Ling H Y, Angeles J G, Horodyski M B
Department of Orthopaedics and Rehabilitation, University of Florida, Gainesville, FL, USA.
Clin Biomech (Bristol). 2009 Mar;24(3):261-6. doi: 10.1016/j.clinbiomech.2008.12.002. Epub 2009 Jan 30.
Latissimus dorsi transfer is the treatment most frequently used for restoring function in shoulders with irreparable posterosuperior rotator cuff tears. Yet, functional outcomes of the transfers are unpredictable and vary among patients.
A three-dimensional upper-extremity computational model was used to simulate and analyze the biomechanical consequences of transferring the latissimus dorsi to four attachment sites: the infraspinatus, supraspinatus, subscapularis and teres minor insertions. Functions of a normal shoulder were simulated, as well as those and of a shoulder with a posterosuperior rotator cuff tear before and after muscle transfers were simulated. Parameters such as active and passive moment-generating capacity, and the moment arm and fiber excursion ratio of the transferred muscle were analyzed.
All muscle transfers resulted in a large increase in shoulder external rotation strength. The latissimus dorsi was an external rotator after the transfer, but the fiber excursion ratio decreased accordingly. When the latissimus dorsi was transferred to the infraspinatus, supraspinatus or subscapularis insertion, it changed from extensor to flexor at the beginning of flexion. The flexion moment arm of the latissimus dorsi after the transfers was generally decreased. Shoulder abduction strength did not improve. Decrease in fiber excursion ratio during abduction and flexion was observed after the transfer. Side effects of the muscle transfers, such as the reduction of active adduction, extension and internal rotation of the shoulder, were explored.
A transfer to teres minor insertion was not recommended. Infraspinatus insertion was found to be a preferred attachment site in latissimus dorsi transfer, provided that the patient had a strong deltoid.
背阔肌转移术是修复不可修复的肩后上盂唇撕裂伤时最常用的恢复肩部功能的治疗方法。然而，该转移术的功能结果不可预测，且患者之间存在差异。
使用三维上肢计算模型模拟并分析将背阔肌转移至四个附着点（冈下肌、冈上肌、肩胛下肌和小圆肌附着点）的生物力学后果。模拟了正常肩部的功能，以及肩后上盂唇撕裂伤肩部在肌肉转移前后的功能。分析了诸如主动和被动力矩产生能力、转移肌肉的力臂和纤维偏移率等参数。
所有肌肉转移均导致肩部外旋力量大幅增加。转移后背阔肌成为外旋肌，但其纤维偏移率相应降低。当背阔肌转移至冈下肌、冈上肌或肩胛下肌附着点时，在屈曲开始时它从伸肌变为屈肌。转移后背阔肌的屈曲力臂通常减小。肩部外展力量未改善。转移后观察到外展和屈曲过程中纤维偏移率降低。探讨了肌肉转移的副作用，如肩部主动内收、伸展和内旋的减少。
不建议转移至小圆肌附着点。如果患者三角肌强壮，发现冈下肌附着点是背阔肌转移的首选附着点。
