Preoperative Hip Extension Strength Is an Independent Predictor of Achieving Clinically Significant Outcomes After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

Abstract

Background: The effect of preoperative hip strength on outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) is unclear. The purpose of this study was to determine whether preoperative isometric hip strength is associated with outcome scores at 6 months as well as achieving the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) in patients undergoing hip arthroscopy for FAIS. Hypothesis: Increased preoperative isometric strength will be correlated with short-term postoperative outcomes and will be predictive of achieving higher functional status. Study Design: Case series. Level of Evidence: Level 4. Methods: Data from 92 consecutive patients undergoing primary hip arthroscopy for treatment of FAIS from March through August 2018 were analyzed. All patients included in the analysis had preoperative measures of isometric hip strength on both affected and unaffected limbs, as well as preoperative and 6-month patient-reported outcome (PRO) scores. Analysis was performed to determine correlations between normalized isometric hip strength measurements and PROs and whether strength measurements were predictive of achieving MCID or PASS. Results: A total of 74 (80.4%) patients had 6-month PROs and were included in the final analysis. Hip extension strength on both sides was correlated with all postoperative PROs (all P > 0.05). Abduction strength on both sides was correlated with postoperative Hip Outcome Score–Activities of Daily Living subscale score, achieving MCID on at least 1 score threshold, and reaching the international Hip Outcome Tool-12 threshold score for achieving PASS (all P < 0.05). Regression analysis showed that extension strength on the affected side was the only strength measurement predictor of achieving PASS (1.043; P = 0.049). Conclusion: Preoperative isometric hip extension and abduction strength are correlated with 6-month postoperative PRO scores. Furthermore, hip extension strength is a predictor of achieving clinically meaningful outcomes. Clinical Relevance: This study highlights the possible importance of preoperative optimization of hip function to maximize outcomes in patients undergoing hip arthroscopy for FAIS.