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

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. 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. 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. 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 III, retrospective cohort study.