• Gyu Rim Baek, KimJung GonJGDepartment of Orthopaedic Surgery, Yeosu Baek Hospital, Yeosu-Si, Jeollanam-Do, Republic of Korea., Andrew P Nakla, Daniel Kwak, Min-Shik Chung, Michelle H McGarry, Gregory J Adamson, and Thay Q Lee.
• Orthopedic Biomechanics Laboratory, Congress Medical Foundation, 800 S Raymond Ave, Pasadena, CA, 91105, USA.
• Arch Orthop Trauma Surg. 2023 Aug 1; 143 (8): 473147394731-4739.

IntroductionLatissimus dorsi and teres major (LDTM) tendon transfer has demonstrated better clinical outcomes compared to Latissimus dorsi (LD) transfer for irreparable anterosuperior cuff (subscapularis/supraspinatus) tears; however, the biomechanical effects of these procedures are unknown. Therefore, the objective of this study was to compare kinematics and internal rotation of LDTM transfer to LD transfer for anterosuperior cuff tear.MethodsEight cadaveric shoulders were tested in four conditions; (1) intact, (2) anterosuperior rotator cuff tear, (3) LDTM transfer, and (4) LD transfer. Glenohumeral kinematics and internal rotation at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane were measured. Muscle loading was applied based on physiological cross-sectional area ratios with three muscle loading conditions to simulate potentially increased tension due to the advanced insertion site of the transferred tendons.ResultsThe anterosuperior rotator cuff tear leads to a significant superior shift of the humeral head compared to intact at 0° and 30° abduction (p < 0.039). Both the LDTM (p < 0.047) and LD transfers (p < 0.032) significantly shifted the humeral head inferiorly compared to the tear condition.; however, the LDTM transfer shifted the head in the anteroinferior direction compared to the LD transfer at 60° abduction and 30° ER (p < 0.045). Both LDTM and LD transfer significantly increased internal resting rotation (p < 0.008) and maximum internal rotation (p < 0.008) compared to anterosuperior rotator cuff tear and intact at 30° and 60° abduction. LDTM transfer resulted in a significant internal resting rotation compared with the LD transfer at 30° abduction with double muscle loading (p = 0.02). At 0° abduction, the LDTM transfer (p < 0.027) significantly increased maximum internal rotation compared to anterosuperior rotator cuff tear and intact.ConclusionAlthough both LDTM and LD tendon transfer improved the abnormal humeral head apex position and internal rotation compared with the tear condition, the LDTM transfer was biomechanically superior to the LD transfer in a cadaveric model.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

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