Lawrence Rebekah L, Ruder Matthew C, Zauel Roger, Bey Michael J
Bone and Joint Center, Department of Orthopaedic Surgery, Henry Ford Health System, 6135 Woodward Avenue, Detroit, MI 48202, USA.
Bone and Joint Center, Department of Orthopaedic Surgery, Henry Ford Health System, 6135 Woodward Avenue, Detroit, MI 48202, USA.
J Biomech. 2020 Aug 26;109:109924. doi: 10.1016/j.jbiomech.2020.109924. Epub 2020 Jul 2.
The rotator cuff is theorized to contribute to force couples required to produce glenohumeral kinematics. Impairment in these force couples would theoretically result in impaired ball-and-socket kinematics. Although less frequently used than traditional kinematic descriptors (e.g., Euler angles, joint translations), helical axes are capable of identifying alterations in ball-and-socket kinematics by quantifying the variability (i.e., dispersion) in axis orientation and position during motion. Consequently, assessing glenohumeral helical dispersion may provide indirect evidence of rotator cuff function. The purpose of this exploratory study was to determine the extent to which rotator cuff pathology is associated with alterations in ball-and-socket kinematics. Fifty-one participants were classified into one of five groups based on an assessment of the supraspinatus using diagnostic imaging: asymptomatic healthy, asymptomatic tendinosis, asymptomatic partial-thickness tear, asymptomatic full-thickness tear, symptomatic full-thickness tear. Glenohumeral kinematics were quantified during coronal plane abduction using a biplane x-ray system and described using instantaneous helical axes. The degree to which glenohumeral motion coincided with ball-and-socket kinematics was described using the angular and positional dispersion about the optimal helical axis and pivot, respectively. No statistically significant difference was observed between groups in angular dispersion. However, symptomatic individuals with a full-thickness supraspinatus tear had significantly more positional dispersion than asymptomatic individuals with a healthy supraspinatus or tendinosis. These findings suggest that symptomatic individuals with a full-thickness supraspinatus tear exhibit impaired ball-and-socket kinematics, which is believed to be associated with a disruption of the glenohumeral force couples.
理论上，肩袖有助于形成产生盂肱关节运动学所需的力偶。这些力偶的损伤在理论上会导致球窝关节运动学受损。尽管螺旋轴的使用频率低于传统的运动学描述符（如欧拉角、关节平移），但它能够通过量化运动过程中轴方向和位置的变异性（即离散度）来识别球窝关节运动学的改变。因此，评估盂肱关节螺旋离散度可能为肩袖功能提供间接证据。本探索性研究的目的是确定肩袖病变与球窝关节运动学改变的关联程度。根据对冈上肌的诊断性成像评估，将51名参与者分为五组之一：无症状健康组、无症状肌腱病组、无症状部分厚度撕裂组、无症状全层厚度撕裂组、有症状全层厚度撕裂组。使用双平面X射线系统在冠状面外展过程中对盂肱关节运动学进行量化，并使用瞬时螺旋轴进行描述。分别使用围绕最佳螺旋轴和枢轴的角度和位置离散度来描述盂肱关节运动与球窝关节运动学的符合程度。各组之间在角度离散度方面未观察到统计学上的显著差异。然而，有症状的冈上肌全层厚度撕裂个体的位置离散度明显高于无症状的冈上肌健康或患有肌腱病的个体。这些发现表明，有症状的冈上肌全层厚度撕裂个体表现出球窝关节运动学受损，这被认为与盂肱关节力偶的破坏有关。
