Predictors of Clinical Outcomes After Hip Arthroscopy: 5-Year Follow-up Analysis of 1038 Patients

Background: Although hip arthroscopy has been shown to have favorable results, there is a paucity of literature describing predictive factors of 5-year clinical outcomes. Purpose: To identify predictive factors of midterm outcomes after hip arthroscopy in a cohort of 1038 patients whose outcomes at minimum 2-year follow-up were previously reported. In addition, to provide a comparison of short- and midterm predictive factors in outcome measures after hip arthroscopy. Study Design: Case-control study; Level of evidence, 3. Methods: Data were prospectively collected and retrospectively reviewed on all patients undergoing hip arthroscopy between February 2008 and June 2012. Patients were included if they had minimum 5-year follow-up on 2 patient-reported outcomes: Nonarthritic Hip Score (NAHS) and modified Harris Hip Score. Patients were excluded if they had any previous ipsilateral hip conditions. Using bivariate and multivariate analyses, we analyzed the effect of 36 pre- and intraoperative variables on the NAHS, modified Harris Hip Score, and conversion to total hip arthroplasty. Results: A total of 1038 patients met the inclusion criteria for the 2-year study, and 860 met our listed inclusion criteria for the 5-year study. The mean follow-up time was 62.0 months (range, 60.0-120.0 months). The bivariate analysis identified 10 variables (4 categorical and 6 continuous) that were predictive of 5-year postoperative NAHS. For the multivariate analysis, 7 variables were identified as being significant: preoperative NAHS, body mass index (BMI), age, lateral joint space, alpha angle, revision hip arthroscopy, and acetabular microfracture. These 7 variables were also predictive in the bivariate analysis. Age, BMI, revision hip arthroscopy, Tonnis grade, sex, trochanteric bursectomy, femoral head cartilage damage, and acetabular inclination were significant predictors of conversion to total hip arthroplasty. Conclusion: This study reports favorable midterm clinical outcomes in the largest cohort of hip arthroscopies with minimum 5-year follow-up in the literature to date. Seven variables were identified as being significant predictors of postoperative NAHS in the bivariate and multivariate analyses: preoperative NAHS, BMI, age, lateral joint space, alpha angle, revision hip arthroscopy, and acetabular microfracture. Of these, preoperative NAHS, BMI, age, and revision hip arthroscopy were predictive of 2- and 5-year postoperative NAHS. These predictive factors may prove useful to clinicians in determining indications for hip arthroscopy and counseling patients on its expected outcomes.