Abstract
Purpose
This study aims to establish critical thresholds for preoperative muscle area and width that predict two-year postoperative outcomes and to explore the correlation between baseline muscle area and two-year postoperative recovery in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).Study design
Retrospective Cohort Study, Level IV.Methods
A cohort of 74 patients treated between March 2021 and March 2022 was analyzed. Preoperative MRI measurements were obtained for the cross-sectional area (CSA) and width of the iliopsoas, gluteus maximus, and gluteus medius/minimus muscles. Two years postoperatively, clinical outcomes including the International Hip Outcome Tool-12 (iHOT-12) and the modified Harris Hip Score (mHHS) were assessed. We evaluated correlations between preoperative muscle areas and postoperative outcomes using Pearson correlation coefficients. Multivariate linear regression models were constructed to identify independent associations between muscle CSA/width and postoperative outcomes. Additionally, receiver operating characteristic (ROC) curve analyses were used to explore potential relationships and thresholds between muscle area and the Patient Acceptable Symptom State (PASS) and the Minimal Clinically Important Difference (MCID).Results
ROC analyses demonstrated that pre-G-med/min width and CSA predicted several two-year endpoints, with notable performance for iHOT-12-PASS (width AUC 0.68, P = 0.0070; CSA AUC 0.66, P = 0.020) and mHHS-PASS (width AUC 0.85, P = 0.0030; CSA AUC 0.80, P = 0.0090); gluteus maximus (width AUC 0.67, P = 0.012; CSA AUC 0.67, P = 0.013) and iliopsoas (width AUC 0.69, P = 0.0060; CSA AUC 0.72, P = 0.0010) can predict iHOT-12-PASS. Correlation analyses revealed small-to-moderate positive relationships between preoperative gluteus medius/minimus width and CSA with postoperative mHHS and iHOT-12 scores. In multivariate models, Pre-G-med/min CSA remained a significant positive predictor of 2-year mHHS (β = 0.33, P = 0.034), while male sex emerged as a significant positive predictor for 2-year iHOT-12 (β = 0.35, P = 0.030 in the cross-sectional area model and β = 0.28, P = 0.049 in the width model).Conclusion
Preoperative widths and cross-sectional areas of the gluteus medius/minimus, gluteus maximus, and iliopsoas muscles may be associated with, and to a limited extent help predict, the clinical outcomes at two years postoperatively in patients with FAIS.