Arthroscopic‐Assisted Lower Trapezius Transfer Improves Outcomes in Patients With Irreparable Posterosuperior Rotator Cuff Tears Irrespective of the Presence of External Rotation Lag Sign

PURPOSE: To evaluate whether arthroscopic-assisted lower trapezius transfer for irreparable posterosuperior rotator cuff tears provides comparable outcomes in patients with and without a preoperative external rotation (ER) lag sign and to analyze the progression of postoperative functional recovery over time. METHODS: Retrospective cohort study of patients with irreparable posterosuperior rotator cuff tears who underwent arthroscopic-assisted lower trapezius transfer with 2-year minimum follow-up. Patients were stratified according to the presence of a preoperative ER at the side (ER1) lag sign, and comparisons were performed. Range of motion, patient-reported outcomes, resolution of ER1 and ER at 90° of abduction (ER2) lag signs, and complications were collected preoperatively and postoperatively. The temporal pattern of functional recovery was assessed by comparing outcomes across successive follow-up time points. RESULTS: Fifty-three patients with a mean age of 56.5 ± 6.2 years were included. Twenty-one patients (40%) had a preoperative ER1 lag sign. Follow-up time was similar between patients with and without ER1 lag sign (39 ± 20 months [range 24-57] vs 30.5 ± 17.2 [range 24-57], respectively, P = .443). Both groups showed improvements in range of motion and patient-reported outcomes at the 24-month follow-up. At 24 months postoperatively, patients without a preoperative ER1 lag sign showed significantly greater ER1 and ER2 than those with an ER1 lag sign (ER1: 58° ± 11 vs 32° ± 16, respectively, P < .001; ER2: 84° ± 11 vs 71° ± 20, respectively, P = .021). Complete resolution of the ER1 and ER2 lag signs occurred in 81% and 80% of patients, respectively, with most recovery observed within the first 3 months postoperatively. At 24 months, the proportion of patients achieving the minimal clinically important difference was similar between groups across all range-of-motion parameters. CONCLUSIONS: Arthroscopic-assisted lower trapezius transfer significantly improves functional outcomes in patients with irreparable posterosuperior rotator cuff tears, irrespective of preoperative ER1 lag sign status, with most improvements occurring at 3 months postoperatively. Although overall outcomes were comparable, patients without a preoperative ER1 lag sign showed greater improvements in strength. LEVEL OF EVIDENCE: Level III, retrospective cohort study.