Rosso Claudio, Nasr Michael, Walley Kempland C, Harlow Ethan R, Haghpanah Babak, Vaziri Ashkan, Ramappa Arun J, Nazarian Ara, DeAngelis Joseph P
Center for Advanced Orthopaedic Studies, Carl J. Shapiro Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
Department of Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States of America.
PLoS One. 2017 Jan 6;12(1):e0164549. doi: 10.1371/journal.pone.0164549. eCollection 2017.
The purpose of this biomechanical study was to determine the effect of shortened clavicle malunion on the center of rotation of the glenohumeral (GH) joint, and the capacity of repair to restore baseline kinematics.
Six shoulders underwent automated abduction (ABD) and abbreviated throwing motion (ATM) using a 7-DoF automated upper extremity testing system in combination with an infrared motion capture system to measure the center of rotation of the GH joint. ATM was defined as pure lateral abduction and late cocking phase to the end of acceleration. Torsos with intact clavicle underwent testing to establish baseline kinematics. Then, the clavicles were subjected to midshaft fracture followed by kinematics testing. The fractured clavicles underwent repairs first by clavicle length restoration with plate fixation, and then by wiring of fragments with a 2-cm overlap to simulate shortened malunion. Kinematic testing was conducted after each repair technique. Center of rotation of the GH joint was plotted across all axes to outline 3D motion trajectory and area under the curve.
Throughout ABD, malunion resulted in increased posterior and superior translation compared to baseline. Plate fixation restored posterior and superior translations at lower abduction angles but resulted in excess anterior and inferior translation at overhead angles. Throughout ATM, all conditions were significantly anterior and superior to baseline. Translation with malunion was situated anterior to the fractured and ORIF conditions at lower angles of external rotation. Plate fixation did not restore baseline anteroposterior or superoinferior translation at any angle measured.
This study illustrates the complex interplay of the clavicle and the GH joint. While abnormal clavicle alignment alters shoulder motion, restoration of clavicle length does not necessarily restore GH kinematics to baseline. Rehabilitation of the injured shoulder must address the osseous injury and the dynamic forces of the shoulder girdle.
本生物力学研究的目的是确定锁骨短缩畸形愈合对盂肱（GH）关节旋转中心的影响，以及修复恢复基线运动学的能力。
使用7自由度自动上肢测试系统结合红外运动捕捉系统，对六个肩部进行自动外展（ABD）和简化投掷动作（ATM），以测量GH关节的旋转中心。ATM定义为从纯外展到加速末期的晚期上举阶段。对锁骨完整的躯干进行测试以建立基线运动学。然后，对锁骨进行中段骨折，随后进行运动学测试。首先通过钢板固定恢复锁骨长度对骨折的锁骨进行修复，然后通过将碎片重叠2厘米进行钢丝固定以模拟短缩畸形愈合。每种修复技术后均进行运动学测试。绘制GH关节在所有轴上的旋转中心，以勾勒三维运动轨迹和曲线下面积。
在整个ABD过程中，与基线相比，畸形愈合导致后向和上向平移增加。钢板固定在较低外展角度时恢复了后向和上向平移，但在过顶角度时导致了过度的前向和下向平移。在整个ATM过程中，所有情况均显著位于基线的前方和上方。在较低外旋角度时，畸形愈合的平移位于骨折和切开复位内固定（ORIF）情况的前方。在任何测量角度下，钢板固定均未恢复基线的前后或上下平移。
本研究说明了锁骨与GH关节之间复杂的相互作用。虽然锁骨排列异常会改变肩部运动，但恢复锁骨长度不一定能将GH运动学恢复到基线。受伤肩部的康复必须解决骨损伤和肩带的动态力量问题。
