Saul Katherine R, Hayon Solomon, Smith Thomas L, Tuohy Christopher J, Mannava Sandeep
Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
Clin Biomech (Bristol). 2011 Oct;26(8):804-10. doi: 10.1016/j.clinbiomech.2011.04.005. Epub 2011 May 19.
Despite surgical advances, repair of rotator cuff tears is associated with 20-70% incidence of recurrent tearing. The tension required to repair the torn tendon influences surgical outcomes and may be dependent on the gap length from torn tendon that must be spanned by the repair. Detailed understanding of forces throughout the range of motion (ROM) may allow surgeons to make evidence-based recommendations for post-operative care.
We used a computational shoulder model to assess passive tension and total moment-generating capacity in supraspinatus for repairs of gaps up to 3 cm throughout the shoulder (ROM).
In 60° abduction, increased gap length from 0.5 cm to 3 cm caused increases in passive force from 3N to 58 N, consistent with those seen during clinical repair. For reduced abduction, passive forces increased substantially. For a 0.5 cm gap, tension throughout the ROM (elevation, plane of elevation, and rotation) is within reasonable limits, but larger gaps are associated with tensions that markedly exceed reported pull-out strength of sutures and anchors. Peak moment for a large 3 cm gap length was 5.09 Nm, a 53% reduction in moment-generating capacity compared to uninjured supraspinatus.
We conclude that shoulder posture is an important determinant of passive forces during rotator cuff repair surgery. Choosing postures that reduce forces intraoperatively to permit repair of larger gaps may lead to failure postoperatively when the shoulder is mobilized. For larger defects, loss of strength in supraspinatus may be substantial following repair even if retear is prevented.
尽管手术技术有所进步，但肩袖撕裂修复术后复发性撕裂的发生率仍为20%-70%。修复撕裂肌腱所需的张力会影响手术效果，并且可能取决于修复时必须跨越的撕裂肌腱间隙长度。详细了解整个运动范围（ROM）中的力，可能有助于外科医生为术后护理提供循证建议。
我们使用一个肩部计算模型，评估在整个肩部ROM中，对于长达3厘米的间隙修复，冈上肌的被动张力和总力矩产生能力。
在60°外展时，间隙长度从0.5厘米增加到3厘米，导致被动力从3牛增加到58牛，与临床修复时观察到的情况一致。对于外展减少的情况，被动力大幅增加。对于0.5厘米的间隙，整个ROM（抬高、抬高平面和旋转）中的张力在合理范围内，但更大的间隙会导致张力明显超过报道的缝线和锚钉拔出强度。对于3厘米的大间隙长度，峰值力矩为5.09牛米，与未受伤的冈上肌相比，力矩产生能力降低了53%。
我们得出结论，肩部姿势是肩袖修复手术中被动力的一个重要决定因素。选择术中能减少力以允许修复更大间隙的姿势，在肩部活动时可能导致术后失败。对于较大的缺损，即使防止了再次撕裂，修复后冈上肌的力量损失可能仍然很大。
