Borderline Hip Dysplasia Is Not Associated With Significant Differences in Hip Survivorship or Patient-Reported Outcomes Following Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Cohort Study

Purpose: To compare hip survivorship and patient -reported outcomes after primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) in patients with versus without comorbid borderline hip dysplasia (BHD) at 2 -year follow-up. Methods: A retrospective matched -cohort study was conducted involving patients who underwent primary hip arthroscopy for FAIS with a single surgeon from 2010 to 2019. BHD was de fi ned as lateral center edge angle (LCEA) of 20 to 25 degrees . Subjects with BHD were matched 1:2 to controls without BHD on age, sex, body mass index, and preoperative modi fi ed Harris Hip Score (mHHS). Alpha angle, LCEA, T & ouml;nnis angle, and acetabular retroversion signs were measured on preoperative and/or postoperative hip radiographs. Patient -reported outcomes were assessed using the mHHS and the Non -Arthritic Hip Score. Hip survivorship, outcome scores, and achievement of the minimum clinically important difference were compared between groups using the Mann e Whitney U test or Fisher exact test, as appropriate. P values < .05 were considered signi fi cant. Results: Thirty-one BHD subjects (mean age 36.8 years, 71.0% female) and 62 controls (mean age 38.0 years, 71.0% female) were included. There were no signi fi cant intergroup differences in demographics or preoperative radiographic measurements besides LCEA and T & ouml;nnis angle (all P > .05). Intraoperatively, subjects with BHD were found to have signi fi cantly shorter labral tears (mean 2.6 vs 2.8 clock -face hours, P = .048), but there were no signi fi cant intergroup differences in acetabular or femoral cartilage status (all P > .05). Postoperatively, there were no signi fi cant intergroup differences in rates of revision arthroscopy (BHD 6.5% vs control 11.3%) or conversion to total hip arthroplasty (BHD 9.7% vs control 1.6%), in 2 -year improvement of the mHHS and Non -Arthritic Hip Score, or in minimum clinically important difference achievement rates (all P > .05). Conclusions: BHD is not associated with a signi fi cant difference in hip survivorship or patient -reported outcomes following primary hip arthroscopy for FAIS. Level of Evidence: Level III, retrospective comparative study.