|Beitragstitel||What are the clinical outcomes of the revisions after large head metal-on-metal total hip arthroplasty ? Thirty-eight cases with at least 2 years of follow-up.|
A particularly high rate of failure with necessity for revision in up to 20% of cases at 14 years has been reported with large-diameter metal-on-metal total hip arthroplasty (>36mm). Clinical results after these operations are still little known. The hypothesis of this study was that results after a revision for a large head metal-on-metal total hip arthroplasty (MoM THA) were comparable to those after primary THA. Thus the aims of this study were to evaluate (1) the complication rate (infection, dislocation, implants loosening) after revision and (2) the clinical results of these revisions in comparison to a primary THA.
38 cases of large head metal-on-metal THA were revised in our service during 2010 and 2014. Mean age at surgery was 66 ± 11 (45–86) years, with a BMI of 27 ± 4 (22–35). The revision group has been paired regarding age, sex, BMI and Charnley score with a group of patient operated for a primary THA. Indication for surgery was made upon a high chromium and cobalt blood level, presence of pain and imaging. Cases with infectious or fracture motive for surgery were excluded. At revision, 100% of the femoral stems were retained and in all cases we substituted the bearing surfaces. In 29 cases a dual-mobility cup has been used with ceramic-on-polyethylene bearing surfaces and in 9 cases a ceramic-on-ceramic cup was chosen. Mean interval between initial hip replacement and revision was 5 ± 2 (3–7) years. Complications were reported. Clinical results were evaluated through the Hip Harris score and the HOOS. Mean follow-up was 3 ± 1 (2–6) years.
In the revision group 1 patient developed an infection which has required another operation. No dislocation or implant loosening has occurred in this group. In the paired primary THA group no complication has been reported. Clinical scores (Hip Harris / HOOS) were comparable in the two groups (p>0,05) at the latest control. Nonetheless, 5 patients showed persistent pain (> 3 months); all these patients had a clear and extended pseudotumor at time of revision.
It is of foremost importance to establish a careful clinical follow-up for patients with a large head MoM THA, in accordance with current recommendations and this to precociously detect complication justifying a revision. Based on our experience we think that it is presumably through an early revision concept that we obtained similar clinical results when comparing revision after large-diameter MoM THA and primary THA.