Lower Trapezius Transfer for Irreparable Posterosuperior Rotator Cuff Tears Shows Improved Outcome Despite Subscapularis Tear Except With Smaller Gains in Internal Rotation

PURPOSE: To compare to clinical outcomes of lower trapezius transfer in patients with irreparable posterosuperior rotator cuff tears between patients with intact versus torn subscapularis tendons. METHODS: A retrospective review was conducted on patients who underwent arthroscopically assisted lower trapezius transfer using an Achilles tendon allograft between May 2017 and April 2023, with a minimum follow-up of 24 months. Subgroups included patients with an intact subscapularis and those with reparable subscapularis tears (based on Lafosse classification), which were managed by either debridement or repair. Patients with incomplete data or lost to follow-up were excluded. Clinical outcomes-including Visual Analog Scale, patient-reported outcome measures, and shoulder range of motion-were reported according to subscapularis integrity, with imaging evaluation of graft integrity assessed by magnetic resonance imaging and arthritis progression evaluated by X-ray. RESULTS: A total of 75 patients (37 males and 38 females) were included (mean age, 62.9 ± 6.7 years in the intact subscapularis group and 64.6 ± 6.0 years in the subscapularis tear group). The mean follow-up was 47.3 ± 11.9 months (range, 24-66) and 51.9 ± 9.2 months (range, 30-68), respectively (P = .156). All patients regardless of subscapularis tear or intact showed significant postoperative improvements in Visual Analog Scale, patient-reported outcome measures, and range of motion. Patients in the tear group had significantly poorer preoperative internal rotation (P < .001), and those with repaired Lafosse type II or III tears showed smaller gains in internal rotation postoperatively compared with the intact group (P < .001). However, there were no statistically significant differences in final postoperative patient-reported outcome measures between groups (American Shoulder and Elbow Surgeons, 74.0 ± 15.2 vs 70.0 ± 10.5, P = .324; Constant, 64.5 ± 12.8 vs 63.9 ± 10.4, P = .86). CONCLUSIONS: Lower trapezius transfer provides favorable postoperative outcomes in patients with irreparable patients with irreparable posterosuperior rotator cuff tears, with overall improvements in pain, patient-reported outcome measures, range of motion, and complication rates generally comparable between patients with intact subscapularis tendons and those with tears. However, the quality and severity of subscapularis pathology can selectively influence specific functional outcomes, as patients with repaired Lafosse types II and III tears may experience relatively smaller gains in internal rotation behind the back. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.