Revision of hip resurfacing arthroplasty

Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation or aseptic loosening after conversion of any resurfacing arthroplasty. Valgus neck-shaft angle (P < .03) was associated with aseptic failure of MOM hip resurfacing. Conversion of aseptic failure of hip resurfacing to conventional THA leads to clinical outcomes similar to those of patients who undergo uncomplicated hip resurfacing. The orientation of the femur and the components placed play a large role in implant survival in hip resurfacing. More work needs to be done to further elucidate these radiographic parameters.     

Sporting and physical activity following hip resurfacing

The aim of this study was to assess sporting and physical activities in patients who had undergone hip resurfacing. Our study included 117 patients who underwent hip resurfacing between 2003 and 2008. University of California at Los Angeles (UCLA) activity level and Oxford hip scores (OHS) were used. Sporting and physical activities of all patients were analysed pre- and postoperatively. The mean age at surgery was 54 years. The mean follow up was 30 months. There was statistically significant improvement in UCLA activity scores from 4.4 to 6.8 (p < 0.05) and Oxford hip scores from 43.4 to 17.7 following surgery. Eighty-seven percent of patients continued to take part in sporting activities following hip resurfacing. Our study has demonstrated that hip resurfacing can allow patients to remain extremely active.     

What Factors Predict Conversion to THA After Arthroscopy?

Background

Failure of hip preservation to alleviate symptoms potentially subjects the patient to reoperation or conversion surgery to THA, adding recovery time, risk, and cost. A risk calculator using an algorithm that can predict the likelihood that a patient who undergoes arthroscopic hip surgery will undergo THA within 2 years would be helpful, but to our knowledge, no such tool exists.

Questions

(1) Are there preoperative and intraoperative variables at the time of hip arthroscopy associated with subsequent conversion to THA? (2) Can these variables be used to develop a predictive tool for conversion to THA?

Materials and Methods

All patients undergoing arthroscopy from January 2009 through December 2011 were registered in our longitudinal database. Inclusion criteria for the study group were patients undergoing hip arthroscopy for a labral tear, who eventually had conversion surgery to THA. Patients were compared with a control group of patients who underwent hip arthroscopy for a labral tear but who did not undergo conversion surgery to THA during the same study period. Of the 893 who underwent surgery during that time, 792 (88.7%) were available for followup at a minimum of 2 years (mean, 31.1 ± 8.1 years) and so were considered in this analysis. Multivariate regression analyses of 41 preoperative and intraoperative variables were performed. Using the results of the multivariate regression, we developed a simplified calculator that may be helpful in counseling a patient regarding the risk of conversion to THA after hip arthroscopy.

Results

Variables simultaneously associated with conversion to THA in this model were older age (rate ratio, 1.06; 95% CI, 1.03–1.08; p < 0.0001), lower preoperative modified Harris hip score (rate ratio [RR], 0.98; 95% CI, 0.96–0.99; p = 0.0003), decreased femoral anteversion (RR, 0.97; 95% CI, 0.94–0.99; p = 0.0111), revision surgery (RR, 2.4; 95% CI, 1.15–5.01; p = 0.0193), femoral Outerbridge Grades II to IV (Grade II: RR, 2.23 [95% CI, 1.11–4.46], p = 0.023; Grade III: RR, 2.17, [95% CI, 1.11–4.23], p = 0.024; Grade IV: RR, 2.96 [95% CI, 1.34–6.52], p = 0.007), performance of acetabuloplasty (RR, 1.83; 95% CI, 1.03–3.24; p = 0.038), and lack of performance of femoral osteoplasty (RR, 0.62; 95% CI, 0.36–1.06; p = 0.081). Using the results of the multivariate regression, we developed a simplified calculator that may be helpful in counseling a patient regarding the risk of conversion surgery to THA after hip arthroscopy.

Conclusion

Multiple risk factors have been identified as possible risk factors for conversion to THA after hip arthroscopy. A weighted calculator based on our data is presented here and may be useful for predicting failure after hip arthroscopy for labral treatment. Determining the best candidates for hip preservation remains challenging; careful attention to long-term followup and identifying characteristics associated with successful outcomes should be the focus of further study.

Level of Evidence

Level III, therapeutic study.

     

Hip Resurfacing: A Single Surgeon U.S. Series With Minimum Ten-Year Follow-up

BackgroundMetal-on-metal hip resurfacing is an alternative to total hip arthroplasty (THA). The aim of this study was to determine implant survivorship, analyze patient-reported outcomes measures and to determine patient satisfaction for patients who underwent metal-on-metal hip resurfacing at a large US academic institution by a single surgeon with a minimum of 10-year follow-up.MethodsPatients who underwent hip resurfacing from September 2006 through November 2009 were included. Patient demographics and variables were collected from a prospectively maintained institutional database and patients completed an additional questionnaire with patient-reported outcomes measures.ResultsA total of 350 patients (389 hips) out of 371 (433 hips) with a minimum 10-year follow-up were successfully contacted (94.3% follow-up). Mean age was 53 years, 258 were male (73%). 377 out of 389 hips (96.9%) did not require additional surgery. Gender was significantly related to implant survivorship (males 99.0%, females 90.9%; P < .001). 330 patients (369 hips, 94.8%) were satisfied with their surgery. Males had higher proportion of satisfaction scores (P = .02) and higher modified Harris Hip Score (odds ratio = 2.63 (1.39, 4.98), P = .003). Median modified Harris Hip Score score for non-revised hips was 84.0 [80.0; 86.0] versus those requiring revision, 81.5 [74.0; 83.0], (P = .009).ConclusionAt a minimum 10-year follow-up, hip resurfacing, using an implant with a good track record, demonstrates 99.0% survivorship in male patients with an average age of 52 years. We believe that the continued use of metal-on-metal hip resurfacing arthroplasty in this population is justified by both positive patient reported outcomes and survivorship.