Impact of body mass index on clinical outcomes following arthroscopically assisted lower trapezius tendon transfer for irreparable posterosuperior rotator cuff tears.

Background: Arthroscopically assisted lower trapezius (LT) tendon transfer is an effective surgical option for irreparable posterior superior rotator cuff tears (PSRCTs). The present study aims to compare postoperative clinical outcomes between patients with normal weight (body mass index (BMI) 18.5-24.9) and those classified as Overweight (BMI 25.0-29.9) following arthroscopically assisted LT transfer for irreparable PSRCTs. It was hypothesized that BMI does not influence postoperative functional outcomes. Methods: Patients with irreparable PSRCTs who underwent arthroscopically assisted LT transfer between May 2017 and December 2022 were retrospectively analyzed. Inclusion criteria were symptomatic irreparable PSRCTs without advanced arthritis and minimum 2-year follow-up. Exclusion criteria included, concomitant biceps superior capsular reconstruction, loss to follow-up, and incomplete data. Clinical outcomes, including pain (visual analog scale), shoulder function (Activities of Daily Living External Rotation, Constant, University of California Los Angeles, American Shoulder and Elbow Surgeons scores), and active range of motion (ROM), were assessed preoperatively and at the final follow-up. The correlation analysis between BMI and postoperative clinical improvements was evaluated. Results: Of the 145 patients initially considered, 124 (normal weight, n = 86; overweight, n = 38) were included in the final analysis after excluding 21 for incomplete data, lost to follow-up, and treated concomitant biceps superior capsular reconstruction. When comparing the 2 groups, both demonstrated significant improvement in pain, shoulder function, and ROM, but there were no significant differences in postoperative outcomes between them. Twenty-one patients (normal, n = 15; overweight, n = 6) experienced tendon retears (17 partial and 4 complete), and 6 of these developed glenohumeral arthritis (normal, n = 4; overweight, n = 2). Three patients with both retear and arthritis underwent reverse total shoulder arthroplasty (normal, n = 2; overweight, n = 1), and 2 patients with complete retears underwent revision LT transfer (normal, n = 1; overweight, n = 1). The remaining patients were managed conservatively. No significant differences in complication rates were observed between groups. Conclusion: This study demonstrated that arthroscopically assisted LT transfer for irreparable PSRCTs leads to significant improvements in pain, function, and ROM in both the normal and overweight groups. There were no significant differences in any postoperative outcomes between the 2 groups, with comparable gains observed across all measured clinical parameters. Furthermore, correlation analysis confirmed that BMI was not associated with the degree of clinical improvement.