Abstract：
Knowledge of acromioclavicular (AC) joint kinematics and distance may provide insight into the biomechanical function and development of new treatment methods. However, accurate data on in vivo AC kinematics and distance between the clavicle and acromion remain unknown.
The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm.
Controlled laboratory study.
A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared.
Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001).
Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased.
These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.
The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm.
Controlled laboratory study.
A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared.
Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001).
Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased.
These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.
摘要：
■肩锁（AC）关节运动学和距离的知识可能会深入了解生物力学功能和新治疗方法的发展。然而,关于体内AC运动学和锁骨与肩峰之间距离的准确数据仍然未知。
■这项研究的目的是研究外展中手臂抬高过程中的3维交流运动学和距离，替罪羊,在健康人群中向前弯曲。假设交流运动学和距离会随着手臂的仰角和平面而变化。
■对照实验室研究。
■共纳入19名健康参与者的肩膀。使用组合的双荧光成像系统和计算机断层扫描来研究AC运动学和距离。计算AC关节的旋转和平移。AC距离测量为肩峰内侧边界与锁骨远端关节面(ASDC)之间的最小距离。最小距离点(MDP)比定义为MDP与ASDC的后边缘之间的长度除以ASDC的前后长度。比较了交流运动学以及不同仰角和角度之间的距离。
■渐进式内旋，向上旋转,在所有高程平面上观察到交流关节的向后倾斜。与肩胛骨相比，肩胛骨在外展时相对于锁骨向上旋转更多（P=0.002）和屈曲（P=0.005）。臂仰角显著影响AC关节的平移。与外展相比，肩峰在肩胛骨中横向平移更多，向后平移更多（P<.001）。在所有平面中，AC距离从初始位置减小到75°，并且在屈曲上明显更大（P<.001）。MDP比率随着仰角的增加而显著增加(P<.001)。
■在不同的高程平面上观察到交流关节的渐进旋转和显着平移。交流距离随着仰角从初始位置减小到75°。随着肩仰角的增加，ASDC与肩峰内侧边界之间的最小距离向前移动。
■这些结果可以作为未来研究的基准数据，旨在改善AC关节异常的手术治疗以恢复最佳功能。
■这项研究的目的是研究外展中手臂抬高过程中的3维交流运动学和距离，替罪羊,在健康人群中向前弯曲。假设交流运动学和距离会随着手臂的仰角和平面而变化。
■对照实验室研究。
■共纳入19名健康参与者的肩膀。使用组合的双荧光成像系统和计算机断层扫描来研究AC运动学和距离。计算AC关节的旋转和平移。AC距离测量为肩峰内侧边界与锁骨远端关节面(ASDC)之间的最小距离。最小距离点(MDP)比定义为MDP与ASDC的后边缘之间的长度除以ASDC的前后长度。比较了交流运动学以及不同仰角和角度之间的距离。
■渐进式内旋，向上旋转,在所有高程平面上观察到交流关节的向后倾斜。与肩胛骨相比，肩胛骨在外展时相对于锁骨向上旋转更多（P=0.002）和屈曲（P=0.005）。臂仰角显著影响AC关节的平移。与外展相比，肩峰在肩胛骨中横向平移更多，向后平移更多（P<.001）。在所有平面中，AC距离从初始位置减小到75°，并且在屈曲上明显更大（P<.001）。MDP比率随着仰角的增加而显著增加(P<.001)。
■在不同的高程平面上观察到交流关节的渐进旋转和显着平移。交流距离随着仰角从初始位置减小到75°。随着肩仰角的增加，ASDC与肩峰内侧边界之间的最小距离向前移动。
■这些结果可以作为未来研究的基准数据，旨在改善AC关节异常的手术治疗以恢复最佳功能。
