Os Acetabuli Do Not Portend Inferior 2-Year Functional Outcomes in Patients Undergoing Arthroscopic Acetabular Labral Reconstruction.

Purpose: To investigate whether os acetabuli identified preoperatively influence functional outcomes 2 years after an arthroscopic acetabular labral reconstruction.

Methods: Retrospective study with prospectively collected data of patients undergoing primary hip arthroscopy by a single, fellowship-trained surgeon at a single institution were retrospectively reviewed. Inclusion criteria included age ≥18 years and completion of patient-reported outcome measures (PROMs) preoperatively and at 3-month, 6-month, 12-month, and last follow-up timepoints. Exclusion criteria included labral debridement, hip dysplasia, advanced hip osteoarthritis (Tonnis >1), or previous surgery on the ipsilateral hip. Patients were divided into two cohorts based on the presence of os acetabuli (OA) or the absence of os acetabuli (NOA). Primary outcomes collected included the International Hip Outcome Tool (iHOT-33) and modified Harris Hip Score (mHHS). Secondary outcomes were the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, Non-Arthritic Hip Score, and visual analog pain scale. Inter-cohort outcomes were compared using linear mixed-effects and Fisher's exact tests. Nonlinear improvement trajectories were accounted for by sensitivity analyses.

Results: 193 hips (49.2% female; mean ± SD age: 35.9 ± 11.0) were included in the final analyses. Of these, 25 (13.0%) had an os acetabulum. No significant differences between patients with and without os acetabuli were found throughout the minimum 2-year follow-up period in terms of iHOT-33 scores (weighted difference: 0.09; 95% CI: -6.81, 6.98;  = .98), mHHS (weighted difference: 2.93; 95% CI: -2.13, 7.98;  = .26), or any secondary outcomes. Additionally, there were no significant differences in any queried clinically meaningful outcomes ( > .05 for all), revision arthroscopy ( =.342), rates of formation of heterotopic ossification ( > .999), or conversion to total hip arthroplasty ( > .999). These results were upheld across sensitivity analyses.

Conclusions: Patients with os acetabuli undergoing arthroscopic labral reconstruction had similar 2-year functional outcomes compared to those without os acetabuli.

Level Of Evidence: Level III, Retrospective cohort study.