Surgical Dislocation of the Hip Versus Arthroscopic Treatment of Femoro-acetabular Impingment: A Prospective Comparative Study with 2-Year Follow-Up

OBJECTIVES: Femoroacetabular impingement (FAI) can be treated by arthroscopy or by surgical dislocation of the hip. Advocates of each have suggested advantages of each technique. To date, there have been no studies that directly compare these two treatment modalities, using patient-reported outcomes (PRO), in a single surgeon design. The purpose of this study was to prospectively compare outcomes of patients receiving surgical hip dislocation to arthroscopic treatment for FAI, using a matched-pair analysis. Our hypothesis is the arthroscopic group will demonstrate improved clinical outcomes when compared to patients receiving open surgical dislocation. METHODS: During the study period between January 2008 and August 2011, data was prospectively collected on all patients <30 years of age treated for FAI. Patients were given the choice of open dislocation versus arthroscopic treatment. Patients with developmental dysplasia of the hip, Legg-Calve-Perthes disease, Tonnis grade >1, and previous hip surgery were excluded. The patients in the surgical dislocation cohort were pair-matched in a 1:2 ratio to patients treated arthroscopically, based on age within 2 years, gender, workers’ compensation status and diagnosis of FAI. PRO tools, including the modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score – Sport Specific Subscale (HOS - SSS) and Hip Outcome Score - Activity of Daily Living (HOS - ADL), were obtained in all patients pre-operatively and post-operatively at 3 months, 1 year, and 2 years, and at latest follow up. Alpha angles were measured pre and post- surgery for both groups. Revision surgery and complications were recorded for each group. RESULTS: Ten patients were included in the surgical dislocation group, and 20 pair-matched patients were included in the arthroscopic group. 100% patient follow-up was obtained at mean 24.8 months in the open group and 25.5 months in the arthroscopic group. Preoperative mHHS, NAHS, HOS-ADL and HOS-SSS were similar between the two groups. Both the arthroscopic group and the surgical dislocation group had significant postoperative improvement at 3 months, 1 year and final follow-up for all scores. In comparing the two groups, the ΔHOS-SSS was significantly higher in the arthroscopic group at final follow-up, improving 42.8 points versus 23.5 in the surgical dislocation (p=0.047). The arthroscopic group also had significantly better NAHS at 3 months (88.1 vs. 75.3, p=0.016) and at final follow-up. (94.2 vs. 85.7, p=0.01). Nine out of 10 patients in the dislocation group had good/excellent results, and 19 out of 20 patients in the arthroscopic group had good/excellent results. Patient satisfaction for the open group was 8.1, and 9.2 in the arthroscopic group (p=0.07). Both groups showed a significant decrease in the alpha angle postoperatively, from 58° to 40° in the dislocation group, and 57° to 40° in the arthroscopic group, with no difference between the groups (p=0.775). The dislocation group had 8 patients undergo hardware removal, and two required hip arthroscopy for continued pain. CONCLUSION: This is the first study to directly compare surgical dislocation to arthroscopic management of FAI in single surgeon design. Favorable results were shown with both approaches, with significant improvement in all PRO measures and high patient satisfaction ratings. However, arthroscopic treatment of FAI showed greater improvement in the HOS-SSS and a higher absolute NAHS score at 2 year follow-up.