Biomechanical comparison of combined latissimus dorsi and teres major tendon transfer vs. latissimus dorsi tendon transfer in shoulders with irreparable anterosuperior rotator cuff tears.

Abstract

Irreparable anterosuperior rotator cuff tears (IASRCTs) can result in a gradual loss of active elevation and internal rotation, superior and anterior translation of the humeral head, and cuff tear arthropathy. Joint-preserving treatment options for IASRCTs in young and high-demand elderly patients remain a subject of ongoing debate. The aim of the study was to evaluate the biomechanical efficacy of the combined latissimus dorsi and teres major tendon (LDTM) transfer and compare it to an isolated latissimus dorsi (LD) transfer in a cadaveric IASRCT model. Eight cadaveric shoulders (mean age, 68.3±5.2 years; range 58-71) were tested with a custom shoulder testing system. All specimens were tested at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane under 4 conditions: (1) intact, (2) IASRCT, (3) combined LDTM transfer, and (4) isolated LD transfer. The superior and anteroinferior translation and subacromial contact pressure were measured. The effects of 3 different LD and LDTM muscle loading conditions were investigated to determine the effectiveness of the muscle transfer conditions. A linear mixed effect model was used for statistical analysis, followed by a Tukey post hoc test. IASRCTs significantly increased superior translation, anteroinferior translation, and subacromial peak contact pressure. Combined LDTM transfer significantly decreased superior and anteroinferior translation compared with IASRCTs in all positions and muscle loadings. Isolated LD transfer did not significantly decrease superior (P>.115) and anteroinferior translation (P>.151) compared to IASRCT at any abduction and muscle loads except superior translation at 60° abduction and 90° of external rotation (ER) (P<.036). LDTM transfer also significantly decreased peak contact pressure from the IASRCT condition at every abduction angle (P<.046). However, isolated LD transfer significantly decreased subacromial peak contact pressure only at 30° abduction and 0° and 30° of ER with triple loading (P<.048), as well as at 60° abduction and 90° of ER (P<.003). Combined LDTM transfer decreased superior translation, anteroinferior translation, and subacromial contact pressure compared with the IASRCT condition. Isolated LD transfer did not improve glenohumeral translation and subacromial contact pressure. Combined LDTM transfer may be a more reliable treatment option than isolated LD transfer in patients with an IASRCT.