Does latissimus dorsi tendon transfer provide a normal scapular rhythm and external rotation strength in posterosuperior massive irreparable rotator cuff tears? A kinematic analysis in a retrospective cohort

Background: Posterosuperior massive irreparable rotator cuff tears (PMIRT) are rare and disabling conditions. When conservative treatment fails, latissimus dorsi tendon transfer (LDTT) is a viable surgical option for symptom relief in carefully selected patients. However, its effectiveness in restoring glenohumeral function and its influence on scapulothoracic rhythm remain subjects of ongoing debate. Purpose: The purpose of this study was to evaluate the clinical outcomes of LDTT and assess its impact on scapulothoracic rhythm using kinematic and electromyographic analysis. Material and methods: A total of 18 patients with PMIRT underwent LDTT. Functional scores consisted of Constant-Murley score (CMS), America Shoulder and Elbow Surgeons (ASES) score, and Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score. Electromyography (EMG) activity of the latissimus dorsi muscle was evaluated in conjunction with three-dimensional (3D) kinematic tracking system. Differences in external rotation strength were compared with and without active adduction. Results: The mean age was 55.9 years (range 40–69 years), with a mean follow-up of 20.4 months (range 6–39 months). At final follow-up, the mean CMS was 68.2 (95% CI 64.9–71.5), ASES was 76.9 (95% CI 66.1–87.6), and QuickDASH was 17.6 (95% CI 9.5–25.6). A significant difference in external rotation strength was observed with and without active adduction (p <.0005). EMG confirmed latissimus dorsi activation in all patients, with no significant differences between rotation conditions (p >.05). Kinematic analysis showed an overall normal scapulothoracic rhythm, with significant differences only in scapular tilting during elevation and external rotation with the shoulder in adduction (p = 0.044 and p = 0.023, respectively). Conclusions: LDTT provides satisfactory clinical outcomes in patients with PMIRT, enhancing external rotation strength when the latissimus dorsi is actively recruited and contributing to near-normal scapulothoracic rhythm restoration. A structured, targeted postoperative rehabilitation protocol is essential to optimize outcomes. Level of evidence: IV.