Effect of Elevated BMI on Shoulder Stabilization Outcomes and Recurrence Rates

Body mass index (BMI) has been commonly studied in relation to hip and knee procedures, but the effect on shoulder instability procedures is less understood. This study aims to analyze BMI's relationship to clinical outcomes and recurrence rates after shoulder instability surgery.

Shoulder instability surgery in patients with elevated BMI will produce similar postoperative functional outcomes and recurrence rates to those with normal BMI.

Cohort study; Level of evidence, 3.

This is a single-institution, retrospective study of patients who underwent operative treatment for shoulder instability and had 6 months of clinical follow-up between 2009 and 2023. Primary procedures included Bankart repair, Latarjet, distal tibial allograft, Hill-Sachs bone grafting, and remplissage. Patients were stratified into 3 cohorts by BMI: underweight or normal weight (U/NW; BMI, ≤25 kg/m²), overweight (OW; BMI, >25 to ≤30 kg/m²), and obese (BMI, >30 kg/m²). Data collected from electronic medical records included patient demographics, clinical outcomes, and functional markers.

A total of 509 patients (391 male, 118 female) underwent surgery for recurrent shoulder instability. Of the total, 210 patients were normal or underweight (23 kg/m² [range, 21-24 kg/m²]), 184 patients were overweight (27 kg/m² [range, 26-28 kg/m²]), and 115 patients were obese (34 kg/m² [range, 32-38 kg/m²]). Age statistically differed across BMI cohorts at time of surgery (U/NW vs OW vs obese, 21 years [range, 18-27 years]; 24 years [range, 20-33 years]; 28 years [range, 20-35 years]; P < .001). Obese individuals had a greater depression rate, 36%, compared with 19% and 21% for U/NW and OW, respectively (P = .001). Preoperatively, the 3 cohorts statistically differed in terms of external rotation, forward elevation, and internal rotation range of motion. Obese patients had significantly lower postoperative internal rotation (T12) compared with the other cohorts (T10) (P < .001). Obese patients had an overall instability recurrence rate of 27%, compared with 16% in U/NW and 13% in OW patients (P = .33).

Our cohort demonstrated no significant association between obesity and outcomes of shoulder instability surgery. While the range of motion differences between the groups were statistically significant, these differences were not clinically significant and may be attributed to body habitus. Our findings suggest that shoulder instability surgery is a safe and effective procedure regardless of BMI.