Poster 232: Clinical Outcomes Among Individuals with Global Acetabular Retroversion who Underwent Hip Arthroscopy for FAI with Minimum 5-Year Follow-Up

OBJECTIVES: The purpose of this study was to compare functional outcomes and clinical threshold achievement rates of patients with radiographic signs of global acetabular retroversion who underwent hip arthroscopy for FAI with minimum follow-up of 5 years. METHODS: Patients were identified from a single-surgeon prospectively-collected database who underwent primary hip arthroscopy for treatment of FAI. Patients completed patient-reported outcome (PRO) surveys at both baseline and at 5-year follow-up. Demographic data was collected including age, sex, BMI at time of surgery, and patient-reported symptom length. Intraoperative findings were recorded, including the Outerbridge grade, presence of labral tears, chondral delamination, subspine impingement, cam lesions, pincer lesions, and mixed-type FAI. Global acetabular retroversion was assessed on AP view using three radiographic signs: ischial spine, posterior wall, and crossover signs. Other radiographic measures included alpha angle measured on three view (AP, 45° Dunn, 90° Dunn), lateral center edge angle (LCEA), and Tönnis grade. RESULTS: We identified 124 primary hip arthroscopy patients who had minimum 5-year follow-up with adequate imaging and complete 5-year PROs. Preoperative X-rays demonstrated presence of ischial spine sign in 65 patients (52.4%), posterior wall sign in 61 patients (49.2%), and crossover sign in 75 patients (60.5%). Mean alpha angle was highest on AP view (62.2°), followed by 45° Dunn view (55.9°) and 90° Dunn view (50.9°) and mean LCEA was 38.5°. A baseline comparison demonstrated no significant differences between groups in age, sex, BMI, preoperative symptom length, Tönnis grade, Outerbridge grade, and preoperative mHHS or NAHS (p>0.05). At 5-year follow-up, patients reported significant improvement in both mHHS (mean 50.4 to 82.7, p<0.001) and NAHS (49.4 to 85.5, p<0.001). Achievement rates were high for MCID (90.3%), SCB (80.7%), and PASS (79.0%) for the mHHS. Three-way frequency comparison of acetabular retroversion signs found that all three signs tended to be present together (40 patients, 32.3%) or absent together (31 patients, 25.0%). Pairwise comparisons with tetrachoric correlation testing found all three signs to be significantly correlated with one another: ischial spine sign versus posterior wall (rtet=0.65, corrected p<0.001), ischial spine sign versus crossover sign (rtet=0.74, corrected p<0.001), and posterior wall sign versus crossover sign (rtet=0.51, corrected p<0.001). Multivariable analysis did not find any of the three signs to be significant independent predictors of 5-year improvement in mHHS or NAHS (p>0.05). Posterior wall sign was associated with lower odds of achieving the MCID (OR = 0.62, 95% CI [0.06 to 1.09]) but this did not achieve significance (χ(2)=3.39, p=0.07). Overall, achievement rates for MCID, SCB, and PASS did not significantly differ between the cohorts with respect to each sign (p>0.05). CONCLUSIONS: Clinical outcomes and achievement rates at 5-year follow-up demonstrated no significant differences among patients with respect to each sign of acetabular retroversion based on mHHS, NAHS, MCID, SCB and PASS. Surgeons should be reassured that these patients regain function at a rate similar to the greater FAI population.