Functional and Clinical Outcomes of Patients Undergoing Revision Hip Arthroscopy With Borderline Hip Dysplasia at 2-Year Follow-up

Purpose: To compare outcomes of borderline hip dysplasia (BHD) patients undergoing revision hip arthroscopy with 1) patients with BHD undergoing primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) and 2) patients without BHD undergoing revision hip arthroscopy for FAIS. Methods: A retrospective cohort study was performed to identify patients who underwent arthroscopy from January 2012 to January 2016 by a single fellowship-trained surgeon, including a 2-year follow-up. Patient demographics, comorbid medical conditions, and preoperative outcome scores were compared between patients with BHD (lateral center-edge angle 18 degrees to 25 degrees) who had revision hip arthroscopy to patients with BHD undergoing primary arthroscopy and patients without BHD (lateral center-edge angle >25 degrees) undergoing revision arthroscopy. Cohorts were matched 2:1 by age and body mass index. Multivariate regressions were used to compare Hip Outcome Score, Activities of Daily Living subscale (HOS-ADL) and Sports subscale (HOS-SS) scores and modified Harris Hip Score (mHHS) between the cohorts at 2-year follow-up. Binomial regression analysis was used to determine predictors of achieving minimal clinically important difference (MCID) and patient-acceptable symptom state (PASS). Results: There was no statistical difference in age and BMI between the BHD revision (29.1 +/- 8.8 years; 25.5 +/- 3.58 kg/m(2)), BHD nonrevision (28.9 +/- 8.5 years; 24.6 +/- 3.1 kg/m(2)), and non-BHD revision (29.15 +/- 8.6 years; 25.01 +/- 3.2 kg/m(2)) cohorts. There were no statistically significant differences in 2-year clinical outcomes between BHD revision patients and either BHD primary or non-BHD revision patient groups, but BHD revision patients were significantly less likely to achieve PASS for HOS-SS compared with BHD primary and non-BHD revision groups (P = .047 and P = .031, respectively). Conclusion: Surgeons should exercise caution when indicating patients for revision hip arthroscopy with BHD. Although the current study lacks statistical power, the available data suggest that patients undergoing revision surgery with BHD may still experience clinical improvement but be less likely to achieve PASS metrics for several patientreported outcomes at 2-year follow up.