BMI Serves as a Predictor of PROMIS Outcomes Following Hip Arthroscopy for Femoroacetabular Impingement at Minimum 1-Year Follow-up.

BACKGROUND: Body mass index (BMI) and metabolic health are increasingly recognized as important predictors of recovery after hip arthroscopy for femoroacetabular impingement, yet limited data exist on how outcomes vary across the full BMI spectrum. PURPOSE: To evaluate the impact of BMI-from underweight to morbidly obese-on Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF), pain interference (PI), and depression (Dep) scores following hip arthroscopy. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A single-institution review was performed for patients undergoing hip arthroscopy for femoroacetabular impingement from 2015 to 2024. Patients were stratified by BMI: underweight (<18.5), normal (18.5 ≤ to <30), obese (30 ≤ to ≤40), and morbidly obese (>40). PROMIS PF, PI, and Dep scores were collected preoperatively and ≥1 year postoperatively. Wilcoxon tests evaluated within-group changes; analysis of variance and regression analyses compared outcomes between BMI groups, adjusting for demographic covariates. RESULTS: A total of 415 patients (mean follow-up, 28.1 ± 15.8 months) met inclusion criteria. Both normal and obese BMI groups demonstrated significant improvements across all PROMIS domains from pre- to postoperative assessments (P < .05). However, compared with the normal group, the obese group had significantly worse scores pre- and postoperatively in PF (P = .0004 and P = .005, respectively), PI (P = .01 and P = .03, respectively), and Dep (P = .002 and P = .007, respectively). Underweight patients had significantly lower preoperative PF scores (P = .02) but showed greater improvement in postoperative Dep scores (P = .04) compared with the other groups. Within-group analysis revealed that underweight patients improved only in PF (P = .005), while morbidly obese patients showed no significant improvement in any PROMIS domain. CONCLUSION: Extremes of BMI are associated with diminished recovery following hip arthroscopy for femoroacetabular impingement, particularly in pain and mental health domain improvement. These findings highlight the need for targeted preoperative optimization and patient counseling for individuals with metabolic or nutritional risk factors.