Evaluation of the alpha angle as a predictor of outcome in the arthroscopic management of hip labral disease

Background: Femoroacetabular impingement is a pre-arthritic condition that, if untreated, may predispose to inferior outcomes after hip arthroscopy. The objective of this study was to evaluate the effect of the alpha angle (AA), an indicator of cam-impingement lesions, on mid-term outcomes in patients undergoing arthroscopic labral debridement without femoral osteoplasty. Methods: Consecutive patients with available imaging who underwent hip arthroscopy for a labral tear from 2001-2006 by two surgeons were retrospectively reviewed. Patients were contacted at a mean of 63.8 months (range 39.8-96.4 months) and administered a standardized telephone survey. Mid-term outcomes were considered successful if patients had no further surgery, had a "good" or "excellent" subjective rating of hip function and less than 5/10 average daily pain on telephone follow-up. Patients with significant osteoarthritis seen on the preoperative films or at the time of arthroscopy were omitted, leaving 55 patients available for mid-term follow-up. Results: At mid-term follow-up, the average AA values of the successful (AA=51.1 ± 10.7; 51%) and unsuccessful (AA=52.8 ± 14.0; 49%) outcome groups were not significantly different (P=0.61). No significant differences were found between groups with an AA <50.51 and an AA Z50.51 (P=0.47). Conclusions: Our results indicate that the preoperative AA may not be a univariate major predictor of outcome after arthroscopic labral debridement.