Patel Bipin, Gustafson Peter A, Jastifer James
Department of Mechanical and Aeronautical Engineering, Western Michigan University, Kalamazoo, Michigan 49008, USA.
Clin Biomech (Bristol). 2012 Jun;27(5):436-42. doi: 10.1016/j.clinbiomech.2011.12.006. Epub 2012 Jan 5.
Clavicle malunion affects the biomechanics of the shoulder joint. The purpose of this study is to establish the abduction, flexion, and internal (medial) rotation biomechanics of the shoulder after clavicle malunion.
A computational study was performed utilizing a three-dimensional, validated computational model of the upper extremity. Sequential shortening of the clavicle up to 20% was simulated. Muscle forces, moment arms, and moments were calculated for the surrounding musculature through a range of flexion, abduction, and internal rotation during the simulated shortening.
Shortening of the clavicle decreases the shoulder elevation moments of the upper extremity muscles during abduction. Internal rotation moments are also decreased with shortening. Flexion moments were affected less through physiologic range of motion. The observed effects are due to a combination of changes in moment arms of the individual muscles as well as a decrease in the force generating capacity of the muscles. Additionally, shortening of the clavicle increases coronal angulation of the clavicle at the sternoclavicular joint.
Shortening causes a decrease in the moment generating capacity as well as the total force generating capacity of the shoulder girdle muscles. The clinical significance of these computational results, which are consistent with recent clinical studies, is validation of the proposed functional deficit caused by clavicle malunion.
锁骨畸形愈合会影响肩关节的生物力学。本研究的目的是确定锁骨畸形愈合后肩部的外展、屈曲和内（中）旋生物力学。
利用经过验证的上肢三维计算模型进行了一项计算研究。模拟了锁骨依次缩短达20%的情况。在模拟缩短过程中，通过一系列的屈曲、外展和内旋，计算了周围肌肉组织的肌肉力量、力臂和力矩。
锁骨缩短会降低外展过程中上肢肌肉的肩部抬高力矩。内旋力矩也会随着缩短而降低。在生理运动范围内，屈曲力矩受影响较小。观察到的这些影响是由于各肌肉力臂的变化以及肌肉产生力量能力的下降共同作用的结果。此外，锁骨缩短会增加锁骨在胸锁关节处的冠状面成角。
缩短会导致肩胛带肌肉产生力矩的能力以及总产生力量的能力下降。这些计算结果与近期临床研究一致，其临床意义在于验证了由锁骨畸形愈合导致的功能缺陷。
