Outcomes After Arthroscopic Treatment of Femoroacetabular Impingement for Patients With Borderline Hip Dysplasia

Background: The outcomes of hip arthroscopy in the treatment of dysplasia are variable. Historically, arthroscopic treatment of severe dysplasia (lateral center-edge angle [LCEA] <18 degrees) resulted in poor outcomes and iatrogenic instability. However, in milder forms of dysplasia, favorable outcomes have been reported. Purpose: To compare outcomes after hip arthroscopy for femoroacetabular impingement (FAI) in borderline dysplastic (BD) patients compared with a control group of nondysplastic patients. Study Design: Cohort study; Level of evidence, 3 Methods: Between March 2009 and July 2012, a BD group (LCEA, 18 degrees-25 degrees) of 46 patients (55 hips) was identified. An age- and sex-matched control group of 131 patients (152 hips) was also identified (LCEA, 25 degrees-40 degrees). 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 at 1 and 2 years postoperatively. Results: The mean LCEA was 22.4 degrees 2.0 degrees (range, 18.4 degrees-24.9 degrees) in the BD group and 31.0 degrees +/- 3.1 degrees (range, 25.4 degrees-38.7 degrees) in the control group (P < .001). The mean preoperative alpha angle was 66.3 degrees +/- 9.9 degrees in the BD group and 61.7 degrees +/- 13.0 degrees in the control group (P = .151). Cam decompression was performed in 98.2% and 99.3% of cases in the BD and control groups, respectively; labral repair was performed in 69.1% and 75.3% of the BD and control groups, respectively, with 100% of patients having a complete capsular closure performed in both groups. At a mean follow-up of 31.3 +/- 7.6 months (range, 23.1-67.3 months) in unrevised patients and 21.6 +/- 13.3 months (range, 4.7-40.6 months) in revised patients, there was significant improvement (P < .001) in all patient-reported outcome scores in both groups. Multiple regression analysis did not identify any significant differences between groups. Importantly, female sex did not appear to be a predictor for inferior outcomes. Two patients (4.3%) in the BD group and 6 patients (4.6%) in the control group required revision arthroscopy during the study period. Conclusion: Favorable outcomes can be expected after the treatment of impingement in patients with borderline dysplasia when labral refixation and capsular closure are performed, with comparable outcomes to nondysplastic patients. Further follow-up in larger cohorts is necessary to prove the durability and safety of hip arthroscopy in this challenging group and to further explore potential sex-related differences in outcome.