Preoperative Paralabral Cysts Predict More Significant Chondral Damage but Not 2-Year Functional Outcomes Following Arthroscopic Labral Repair.

PURPOSE: To investigate whether paralabral cysts identified incidentally on preoperative magnetic resonance imaging (MRI/MRA) predict 2-year functional outcomes after arthroscopic acetabular labral repair. METHODS: Prospectively collected data for patients undergoing primary hip arthroscopy by a single surgeon from 2014 to 2020 were retrospectively reviewed. Included patients were ≥18 years and completed baseline patient-reported outcome measures (PROMs) with additional follow-up at 3, 6, 12, and 24 months. Exclusion criteria were labral debridement, hip dysplasia, advanced hip osteoarthritis (Tönnis >1), or previous ipsilateral hip surgery. Patients were stratified based on the presence of paralabral cysts identified on MRI/MRA. Primary outcomes were International Hip Outcome Tool (iHOT-33) and modified Harris Hip Score (mHHS). Secondary outcomes included other PROMs and the visual analog pain scale. Outcomes were compared between cohorts using linear mixed-effects models and Fisher's exact tests. Sensitivity analyses accounted for preoperative PROMs, nonlinear improvement trajectories, and relevant baseline characteristics. RESULTS: Of the 182 included hips (47.8% female; mean ± standard deviation age, 36.9 ± 11.4), 30 (16.4%) had paralabral cysts. During the 2-year study period, there were no significant differences between patients with and without paralabral cysts in terms of iHOT-33 scores (weighted difference = 1.60; 95% confidence interval [CI], -5.09, 8.28; P = .64), mHHS scores (weighted difference = 0.56; 95% CI, -4.16, 5.28; P = .82), or any secondary outcomes (except for HOS-Sports Subscale at 3 months [mean difference = -11.85; 95% CI, -22.85, -0.84; P = .035]). Furthermore, there were no significant differences in clinically meaningful outcomes (P > .05 for all), revision rates (P = 1.00), or conversion to total hip arthroplasty between cohorts (P = 1.00). These results held across all sensitivity analyses. CONCLUSIONS: Although preoperative paralabral cysts were associated with worse cam impingement and more severe chondral damage observed intraoperatively, they did not predict 2-year functional outcomes or clinically meaningful improvements, suggesting that incidentally discovered paralabral cysts are not a contraindication for arthroscopic labral repair. LEVEL OF EVIDENCE: Level III, retrospective cohort study.