Abstract：
BACKGROUND: The role of tendon transfer and ideal insertion sites to improve axial rotation in reverse total shoulder arthroplasty (RTSA) is debated. We systematically reviewed the available biomechanical evidence to elucidate the ideal tendon transfer and insertion sites for restoration of external and internal rotation in the setting of RTSA and the influence of implant lateralization.
METHODS: We queried the PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify biomechanical studies examining the application of tendon transfer to augment shoulder external or internal rotation range of motion in the setting of concomitant RTSA. A descriptive synthesis of six included articles was conducted to elucidate trends in the literature.
RESULTS: Biomechanics literature demonstrates that increasing humeral-sided lateralization optimized tendon transfers performed for both ER and IR. The optimal latissimus dorsi (LD) transfer site for ER is posterior to the greater tuberosity (adjacent to the teres minor insertion); however, LD transfer to this site results in greater tendon excursion compared to posterodistal insertion site. In a small series with nearly 7-year mean follow-up, the LD transfer demonstrated longevity with all 10 shoulders having>50% ER strength compared to the contralateral native shoulder and a negative Hornblower\'s at latest follow-up; however, reduced electromyography activity of the transferred LD compared to the native contralateral side was noted. One study found that transfer of the pectoralis major has the greatest potential to restore IR in the setting of lateralized humerus RTSA.
CONCLUSIONS: To restore ER, LD transfer posterior on the greater tuberosity provides optimal biomechanics with functional longevity. The pectoralis major has the greatest potential to restore IR. Future clinical investigation applying the biomechanical principles summarized herein is needed to substantiate the role of tendon transfer in the modern era of lateralized RTSA.
METHODS: IV; systematic review.
METHODS: We queried the PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify biomechanical studies examining the application of tendon transfer to augment shoulder external or internal rotation range of motion in the setting of concomitant RTSA. A descriptive synthesis of six included articles was conducted to elucidate trends in the literature.
RESULTS: Biomechanics literature demonstrates that increasing humeral-sided lateralization optimized tendon transfers performed for both ER and IR. The optimal latissimus dorsi (LD) transfer site for ER is posterior to the greater tuberosity (adjacent to the teres minor insertion); however, LD transfer to this site results in greater tendon excursion compared to posterodistal insertion site. In a small series with nearly 7-year mean follow-up, the LD transfer demonstrated longevity with all 10 shoulders having>50% ER strength compared to the contralateral native shoulder and a negative Hornblower\'s at latest follow-up; however, reduced electromyography activity of the transferred LD compared to the native contralateral side was noted. One study found that transfer of the pectoralis major has the greatest potential to restore IR in the setting of lateralized humerus RTSA.
CONCLUSIONS: To restore ER, LD transfer posterior on the greater tuberosity provides optimal biomechanics with functional longevity. The pectoralis major has the greatest potential to restore IR. Future clinical investigation applying the biomechanical principles summarized herein is needed to substantiate the role of tendon transfer in the modern era of lateralized RTSA.
METHODS: IV; systematic review.
摘要：
背景：肌腱转移和理想的插入部位在反向全肩关节成形术（RTSA）中改善轴向旋转的作用存在争议。我们系统地回顾了现有的生物力学证据，以阐明在RTSA设置中恢复外部和内部旋转的理想肌腱转移和插入部位以及植入物侧向化的影响。
方法：我们查询了PubMed/MEDLINE，Embase,WebofScience,和Cochrane数据库，以确定生物力学研究，检查肌腱转移的应用，以增加伴随RTSA设置的肩关节外部或内部旋转运动范围。对六篇纳入的文章进行了描述性综合，以阐明文献中的趋势。
结果：生物力学文献表明，增加肱骨侧偏侧可以优化ER和IR的肌腱转移。ER的最佳背阔肌（LD）转移部位在大结节后面（邻近小圆插入）；但是，与远端后插入部位相比，LD转移到该部位会导致更大的肌腱偏移。在一个近7年平均随访的小系列中，在最近的随访中，LD转移证明了与对侧天然肩部相比，所有10个肩部的ER强度均>50％，并且Hornblower呈阴性；但是，与天然对侧相比，转移的LD的肌电图活动降低。一项研究发现，在肱骨RTSA偏侧的情况下，胸大肌的转移具有最大的恢复IR的潜力。
结论：要恢复ER，LD在更大结节上的后部转移提供了具有功能寿命的最佳生物力学。胸大肌具有最大的恢复IR的潜力。需要应用本文总结的生物力学原理进行未来的临床研究，以证实肌腱转移在现代横向RTSA中的作用。
方法：IV；系统评价。
方法：我们查询了PubMed/MEDLINE，Embase,WebofScience,和Cochrane数据库，以确定生物力学研究，检查肌腱转移的应用，以增加伴随RTSA设置的肩关节外部或内部旋转运动范围。对六篇纳入的文章进行了描述性综合，以阐明文献中的趋势。
结果：生物力学文献表明，增加肱骨侧偏侧可以优化ER和IR的肌腱转移。ER的最佳背阔肌（LD）转移部位在大结节后面（邻近小圆插入）；但是，与远端后插入部位相比，LD转移到该部位会导致更大的肌腱偏移。在一个近7年平均随访的小系列中，在最近的随访中，LD转移证明了与对侧天然肩部相比，所有10个肩部的ER强度均>50％，并且Hornblower呈阴性；但是，与天然对侧相比，转移的LD的肌电图活动降低。一项研究发现，在肱骨RTSA偏侧的情况下，胸大肌的转移具有最大的恢复IR的潜力。
结论：要恢复ER，LD在更大结节上的后部转移提供了具有功能寿命的最佳生物力学。胸大肌具有最大的恢复IR的潜力。需要应用本文总结的生物力学原理进行未来的临床研究，以证实肌腱转移在现代横向RTSA中的作用。
方法：IV；系统评价。
