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.