literature suggests that decreasing the femoral offset (FO) and/or the global offset (GO) leads to decreased function [2] and pain [3] and recommends to restore GO by increasing FO and reducing acetabular offset (AO) [2]. Still, the literature presents discrepancies in definitions of post-surgery change in offsets and lacks assessment of the effect of change in AO [2]. This study evaluated the independent effect of increasing, restoring, or decreasing the femoral, acetabular and global offsets on pain and function.

All patients undergoing primary THA between 2018 and 2020 in our institution (n=766) were retrospectively selected based on the following criteria: surgery for end-stage coxarthrosis, no other arthroplasty of the lower limb or spine, bi-plane X-rays (to assess offsets [5,6]) before and after surgery, and WOMAC pain and function scores before and one year after surgery. The change in offsets (dO) was classified in three groups based on the Smallest Detectable Changes (SDC) [4], assessed on a similar population (4.8mm, 6.3mm and 6.2mm respectively for the femoral, acetabular, and global offset) [5,6]: increased (I, dO > SDC), restored (R, -SDC < dO < SDC) and decreased (D, dO < SDC). Differences were assessed with Kruskall-Wallis tests or Chi2 test (p < 0.05).

A total of 166 patients were included (sex: 58% F, age: 68.3+/-11.4 years old, BMI: 26.8+/-5.0kg/m2). Group populations were as follows: FO (11D, 111R, 44I), AO (67D, 98R, 1I), GO (46D, 111R, 9I). No differences in terms of age, BMI or sex were found. The decreased FO group had more pain (median [interquartile range] WOMAC pain: 80 [45]) than the increased FO group (100 [10]), and lower function (WOMAC function: 75 [52]) than increased (95 [12]) and restored (93 [21]) FO groups. The decreased GO group had more pain (WOMAC pain: 90 [24]) than the restored group (100 [15]). No differences were found between AO groups.

These results support recommendations to avoid decreasing the femoral and global offsets for optimal function and pain scores one year post-surgery. No isolated effect of the acetabular offset was found.

[1] Ferguson, The Lancet, 2018
[2] DiGiovanni, EFORT Open Reviews, 2023
[3] Bullen, Journal of Arthroplasty, 2023
[4] de Vet, Cambrige University Press, 2011
[5,6] Gasparutto, Scientific Reports, 2023, 2022

Introduction: Cobalt-chromium (CoCr) wear and corrosion products from total hip arthroplasty (THA) have been linked to adverse local tissue reactions (ALTR). Widespread use of large diameter (>40 mm, LD), third-generation metal-on-metal (MoM) THA lead to awareness regarding this issue. However, second-generation, small-diameter (28/32 mm, SD) MoM THA performed well, with excellent long-term survival. This study aimed to characterize the wear behavior of SD MoM THA.
Methods: Thirty-nine cases with revised SD MoM THA were analyzed. Median (range) time in situ was 18.2 years (0.6-27.9). Inclination and anteversion angles were measured from pre-revision radiographs. Adverse events and demographic data were recorded. Bearing surfaces were measured with an optical coordinate-measuring-machine to quantify material loss.
Results: Median (range) inclination and radiographic anteversion angles were 44° (32 - 61) and 22° (0 - 47), respectively. Reasons for revision included ALTR, periprosthetic fracture, and malposition. Median (range) volumetric material loss of the heads and metal liners were 3.71 mm3 (0.17-82.32) and 11.72 mm3 (0.2 – 126.25), respectively, with a combined median bearing surface material loss of 15.75 mm3 (1.08-165.17). There was no correlation between total bearing wear and any patient demographics or cup orientation. Head wear volume had a trending correlation with patient age (p=0.076), which was significant (coef=-0.46, p=0.03) when controlled for time in situ (coef=0.59, p=0.17). Local tissue responses were mild to moderate, with marked particle-laden macrophages but little to no lymphocytic responses. Co and Cr ion whole blood ion levels were 2.1 ug/L (0.5, 73.5) and 2.2 ug/L (0.3, 29.10), respectively, significantly correlated only with the occurrence of secondary cup dislocation (p=0.016 and p=0.05) and showed a trend of a positive correlation with inclination angle (p=0.12 and p=0.068).
Conclusion: This relatively large cohort of SD MoM retrievals exhibited remarkably low wear, especially compared to later generations of LD MoM bearings. Wear was independent from time in situ and implant positioning indicating unknown factors, such as patient activity levels, probably had a large impact. The theoretical wear rate of 0.97 mm3/year was lower than predictions from simulators, and ~66% of bearings exhibited no wear beyond the running-in period.

Introduction
The hip abductors are one of, if not the most important muscle group of the hip. They play a relevant role in everyday activities, not least because they are essential for efficient ambulation. Weakness of the hip abductors leads to pain and limping. Treatment of a relevant weakness can be frustrating and surgical treatment in particular must be carefully considered. In order to understand abductor weakness in detail, it is important to know which muscles are involved and to what extent. The aim of this study was to investigate the effects of an experimentally induced weakness of the gluteal muscles on abduction power of the hip.

Methods
Ten healthy adults received a sequential nerve block of the supplying branch of the tensor fasciae latae (branch of the superior gluteal nerve), the gluteus maximus (inferior gluteal nerve) and the supplying branch of the gluteus medius and minimus (branch of the superior gluteal nerve). Subsequently, the maximal abduction force (Newton) was measured in the lateral decubitus position in three positions of the hip (30° flexion, neutral position, 30° extension in the hip joint).

Results
In 30° flexion average abduction force was 220 newton without block, 187 newton with block of the tensor fasciae latae, 97 newton with block of the gluteus maximus and 83 newton with block of the gluteus medius and minimus, respectively. In neutral position average abduction force was 213 newton without block, 200 newton with block of the tensor fasciae latae, 115 newton with block of the gluteus maximus and 82 newton with block of the gluteus medius and minimus, respectively. In 30° extension average abduction force was 116 newton without block, 146 newton with block of the tensor fasciae latae, 94 newton with block of the gluteus maximus and 61 newton with block of the gluteus medius and minimus, respectively.

Conclusion
An experimentally induced weakness of the tensor fasciae latae only reduces the abduction force by a maximum of 15% in all positions and is most involved when the hip is flexed. It is therefore overestimated as an abductor.
An experimentally induced weakness of the gluteus maximus reduces the abduction force in neutral position by 46%, in extension of the hip by 43% and in flexion by 56%. It is therefore not as important as the gluteus medius and minimus muscles, but is underestimated as an abductor.

Background: ETO offers excellent exposure of the femoral canal and the acetabulum in revision arthroplasty while being a true intermuscular and internervous approach. While initially described by Wagner with a split of the gluteus medius tendon (“transgluteal”) and later by Younger et al as an extension of a posterior approach, Lakstein et al described an approach similar to a surgical hip dislocation with preservation of the posterior soft tissues and an anterior dislocation of the hip. We have applied this technique routinely with reconstruction with a primary stem, which has not been described before. The aim of this study is to describe the technique, the safety and outcome of this approach in our series.
Patients and Methods: Patients undergoing total hip revision surgery between 01.01.2018 until 31.12.2021 at our clinic using an ETO and reconstruction with primary implants have been included. The decision to perform an ETO was taken prior to the operation. The ETO was performed without detaching the short external rotators or posterior capsule in all cases. The length of the ETO was 60-90mm distal of the vastus ridge (inominatum). Similar to a surgical hip dislocation, the anterior capsule was exposed and opened, followed by an anterior dislocation. Reconstruction was performed using a primary stem. The ETO fragment was fixed with 2 standard cerclages and a monocortical 8-plate or 2 trochanteric screws. All patients were invited for a clinical review (including PROMS) and x-ray.
Results: 19 patients (age 66+8; 39% male) have been included. ASA score was 2 in 11(61%) and 3 in 7 (39%) cases. No patients were lost to follow-up. 14 were available for clinical exam, 4 patients were interviewed by phone and 1 patient died of an unrelated cause, with the implant still in place. Average F-up was 30+7 months (range 20-40 months). No re-revisions were necessary with no evidence of radiological loosening. ETOs fully consolidated in all cases. At the latest f-up, all PROMs improved compared to the preoperative score: COMI from 7.3+1.3 to 1.3+1.7, OHS from 23+6 to 44+6 UCLA score from 3.1+0.8 to 6.3+1.4.
Summary/Conclusions: ETO with anterior joint dislocation and reconstruction with primary implants is safe in selected cases and may lead to good clinical results, while being cost effective, and avoiding the downsides of long revision stems or unnecessary stem modularity.

Introduction:
Early aseptic loosening is caused by deficient osteointegration of the femoral stem due to increased micromotions and represents a common mode of failure in uncemented total hip arthroplasty. This study hypothesized that a higher femoral offset, a smaller stem size and obesity increase femoral micromotion, potentially resulting in early aseptic loosening.

Methods:
A Finite-Element-Analysis was conducted based on computed tomography segmented model of four patients who received a total hip arthroplasty with a triple-tapered straight stem (size 1, 3, 6). The influence of femoral stem offset (short neck, standard, lateral), head length (S to XXL), femoral anteversion and obesity during daily activities of fast walking and stair climbing was analyzed. The micromotions for the femoral stem zones were compared to a threshold representing a value above which only partial osseointegration is expected.

Results:
The minimum femoral offset configuration compared to the maximum offset configuration (short neck stem, S head vs lateral stem, XXL head) leads to a relative mean micromotion increase of 24% for the upper stem zone. Increasing the body weight (BMI 30 to 35 kg/m2) increases the micromotion by 20% for all stem zones. The obese population recorded threshold-exceeding micromotions for stem sizes 1 and 3 for all offset configurations during stair climbing.

Conclusion:
Higher femoral offset, a smaller stem size, and higher loading due to obesity lead to an increase in micromotion between the prosthesis and proximal femur and represent a risk configuration for impaired osseointegration of a triple-tapered straight stem, especially when these three factors are present simultaneously.

Background: Identifying hip instability in symptomatic patients with borderline dysplasia of the hip (BDH) is of paramount importance as it can influence both surgical decision-making and surgical outcomes. The femoroepiphyseal acetabular (FEAR) index is strongly affected by the hip add-/abduction angle during pelvic radiograph, which until now has not been considered in the recommended threshold values.
Purpose: The aim of the present study was to report the optimal threshold of the corrected FEAR index in detecting hip instability in patients with BDH.
Methods: Patients with oligosymptomatic BDH treated conservatively (n = 25), patients treated with a periacetabular pelvic osteotomy (PAO) due to hip instability (n = 42) or hip arthroscopy due to symptomatic femoroacetabular impingement (FAI) (n = 50) with good patient-reported outcomes at the final follow-up were identified. The FEAR index was measured on the pelvic radiograph at the initial hip add-/abduction angle (uncorrected FEAR index) and 0° of hip add-/abduction angle (corrected FEAR index).
Results: The corrected FEAR index varied significantly from the uncorrected FEAR index in all groups with an average deference of 9 ± 9° in the oligosymptomatic BDH group, 6 ± 4° in the BDH group with instability, and 5 ± 5° in the BDH with FAI. The optimal threshold for the corrected FEAR index was - 13° (OR = 7.8 ; 95% CI = 2.6 to 23.1, p < .001), which yielded a sensitivity of 86% and specificity of 52% for detecting hip instability in the current cohort.
Conclusion: The corrected FEAR index might vary significantly from the uncorrected FEAR index, which is highly dependent on the hip add-/abduction angle during the pelvic radiograph. The optimal threshold of the corrected FEAR index to predict hip instability in a painful hip with a BDH was ≥ -13°.

Introduction: Highly cross-linked polyethylene (XLPE) is an important progress in total hip arthroplasty (THA), greatly reducing wear, compared to conventional polyethylene (CPE). Crosslinking is commonly achieved by irradiation. Irradiation dose and thermal treatment are the main material determinants of revision after THA identified so far. How the degree of crosslinking varies between products and how this impacts tribological behaviour is unclear so far. This study compares the degree of crosslinking and in vitro wear rates across a cohort of retrieved and unused polyethylene (PE) cups/liners from various manufacturers.
Methods: PE acetabular cups/liners were collected from one centre from April 2021 to April 2022. The trans-vinylene index (TVI) and the oxidation index (OI) were determined by Fourier-transformed infrared spectrometry. Wear was measured using a pin-on-disc test.
Results: 47 PE specimens from 8 manufacturers were included. The TVI was stable within each group and independent of time in situ. A linear correlation (r2=0.995) could be observed between the old and the current TVI standard, except for vitamin E infused PE. No excessive oxidation interfered. The absorbed irradiation dose calculated from the TVI corresponded to product specifications for all but two products. For one, an equivalent mean irradiation dose of 241% was observed, likely explained by higher crosslinking from electron, compared to gamma irradiation. For another XLPE, much lower than expected (mean 41% ± 13%) doses were measured than indicated by the manufacturer. Lower wear was observed for higher TVI. The one XLPE with unexpectedly low TVI showed wear more comparable to CPE. Despite adequate TVI, another vitamin E infused XLPE showed slightly higher in vitro wear than the other ones.
Conclusion: The TVI is a reliable measure of the absorbed dose of irradiation of PE and does not alter over time. Conversion from the old to the current standard is linear, except for vitamin E infused PE. Various brands differ by manufacturing details and consequently characteristics. Absorption and penetration of electron irradiation and gamma irradiation differ, potentially leading to different degrees of cross-linking. There is a non-linear, inverse correlation between TVI and in vitro wear. Irradiation doses calculated from the measured TVI deviated from specifications for one XLPE, which correlated with an inferior in vitro wear rate, comparable to CPE rather than the other XLPE.

Introduction: Needling of medial collateral ligament (MCL) complex for knee arthroscopy was introduced in 2006 to avoid cartilage damage and enhance posteromedial (PM) compartment visualization. Over two decades it gained acceptance. Although studies showed no remaining MCL instability on postoperative valgus stress radiographs at 20° of knee flexion, some case reports noted residual MCL microinstability, raising concerns about the true impact of needling on MCL complex integrity. This study aims to detail the anatomical lesion of the MCL complex from needling via surgical exploration through a PM approach used during meniscal repair.

Methods: Between January 2021 and December 2023, 50 patients underwent posterior horn suture of the medial meniscus using an outside-in approach with systematic needling. The "magic point" guided percutaneous release directly over the meniscal wall with a maximum of 10 perforations until an audible pop indicated release under valgus stress. A PM open approach allowed sutures placement under the sartorius fascia and systematic exploration of the superficial MCL and posterior oblique ligament (POL) for lesions.

Results: Macroscopic anatomical lesions were observed in 96% of patients (48/50), primarily complete transverse rupture of the POL (AP diameter: 1 to 1.5cm). Tears, 3-5mm above the meniscal wall and 1-1.5cm anterior to the tibial insertion of the semimembranosus, exhibited sharp edges amenable to direct suture repair. Tears consistently opened during intraoperative valgus stress in extension, rather than at 20° of flexion. They were found between an intact sartorius fascia and synovial membrane and no macroscopic lesion of the superior MCL was observed.

Conclusion: Contrary to common belief that MCL complex needling creates opening of the medial compartment by microlesions comparable to pie crusting, our study reveals macroscopic transverse tear of the POL. Literature may underestimate residual postoperative instability because studies were based on valgus stress knee radiographs at 20° of flexion, selectively testing the superficial and deep MCL rather than the POL. The lack of a validated method to objectively measure POL laxity calls these conclusions into question. Further studies are needed to establish the relationship between POL lesions and radiologic/clinical instability, to better understand whether these lesions heal spontaneously postoperatively and whether patient-related anatomic factors may impede this.

Introduction: Rupture of the anterior cruciate ligament (ACL) is an increasing problem in sportsmedicine and hamstring (HS) autograft is the most utilized ACL-R technique (53%). The isokinetic test has been identified as the gold standard for assessing muscle strength after ACL-R but does not distinguish between lateral and medial HS activation. Grafting the patient’s HS in ACL-R generates a medial HS muscle injury hence a non-physiologic HS activation pattern that the isokinetic test could not detect at RTS. This study aimed to evaluate ACL-Rs at RTS with concurrent isokinetic tests and surface electromyography (EMG) of the lateral Vs medial HS compared to a group of healthy controls.

Methods: Mean lateral Vs medial HS EMG amplitude and timing were measured during isokinetic tests at 60-180-300°/s in 92 subjects (46 primary HS grafted ACL-Rs Vs 46 healthy controls matched per age, sex, level of physical activity). The ACL-Rs’ EMG data were included only if they passed the minimum criteria to be cleared for RTS according to the published literature (HS/quad ratio > = 60% and quad & HS interlimb peak torque difference at 60-180-300°/s < = 10%).

Results: The isokinetic normalized peak torque resulted significantly lower for the ACL-R subjects in all the tested angular velocities. Mean sEMG amplitude for the lateral HS of ACL-R Vs control groups resulted significant at 180°/s (0.54 ±0.05 Vs 0.58 ±0.08, p=0.005), and 300°/s (0.53 ±0.06 Vs 0.56 ±0.06, p=0.01) whereas n.s. for the medial HS. The medial/lateral HS ratio in ACL-R Vs control groups emerged significant at 180°/s (1.00 ±0.10 Vs 0.95 ±0.13, p=0.01). Moreover, the EMG mean timing of the lateral HS of ACL-R Vs control groups was n.s. whereas, for the medial HS of ACL-R Vs control groups, it was 30 ±12 Vs 41 ±18 at 60°/s (p=0.006), 40 ±8 Vs 45± 9 at 180°/s (p=0.002), and 45 ±5 Vs 48 ±4 at 300°/s (p=0.02).

Conclusions: ACL-R subjects presented lower strength values than controls. The mean EMG amplitude of the medial HS showed no intergroup difference at any angular velocity but the EMG mean timing of the medial HS highlighted a consistent faster time-to-peak across all the tests in ACL-Rs. The simultaneous significantly lower mean EMG amplitude of the lateral HS at both 180-300°/s in the ACL-Rs proves an altered latero-medial HS muscular activation pattern at angular velocities closer to sports-specific tasks. This highlights a higher neuromuscular demand on the grafted medial HS in ACL-Rs at RTS.

Purpose: The aim of our study was to evaluate the clinical results, return to sport and complications after anterior cruciate ligament reconstruction associated with anterolateral tenodesis using continuous plasty with an iliotibial band.

Methods: This was a prospective multicenter study involving 186 patients who had surgery for ACL rupture. Patients with multiligament ruptures and revision surgery were excluded from the study. All patients included were involved in pivoting sports and wished to resume their activity after surgery. Patients were assessed at a minimum 2-year follow-up using functional and psychological questionnaires (subjective IKDC, Tegner, Lysholm and ACL- RSI scores), ligament assessment including instrumented laxity measurement (Rollimeter), Lachmann test and pivot shift, and isokinetic testing. Return to sport was assessed using a questionnaire, and complications and repeat surgeries were recorded.

Results: At a mean follow-up of 43.1 months, the subjective IKDC, Lysholm, ACL RSI and objective IKDC scores were significantly improved (59.8 vs. 94.5 p< 0.0001, 75 vs. 99 p< 0.0001, 60 vs. 93 p< 0.0001, IKDC A 0 vs. 72, B 12 vs. 27, C 60 vs. 1, D 28 vs. 0 p< 0.0001). The Tegner activity level was 8.1 (+/- 1.3) before the accident and 8.2 (+/- 1.2) at the last review. Seventy-six percent of the patients had returned to sports at the same level. The differential laxity was 6.6 mm (+/-1.7) preoperatively and 1.1 mm (+/- 1.4) postoperatively. Additionally, 97% were free of protrusion at the last recoil. At the 6-month isokinetic assessment, the muscle strength recovery for the quadriceps and hamstring was over 85% compared with the healthy side for 79% and 70% of the patients, respectively. Ten patients had graft rupture (5.6%). Four (2.4%) patients had a contralateral ACL rupture, and seven (4%) underwent a reoperation for meniscectomy.

Conclusion: ACL reconstruction with lateral tenodesis using a continuous strip of fascia lata enables 76% of patients in a population with a high demand for sports to resume their activities at the same level. The clinical results and complication rates, particularly reruptures (5.6%), were similar to those of other techniques involving anterolateral plasty.

Background
The ACL rupture leads to multidirectional instability. Ligamentoplasty is the preferred surgical
intervention to restore knee stability. Patients often experience apprehension affecting their return to
physical activities (Brophy, J. Arthrosc. R. Surg 2009). This is associated with a proprioceptive control
deficit, extending from mechanical and sensory deficits to higher sensory-motor brain circuits (Martini, BMC Sports Sci. 2022). The notion of perceived instability does not necessarily correlate with mechanical knee stability (Ferrell, J. Physiol. 1987).

Study Design & Methods
We enrolled a cohort of 10 patients who had undergone primary ACL ligamentoplasty and 5 control
participants. Patients with low (ACL-RSI > 70) and high (ACL-RSI < 50) apprehension scores were
compared (Webster, Phys. Ther. Sport 2007). Participants were prepared with a set of reflective
markers (Lebouef, Gait Posture 2019), a 64-channel mobile EEG headset and virtual reality headset.
Tasks involved participants walking on grass (stable) and cross a river over rocks (unstable) in three
different VR configurations. Beta and Theta waves in frontal-brain areas were measured together with
gait parameters. Non-parametric Wilcoxon test was used to compare the results amongst groups and
tasks, with statistical significance set at p < 0.05.

Results
Distinct cortical activation patterns with heightened theta wave intensities in virtual reality (VR) tests in both groups were observed. The low ACL-RSI group shown higher theta waves, mainly during
challenging conditions, and distinct peak in beta waves was also observed across all conditions. This
heightened theta wave activity in the low ACL-RSI group during harder tasks suggest added cognitive
processing in more unstable VR conditions. Note that theta waves play a role in movement preparation
and coordination across different brain regions (An, Biology 2022).

Conclusions
The EEG results show an elevation in frontal cortex theta power among certain postoperative patients, consistent with previous findings. Theta, Beta, and alpha
frequencies in EEG measurements serve as temporal regulators for neuronal activation, orchestrating
sensorimotor processing during specific tasks involving cortical structures (Baumeister, J. Orthop. Res. 2011). The frontal theta power observed in ACL group may indicate heightened and focused attention, reflecting increased neurocognitive engagement during unstable scenarios.

Introduction: Increased tibial slope is correlated with increased tibial translation and higher failure rates of ACL reconstruction. Cadaveric studies have shown that slope-reducing high tibial osteotomy (SR HTO) decreases ACL-graft forces and anterior tibial translation under axial load. However, the effect of SR HTO on ACL revision outcomes has not been comprehensively analyzed on the midterm. The purpose is to evaluate the midterm functional outcomes after slope-reducing osteotomy associated with revision ACL reconstruction.

Methods: 42 consecutive patients with ACL reconstruction failure and increased tibial slope (18.8±2.0 degrees) were included. Tibial slope was calculated from full length standing lateral views using the tibial mechanical axis. Revision was staged in two procedures in all cases: first surgery for SR HTO and tunnels bone grafting; second for ACL graft preimplantation. The amount of slope reduction was measured with a target of slope at 6 to 8 degrees. The SR HTO was performed by an anterior approach with a tibial tubercle osteotomy for access. It was guided by a 3D printed patient-specific cutting jig to avoid alteration of coronal plane alignment and fixed with staples.

Results: Patients were followed for 3.1±1.4 years. Age 25.6±6.7 years, sex ratio 1.6, BMI 25.1±6.7 Kg/m2. Adverse events occurred in 7.1%: secondary displacement (2/42), deep infection (1/42). At the time of follow-up: ACL-RSI 48.8±22.6, IKDC 60.1±14.9, no recurrence in ACL graft failure. No iatrogenic coronal plane alterations or no tibial slope over/under correction was observed on postoperative EOS long standing AP and lateral x-rays. Secondary knee hyperextension was not reported. Return to sport was observed in 71.4% (30/42) with half of these patients involved in level I sports according to the classification by Hefti et al.

Conclusion: In patients with ACL graft failure and increased tibial slope, anterior closing wedge high tibial osteotomy provides a safe and reliable technique to control ACL graft re-tear and offer good functional outcome on the midterm.

Purpose
To analyze sex-specific differences contributing to dynamic valgus in competitive soccer players before and after a standardized fatiguing protocol.

Methods
Thirty-nine healthy female and male competitive soccer players (19 females, 20 males) were recruited for the purpose of this study. Bilateral medial knee displacement (MKD) was assessed during drop jumps using a 3D motion capture system at rest and after a standardized fatiguing protocol. In addition, all soccer players underwent clinical examinations, including hip range of motion (ROM), isokinetic strength testing and MRI of the hip and knee. Sex-specific and fatigue-dependent differences were reported and the influence of demographic, clinical and radiographic factors on MKD was analyzed via multiple linear regression models.

Results
Compared with male soccer players, female soccer players demonstrated an increased MKD at rest (p = 0.09) and after the fatiguing protocol (p = 0.04). Sex-specific differences included increased hip internal rotation (IR) ROM, decreased hip external rotation (ER) strength and increased femoral torsion in females (all p < 0.002). In the multiple linear regression models (stepwise approach) increased hip IR ROM (90° of flexion) and the non-dominant leg remained the sole independent predictors for increased MKD at rest (p < 0.01 and p = 0.02 respectively), and after fatiguing (p < 0.01 and p < 0.01, respectively). An increase in hip IR ROM in females was linearly related to MKD after fatiguing (R2 = 0.25; p < 0.01).

Conclusion
Female soccer players exhibit greater dynamic valgus than males, at rest and after the fatiguing protocol, likely attributed to joint mobility, muscular and anatomical differences, such as increased hip IR ROM, reduced hip ER strength, and increased femoral torsion.
In particular, females with increased hip IR ROM are more susceptible to a fatigue -induced increase in MKD, which may increase their risks for ACL injuries. In addition to sex-specific differences, prevention efforts in competitive soccer players should prioritize the non-dominant leg.

Background: Patellofemoral instability is multifactorial. Different procedures exist to address the underlying causes. Recently, increased tibiofemoral (TF) rotation has been shown to contribute to patellar instability by further lateralizing the muscle force vector acting on the patellar. However, it is not yet known how to surgically address this parameter.
Hypothesis/Purpose: The aim of this study is therefore to assess the effect of tibial tubercle osteotomy (TTO) on TF rotation in patients with trochlear dysplasia (TD) in the setting of patellar instability.
Methods: 144 patients with patellar stabilizing surgery between January 2010 and December 2020 were retrospectively analysed. Pre- and postoperative TF rotation, TD, tibial tuberosity trochlear groove (TTTG) distance, tibial tubercle-to-posterior cruciate ligament (TT-PCL) distance, tibial tuberosity (TT-) torsion and Caton-Deschamps index (CDI) were assessed. Based on the performed patellofemoral stabilizing procedures, patients were stratified in 4 groups: 1: Isolated medial patella-femoral ligament (MPFL) reconstruction (n=51), 2: MPFL reconstruction and TTO (n=24), 3: MPFL reconstruction and trochleoplasty (n=37), 4: MPFL reconstruction, trochleoplasty, and TTO (n=32).
Results: Preoperative TF rotation differed significantly between groups (-0.2 ± 6.1° vs 3.1 ± 6.7° vs. 5.0 ± 5.6° vs. 9.6 ± 6.0°, p < 0.001). Groups 2 and 4 (with TTO) showed a reduction of TF rotation postoperatively, yet group 2 did not reach statistical significance (delta TF rotation: group 2: -1.3 ± 7°, p=0.370, group 4: -2.0 ± 3.5°, p=0.003). Group 1 and 3 showed no reduction of TF rotation. Patients with concomitant TTO (group 2 + 4; n=56 patients) had a significantly reduced postoperative TF rotation by a mean of 1.7 ± 5.3° compared to patients without TTO (0.3 ± 5°, group 1 + 3, n=88 patients) (p < 0.021). Reduction of TF rotation significantly correlated to the reduction of the TT-torsion but not medialization achieved by TTO (r=0.511, p < 0.001 and r=0.185, p=0.173, respectively).
Conclusion: TTO reduces TF rotation in patients with PF instability, which is directly correlated to the reduction of the TT-torsion. Hence, distal realignment of the extensor mechanism can not only decrease TTTG, unload the patellofemoral joint, but also reduce TF rotation in patients with patellar instability.

Introduction
The multifactorial nature of patellofemoral instability requires a comprehensive assessment of affected patients. While there is a known association between tibial tuberosity (TT) torsion and patellofemoral instability, its specific impact has not yet been investigated. This study aimed to investigate the impact of TT torsion on patellofemoral instability and comparing this relative new parameter to other commonly assessed patellofemoral instability measurements.
Methods
A retrospective cohort study was conducted, involving patients who had undergone surgical intervention for patellofemoral instability compared to asymptomatic controls. TT torsion was measured beside other commonly assessed risk factors for patellofemoral instability, including tibial tuberosity-trochlear groove distance, tibial tuberosity-rotational angle, tibiofemoral rotation, tibial tuberosity lateralization, femoral and tibial torsion, Caton-Deschamps index, and hip-knee-ankle angle. Measurements were performed using standardized computed tomography (CT) data of the lower extremity and whole leg radiographs. Diagnostic performance among assessed parameters was evaluated using receiver operating characteristic curve (ROC) analysis. Odds ratios (OR) were calculated.
Results
The patellofemoral instability group consisted of 79 knees compared to 72 knees in the asymptomatic control group. Both groups significantly differed in all assessed parameters (p < 0.001), except tibial torsion (p = 0.598). Among all parameters, TT torsion showed the best diagnostic performance for predicting patellar instability with an area under the curve of 0.95 (0.91-0.98, 95% CI, p < 0.001). A cut-off value of 17.7° yielded a sensitivity of 0.87 and a specificity of 0.89 to predict patellar instability (OR, 55.2, 95% CI, 20.5 - 148.6, p < 0.001)
Conclusion
TT torsion showed the highest predictive value for patellofemoral instability among the evaluated risk factors. Patients with a TT torsion of ≥ 17.7° showed a 55.2-fold increased probability to suffer from patellofemoral instability. Thus, TT torsion should be included in the assessment of patients with patellofemoral instability. This parameter could potentially serve as a basis for developing a novel surgical technique by a modified tibial tuberosity osteotomy, including not only anteromedialization, but also rotation of the tibial tuberosity.

Purpose: The aim of the herein presented study was to assess the mid-term effect of trochleoplasty on the PF cartilage integrity in patients with severe trochlear dysplasia treated for patellar instability.
Methods: Seventy-five patients with high-grade trochlear dysplasia (Dejour type B and C) who underwent patellar stabilizing surgery for patellar instability at a single institution were included. Of these, 42 patients had patellar stabilizing surgery without trochleoplasty (group I), while 33 patients received sulcus deepening trochleoplasty as part of their surgical treatment (group II). Pre- and postoperative magnetic resonance imaging (MRI) was retrospectively assessed to evaluate the PF cartilage from 0 (intact) – 4 (full-thickness lesion) separately scoring the medial, central, and lateral patella and trochlea, respectively. Associations between patient-specific characteristics, anatomical parameters and chondral integrity were also assessed.
Results: Patients underwent patellar stabilizing surgery at an average age of 23.2 +- 8.0 years with a BMI of 25.5 +- 5.0 kg/m2. Postoperative MRI was attained at an average of 35.2 +- 26.3 months (range, 6-118 months). Patients in group II were slightly older (21.8 +- 8.2 years vs. 25.0 +- 7.5 years, p = 0.032) and presented with a significantly higher TTTG distance (14.1 +- 3.4 mm vs. 18.4 +- 4.0 mm, p < 0.001) and patellar tilt (13.2 +- 6.7° vs. 26.4 +- 12.5°, p < 0.001) compared to group I. Both groups showed similar preoperative cartilage integrity in the PF joint (n.s.). Postoperatively, both groups had similar patellar chondral damage (n.s.) but group II showed significantly greater trochlear (all zones) cartilage damage (p < 0.001 (medial), p = 0.001 (central), p = 0.002 (lateral)). Compared to the preoperative state, 92.9-97.6% of patients in group I had an intact or unchanged status of the trochlear cartilage compared to 32.8-63.6% in group II, depending on the location (p < 0.001 (medial), p = 0.001 (central), p = 0.008 (lateral)). Among all PF parameters, only the postoperative sagittal TTTG was associated with the progression or new occurrence of chondral damage on the medial trochlea (r = 0.232, p = 0.045).
Conclusion: The integrity of the PF chondral layer remains unchanged in most patients treated for patellar instability in the setting of trochlear dysplasia. Yet, patients who underwent trochleoplasty showed significantly more often trochlear chondral status decline at mid-term follow-up.

Introduction
The aim of this study is to quantify the presence of recall bias in the evaluation of knee pain and function in knee osteoarthritis (OA) and to identify its determinants to prevent a biased symptom interpretation.
Methods
This prospective multicentric study enrolled 115 patients with knee OA who used a mobile App for their smartphone to collect punctual pain and function on two 0-10 numerical rating scales (NRS) 2 times a day for 2 months. At the 1-month and at the 2-month follow-up visits, patients were asked to retrospectively evaluate the mean level of pain and function of the last month on a 0-10 NRS. Recall bias was computed as the difference between the mean level of pain/function reported using the App and the level of pain/function reported with the retrospective assessment.
Results
Recall bias documenting an overestimation of symptoms with the retrospective assessment was documented for pain at the first (MD = -0.24; p = 0.04) and at the second (MD = -0.64; p < 0.001) month of follow-up. Recall bias affected also function assessment both at the first (MD = 0.96; p < 0.001) and at the second (MD = 0.80; p = 0.001) month of follow-up. A longer duration of symptoms, greater baseline symptoms in terms of both pain and function NRS, and symptoms worsening during the month before the evaluation were all significantly correlated with a higher recall bias.
Conclusion
The retrospective assessment of pain and function in knee OA, as commonly performed in the clinical practice and in research studies, is significantly affected by recall bias. Patients reporting worse outcomes are more prone to recall bias and part of their symptoms may be overestimated. Daily assessment of symptoms with a smartphone may improve patient management and research outcome assessment in knee OA.

Objectives
This study aimed to (1) assess rotational alignment parameters in a non-OA and an OA population, (2)
expand the functional knee phenotype system based on this assessment and (3) evaluate combinations of distal femoral, posterior femoral, and proximal tibial joint lines by using the extended version of the functional knee phenotype system. In addition, the impact of four alignment concepts on the orientation of these joint lines will be simulated in the most common phenotypes.
Materials and Methods
Rotational alignment parameters of 2692 OA and 265 non-OA knees were measured based on 3D
reconstructed CT data using validated planning software. The following rotational alignment
parameters: Posterior condylar angle (PCA) and anterior trochlear angle (ATA). Phenotypes represent
an alignment variation of either the posterior femoral joint line or the trochlea orientation. A specific mean defines each phenotype and covers a range of ± 1.5° from this mean. Mean values and
distribution among the phenotypes are reported.
Results
There were 21 and 28 flexion phenotypes (combinations of PCA and proximal tibia mechanical angle
(TMA)), 16 and 29 femur phenotypes (combinations of PCA and distal femoral mechanical angle
(FMA)) in the non-OA and OA populations, respectively. There were 24 combinations of PCA and ATA
in the non-OA population. PCA and TMA were orientated parallel in 35.5% and 30.3% of all non-OA
and OA patients, respectively. PCA and FMA were orientated parallel in 43.2% and 37.1% of all
non-OA and OA patients, respectively. In 14.3%, PCA and ATA were aligned parallel. FMA, TMA,
and PCA were aligned parallel in 17.0% and 11.2% of the non-OA population and OA population
respectively.
Conclusions
Preoperative assessment of a patient's anatomy should include the distal femoral and proximal tibia
joint lines and the anterior and posterior femoral joint lines. The extended functional knee
phenotype system was introduced.

Objectives
The present study focuses on testing the capability of a restricted tibia-first, gap-balanced
patient-specific alignment technique (PSA) to restore bony morphology and phenotypes.
Materials and Methods
367 patients were treated with navigated total knee arthroplasty (TKA) and tibia-first gap-balanced PSA
technique. The medial proximal tibial angle boundaries were 86-92°, mechanical lateral distal femoral
angle 86-92°, and hip-knee-ankle angle (HKA) 175-183°. Knees were classified by CPAK, with
subsequent analyses comparing pre- and postoperative distributions. Phenotype classification within
CPAK groups assessed pre- and postoperative distributions.
Results
Pre-operatively, the largest CPAK group was type II (30.8%), followed by I (20.4%) and V (17.8%).
Post-operatively, type II remained the largest group (39%) followed by type V (30%). All groups with
varus/valgus deformities (I, III, IV, and VI) became smaller. In straight legs (II, IV), the CPAK was
restored in more than 70-75%, in varus groups (I, IV) in 40-50%, and in valgus (III and VI) in 5-18%.
The joint line obliquity remained the same in the majority of knees (straight > 75%; varus 63-80%;
valgus VI 95%), except CPAK III (40%). The phenotype analysis showed for straight
legs a phenotype restoration of 85%, for varus 94%, and valgus 37%. JLCA was reduced
significantly in all groups from pre- (1,8 - 4,3°) to post-operatively (0,6 - 1,2°).
Conclusions
PSA restores bony phenotypes and joint line obliquity in the majority of straight and varus knees while
most of the valgus and extreme varus knees are normalized.

Introduction
Higher surgeon volume has been correlated with improved health outcomes following total knee arthroplasty (TKA). Due to the great variation in health care systems and demographic circumstances and the resulting heterogeneity of the existing studies and systematic reviews, it is difficult to draw conclusions for our national health system. This nationwide large cohort study therefore assesses the early revision rate (within two years from index procedure) following TKA for knee osteoarthritis (OA) and it’s relation to the surgeon’ case load (SCL) using data from the Swiss National Joint Registry (SIRIS).


Materials and Methods
The SIRIS Database was searched to identify all primary TKA procedures that were performed for the treatment of OA between 2015 and 2021. The SCL was defined as the annual volume of TKA procedures performed by a surgeon. Multiple logistic regression was employed to model the odds of revision surgery as a function of SCL. Two-year revision rates, the proportional reduction of the revision burden and the number of patients hypothetically needing treatment re-assignment to higher volume surgeons were simulated for increasing SCL thresholds.

Results
65.071 TKA procedures (41.127 male and 24.842 female patients) by 423 surgeons were included. The mean SCL was 23 (min/max: 1.6-130.4). During a follow up period of 2 years 2398 primary TKAs have been revised (3.82%). Between 12 and 25 SCL, the revision rate falls steadily; overall, the revision rate can be reduced by 6.5% with performing 25 or more interventions a year.


Discussion
The 2-year revision rate in Switzerland decreases with a higher SCL, although there no longer appears to be any relevant improvement above 25 interventions per year. However, the implementation of a minimal SCL to reduce the revision rate would mean the reassignment of many patients to a "high volume" orthopaedic surgeon.

Purpose:
Total knee arthroplasty (TKA) aims to restore physiological knee kinematics, but conventional techniques may lead to inaccuracies with potentially poorer outcomes. Robotic-assisted arthroplasty (RA-TKA), particularly using the ROSA knee system, is becoming increasingly popular as it may increase accuracy. This study evaluates and compares the clinical and radiographic outcomes between the ROSA system and conventional TKA (cTKA).

Methods:
This retrospective propensity score-matched cohort study compared primary RA-TKA and cTKA outcomes. Patients from our institutional TKA registry (surgery period RA-TKA: 2021-2022, cTKA: 2016-2020), operated by one senior orthopedic surgeon (> 200 TKAs/year), were matched based on age, sex, ASA class, and BMI. Implant positioning angles were assessed, and patient-reported outcomes were compared preoperatively, at 6 and 12 months postoperatively.

Results:
After matching 55 patients per group, similarities in demographics were found. For the RA-TKA group, surgery time was on average 13 minutes longer and blood loss was 15 ml higher. In contrast, cTKA patients have stayed on average 1.37 days longer in the clinic. Radiologically, there was low correlation between RA-TKA implant angles measured 6 weeks postoperatively and the preset ROSA system angles for mLDFA and MPTA, and no correlation was found for femoral flexion (FF) and tibial slope (TS). In the comparison of both groups, there was no significant difference with regard to mLDFA and FF. On the contrary, MPTA (mean: RA-TKA 1.78°, cTKA 1.19°, p=0.035) and TS (mean: RA-TKA 5.40°, cTKA 7.74°, p < 0.001) showed significant differences. Patient reported outcome measures showed a significant increase for all instruments already at 6 months after the surgery, which was maintained at 1 year. RA-TKA patients showed better OKS outcomes at 6 months follow-up compared to cTKA (mean difference 16.7% higher for female (p=0.02079) and 7.4% higher for males (p=0.1104)). No statistical difference could be observed for the COMI or UCLA score between the two patient groups.

Conclusion:
This study reveals comparable clinical and radiological outcomes between RA-TKA using the ROSA system and cTKA. The ROSA system demonstrated higher accuracy in the coronary plane than in the sagittal plane. While both methods showed similar results in the hands of a skilled surgeon, long-term studies are necessary to establish clear method superiority.

Introduction
In September 2018, we introduced an image-based robotic system for partial (PKA) and total knee (TKA) arthroplasty. Assessing the cost-benefit of such technology, minimizing revision surgeries is crucial. National joint registries lack specific data on individual technologies, as data is pooled. This study evaluates the impact of the MAKO system (Stryker, Mahwah, New Jersey, USA) on revision rates compared to the conventional technique.

Methods
Combined data from 2 senior surgeons of a specialized arthroplasty unit before (01/2015-08/2018) and after (09/2018-12/2022) implementation of the MAKO system were analysed for PKA and TKA cohorts. Revision rates were compared using Kaplan Meyer estimates with right-censoring events as recorded by the Swiss National Joint Registry (SIRIS) and Cox proportional hazard models with standard SIRIS risk adjustment (age, BMI, sex, Charnley restriction, ASA morbidity).

Results
At 5-year follow-up, MAKO PKA (n=309) had a significantly lower revision risk compared to conventional PKA (n=188) with 2.31% vs 8.71%; HR=0.31; p=0.011. No component malposition, instability, aseptic loosening or infection was noted in the MAKO PKA group and most common reason for revision was progression of disease (n=5, 71.4%).
MAKO TKA (n=355) showed a lower revision risk compared to conventional TKA (n=184) at 5 years, although not statistically significant with 4.73% vs 6.13%; HR 0.67; p=0.367. Periprosthetic infection (PJI) was the most common reason for revision for MAKO TKA (n=6, 50% of revisions) and relatively higher than conventional TKA (n=3, 27.3%)

Conclusion
Implementing an imaged-based robotic system reduced mid-term revision rates significantly in PKA. Progression of disease remained the primary reason for revision, emphasizing the importance of proper indication.
A higher incidence of PJI was observed in MAKO TKA, which might be attributable to the learning curve with initially prolongation of surgery and more personnel in the operating theatre. This topic was addressed by optimizing the workflow and additional application of local antibiotic powder as prophylaxis of PJI.

Purpose: To directly compare home-based vs traditional rehabilitation programs following TKA, in order to prove if an unsupervised approach leads to similar clinical and functional results as the usual rehabilitation standard-of-care.

Methods: A comprehensive literature search was performed on the Pubmed, Web of Science and Wiley Cochrane Library database up to January 08, 2024. RCTs describing addressing home-based vs inpatient rehabilitation following TKA. A systematic review and meta-analysis were performed on clinical and functional outcomes. Assessment of risk of bias and quality of evidence was performed with the “Cochrane Collaboration Risk of Bias tool”.

Results: Twenty-three studies including 3946 patients were included. The home protocol was used by 1986 patients, while 1960 patients underwent supervised rehabilitation. In the latter group, short-term showed significant improvement (p < 0.05) in terms of SF-36, OKS, and ROM downturn compared with baseline values, whereas with the home protocol these outcomes were not found. In contrast, in the long term, all outcomes analyzed showed statistically significant improvement over baseline values in both groups (p < 0.05).

Conclusions: This meta-analysis and systematic review did not demonstrate the non-inferiority of unsupervised rehabilitation compared with supervised rehabilitation post-TKA. However, it did find that supervised rehabilitation is associated with superior functional outcomes and faster quality-of-life recovery than unsupervised rehabilitation.

Introduction: The purpose of this study was to compare reoperation and revision rates of double plating (DP), single plating using a lateral locking plate (SP) or distal femur replacement (DFR) for the treatment of periprosthetic distal femur fractures (PDFF).

Methods: All patients with PDFF primarily treated with DP, SP or DFR between 2008 and 2022 at a university teaching hospital were included in this retrospective cohort study. The primary outcome was revision surgery for failure following DP, SP or DFR. Secondary outcome measures included any reoperation, length of hospital stay and mortality. All basic demographic and relevant implant and injury details were collected. Radiographic analysis included fracture classification and evaluation of metaphyseal and medial comminution.

Results: 111 PDFFs (111 patients, median age 82 years (IQR, 75-88 years), 86% female) with 32 (29%) Su 1, 37 (34%) Su 2 and 40 (37%) Su 3 fractures were included. The median follow-up was 2.5 years (IQR, 1.2 to 5.0 years). DP, SP and DFR were used in 15, 66 and 30 patients, respectively. Compared to SP, patients treated with DP were more likely to have metaphyseal comminution (47% vs. 14%, p=0.009), to be low fractures (47% vs. 11%, p=0.009), and to be anatomically reduced (100% vs 71%, p=0.030). Patients selected for DFR displayed comparable amounts of medial/metaphyseal comminution as those who underwent DP. At a minimum follow up of 2 years, revision surgery for failure was performed in 11 (9.9%) cases at a median of 5 months (IQR, 2-9 months): 0 DP patients (0%), 9 SP (14%) and 2 DFR (6.7%) (p=0.2).

Conclusion: Using a strategy of DP fixation in fractures where 1) the fracture was low but there was enough distal bone to accommodate locking screws, and 2) where there is metaphyseal comminution, resulted in equivalent survival free from revision or reoperation compared to DFR and SP fixation.

Introduction: Neuropathic pain (NP) is a significant concern for patients after total knee arthroplasty (TKA). Factors associated with NP in the literature include age, sex, BMI, education, working status, radiological osteoarthritis severity, symptom duration and presence of comorbidities. However, NP is still insufficiently understood. This study aimed to identify predictors of reduced risk for NP one year after TKA among patients who did not report NP before TKA.
Methods: We included primary TKAs performed between 01.01.2010 and 30.06.2022 (N = 2913). We defined NP as DN4 questionnaire scores ≥ 4 before TKA and at 1 year post-surgery. We selected patients without NP before surgery and ran a multiple logistic regression on the presence or absence of NP at 1 year post-surgery. We included predictive variables associated with patients’ characteristics (i.e., sex, age at surgery, BMI, smoking status, diabetes, medication, SF-12 physical and mental scores, self-rated health) and operative variables (i.e., implant constraint, tourniquet time, patella resurfacing, type of anesthesia, local infiltration analgesia (LIA), corticoids, tranexamic acid, drain).
Results: We found that higher age (p=.10), BMI < 35 (p=.12), higher SF-12 mcs scores (p=.01), and use of LIA (p=.005) were associated with lower risks of NP at 1 year post-surgery. Among patients with LIA NP was present in 6.5% compared to 12% among those without LIA (risk difference 5.5% (95%CI 1.0-10.1). Unadjusted OR was 0.51 (95%CI 0.30-0.87) and after adjustment it was 0.40 (95%CI 0.21-0.76). The reduction with LIA was observed under general as well as under spinal anesthesia.
Conclusions and perspective: Our study identified factors associated with a reduced risk of NP one year after TKA among patients without preoperative NP. Among those, higher age, BMI below 35, and higher SF-12 mental component scores were re-identified, whereas the use of LIA was newly identified as being significantly associated with a lower likelihood of NP post-surgery. These findings underscore the potential impact of incorporating LIA during surgery to reduce the occurrence of NP following TKA.

Introduction: Neuropathic pain (NP) is a significant concern for approximately 20% of patients undergoing total knee arthroplasty (TKA). Previous studies on NP following TKA were often limited by small sample sizes and short follow-up periods. This study aims to (1) assess NP prevalence before and at 1, 5, and 10 years post-TKA, (2) investigate impact of TKA surgery and follow-up time on NP, (3) describe specific NP characteristics before and one year after surgery, and (4) examine its influence on clinical outcomes.
Methods: We included primary TKAs performed between 01.01.2010 and 30.06.2022. NP was assessed with the DN4 questionnaire. The main outcomes included clinical parameters (patient satisfaction, WOMAC pain and function, general health). NP prevalence (DN4 score ≥ 4) was evaluated before TKA and at 1, 5, and 10 years post-surgery. We assessed the impact of TKA on NP prevalence using a McNemar test. Clinical outcomes of preoperatively NP-free patients were compared between those with and without NP 1 year after TKA.
Results: 2913 patients were included TKAs (1937 women, mean age 71 years). Prevalence of NP decreased from 19.9% before TKA to 11.2% at one year, 9.1% at five years, and 7.1% at ten years post-surgery. We identified four patient groups: 1) no NP before and after TKA (76%), 2) no NP before TKA but NP after TKA (6.4%), 3) NP before TKA but no NP after TKA (13.4%), and 4) NP before and after TKA (4.2%). A McNemar test indicated a significant reduction of NP after TKA. However, a significant proportion of patients without NP before TKA reported NP after TKA (6.4%, 95% CI 6.1% to 9.7%). These patients reported lower satisfaction and poorer clinical outcomes compared to those without NP after TKA one year post-TKA.
Conclusions and perspectives: Over a 10-year follow-up after TKA, there was a significant decrease in NP prevalence, demonstrating the positive impact of surgery on NP. Most patients with NP before TKA did not experience NP after surgery, highlighting the effectiveness of TKA. A small proportion without preoperative NP developed NP post-TKA. In these patients 1-year post-TKA, NP was associated with substantially poorer clinical outcomes and reduced satisfaction, emphasizing the need for early identification and management of new-onset NP after TKA.

Introduction: The Coronal Plane Alignment of the Knee (CPAK) has been introduced as a comprehensive classification of functional knee phenotypes underlining the variability of knee morphology in the context of the alignments debate in primary total knee arthroplasty (pTKA). The knee phenotype should impact patient’s overall movement. Thus, the goal of this study is to evaluate the impact of the CPAK type on the full-body kinematics during gait in patients with end-stage knee osteoarthritis before surgery.

Methods: This study included 55 patients with end-stage knee osteoarthritis, planned for pTKA (median [IQR], age: 71.0 [10.7] years, height: 162.0 [14.0] cm, BMI: 29.2 [7.9] kg/m2, WOMAC function 46.4 [25], WOMAC pain 45 [20], SF12 mental 44.8 [22.5], SF12 physical 34 [9]) and 33 asymptomatic controls (66 [10.5] years, 166.5 [13.8] cm, 24.2 [3.3] kg/m2). Patients performed full-body clinical gait analysis before their surgery and controls performed it once. CPAK types were assessed on long-leg axis X-rays before surgery as well as PROMs (WOMAC, SF12, pain during gait). CPAK types with less than 5 patients were excluded from the analysis. The differences between groups were evaluated with Kruskall-Wallis tests and post-hoc Wilcoxon tests (p < 0.05) for continuous variables and with Chi2-tests for quantitative variables

Results: The CPAK types I (n=5, 1F), II (n=14, 4F), III (n=7, 6F), IV (n=9, 7F), V (n=13, 10F) and VI (n=7, 7F) were analysed. The type IV was characterised by full-body compensations including increased inclination of the trunk, increased obliquity of the pelvis, and limited hip adduction and ankle flexion. These signs indicate compensations of the upper body and limping typical of antalgic gait. The other types were mostly characterised by knee kinematics consistent with their knee phenotypes, especially for the varus/valgus angles and consequent hip adduction/abduction angles. The type I and V presented higher a step length but no other differences were present in terms of spatio-temporal parameters. Finally, no differences between CPAK types were found in terms of PROMs.

Conclusion: Overall, type IV patients seemed to present the largest functional impairments during gait before surgery, with an impact at a full body level, while limitations of other groups seemed to remain at the knee. A larger population should help identifying functional and clinical differences as well as their post-surgery evolution per type.

Apprehension of the shoulder is a complex pathological process, not limited to peripheral mechanical problems. In fact, this process can be linked to peripheral or central neurological alterations. The latter aspect having been investigated 10 years ago in previous works, our team was able to demonstrate morphological alterations in white matter and changes in the activity of neuronal networks, such as primary sensory-motor areas, dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex/dorsomedial prefrontal cortex and anterior insula, 10 years after shoulder stabilization surgery. The aim of this study was to evaluate the evolution of these modifications 10 years after shoulder stabilization surgery.

Ten patients (average age 38.6±9.7 years) who had undergone shoulder stabilization and nine controls (average age 40.6±2.9 years) from the original study (Y0) took part in this ten-year follow-up prospective comparative study (Y10). We replicated the same experimental procedure, which included functional magnetic resonance imaging (fMRI) with videos designed to induce shoulder apprehension, structural MRI, and comprehensive clinical assessments.

In terms of task-related functional imaging, patients exhibited a complete reduction in apprehension-related brain activations at Y10 compared to Y0. Notably, there were no significant differences in the equivalent analysis of the control group, which eliminates the potential bias of re-testing or aging. In terms of functional connectivity, the differences observed in several brain networks at Y0 between patients and controls nearly completely normalized at Y10, except for a minor remaining difference in the insula/auditory network. There were no significant structural differences in brain grey matter or white matter observed between Y0 and Y10 in both patients and controls. Regarding clinical parameters, patients showed improvement at Y10 compared to Y0 across all scores.

In patients experiencing shoulder apprehension, brain activations associated with apprehension showed a near-complete normalization ten years after successful shoulder stabilization.

Résumé
Contexte : La stabilisation osseuse de l'épaule par la technique arthroscopique de Latarjet est connue depuis 2007.
Nous souhaitons évaluer de manière innovante et objective l'état postopératoire du patient en analysant l'épaule selon la méthode S-START, permettant de valider la reprise du sport après chirurgie stabilisatrice de l'épaule.
L'objectif principal de cette étude est d'évaluer la satisfaction des patients après la réalisation de ce test.
Méthodes : Nous avons réalisé une étude monocentrique rétrospective de 2018 à 2023 incluant tous les Latarjet arthroscopiques, réalisés par 1 chirurgien senior, selon 1 technique. Nous avons inclus 81 patients ayant bénéficié d'une arthroscopie et adressés à notre équipe de médecins du sport et de kinésithérapeutes pour une étude approfondie de leur épaule selon la méthode S-Start (Shoulder-SanTy Athletic Return To Sport). Le S-START combine une analyse de la composante psychologique, le rapport dominant/non-dominant de la force maximale IR, le rapport dominant/non-dominant de la force maximale RE, le rapport dominant/non-dominant USSPT (%) (Unilateral Seated Shot Put Test in Rehabilitation), le rapport RE/RI du côté opéré, le rapport dominant/non-dominant UQYBT (The Upper Quarter Y-Balance Test), l'analyse CKCUEST (Closed Kinetic Chain Upper Extremity Stability Test) et l'indice d'endurance aboutissant à un score total sur 100.
Résultats : Nous avons eu 100% de Latarjet arthroscopique, un âge moyen de 28,9 ans, 75% d'hommes, 45,8% de côté droit, 73% opérés du côté dominant.
En moyenne, nos patients se sentaient prêts psychologiquement à 71% à reprendre les sports à risque et avaient un score total de 66/100.
En ce qui concerne notre objectif principal, 92% de nos patients se sont sentis satisfaits du test, dont 94% qui le referaient, 90% qui en ont retiré un bénéfice et 88% qui l'ont trouvé adapté à leur situation.
Conclusions : Nous avons un score de satisfaction de 92% pour ce test qui fournit une indication fiable et objective permettant d'autoriser une reprise des sports à risque en toute sérénité. D'autres études sont nécessaires et nous souhaiterions réaliser une étude prospective pour évaluer les bénéfices des indications du S-start à court terme.

Background
Concern exists that the Latarjet procedure may negatively affect range of motion (ROM). We hypothesize that the Latarjet procedure results in full recuperation of ROM postoperatively and significantly improved patient reported outcome measures.
Methods
Patient data were prospectively collected in a database to analyze outcomes after open Latarjet procedure. Inclusion criteria involved a minimum follow-up of six months and unilateral shoulder instability. Study outcome was assessed by postoperative ROM at six months postoperatively and compared to the preoperative ROM of the ipsilateral shoulder as well as the ROM of the unaffected contralateral shoulder. All ROM measurements were performed utilizing a motion capture system to ensure consistent and reliable measurements. As a secondary outcome, the effect of sling on postoperative ROM was analyzed. Patient reported outcomes were also evaluated.
Results
The study included a total of 84 patients. ROM was measured in external rotation with the shoulder adducted (ER1), external rotation with the shoulder abducted 90 degrees (ER2), internal rotation with the arm abducted 90 degrees (IR2), and active forward elevation (AE). The average difference in ROM between the operated arm vs. the contralateral healthy arm at six months postoperatively was 3.4 degrees in ER1 (p=0.19), 4.2 degrees in ER2 (p=0.086), 2.2 degrees in IR2 (p=0.36), and 2.4 degrees in AE (p=0.045). Sub-analysis of patients with and without sling use revealed no significant difference in ROM between the operated shoulder and contralateral shoulder at six months in either group, with the exception of ER2 in the sling group. In this latter group, ROM was 71 degrees in the operated arm and 79 degrees in the contralateral arm (p=0.0094).

Conclusions
Latarjet procedure performed for anterior instability utilizing a capsular repair result in complete ROM recovery in ER1, ER2 and IR2 at six months postoperatively, with only a slight discrepancy in active elevation.

Introduction: The assessment of posterior humeral head subluxation (HSI) is important for preoperative planning of total shoulder arthroplasty. As 3D planning tools gain popularity, two 3D measurement techniques for posterior humeral head subluxation have been introduced: an offset-based type similar to the original 2D measurement, and a volumetric type using the volumes of the humeral head as divided by the plane of the scapula. The purpose of this study was to compare both 3D measurement techniques in a mathematical model and a clinical cohort.

Methods:
For the mathematical model, both offset-based and volumetric HSI were computed using a humeral head diameter of 50 mm. Offset-based HSI was calculated with 0.5 mm increments of posterior offset to the scapula in relation to the humeral head diameter. Volumes of the corresponding spherical caps were calculated for the same offset increments according to the mathematical formula. Volumetric HSI was calculated by putting the spherical cap volume in relation to the remaining volume of the corresponding sphere. Differences between both methods were plotted on a comparative graph.
In a clinical cohort of 55 patients with primary osteoarthritis, both offset-based and volumetric HSI were measured in 3D. Bland-Altman plots and paired t-tests were used for comparison.

Results:
Given the mean difference of 0.05% (p = 0.830), the clinical cohort validated the mathematical model. Volumetric HSI was greater for all values except for 0%, 50%, and 100% of posterior subluxation. The mean difference between both HSI techniques was 6% (p < 0.001), with a maximum difference of 9% between 73% and 84% offset-based HSI. A non-linear relationship was shown between the two.

Conclusion:
Offset-based HSI and volumetric HSI are inherently different measurements with a non-linear relationship. Therefore, the values of both measurements cannot be interchangeably used. The plotted differences of this study can be used as a correction table, allowing values to be compared within the literature. The geometrical differences between the two measurements explain the inherent differences: offset-based HSI corresponds to a cube in 3D, whereas volumetric HSI corresponds to a sphere. Because the sphere "cuts the corners" of the corresponding cube, the sphere cap at a given posterior offset will be smaller than the cube section at the same point, resulting in a larger posterior HSI unless the humeral head is centered or fully subluxated.

Background: The Latarjet procedure enables effective shoulder stabilization and rapid functional recovery of shoulder in most cases. However, the influence of the coracoid graft position at the glenoid on patient reported outcome measures (PROMs) remains uncertain.

Aim: This study aimed therefore to analyze the effect of graft position on 6-month PROMs after the Latarjet procedure.

Hypothesis: We hypothesized that, while lateralization and/or distalization of the graft at the glenoid would improve apprehension, it would also be a cause of pain and reduced function.

Methods: This was a prospective monocentric sturdy. All patients operated on with a Latarjet procedure and had available preop and 6-month postop CT scans were eligible. Patients with incomplete radiological data sets, poor image quality or lost to follow-up before 6 months were excluded. An experienced surgeon performed all procedures using a free-hand technique to place the graft at the glenoid. All patients underwent a standardized assessment before and at 6 months after surgery. Collected data included The ROWE score, Single Assessment Numeric Evaluation (SANE) for instability and Visual Analogue Scale (VAS) for pain. In addition, an independent observer performed a standardized 3D CT scan analysis with the Osirix software for preoperative bipolar glenoid bone loss (Sugaya H et al, JBJS Am 2003; Di Giacomo G et al, Arthroscopy 2014) and postoperative coracoid graft positioning separately in the axial and frontal planes (Kraus TM et al, KSSTA 2013)

Results: Of 108 Latarjet procedures between 04/2018 and 03/2021, 82 could finally be include (76%). The mean age at surgery was 28.0±9.0. Preoperatively, the mean glenoid bone loss was 14.4% and 79 patients (96%) had an Hill-Sachs lesion. Preoperatively, 25% cases were "off-track" vs. 6% at last follow-up. There was a postoperative improvement in the VAS for pain (27±21 vs. 13.8±17.2, p < 0.001), SANE score (41.8±21 vs 85.7±12.7, p < 0.001) and ROWE score (38.0±19.4 vs. 83.3±15.6, p < 0.001). Graft lateralization was associated with a lower postoperative ROWE score improvement and worse VAS for pain.

Conclusion : This study highlighted the importance of coracoid graft position after a Latarjet procedure. At 6 months, graft lateralization was associated with reduced function and increased pain.

Background: The popularity of team handball is increasing with over 10 million children playing this overhead, throwing and collision sport with highest demands on the shoulder joint. Due to the risk for recurrent instability, the Latarjet-Patte (LP) procedure has been recommended to treat young competitive players. This is the first LP outcome study in professional handball.
Methods: We included 20 shoulders retrospectively (18 players/17 males/mean age 22.9 years, range 17-35 years; minimum/mean follow-up: 2/6.6 years) operated on by three expert surgeons (2011-2020) with Walch’s LP-technique. Preoperative hyperlaxity (25%/n=5), affected throwing arm (55%/n=11), position (backcourt, winger, goalkeeper: 22% each; full back, pivot: 17% each), >2 dislocations prior (20%/n=4), >10 dislocations (5%/n=1), previous failed Bankart/HAGL repair (10%/n=2) and large Hill-Sachs lesions (HSL: 20%/n=4) were documented. Clinical and radiographic outcomes, visual analogue scale (VAS), subjective shoulder value (SSV), Walch-Duplay (WDS), Rowe score (RS) and return to sports (RTS) parameter were recorded.
Results: RTS was 85% (n=17/20), RTS to same-level 80% (n=16/20), RTS with no throwing pain 73% (n=8/11), time to training with ball: 3.2/12 and to competition 4.9/12. The mean RS, WDS and SSV were 90, 88, 89 % respectively. Shoulder symptoms lead to giving up handball in 2 cases (10%). One player (5%) stopped for other reasons. One recurrent dislocation (5%) was recorded (non-throwing arm, winger, no recurrence after rehabilitation). Persistent apprehension occurred in one goalkeeper (5%). Four shoulders showed residual pain (20%) relieved in one by screw removal. Resistant pain (throwing shoulder) was seen in 2 backcourt players (10%/one large HSL) and one goal keeper (5%/large HSL; >10 dislocations prior), all three >30years of age. Bone block positioning was correct (no lateral overhang) in all shoulders. One shoulder (5%) showed mild arthritic changes at final follow up (>10 dislocations, large HSL).
Conclusion: The open Latarjet-Patte is consistent in providing shoulder stability combined with return to throwing performance in professional handball players with a short time to RTS and high same-level RTS rate without increasing the risk of arthritic changes. Throwing shoulders of backcourt players, with large HSL or shoulders at age >30 years may have an increased risk for persistent symptoms.

Background : The success of anterior shoulder stabilization with the Latarjet procedure depends on the correct positioning of the coracoid graft at the glenoid. However, its ideal 3D position remains a source of debate.

Aim : This study aimed to analyze the effect of graft position on 6-month range of motion (ROM) after the Latarjet procedure.

Hypothesis : We hypothesized that ROM would gradually decline with increasing lateralization and/or distalization of the graft at the glenoid.

Methods : This was a prospective monocentric sturdy. All patients operated on with a Latarjet procedure and had available preop and 6-month postop CT scans were eligible. Patients with incomplete data sets, poor image quality or lost to follow-up before 6 months were excluded. An experienced surgeon performed all procedures using a free-hand technique to place the graft at the glenoid. All patients underwent a standardized assessment before and at 6 months after surgery. An independent observer collected active ROM with a motion-capture system (Vicon, Oxford Metrics, Oxford, UK). Another independent observer performed a standardized 3D CT scan analysis for preoperative bipolar glenoid bone loss (Sugaya H et al, JBJS Am 2003; Di Giacomo G et al, Arthroscopy 2014) and postoperative coracoid graft position separately in the axial and frontal planes (Kraus TM et al, KSSTA 2013)

Results : Of 108 Latarjet procedures between 04/2018 and 03/2021, 82 could finally be include (76%). The mean age at surgery was 28.0±9.0. Preoperatively, the mean glenoid bone loss was 14.4% and 79 patients (96%) had an Hill-Sachs lesion. Preoperatively, 25% cases were "off-track" vs 6% at last follow-up. Anterior elevation (AE) improved from 170° to 175° (p < 0.001) and external rotation (ER1) improved from 48° to 54° (p < 0.003). Graft overhang was associated with decreased AE (beta, -8.2°, p = 0.034). Graft distalization was correlated with a greater postoperative improvement in ER1 (beta, 0.3°, p = 0.028) .

Conclusion: This study highlighted the importance of coracoid graft position after a Latarjet procedure. At 6 months, graft overhang was associated with decreased AE (beta, -8.2°, p=0.034) and graft distalization was correlated with a greater postoperative improvement in ER1.

Introduction:
The most commonly reported complication after AC joint stabilization is loss of reduction. One possible cause is tunnel positioning. The aim of this study was to investigate the association between coracoclavicular (CC), coracoidal tunnel position and LOR.

Methods:
We included male patients (aged 18-55 years) with an acute, high-grade ACJ dislocation (Rockwood type V), who were treated arthroscopically-assisted with a Low-Profile TightRope combined with a percutaneous acromioclavicular cerclage.
Panorama views were used to measure the CC tunnel angle (CCAP) and offset angle (CCTA) as well as the mediolateral coracoidal tunnel position (from medial, in absolute and relative terms regarding coracoid diameter) at the 6 weeks-follow-up.
We analyzed these factors in relation to LOR (difference in side-comparative CC distance at the 6-weeks-FU and the final FU of at least 2 years). A p-value of less than 0.05 was considered statistically significant. Statistical analysis included Pearson’s correlation coefficients and the Mann-Whitney-U-test.

Results:
Twenty-five patients with a mean age of 37.8 years (range, 23 years to 54 years) at a mean FU of 25.8 months (range, 24 months – 36 months) were included.
The mean LOR was 3.5mm (95% confidence interval, CI: 2.5mm – 4.5mm). No significant correlation were found with CTAP (mean 2.4°, 95% CI: 1.8° – 3.1°) (r = -0.137; p = 0.513), but there was a trend towards correlation with the CCTA (mean: 11.8°, 95% CI: 7.0° – 16.6°) (r = -0.347; p = 0.090).
The LOR was not associated with coracoid diameter (22.5mm, 95% CI: 21.4mm – 23.7mm) (r = -0.256, p = 0.216), or the absolute mediolateral coracoidal tunnel position (r = 0.226; p = 0.277; mean: 12.6mm, 95% CI: 11.6mm – 13.6mm). However, there was a positive correlation with the relative mediolateral coracoidal tunnel position (r = 0.41; p = 0.03) (mean: 0.56, 95% CI: 0.52 – 0.60). Specifically, LOR was higher in cases with a relative tunnel position of > =0.61 (5.1mm, 95% CI: 2.9mm – 7.2mm vs. 2.6mm, 95% CI: 1.7mm – 3.5mm; p = 0.014).

Conclusion:
After bidirectional, arthroscopically-assisted ACJ stabilization, a laterally positioned coracoid tunnel was associated with more LOR, while overreduction according to the CCTA trended towards an association with less LOR.
Considering these aspects appears to improve the postoperative healing result in the longer term.

Background: Posterior labral tears, glenoid retroversion and posterior glenoid bone loss are clinically and biomechanically proven factors that decrease resistance to humeral head translation in response to a posteriorly directed force. However, failure rates of conservative and surgical treatment are high. A high and flat acromion, implying less posterior humeral head coverage, has been shown to be associated with posterior instability. It was the purpose of this study to evaluate the stabilizing effect of the acromion to posterior humeral head translation.
Methods: Eight fresh-frozen cadaver shoulders were biomechanically tested in a shoulder simulator in the load-and-shift and the Jerk test position. Prior to testing, CT scans were performed on all shoulders to measure native glenoid width, glenoid retroversion, posterior acromial coverage (PAC), sagittal acromial tilt (SAT) and posterior acromial height (PAH). Each of the specimens underwent six testing conditions using 3D printed cutting and reduction guides: (1) Intact joint, native acromion (2) Intact joint, severe acromial pathology (SAT 69°, PAC 47°, PAH 26mm) (3) Scenario 2 + posterior acromial bone block (PABB) (4) Intact joint, medium acromial pathology (SAT 59°, PAC 57°, PAH 20mm) (5) Scenario 4 + PABB and (6) Intact joint, corrected acromial alignment (SAT 48°, PAC 70°, PAH 11mm). The degree of acromial malalignment and acromial reorientation was chosen based on a previous study that defined acromial anatomy in patients with posterior instability. The humeral head was translated posteriorly until either (1) a peak force of 150N or (2) a maximum posterior translation of 50% of the glenoid width were reached. Forces (N) and translations (mm) were recorded. Testing was repeated three times per condition and mean values were used for analysis.
Results: Mean native glenoid width was 25.4mm (21-31mm), glenoid retroversion was 3.1° (1.3-5.8°), SAT was 58.6° (41.1-72.6°), PAC was 63.6° (54.4-77.6°), PAH was 18.9mm (8.5-24.5mm). Realigning the acromion or adding a PABB significantly increased stability compared with the medium and severe pathology in all tests (p < 0.05). There were no significant differences between the native shoulder and the medium pathology.
Conclusions: The acromion acts as a restraint to posterior humeral head translation. Correction of acromial malalignment or addition of a PABB can effectively restore glenohumeral stability.

Introduction:
The etiology of posterior shoulder instability (p.s.i.) is unknown. Recent 2- and 3-D studies documented consistent abnormalities in position and orientation of the acromion and the glenoid. Biomechanical studies suggest that correction of the specific deformities may correct p.s.i.. It was the purpose of the present, preliminary study to test the hypothesis that isolated correction of scapular anatomy could correct p.s.i..
Methods:
Nine consecutive cases with p.s.i. refractory to conservative and in in 6 cases operative treatment were entered. A CT of the affected shoulder was segmented and compared with a statistical mean shape model of a normal shoulder. Corrective osteotomies of the acromion and of the glenoid were 3-D planned and personalized cutting and reduction jigs manufactured to allow restoration of normal anatomy. After informed consent all patients were operated and followed up for a minimum of 24 months.
Results:
At 24 months there was one clinical failure with pain and progressive static posterior subluxation. Repeat CT showed that anatomic correction had not been achieved in this case. All patients were dynamically stable. The median SSV had increased from 30 to 80%, the median Constant Score from 54 to 81%, the median pain score from 6 to 13 points. Subjective shoulder state was excellent in 6, good in 1, fair and 1 and poor in 1 case (Preop assessment 0/0/3/6).Static subluxation was better in 4, same in 4 and worse in 1 case.
Discussion:
Acromial position and orientation have never been considered as a cause of p.s.i., but their consistent abnormal position and form in p.s.i. have been established in former investigations. Biomechnical studies support that the pathological anatomy of glenoid and particularly the acromion are (co-) responsible for p.s.i. This preliminary report documents that restoration of scapular anatomy to normal corrects dynamic p.s.i in 8 of 8 patients up to two years and isolates static p.s.i in one. In a case where the correction was unsuccessful, static subluxation increased. At this time, the precision of the realization of the procedure needs further improvement. The results, however, already support the hypothesis that p.s.i. may be successfully treated with restoration of normal scapular anatomy using the SCOPE (scapular corrective osteotomies for posterior escape) procedure and that this approach might open a new pathway for prevention or correction of static and dynamic p.s.i.

Partial rotator cuff tears (PTRCTs) are a common cause of shoulder pain. While PTRCTs are preferably managed conservatively, conversion to a surgical approach may be indicated. It is unclear, which technique provides best outcome for different tear locations. Our objective was to investigate the epidemiology of partial rotator cuff tears and applied arthroscopic surgical repair techniques and to compare outcomes of different PTRCTs based on tear location.

From June 2020, a cohort of 973 arthroscopic rotator cuff repair (ARCR) patients was prospectively enrolled at 19 centers and was followed up for 24 months. Patients with a PTRCT underwent surgery using the technique applied on each study site. Tear location and surgical technique were documented intraoperatively. Functional outcome (Constant Murley Score [CMS], pain level, range of motion [ROM], strength) was assessed at baseline and 12-months follow-up. Structural outcome was assessed using ultrasound after 12 months. The variability of tear patterns and applied treatment between sites were described. For PTRCT involving the supraspinatus (SSP) tendon functional and radiographic outcomes were compared between tear locations (articular-side vs bursa-side vs interstitial).

The ARCR cohort included 147 (15.7%) partial tears, thereof 128 (87%) involved the SSP tendon with 69 (54%) articular-sided, 35 (27%) bursa-sided, and 24 (19%) interstitial tears. SSP PTRCTs were repaired in 122 patients, using single row (45%), double row (19%) or transosseous-equivalent (36%) techniques. ROM at 12-month follow-up significantly differed for flexion (164°, 150°, 156°; p=0.007), abduction (160°, 145°, 154°, p=0.044) and internal rotation (53°, 33°,27°; p < 0.001) in favour of articular-sided tears when compared to bursa-sided and interstitial tears, respectively. CMS, pain level and strength did not significantly differ between groups. Ultrasound revealed no repair failure in the articular-side group and 2 repair failures each in the bursa-side (7%) and interstitial (11%) groups (p=0.054).

PTRCT account for a non-negligible number of ARCRs. No common surgical approach exists, resulting in a variety of applied techniques. While all within-tendon tear locations showed similar improvement in functional outcomes, pain and strength at 12-month follow-up, ROM for flexion, abduction and internal rotation recovered better in patients with articular-sided tears when compared to bursa-sided and interstitial tears.

Prediction models for outcomes after orthopedic surgery provide patients with evidence-based postoperative outcome expectations. The objective of this study was to update and validate a clinical prediction model for the improvement of shoulder function, using the 6-month Oxford Shoulder Score (OSS), for patients undergoing an arthroscopic rotator cuff repair (ARCR) in Switzerland.

Methods

Between June 2020 and November 2021, included 973 primary ARCR patients were prospectively enrolled in the ARCR_Pred study across 18 Swiss and one German orthopedic center and were followed up for 24 months postoperatively. Available patient-reported Oxford Shoulder Score (OSS) data were used at 6-month (N = 910). An already developed 7-factor model (ASA Classification, symptom duration, baseline level of depression and anxiety, baseline OSS, operation duration, tear severity, and biceps status and treatment) was externally validated on the ARCR_Pred data. Models were compared in terms of R-squared and root-mean-squared-error (RMSE). The same set of 32 prognostic factors identified through a systematic review and completed by an expert opinion were used for model update. Final updated model was identified using a backward elimination procedure minimizing the Akaike’s Information Criterion (AIC).

Results

After recalibration on the ARCR_Pred data, the apparent model performance was R-squared = 20.7% and RMSE = 6.77. The final updated model had a better apparent R-squared = 24% and a RMSE = 6.62 and included the following parameters: age, smoking status, pre-operative medication, pre-operative steroid infiltrations, length of symptoms duration, baseline level of anxiety, baseline OSS, performance of an acromioclavicular joint resection and performance of a capsulotomy.

Conclusion

Performance of a similar model development procedure on an independent dataset highlighted the importance of the following selected variables in the prediction of the OSS at 6-month: symptoms duration, baseline level of anxiety, baseline OSS. We also highlighted the improvement in our model performance using our nationwide multicenter cohort study, the ARCR_Pred data.

Introduction
A prospective multicenter study (ARCR_Pred) was implemented to document the effectiveness of arthroscopic rotator cuff repair (ARCR) in a representative Swiss patient cohort. The purpose of this analysis was to investigate the diagnostic value of the lift-off test for subscapularis (SSC) tendon rupture with consideration of intraoperative findings as reference standard.

Methods
Between June 2020 and November 2021, a cohort of 973 primary ARCR patients was prospectively enrolled at 18 Swiss orthopedic centers and one German center. Prior to shoulder arthroscopy, patients were evaluated with the lift-off test when possible to assess for SSC tendon tears. The intraoperative finding of SSC lesions was used as the reference standard to investigate the test characteristics of the lift-off test. Patient characteristics and concomitant pathologies influencing the ability to implement the test, as well as test sensitivity were explored.

Results
Among the 973 patients enrolled, 679 (69.8%) were able to perform a lift-off test at baseline. Of these,154 (22.7%) tested positive. Intraoperatively, SSC tendon tears were diagnosed in 309 (45.5%) patients, with 68.6% classified as complete tears and 31.4 % as partial tears. The lift-off test demonstrated a sensitivity of 64% (95% CI 56% to 71%) and specificity of 77% (74% to 81%) for detecting any type of SSC tendon injury. Notably, a positive correlation was observed between lift-off test sensitivity and the severity of the subscapularis tear. For full-thickness tears (Lafosse II-V), sensitivity and specificity were calculated at 45.6% (38.8% to 52.5%) and 74.5% (64.3% to 82.7%), respectively. The positive and negative predictive values were 45.6% (38.8% to 52.5%) and 37.4% (30.6% to 44.8%), respectively. Despite of SSC lesions, a tear of the supraspinatus tendon and a rupture of the biceps pulley or the long head of the biceps (LHB) were associated with a positive result of the lift-off test (p < 0.05). Several factors like age, body mass index (BMI), trauma or pain level decreased the clinical feasibility of the lift-off test due to limitation of active internal rotation.

Conclusion
Our analysis confirms prior research, indicating the lift-off test's limited sensitivity in detecting SSC tendon tears. Sensitivity increased slightly when considering full-thickness SSC tears only. The implementation of the lift-off test is affected by age, BMI, trauma and pathologies to the supraspinatus tendon and the LHB.

Studien zeigen, dass die Erfahrung der Chirurgen und hohe chirurgische Fallzahlen bei orthopädischen Eingriffen mit den klinischen Ergebnissen korrelieren. Diese Studie untersucht, ob chirurgische Erfahrung oder hohe Fallzahlen mit besseren klinischen Ergebnissen nach arthroskopischer Rotatorenmanschettenrekonstruktionen (ARCR) assoziiert sind.
Primäre ARCR bei 973 Patienten aus 19 orthopädischen Kliniken wurden prospektiv über 24 Monate beobachtet. Nebst klinischem Assessment, sonographischer Integrität und Patientenevaluation nach 12 Monaten wurden der Subjective Shoulder Value, Constant Score, Oxford Shoulder Score und die Lebensqualität (European Quality of Life 5 Dimensions 5 Level questionnaire, EQL5D5L) erfasst. Multiple Regressionsmodelle (adjust. n. Alter, Rupturausmaß, Nebenerkrankungen) wurden erstellt, um die Vorhersagemöglichkeit der klinischen Entwicklung anhand der jährlichen ARCR-Fallzahlen zu testen. Zudem wurde ein multivariates, logistisches Regressionsmodel konzipiert, um zu prüfen ob chirurgische Fallzahlen Komplikationen (Adverse Events (AE)) vorhersagen können. Mittels Clusteranalyse mit Gruppierung der Patienten anhand der chirurgischen Erfahrung (orthopädische bzw. schulterchirurgische Erfahrung; hierarchische Position) wurde der Zusammenhang mit den klinischen Ergebnissen untersucht.
ARCR-Fallzahlen waren ein starker Prädiktor für verbesserte klinische Ergebnisse nach ARCR: In der multivariaten, linearen Regressionsanalyse waren die Fallzahlen unabhängig mit der Lebensqualität (EQL5D5L) (β = 0.02, 95% CI: 0.0098, 0.0347,p < 0.001), Constant Score (β = 2.68,95% CI: 1.57,3.79,p < 0.001), Schulter Funktion (β = 1.10, 95% CI: 0.48, 1.72, p < 0.001) und Schmerz assoziiert (β = -0.35, 95% CI: -0.54,(-0.17), p < 0.001). Im Gruppenvergleich zeigte sich ein Trend für bessere klinische Ergebnisse ab 50 Operationen/Jahr. Fallzahlen waren kein Prädiktor für weniger AE (OR 1.36, 95% CI: -0.25, 0.92;p= 0.29). Die Cluster Analyse ließ 3 Patientengruppen (operiert von: Kaderarzt mit langjähriger und schulter-spezifischer Erfahrung oder intermediärer Erfahrung oder Oberarzt mit eingeschränkter Spezialisierung) erkennen, ohne sign. Unterschiede bzgl. aller klinischen Parameter oder AEs (p > 0.05).
Höhere ARCR-Fallzahlen können ein besseres klinisches Ergebnis prognostizieren. Gleichzeitig scheinen die Jahre an orthopädischer. bzw. schulterchirurgischer Praxis keine direkte Assoziation zu den untersuchten klinischen Parametern oder AEs aufzuweisen.

Purpose: To compare the clinical and functional outcomes of arthroscopic rotator cuff repair over a period of 2 years using three postoperative rehabilitation modalities: aquatic therapy, land-based therapy, and self-rehabilitation therapy. The null hypothesis was that aquatic therapy would provide no difference in Constant score compared to land-based therapy and self-rehabilitation therapy.

Methods: A prospective study was performed on subjects scheduled for arthroscopic rotator cuff repair between 2012 and 2017 that complied with the following criteria: (i) small to medium sized symptomatic supraspinatus and/ or infraspinatus tendon tears, (ii) low to moderate tendon retraction according to Patte, and (iii) fatty infiltration stage ≤2 according to Goutallier. Patients were allocated to perform either aquatic therapy, land-based therapy, or self-rehabilitation therapy for 2-4 months. Independent observers blinded to the study design collected Constant score, SSV, and patient satisfaction at 2 months, 3 months, 6 months, 1 year and 2 years.

Study design: Level III, cohort study

Results: At 2 months follow-up, patients performing aquatic therapy had significantly higher Constant scores (p < 0.001) and SSV (p < 0.001) compared to those performing land-based therapy or self-rehabilitation therapy. At 3 months follow-up, patients performing aquatic therapy kept significantly higher Constant scores (p < 0.001), and SSV (p < 0.001), both of which exceeded the respective minimal clinically important differences (MCIDs) of 10.4 and 12.
Patients performing aquatic therapy continued to have higher Constant scores and SSV at 6 months, 1 year, and 2 years, although the difference in Constant scores were less marked between the 3 groups.

Conclusion: Aquatic therapy has a positive effect on clinical outcomes until 6 months after surgery, but yields little improvements on function or satisfaction at 1 to 2 years follow-up.

Introduction
Stress shielding has received increased attention in research, with higher filling ratios and female gender identified as risk factors. The aim of this study was to investigate the effect of the remaining rotator cuff tendons (RCT) and soft tissue tensioning on stress shielding in uncemented RTSA.

Methods
A prospectively collected database of patients undergoing RTSA between 2017 and 2021 was reviewed. Excluded were patients with tumors, fractures, cemented RTSA, and incomplete radiographic data at 2-year follow-up. Demographic variables included age and gender. Radiographic variables included stress shielding, bone quality (deltoid tuberosity index [DTI]), metaphyseal and distal filling ratios (mFR and dFR), lateralization angle (LSA), and distalization angle (DSA). The number of intact RCT was determined based on available imaging and intraoperative evaluation. The effect of the assessed variables on stress shielding was analyzed with regression analyses. Optimal thresholds were calculated using recursive partitioning.

Results
In 77 consecutive patients (mean age 72 years), RTSA resulted in a mean absolute CS (aCS) of 71 points and a mean relative CS of 98% at 2-year follow-up. The presence of stress shielding, seen in 32 cases (aCS: 70 points), did not affect functional outcome compared to those without stress shielding (aCS: 72 points; p = 0.39). Linear regression analyses identified female gender (p = 0.041), higher dFR (p < 0.001), < 3 intact RCT (p = 0.006), and lower DSA (p = 0.044) as independent risk factors for stress shielding. Age, DTI and LSA had no influence. Cut-off values to prevent stress shielding were > 55° for DSA and < 0.79 for dFR, reducing stress shielding by a factor of 15 when both are met.

Conclusion
In addition to known risk factors such as higher filling ratios and gender, < 3 intact RCT and lower DSA were found to be independent risk factors for stress shielding. This suggests that an intact rotator cuff and an optimal soft tissue tensioning through distalization reduces bone resorption, possibly due to a better tensile load transfer from soft tissue to bone. Lower filling ratios, ideally < 0.79, remain the most important factor. However, additional distalization with a DSA > 55° substantially reduces stress shielding at 2 years, with a 15-fold decrease in occurrence when both thresholds are met.

Introduction: The risk of recurrent defect after arthroscopic rotator cuff repair (ARCR) differs over postoperative time and depends on the severity of the initial tear. Data assessing the most reliable imaging modality for the routine evaluation of tendon integrity after rotator cuff repair is limited. The objective of this study was to identify the accuracy of ultrasound (US) in the routine postoperative evaluation of repaired rotator cuff tendons.

Methods: Between June 2020 and July 2022, we prospectively recruited 310 patients undergoing ARCR from the ARCR_Pred cohort in 9 Swiss orthopaedic centers. All patients underwent routine magnetic resonance imaging (MRI) und US 1 year post-ARCR. Tendon integrity was classified according to Sugaya et al for MRI and a three-staged classification system (intact, partial, complete tear) for US. MRI readings were performed by two independent assessors (orthopaedic surgeon and radiologist). MRI assessments were then regrouped to intact (Sugaya I, II), partial (Sugaya III) and complete retears (Sugaya IV, V). Interobserver reliability for MRI readings was assessed by the Kappa statistics (k). Sensitivity, specificity and accuracy of US imaging to identify recurrent defects were assessed with regards to MRI as reference standard.

Results: Values of k for interobserver reliability of MRI readings were 0.65 for partial and 0.73 for full-thickness tendon defects. While 26 (8%) partial and 54 (17%) full-thickness defects were detected by MRI, 38 (12%) partial and 10 (3%) full-thickness defects were detected by US. Both imaging modalities showed that the number of recurrent defects increased with an increasing tear severity. US had 13.0% (95% CI 9.2% to 16.7%) sensitivity for full repair defects and 26.3% (21.4% to 31.2%) for partial repair defects, when MRI was taken as the reference. The specificity was 98.8% (97.6% to 100%) for full and 88.3% (84.7% to 91.8%) for partial repair defects.

Conclusion: When MRI is considered the reference standard, US has an overall high specificity but poor sensitivity to detect repair failures in routine postoperative imaging one year post-ARCR. The routine use of US imaging after ARCR in asymptomatic patients should therefore be critically scrutinised.

Abstract
Purpose: The purpose of this study was to quantify sleep quality and define its evolution in patients treated for rotator cuff tears with arthroscopic rotator cuff repair (ARCR). Moreover, sleep quality was correlated with patients’ psychological characteristics in terms of depression and anxiety.
Methods: Nine-hundred-and-seventy-three patients (611 men) were enrolled in a prospective multicenter cohort study (ARCR_Pred). Subjective sleep quality (prevalence and level of disturbance), psychological characteristics (PROMIS Sf questionnaire) and functional outcomes were investigated before the operation and prospectively at 6 and 12 months of follow-up. A gender-based analysis was performed as well.
Results: A high prevalence of sleep disturbances was found before ARCR (88.4%), with 59% of the patients complaining of disturbance every night. Sleep disturbances progressively improved at 6 months (37.2%) and 12 months (22.0%). Also, nocturnal pain (frequency of night disturbed by pain) progressively improved from a prevalence of 94.3% to 62.4%, and then 37.9%. Anxiety and depression were found to be related to worse sleep quality and nocturnal pain. On the other hand, the post-op improvement led to a decrease of anxiety and depression levels passing from 50.1 and 51.4 points at baseline to 45.0 and 45.4 at 12 months, respectively. Women had statistically worse sleep quality at 6 and 12 months when compared to men, with a 27% disturbance prevalence compared to the 19% retrieved in the men at 12 months.
Conclusions: Rotator cuff tears cause a high prevalence of sleep disturbance and nocturnal pain, which progressively resolves after an arthroscopic tendon repair. Women have a higher risk than men to develop these problems, and clinicians should take this into account when planning the rehabilitation program for their patients.

Background:
The severity of fatty infiltration (FI) predicts the treatment outcome of rotator cuff tears. The purpose of this investigation was to quantitatively analyze supraspinatus (SSP) muscle FI and volume at the initial presentation and after a 3-month minimum of conservative management. We hypothesized that progression of FI could be predicted with initial tear size, FI, and muscle volume.
Methods:
Seventy-nine shoulders with rotator cuff tears were prospectively enrolled, and 2 magnetic resonance imaging (MRI) scans with 6-point Dixon sequences were acquired. The fat fraction within the SSP muscle was measured on 3 sagittal slices, and the arithmetic mean was calculated (FISSP). Advanced FISSP was defined as ≥8%, pathological FISSP was defined as ≥13.5%, and relevant progression was defined as a ≥4.5% increase in FISSP. Furthermore, muscle volume, tear location, size, and Goutallier grade were evaluated.
Results:
57 shoulders (72.1%) had normal FISSP, 13 (16.5%) had advanced FISSP, and 9 (11.4%) had pathological FISSP at the initial MRI scan. 11 shoulders (13.9%) showed a ≥ 4.5% increase in FISSP at 19.5±14.7 months, and 17 shoulders (21.5%) showed a ≥ 5mm3 loss of volume at 17.8±15.3 months. 5 tears (7.1%) with initially normal or advanced FISSP turned pathological. These tears, compared with tears that were not pathological, had significantly higher initial mediolateral tear size (24.8 vs. 14.3 mm; p=0.05), less volume (23.5 vs. 34.2 mm3; p=0.024), more FISSP (9.6% vs. 5.6%; p=0.026), and increased progression of FISSP (8.6% vs. 0.5%; p < 0.001). An initial mediolateral tear size of ≥20 mm yielded a relevant FISSP progression rate of 81.8% (odds ratio [OR], 19.0; p < 0.001). Progression rates of 72.7% were found for both initial FISSP of ≥9.9% (OR, 17.5; p < 0.001) and an initial anteroposterior tear size of ≥ 17 mm (OR, 8.0; p = 0.003). The correlation between FISSP progression and the time between MRI scans was weak positive (ρ = 0.31).
Conclusions:
Three risk factors for relevant FI progression, quantifiable on the initial MRI, were identified: ≥ 20mm mediolateral tear size, ≥ 9.9% FISSP, and ≥17-mm anteroposterior tear size. These thresholds were associated with a higher risk of tear progression: 19 times higher for ≥ 20mm mediolateral tear size, 17.5 times higher for ≥ 9.9% FISSP, and 8 times higher for ≥ 17mm anteroposterior tear size. The presence of all 3 yielded a 91% chance of ≥ 4.5% progression of FISSP within a mean of 19.5 months.

Introduction:
Comprehensive standardized recording of adverse events (AE) is essential for personalized decision-making in arthroscopic rotator cuff repair (ARCR). Relevant events were defined in a "core event set" (CES). The objectives of this study were to 1) describe the AE risks observed in a large Swiss multicenter ARCR cohort, 2) evaluate patient-reported events and 3) investigate variability between clinics.

Methods:
Between 06/2020 and 11/2021, 973 primary ARCR patients were prospectively enrolled at 19 orthopedic centers and followed up for 24 months. Events local to the operated shoulder were reported by patients, surgeons and other project staff. They were documented using a structured CES and classified by severity in 5 grades from I (low severity) to V (dead). All events were reviewed by three experienced shoulder surgeons. Patients and surgeons independently re-assessed AE severity on a VAS scale (0-100). Complication risks (CR) were calculated stratified by rotator cuff tear severity. The distributions of severity ratings were compared between patients and surgeons. CRs across clinics were explored.

Results:
A total of 356 local AEs were documented in 322 patients within 2 years after ARCR, of which 45% and 37% were reported by all project staff and patients only, respectively. The CR for postoperative local adverse events (plAE) were 22.4%, 28.6% and 31.7% at 6, 12 and 24 months, respectively, with 92% of patients experiencing only one event. Patients with partial tears, single full-thickness tears, multiple tears with one full-thickness tear, and massive tears had 39.5%, 33.7%, 31.5% and 27.8% CR within 2 years, respectively. The most incident AEs were persisting or worsening pain (CR 11.7%), symptomatic shoulder stiffness (8.0%) and symptomatic recurrent rotator cuff defects (4.9%). Severity classification of plAEs revealed 61% grade I, 25% grade II, 13% grade III, 1% grade IV. Median severity assessment on VAS by patients, operating surgeons and non-operating surgeons were 60, 22 and 31, respectively (p < 0.001). The CRs of plAE ranged from 15.4% to 44.8% across clinics.

Conclusion:
About one third of ARCR patients experienced a local event, the majority showing low severity as classified by surgeons; patients however rated their events more severely than surgeons. Large variability of AE occurrence across clinics was observed. Clinic, surgeon and patient profiles associated with AE occurrence should be further explored.

Establishing minimal important change (MIC) thresholds is crucial in orthopedics for interpreting patient-reported outcome measure (PROM) data. Various methods have emerged to determine MIC, each with its own advantages and drawbacks. However, MIC values for PROM to assess patients undergoing arthroscopic rotator cuff repair (ARCR) in Switzerland remain unclear. This study aims to compare MIC values using three different methods for the Oxford Shoulder Score (OSS) among ARCR patients in Switzerland.

Methods

Between June 2020 and November 2021, 973 primary ARCR patients were prospectively enrolled in a multicenter cohort across 18 Swiss and one German orthopedic center. OSS data were collected at 6- (N = 910), 12- (N = 873), and 24-month (N = 854) follow-ups. We used a 5-item Likert anchor question to assess subjective shoulder function. We assessed the ceiling effect of OSS, the proportion of minimally improved patients, and the present state bias (PSB). Three methods (receiver operating characteristics-based, predictive modeling, adjusted predictive modeling) were compared to establish MIC values.
Results
The proportion of minimally improved patients was 86%, 93%, and 94% at 6-, 12-, and 24-month follow-up. Ceiling effect occurred in 9%, 30%, and 42% at the respective timepoints. PSB was 0.56, 0.65, and 0.75. MIC values ranged from 5 to 8 points at 6-month follow-up, increasing to 10-14 points at 12- and 24-month follow-ups.

Conclusions

Our study highlighted that nearly all patients with available data at follow-up experienced a minimal improvement after an ARCR in Switzerland. We found that an OSS improvement of between 10 and 14 points at the 12- and 24-month follow-up was sufficient to categorize patients as being minimally improved in the Swiss population, a high threshold in comparison to other reported values in the literature. The large proportion of minimally improved patients, ceiling effects, and PSBs in our setting suggest that our MIC estimates may be overestimated. Alternative analytical approaches addressing these issues should be considered.

Introduction
Patient reported outcomes (PROs) are typically used as summary scores without considering individual items.
This study aims to evaluate and compare the influence of WOMAC Pain and Function summary scores as well as individual items on patient satisfaction one year after total hip (THA) and knee arthroplasty (TKA).

Methods
All patients who underwent primary elective THA or TKA at a tertiary hospital between 01.01.2012 and 30.06.2022 were included. Main outcomes were patient satisfaction (5-point Likert scale) and the short-form WOMAC questionnaire (12-item scale) one year after surgery. Ordinal logistic regression models were used for the analysis.

Results
1772 THAs (55.4% women, mean age 68.8) and 1323 TKAs (63.7% women, mean age 70.9) were included. In both populations, both WOMAC summary scores and all items were associated individually with patient satisfaction. However, WOMAC Pain showed a greater impact than WOMAC Function (THA t-values: 12.89 and 3.61; TKA t-values: 12.43 and 2.04 respectively). Moreover, some items showed stronger associations than others. Two pain items in both populations – “walking on flat” and “going up/down stairs” – stood out showing the strongest associations. Three function items, different for each population – “ascending stairs”, “walking on flat”, “putting on socks” for THA and “rising from sitting”, “walking on flat”, “getting in/out of car” for TKA – stood out with the strongest associations.

Conclusion
With regard to patient satisfaction, the results support the validity and sensitivity to context of the WOMAC scales. Overall, both summary scores were strongly associated with satisfaction, but pain during activities had more influence on satisfaction than functional abilities. The 12 WOMAC items varied in their associations with overall satisfaction. For pain-specific items, between-item differences were the same after THA and TKA, but for function-specific items patterns varied between THA and TKA, reflecting the strain that each activity imposes upon each joint. Overall, considering two pain items and three function items might be sufficient in some settings as their association with patient satisfaction was similar to the WOMAC summary scores.

Introduction: In vitro joint simulators are commonly used to assess joints in native, injured, and reconstructed conditions. Robotic platforms now appear as the new gold standard to explore all degrees of freedom of a joint in a reliable and accurate manner. They allow for controlling joints in force or displacement and have been applied to hip, knee, spine, and shoulder joint assessment. Current approaches are most frequently dedicated to study of a unique isolated joint, mainly oriented towards an accurate force control, and requesting precise alignment of anatomical and robotic axes. The purpose of this study is to present a versatile robotic testing platform allowing advanced biomechanical analyses of multiple joints while inducing physiological motions and/or forces.

Methods: The platform is composed of a robotic manipulator equipped with a six-axis universal force-moment sensor, a Tripteron-type parallel robot driven by linear actuators, an optical motion capture system, and bespoke bone holders. A calibration process allows the robotic platform and motion capture system to share the same coordinate system. Requested joint motions can be defined 1) by reproducing operator-induced joint testing or 2) by generating trajectories around anatomical axes. Requested joint contact forces can be defined in the distal or proximal bone coordinate systems. Bespoke bone holders allow for positioning anatomical pieces without requiring precise alignment between anatomical and robotic/sensor axes.

Results: The robotic platform demonstrated a reliability of 0.28 ± 0.57 mm and 0.15 ± 0.25°, and fidelity of 0.27 ± 0.56 mm and 0.22 ± 0.28° to produce requested joint motions. It has been applied to shoulder and wrist joints with current research and development in hip joint biomechanics. In particular, the platform has already allowed to identify optimal acromioclavicular joint reconstruction surgical steps and construct design on joint alignment and kinematics. To date, both isolated joint and whole cadaver conditions have been tested, with or without removing soft tissues, demonstrating the high versatility of the platform.

Conclusion & perspectives: By allowing the reproduction of physiological joint motions and contact forces in a reliable way, the robotic platform open new avenues in the exploration of joints in native, injured, reconstructed, and replaced conditions. This platform will now be used to compare and validate surgical procedures and medical devices.

Background - The administrative burden in healthcare is a major contributor to physician burnout, deteriorating patient care and increasing costs. Recently, large language models like ChatGPT-4 have emerged.Large language models like ChatGPT-4 have emerged. They hold the potential of reducing the administrative burden by optimizing the generating everyday creation of clinical documents, and thus allowing the physician to spend more time with the patient. We aimed to assess both the quality and efficiency of discharge documents generated by ChatGPT-4 in comparison with those produced by physicians.

Methods – To emulate real-world situations, the health records of 6 fictional orthopedic cases were created. Discharge documents for each case were generated by a junior attending orthopedic surgeon and an advanced orthopedic resident. Then ChatGPT-4 was prompted to generate the discharge documents using the same health record information. The quality assessment was performed by an expert panel (n = 15) blinded to the source of the documents. As secondary outcome, the time required to generate the documents was compared logging the duration in the creation of the discharge documents by the physician and by ChatGPT-4.

Results – After exclusion, the panel conducted a total of 126 evaluations. 6 were discarded. Of the documents produced by ChatGPT-4, most (38 assessments) were deemed suitable for clinical use. Some required corrections (21 assessments), while a small number (2 assessments) were deemed unsuitable for clinical use. In contrast, human-generated notes were evaluated 32 times as suitable for clinical use, received 25 indications for corrections, and were considered unsuitable for clinical use on 2 occasions. There were 4 instances of hallucinations in GPT-4-crafted content, in contrast to 6 in human generated documents. ChatGPT-4 generated discharge documents 10 times faster than the traditional manual method.

Conclusion – ChatGPT-4 creates orthopedic discharge notes faster than doctors, with comparable quality. This shows it has great potential for making these documents more efficiently in orthopedic care. Although further evaluation using a larger sample size and real patient data is essential, ChatGPT-4 has the potential to significantly reduce the administrative burden on healthcare professionals.

Introduction:
In osteoarthritis (OA), articular cartilage follows progressive degeneration, where low-grade inflammation plays a pivotal role via exposure to reactive oxygen species (ROS). In chondrocytes, the only cells in cartilage, NADPH oxidase 4 (NOX4) is a major producer of ROS, significantly impacting regulation of catabolism. Our prior study showed that NOX4 deletion reduces cartilage degradation and regulates the anabolism/catabolism balance. As IL-1β is a key cytokine involved in OA, we hypothesize that NOX4 may influence the IL-1β secretion pathway through the NLRP3 inflammasome. This study evaluates the mechanisms of NOX4-induced OA in mice.

Methods:
OA was induced in vivo by destabilization of the medial meniscus (DMM) in WT and NOX4-/- mice. After 8 weeks, mice were sacrificed for immuno-histo-chimistry (IHC) analysis. Femoral heads from 9/10-week-old mice were cultured for 72 hours with PBS or IL-1β to induce OA ex vivo. Primary chondrocytes (PC) extracted from 4/6-day-old pups femoral heads and knees were cultured for 24 hours with PBS or IL-1β to induce OA in vitro. IL-6, IL-18, and MMP3 were quantified in ex vivo and in vitro supernatants by ELISA. Sulfated glycosaminoglycans (sGAG) concentration was assessed in supernatants by colorimetric dosage. Genes expressions of PC were quantified by RTqPCR.

Results:
IHC revealed stronger IL-1β and NLRP3 expression after DMM surgery in WT compared to NOX4-/- mice. In PC supernatant, we observed an IL-18 increase post IL-1β in WT but not in NOX4-/-.
In WT, RTqPCR showed a decreased anabolism genes transcription (AGG, COL2, SOX9) and NOX4 and increased catabolism and inflammation genes transcription (MMP3, MMP13, ADAMTS4, ADAMTS5, and IL-1, IL-6, TNF, COX2) post IL-1β.
In ex vivo supernatants, we observed increased IL-6 and sGAG concentration post IL-1β. In vitro, we observed increased MMP3, IL6, and decreased sGAG concentration in supernatants post IL-1β.
In NOX4-/- compared to WT, post IL1-β, we observed lower ADAMTS4/5 and IL1-β transcription, higher COX2 and IL6 transcription, but no IL6 concentration increase in supernatant. In the PC supernatants, we found a lower sGAG concentration.

Conclusion:
We demonstrate that NOX4 deletion inhibits NLRP3 inflammasome activation and IL-18 secretion. We showed that NOX4 deficiency inhibits ADAMTS gene expression. These results underline that NOX4 could aggravate OA by activating ADAMTS enzymes via the NLRP3/IL-18 pathway.

Introduction:
The effects of THA/TKA can be calculated as treatment effects (proportional symptom reduction). TE= symptom reduction/baseline symptoms; 1= complete reduction, 0= unchanged, >0= increased symptoms. We wanted to analyse the effects of THA/TKA in a registry with clinical assessment and compare them with trial results.
Methods:
All patients with THA/TKA in Kt. Zurich and complete data in SIRIS registry were included. Since 07/2019 all patients with THA/TKA had to fill out a Euro-QoL 5D questionnaire (assessing mobility/self-care/usual activities/pain-discomfort/anxiety-depression). The Euro-QoL score was calculated according to a defined algorithm before and 1 year after surgery. The treatment effect was calculated for each THA/TKA.
Results:
From July 2019 to December 2023, 5121 THA patients with a mean age of 68.8 years, 54% women, and 4375 TKA patients with a mean age of 70 years, 58.2% women, could be included. The effects varied from 1 to -1 for THA and from 1 to -1 for TKA. For THA, 4793 (93.6%) patients had an improvement, 236 remained unchanged (4.6%) and 92 had more symptoms (1.8%). For TKA, 3684 patients (84.2%) had an improvement, 503 remained unchanged (11.5%) and 188 had more symptoms (4.3%).
The published study results for THR were 91% improvement (KSA) and 85.4% improvement in EUROHIP. The results for TKA were 81% improvement (KSA) and 85.8% (Dresden registry).
Conclusion:
The effects of THA/TKA can be measured and demonstrate the variability of individual results. The results of THA in the canton of Zurich are comparable to those in studies and show that THA is a "winning operation". The results of TKA in the Canton Zurich are also comparable or even slightly better than in studies. Further analysis of the treatment processes may reveal important confounding factors.

Introduction:
Pain localization is important information for diagnosis in orthopedic/spine patients. It can be assessed through questions about neck-arm pain, back-leg pain, or pain-drawing (which can be difficult to evaluate). A new method was used to assess pain using a mannequin with a grid of 105 localizations on the body surface, which were then evaluated as a sum. This study presents a description of the method, grid, and results of an observational analysis. The correlation between pain localizations and symptom scores is examined.
Methods:
The study included all patients with spinal/orthopedic pathologies and mixed conditions. Patients marked their pain localizations on a semi-oblique mannequin (front and back). The body surface was divided into palm-sized elements or clearly defined locations (total of 105 elements). The questionnaires were analyzed digitally. The symptom score (0 to 100) was calculated as the sum of intensities of five symptoms: difficulties getting up, pain during daily activities, night pain, muscle weakness/instability, and sensory disturbances/cramps. The analysis and statistics were conducted at ETH Zurich. The study analyzed men and women separately due to slightly higher symptom scores in women. The correlation between the number of pain localizations and symptom score was analyzed using the Spearman correlation coefficient (rho).
Results:
The study included 4236 assessments from October 2016 to May 2023, with 2340 women (55.2%). The mean pain localizations were 5.25 for women (4.84 men), with a median of 3 pain localizations for both genders. The mean symptom score was 36.29 for women (32.56 for men). The correlation between pain localizations and symptom scores was high (rho=0.59 for women, 0.66 for men).
Conclusion:
Pain localizations can be easily assessed and analyzed using a pain drawing mannequin and grid in routine practice. Women tend to have more pain localizations and a higher symptom score. There is a strong linear relationship between pain localizations and symptom score. The combination of pain localizations and symptoms has great potential for diagnosis (It is important to note that this is only a first impression and further evaluation is necessary. < =3 pain localizations and score < 40 for osteoarthritis, > 5 pain localizations and score > 50 for neuropathy)

Introduction
Since the introduction of computer assisted surgery (CAS) in total knee arthroplasty there has always been critique about increased cost. 4 years ago, we published a cost analysis of four different computer assisted technologies to implant a total knee arthroplasty in comparison to conventional instrumentation and the use of image-based robotics has shown additional costs of 2600 CHF / case. Since then the method has become the new gold standard for TKA in our unit.

Methods
All the additional costs for image-based robotic compared to conventional TKA were re-evaluated for calculation. Some were deriving from the new contract with the company in 2023, some were collected in the OR and compared to the costs in 2018. Costs for OR time were set to 15 USD per minute, an additional tray to 210 USD, a CT scan to 420 USD as in 2018. Since 2018 we changed to cementless fixation in 95% of the TKA cases which reduced OR time by 15 minutes in mean (-225 USD) and such equalized OR time of a conventional TKA.

Results
Additional costs for one tray with specific instruments (+160 USD), additional OR time of 14 min for computer navigation, calibration, registration, adjusting the preset surgical plan (+210 USD). The cost for the preoperative CT scan decreased to 300 USD (-120 USD or minus 28%).
The costs for disposables were 600 USD in 2018 and increased to 766 USD in 2023 (+166 USD). Due to the new contract the costs for the technology itself (leasing contract, costs for the technician) could be reduced from 1210 USD in 2018 to 770 USD in 2023 (-440 USD or minus 36%).
By switching from cemented TKA in 2018 to mainly cementless in 2023 OR time could be reduced by 15 min (-225 USD) equalizing mean OR time for a conventional TKA.
Additional costs for image-based robotic TKA could be reduced from in mean 2180 USD in 2018 to 1681 USD in 2023 (minus 22%) in the OR itself or from totally 2600 USD in 2018 to 1981 USD (minus 23%) in average when including costs for the preoperative CT scan.

Conclusion
Total additional costs for image-based robotic TKA could be reduced by 23% in 5 years’ time due to negotiation after doubling the cases and increasing efficiency in OR by declaring the technology to the new gold standard and converting to mainly cementless fixation although costs for disposables increased by 28% during the same period.

Minimally invasive surgical techniques, including endoscopic and robotic procedures, continue to revolutionize patient care, for their ability to minimize surgical trauma, thus promoting faster recovery and reduced hospital stays. Yet, the suturing of soft tissues ensuring damage-free tissue bonding dur-ing these procedures remains challenging due to missing haptics and the fulcrum effect. Laser tissue soldering has potential in overcoming these issues, offering damage-free seamless tissue fusion. To en-sure the precision and safety of laser tissue soldering, we introduce feedback controlled fluorescent nanothermometry-guided laser tissue soldering using nanoparticle-protein solders within endoscopic and robotic contexts. Temperature-sensitive fluorescent nanoparticles embedded in the solder provide surgeons with immediate feedback on tissue temperatures during laser application, all while within the confines of minimally invasive surgical setups. By integrating fluorescent nanothermometry-guided laser tissue surgery into endoscopic and robotic surgery, we pave the way for a new approach for safe and atraumatic soft tissue joining, especially in regions where traditional suturing is unfeasible.

Introduction: Main oncological outcome parameters in soft tissue sarcoma (STS) patients include risk for local recurrence (LR) and distant metastasis (DM), as well as overall survival (OS). Over the past years, risk prediction tools have been developed to estimate patients’ outcome, incorporating established prognostic factors (e.g. tumour size, histological subtype) in conventional time-to-event models.
The aims of this multicenter study were to 1) assess LR and DM risk, as well as OS in a large, multicenter retrospective multinational cohort of STS patients from Austria and Switzerland, and to 2) investigate established and eventually identify novel prognostic factors for LR, DM and OS.

Methods: 746 patients with STS (mean age: 62.5±16.3 years; 49.9% males) were retrospectively included, treated for localised disease at 4 sarcoma centres. Multivariate (including age, gender, size, grading, depth, histology, location) time-to-event models (i.e. Fine&Gray models, Cox-regression models) were carried out to analyse the potential impact of variables on LR, DM, and OS.

Results: Median follow-up was 24.2 months (IQR 11.8-71.7 months). During this period, 117/596 (19.6%) and 211/619 (34.1%) patients, respectively, developed LR and DM, and 202/676 patients died (29.9%). The most common histologies were myxofibrosarcoma (n=199; 26.6%) and liposarcoma (n=165; 22.1%). The majority of tumours were high grade (n=344; 59.8%) and located in the lower limbs (n=426; 57.2%). High-grade STS were per tendency independently associated with increased LR-risk (SHR 3.13, 95%CI 0.91-10.70, p=0.069. High-grade STS (SHR 3.63, 95%CI 1.12-11.73, p=0.031) and leiomyosarcoma (SHR 3.20, 95%CI 1.14-8.98, p=0.027) showed an independent association with increased DM-risk. Advanced patient age (HR 1.06, 95%CI 1.04-1.07, p < 0.001), large tumour size (HR 1.05, 95%CI 1.02-1.08, p=0.001), and histologies UPS (HR 1.86, 95%CI 1.01-3.42, p=0.045) and “other” (HR 2.29, 95%CI 1.16-4.50, p=0.016) were independently associated with reduced OS.

Conclusion: Our preliminary findings identified similar prognostic factors as previously reported for LR, DM and OS in STS patients. Interestingly, though, some parameters (e.g. tumour size) appeared to only slightly contribute to LR- and DM-risk in this population. Future steps include refinement of the models to further enhance prognostication in patients with STS.

Introduction: Intralesional curettage is commonly used for treatment of benign bone tumours including enchondroma, chondroblastoma, and giant cell tumour of bone. This technique naturally harbours the risk of tumour cells remaining within the cavity, potentially leading to local recurrence. In order to enhance visualisation and reduce risk of remnant tumour cells, endoscopic-assisted curettage may be performed. However, a study comparing the performance of conventional and endoscopic-assisted curettage in terms of surgical time and remnant tumour cells has not been carried out thus far.
The aim of this experimental study was to assess whether endoscopy-assisted curettage is superior to conventional curettage regarding residual tumour tissue (RTT).

Methods: Within this experimental study, three orthopaedic surgeons (trainee, orthopaedic physician, orthopaedic consultant) performed both conventional (4x each) and endoscopic-assisted curettages (4x each) on specifically prepared cortical-soft cancellous lower extremity sawbone models. “Tumours” consisted of radio-opaque polyurethane-based foam injected into prepared holes at the proximal and distal ends of the femur and tibia. Pre- and postinterventional CT-scans were performed. RTT was assessed on CT-scans by an expert radiologist. For statistical analyses, percentage of RTT in relation to total lesion’s size was used. T-tests, Wilcoxon rank-sum tests, and Kruskal-Wallis tests were applied to assess differences between surgeons and surgical techniques regarding outcome. A p-value of < 0.05 was considered statistically significant.

Results: Over all lesions and locations, median RTT amounted to 1.3% (IQR 0.7%-4.1%). Significantly more RTT was present following conventional (3.5%, IQR 1.3%-5.1%) compared to endoscopy-assisted curettage (0.9%, IQR 0.5%-1.8%; p=0.024). Mean surgical time was 7.5±3.0 minutes, and significantly longer during endoscopy-assisted (9.2±2.9 minutes) compared to conventional curettage (5.9±2.0 minutes; p=0.004). Between the three surgeons, no significant difference in RTT (p=0.394) or surgical time (p=0.251) was found.

Conclusion: Our findings strength the hypothesis to use endoscopy-assisted curettage to reliably remove tumour tissue, although at expense of increased surgical time. Interestingly, no difference in RTT or surgical time depending on surgeon’s experience level was present.

Introduction: The prognosis of extremity soft tissue sarcomas (STS) is of great importance for the treatment and outcome of the patient. Nomograms are excellent prognostic tools in providing individualized estimates for disease specific survival, prognosis and guide the decisions process for treatment of STS. Aim of this study was to study the reliability and value of two nomograms as prognostic tools in patients with extremity soft tissue sarcoma (STS) treated at the University Hospital Balgrist in Zürich, Switzerland.

Methods: Patients with an extremity STS treated between 01.01.2002 – 31.12.2019 were retrospectively analyzed. Whoops lesions (R2 resections from external institutions) were excluded as were WDLPS. Statistical analysis was used to assess the nomograms accuracy.

Results: 88 Patients were eligible, with a median age of 56.1 years, median tumor size of 14.1 cm, and median follow up of 58 months. The most common tumor entity were liopsarcoma (41.1%), undifferentiated pleomorphic sarcoma (32.6%) and myxofibrosarcoma (10.5%). During the observation period a total of 41.1 % have passed away from sarcoma. The most common recurrence was observed with 43.2 % distant relapses. The median sarcoma specific survival (SSS) was 118 months. The 4 year, 8 year and 12 year overall survival OS were 66.1%, 47.3% and 47.3% respectively. The concordance indices for 5 and 10 year disease free survival (DFS) and overall survival (OS) Sarculator were 0. 681 and 0.682. The concordance indices for 4-, 8- and 12-year SSD MSKCC-Nomogram were 0. 671, 0. 667 and 0. 672.

Conclusion: Both nomograms were effective and accurate in our cohort, but both could be further improved by specifying the type of relapse and including a longer endpoint for the sarculator. The applicability of nomograms is in change, newer dynamic nomograms allow for calculating a patients prognosis during a treatment. Further investigations will have to proof their reliability and safety.

Introduction : Soft tissue sarcomas (STS) are malignant tumors that arise from skeletal and extraskeletal connective tissues at any site. In Europe, the estimated incidence averages 4-5/100 000/year in Europe - representing less than 1 percent of all newly diagnosed malignant tumor. The local management of STS is based on wide monobloc excision with negative margins in reference centers mostly combined with peri operative radiotherapy (RT). The identification of subsets of patients who do not require RT remains challenging. We proposed to investigate histologic and imaging response factors predictive of local control after preoperative RT in patients with limb or trunk wall LG and HG STS.

Methods and Materials: This is a retrospective multicenter study of nonmetastatic patients who underwent preoperative RT and surgery for limb or trunk wall STS between 2007 and 2018 in the French Sarcoma Group centers and enrolled in the "Conticabase." Patterns of local relapse were investigated taking into account the multimodal response after preoperative RT. Diagnostic and surgical samples were compared after systematic review by expert pathologists. The patients were stratified according to the grade defined by the French Federation of Cancer Centers Sarcoma Group. Log-rank tests and Cox models were used to identify prognostic factors of radiation response and local control.

Results: 257 patients were included with 17% low grade (LG) and 72.5% High Grade (HG) sarcomas. The median follow-up was 33 months. After adjusting to the location, the combination of histotype and cellularity rate significantly correlated with LR. We described 3 prognostic subgroups: from the higher risk to the lower risk: undifferentiated sarcoma (US) with cellularity rate greater than or equal to 20%, non-US (NUS) with cellularity rate greater than or equal to 20 % or US with cellularity rate < 20%, and NUS subgroup with cellularity rate < 20% or LG group.

Conclusions and perspectives : Both HG and LG tumors have different morphological and biological behaviors in response to RT. Cellularity rate greater than or equal to 20% taking into account histological subtypes could be major prognostic factors for LR. The US HG sarcomas with cellularity rate greater than or equal to 20% after preoperative RT had the higher risk of LR and specific death.

Introduction: Liquid biopsy (LB) as a non-invasive method to investigate cancer biology and monitor residual disease has gained significance in clinical practice over the years. Whilst its applicability in carcinomas is well established, the low incidence and heterogeneity of bone and soft tissue sarcomas explains the less well-established knowledge considering LB in these highly malignant mesenchymal neoplasms. However, more and more studies investigating the use of various methodologies of LB in diagnosis, prognostication, and disease monitoring of sarcoma patients are being published.

Methods: A systematic literature review in PubMed was performed according to the PRISMA guidelines, including all original English and German articles (including case reports) published until 08.02.2023 and dealing with LB in sarcoma. From initially 920 studies, 466 duplicates were removed. The resulting 454 records were screened, and 206 of these excluded based on the title. Abstracts of the remaining 248 articles underwent in-depth screening, with 68 articles ultimately included in this systematic review.

Results: The 68 articles contained evidence on use of LB in 2636 sarcoma patients. The 5 most common histological subtypes analysed were osteosarcoma (n=602; 22.8%), Ewing sarcoma (n=384; 15.0%), gastrointestinal stromal tumour (n=203; 7.7%), rhabdomyosarcoma (n=193; 7.3%) and leiomyosarcoma (n=145; 5.5%). Of the 11 liquid biopsy analytes discussed, largest evidence was present for ctDNA (26 studies), cfDNA (18 studies), miRNA (9 studies), and circulating tumour cells (7 studies).

Conclusion: This systematic literature review provides an extensive up-to-date overview about the current and potential future uses of different liquid biopsy modalities as diagnostic, prognostic, and disease monitoring markers in sarcoma.

Introduction: In soft tissue sarcomas (STS), surgery with wide margins may be preceded by neoadjuvant radiotherapy (NRTX) and/or chemotherapy (CTX). Depending on local policies, definite surgery is usually delayed 3 to 10 weeks following NRTX. Whilst early resection may be associated with higher risk for wound healing deficits and infections, late surgery may reduce the local effect of NRTX in terms of tumour control.
The aims of this literature review were to 1) systematically analyse necrosis rates following NRTX in STS, and to investigate potential associations between necrosis rates and oncological outcome parameters.

Methods: A systematic literature review adhering to the PRISMA guidelines was performed on PubMed, using specific search terms (tumor necrosis rate AND soft tissue sarcomas; soft tissue sarcoma AND radiotherapy AND necrosis; soft tissue sarcoma AND radiotherapy AND tumour necrosis). All original articles in German or English providing information on radiological and/or histopathological necrosis rate following NRTX were included.

Results: Of initially identified 2284 articles, 817 duplicates were removed. Of the remaining 1467 articles, 1381 were excluded based on their title, and 45 based on the abstract. Full texts could be retrieved in 34 of the remaining 41 articles. These original articles underwent in-depth screening, with 24 original articles finally included in this systematic review. These involved results of 1731 STS patients (52.4% males), of whom 1462 (84.5%) had received NRTX. Definite surgery was most commonly scheduled 4-6 weeks from end of NRTX (12/23 studies). Median overall histopathological necrosis rate following NRTX amounted to 41.1% (IQR 25.5 – 63.7%). Only one study discovered a potential association between a surgical delay > 7 weeks and increased necrosis rate. Altogether, 16/24 studies reported on associations between necrosis rate and oncological outcome. Increased necrosis rate associated with better distant-metastasis- or disease-free survival in 5/16 and with better overall survival in 2/16 studies. A worse association between necrosis rate and oncological outcome was reported in 3/16 studies, and 8/16 discovered no significant association.

Conclusion: According to this systematic literature review involving data of 1731 STS patients (1462 with NRTX), median necrosis rate following NRTX amounts to 41.1%. Findings on associations between necrosis rate and oncological outcome are contradictory, thoug

Background: Results after debridement and implant retention (DAIR) for early-acute periprosthetic knee joint infections (PJI) vary widely. Surgeon expertise and procedural consistency likely influence outcomes, though data are limited. We hypothesized that standardized DAIR performed by experienced surgeons dedicated to the treatment of PJI improves treatment success.

Objectives: To compare treatment outcomes of standardized DAIR performed by dedicated arthroplasty surgeons with non-standardized procedures in historical cohorts.

Methods: The EBJIS 2021 criteria were used to define PJI. All patients with early-acute PJI treated with DAIR between October 2019 and October 2022 were included. The DAIR procedures followed a predefined protocol. Treatment success was assessed using Delphi consensus criteria and compared to a historical cohort treated with non-standardized DAIR at the same center between January 2005 and May 2015 before establishment of a dedicated team for musculoskeletal infections.

Results: After exclusion, 36 patients from the present cohort were considered in the analysis and compared against the 31 TKA that underwent open DAIR in the historic cohort. Overall treatment success was achieved in 32 (88%) and 25 (80%) patients . The Chi-squared statistical test revealed no significant difference in the overall treatment success and failure rates between the historic and present cohorts (p=0.768). The subgroup analysis of the present cohort showed that 4 (11%) were treated without curative intention , while 32 (89%) underwent DAIR with curative intent. Hematogenous PJI was found in 22 (88%) cases.

Conclusions: Implementing a standardized DAIR protocol performed by surgeons from a dedicated musculoskeletal infection center resulted in better clinical outcomes for patients with periprosthetic knee joint infections, signifying a superior approach over non-standardized methods. Despite the lack of statistical significance compared to historical cohorts, the marked clinical improvements underscore the robustness and efficacy of a standardized treatment regimen.

Introduction:
Using iNPWT could potentially decrease surgical site infections by reducing wound dehiscence, improving fluid drainage, and protecting against microorganisms from entering the wound from the environment.
This study aims to assess wound healing in patients with primary closed surgical incisions following high-risk procedures (such as major limb amputations) compared to those using conventional postoperative wound dressings.
The primary outcome measure was the absence of oozing by the seventh-day post-operation.

Methods:
This prospective randomized controlled trial aims to compare the effectiveness of iNPWT with standard dry dressings in patients undergoing lower-limb amputation (including trans-femoral, trans-tibial, or trans-metatarsal procedures). Two experimented surgeons performed all amputations. Following the amputation, patients in the iNPWT group received an intra-operative application of Prevena® by 3M, maintained sterilely for seven days before being replaced by a dry dressing. Patients in the standard group received a dry sterile dressing. All surgical wounds were evaluated on the seventh-day post-operation, and the dressing stains were examined for drainage.

Results:
Between 2020 and 2022, a total of 66 patients underwent lower-limb amputation, with a mean age of 71 years (+/- 11.8), of whom 81.8% were men. The distribution of amputation included 24 trans-metatarsal, 19 trans-tibial (Burgess), and 23 trans-femoral (Gritti-Stockes) procedures. Among them, 35 received standard dry dressings, while 31 were treated with iNPWT.
After the seventh day, the iNPWT group exhibited a significant reduction in oozing compared to those treated with dry dressing only (27 out of 31 vs. 18 out of 35; p=0.0019). Furthermore, iPNWT demonstrated even greater efficacy in the trans-tibial Burgess group (8 out of 8 vs. 6 out of 11, p=0.0445). No adverse events were reported in either in each group.

Conclusions:
This randomized controlled trial demonstrates that applying iNPWT therapy postoperatively in patients undergoing major lower limb amputations significantly reduces oozing after seven days post-operation. Moreover, it appears to be even more effective in patients undergoing the trans-tibial Burgess procedure.

Introduction: Existing knowledge about Candida spondylodiscitis is primarily derived from case reports and smaller case series. This systematic review summarized all reported cases of Candida spondylodiscitis to date.

Methods: Using a PRISMA-based approach, we conducted a comprehensive search of PubMed, Web of Science, Embase, Scopus, and OVID Medline from their inception to November 30, 2022. The study was registered in PROSPERO prior to study initiation. The search syntax “albicans” AND “spondylodiscitis” was used in different variations. We included all reported cases of Candida spondylodiscitis, regardless of Candida strain or affected spinal levels. 1038 studies were identified and 72 met the inclusion criteria. Statistical analyses included Kaplan-Meier curves, Fisher's exact tests, and Wilcoxon's rank sum tests.

Results: In total, the study encompassed 89 patients (67% males) treated for Candida spondylodiscitis. The median age was 61 years, with 23% being immunocompromised and 15% identified as intravenous drug users. The median duration of antifungal treatment was six months, and fluconazole (68%) was the most frequently employed antifungal agent. The median follow-up period was 12 months. The two-year survivorship free of death was 80%, and free of revision was 94%. Younger age (p = 0.042) and a longer duration of antifungal treatment (p = 0.061) were identified as predictive factors for survival.

Conclusion: The majority of individuals affected by Candida spondylodiscitis were males in their sixties. Importantly, one in four patients was immunocompromised. One in five patients died within two years of diagnosis.