OP1.7 Preoperative Gait Metrics Correlate with 2-Year Outcomes After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

Purpose: To use a novel smartphone app (“rHip”) to understand the relationship between preoperative gait metrics and 2-year outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

Methods: Patients who underwent primary hip arthroscopy for FAIS by a single surgeon between 07/2019 and 04/2022 with 2-year follow-up were identified. A novel smartphone app (“rHip”) was used to record patients’ preoperative step count, walking speed, stride length, and stride asymmetry as an average of the 14 preoperative days. Patient-reported outcomes (PROs) collected preoperatively and at 2-year follow-up included Hip Outcome Score Activities of Daily Living and Sports Subscale (HOS-ADL/SS), international Hip Outcome Tool 12 (iHOT-12), and Patient-Reported Outcomes Measurement Information System Physical Function and Pain Interference (PROMIS-PF/PI). Preoperative gait metrics were correlated to preoperative and 2-years PROs using Pearson correlations. Cohort-specific MCID and PASS were calculated. PASS achievers were compared to PASS non-achievers to identify variables associated with PASS achievement.

Results: In total, 37 patients were evaluated. Patients were of mean age 35.1 ± 13.9 years, BMI 24.4 ± 4.6, and 89% were female. The average preoperative gait metrics included step count of 3947 ± 2094, walking speed of 1.1 ± 0.2 m/s, stride length of 0.6 ± 0.1m, and gait asymmetry of 2.6 ± 2.3%. Preoperatively, walking speed, step length, and stride asymmetry showed significant, moderate correlations with at least one PRO (r = 0.394-0.611). At 2-year follow-up, all preoperative gait metrics correlated with at least one PRO, with correlation strengths ranging moderate to strong (r = 0.373-0.794). Comparing the PASS achievers and PASS non-achievers, significant differences in step count (4403±2183 vs. 2002±1530, p=0.014), walking speed (1.1±0.1 vs. 0.8±0.3, p=0.001), and stride length (0.6±0.5 vs. 0.5±0.2, p=0.044) were observed.

Conclusion: This study demonstrated that preoperative gait metrics showed moderate correlations with preoperative PROs, and moderate to strong correlations with 2-year PROs. Patients who achieved 2-year PASS were observed to have a significantly greater preoperative step count, walking speed, and stride length than patients who did not achieve PASS.