Paper 23: Long Term Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients with Borderline Dysplasia

OBJECTIVES: Outcomes following isolated hip arthroscopy for patients with dysplasia have been unfavorable, results have included iatrogenic instability and conversion to total hip arthroplasty (THA) at a young age. However, patients with borderline dysplasia have portended more favorable results at short and medium term follow-up. The purpose of this study was to assess long term outcomes after hip arthroscopy for femoroacetabular impingement (FAI) in borderline dysplasia (BD) patients (LCEA, 18°-25°) compared to a control cohort of nondysplastic patients (LCEA, 25°-40°). METHODS: Between March 2009 and July 2012, a BD group of 33 patients (38 hips) was identified. An age- and sex-matched control group of 83 patients (96 hips) was also identified. Patient-reported outcome scores, including the modified Harris Hip Score (mHHS), the Hip Outcome Score–Activities of Daily Living (HOS-ADL) and Sport-Specific Subscale (HOS-SSS), and the International Hip Outcome Tool (iHOT-33), were collected preoperatively and subsequently at an average of 9.6 years post-operatively. RESULTS: The mean LCEA and Tönnis angle was 22.4° ± 2.02° and 6.2° ± 3.23° in the BD group and 31.7° ± 3.52° and 2.42° ± 3.02° in the control group, respectively (P <0.001). A labral repair was performed in 78.9% and 76% of the BD and control groups, respectively, all patients underwent capsular closure as part of routine hip arthroscopy. A cam decompression was performed in 97.4% of the BD patients and 99.0% of the control patients. At mean follow-up of 9.6 years (range, 8.2-11.6 years) on average there was significant improvement in all patient-reported outcomes scores in both groups (P<0.001). There were no significant differences between pre and post-operative scores between BD and control groups. Two hips (5.2%) underwent revision surgery in the BD group and 10 hips (10.4%) in the control group, of these one patient in the BD group underwent THA and one patient who underwent bilateral hip arthroscopies in the control group underwent bilateral hip resurfacing. CONCLUSIONS: Durable outcomes (>9 years) with low revision rates can be expected after isolated hip arthroscopy that includes cam resection, labral refixation and capsular closure in BD patients with equivalent outcomes to a nondysplastic cohort.