FP10.1 Peak Pelvic Drop During Gait Is Associated With Preoperative Outcomes in Patients Undergoing Revision Hip Arthroscopy Surgery

Abstract ICLA10 - Unraveling the Failure: Diagnostic Algorithms and Why Hip Preservation Fails, Auditorium A (BMCC Level 1), October 9, 2026, 10:30 - 12:30 Introduction The relationship between coronal plane gait features such as pelvic drop (PD) and compensatory femoral adduction (FAD) in patients undergoing revision hip arthroscopy (HA) remains unclear. It was hypothesized that preoperative PD and FAD during gait would differ in patients undergoing primary versus revision HA and would be associated with preoperative patient reported outcomes (PROs). Methods From a prospective hip preservation registry, 111 patients with femoroacetabular impingement syndrome undergoing HA were identified, including 89 primary and 22 revision surgeries. Motion capture gait analysis was performed using wearable inertial measurement units during level walking. The peak PD of both hips was extracted, along with FAD of the operative hip. Patients undergoing revision HA were propensity-matched to patients undergoing primary HA according to age, sex, and body mass index. Preoperative gait parameters and PROs, including the International Hip Outcome Tool (iHOT-12), Hip Outcome Score – Sport Specific Subscale (HOS-SSS), Patient-Reported Outcome Measurement Information System (PROMIS) Pain Interference (PROMIS-PI), Physical Function (PROMIS-PF), Depression (PROMIS-D), Anxiety (PROMIS-A), and EQ-5D Visual Analog Scale (VAS) were compared between revision and primary HA patients. Associations between gait variables, demographics, and PROs were assessed using regression analyses. Results A total of 18 revision HA patients were matched to 36 primary HA patients. Primary patients had greater average pelvic drop (5.6±2.3° vs 4.6±1.2°, p=0.043). Primary patients also had superior preoperative outcomes with higher iHOT-12 (39.6±18.9 vs 26.7±11.3, p=0.010) and HOS-SSS scores (50.8±20.1 vs 37.5±16.2, p=0.027). In primary patients female sex predicted inferior PROMIS-PI scores (odds ratio [OR] 9,034, p=0.015) and PROMIS-PF scores (OR 6.2e-5, p=0.025). For revision HA patients, greater pelvic drop was associated with improved PROMIS-A (OR 0.0005, p = 0.008) and PROMIS-D scores (OR 0.004, p=0.046), while higher non-operative pelvic drop was associated with better iHOT-12 scores (OR 434, p=0.023) and EQ-5D VAS (OR 3.2e+5, p=0.013). Conclusion Symptomatic pelvic drop was significantly greater for patients undergoing primary versus revision HA. Gait features including symptomatic and asymptomatic PD predicted preoperative function for revision HA, but not in primary HA, suggesting compensatory coronal plane gait mechanics may have greater influence on outcomes in the revision setting.