Abstract
Background: Prior studies have identified demographic, radiographic, and intraoperative predictors of outcomes following hip arthroscopy for femoroacetabular impingement syndrome (FAIS), yet no studies have identified if preoperative gait metrics can predict outcomes. We hypothesized that increased preoperative step count, walking speed, step length, and gait symmetry would be associated with better outcomes following surgery. Study Design: Retrospective cohort study, Level of Evidence IV Methods: Patients who underwent hip arthroscopy between 2019-2022 download the smartphone app rHip, allowing for retroactive access of gait metric data. Preoperative gait metrics, age, sex, body mass index (BMI) and exercise participation were analyzed via multivariate stepwise linear regression for a relationship with 1-year postoperative patient-reported outcomes (PROs), including Hip Outcome Scale-Activities of Daily Living (HOS-ADL); HOS-Sports Subscale (HOS-SS), 12-item international Hip Outcome Tool (iHOT-12), Patient-Reported Outcomes Measurement Information System (PROMIS) for Physical Function (PROMIS-PF) and Pain Interference Subscale (PROMIS-PI). Thresholds for preoperative gait metrics were analyzed via receiver operator characteristic (ROC) curve. A subgroup analysis was performed to compare those who did and did not reach this threshold. Results: Forty-three patients (86% female; age: 33.1±13.7 years; BMI: 23.9±4.4 kg/m2) met inclusion criteria. Multivariate regression found that preoperative walking speed was significantly associated with postoperative HOS-ADL, HOS-SS, and iHOT-12 (p0.006). A preoperative walking speed threshold of 1.065 m/s was found to be predictive of outcome achievement. Those that failed to achieve this threshold were shown to be significantly older, with larger BMIs, and were less active (p0.013). They also showed significantly worse 1-year postoperative scores (p0.009) and lower PASS achievement for HOS-ADL, HOS-SS, and iHOT-12 (p0.042). Conclusion: Preoperative walking speed is significantly associated with 1-year outcomes following hip arthroscopy and patients who average < 1.065 m/s show significantly worse outcomes following surgery. Keywords: hip arthroscopy, FAIS, gait metrics