PURPOSE: To quantify the improvement of patients undergoing scope-assisted lower trapezius tendon transfer (SALTT) for irreparable rotator cuff tears (IRCTs) and whether intraoperative subscapularis management affected these outcomes. METHODS: From 2015 to 2023, patients undergoing primary SALTT for IRCTs without osteoarthritis or brachial plexopathy with serial follow-up at 6 months and a minimum of 12 months postoperatively were identified. Subjective shoulder value (SSV) scores, active forward elevation (FE), external rotation (ER) lag, and cuff strength were recorded. Continuous variables were analyzed with 1-way or repeated-measures analysis of variance, and a multivariate linear regression was performed evaluating demographic, radiographic, and intraoperative variable effects on SSV and ER lag. RESULTS: Seventy-six (mean age: 56.5 ± 8.1 years
body mass index: 29.0 ± 4.3
73% male) patients, operated on by 4 surgeons (A: 66%
B: 15%
C: 13%
D: 4%), had significant improvement in baseline SSV scores (mean: 23.9 ± 13.1) to 6-month (mean: 73.5 ± 10.6, 91% minimal clinically important difference achievement, P <
.001) and final (mean: 43.5 ± 29.5 months) follow-up scores (mean: 79.9 ± 16.5, 92% minimal clinically important difference achievement, P <
.001
n = 45/122: 37% 2-year inclusion rate). Regression analysis for final SSV showed age (β: 0.8, P = .017) to have a positive effect and subscapularis fatty infiltration (β: -10.6, P <
.001) to have a negative effect. Active FE improved from 6-month (139° ± 23.8°) to final (146° ± 23.0°, P = .013) follow-up while ER lag (17° ± 17°) improved as well (6-month mean: 3° ± 7.8°, P <
.001
final: 3° ± 5.6°, P <
.001). Regression analysis revealed subscapularis fatty infiltration (β: -11.6, P = .003) had a negative effect on final active FE, while infraspinatus fatty infiltration (β: -1.2, P = .048) and concomitant subscapularis repair (β: -5.0, P = .023) had a negative effect on final ER lag. Presence of subscapularis tears alone (β: 4.5, P = .030) had a positive effect on ER lag. Overall, 5 (7%) patients underwent reoperations. CONCLUSIONS: Patients with IRCT undergoing SALTT with or without subscapularis tears requiring repair achieve excellent short-term clinical outcomes while improving from an examination standpoint. LEVEL OF EVIDENCE: Level III, retrospective case series.