Abstract：
In unstable shoulders, excessive anteroinferior position of the humeral head relative to the glenoid can lead to a dislocation. Measuring humeral head position could therefore be valuable in quantifying shoulder laxity. The aim of this study was to measure (1) position of the humeral head relative to the glenoid and (2) joint space thickness during passive motion in unstable shoulders caused by traumatic anterior dislocations and in contralateral uninjured shoulders. A prospective cross-sectional CT-study was performed in patients with unilateral anterior shoulder instability. Patients underwent CT scanning of both injured and uninjured side in supine position (0° abduction and 0° external rotation) and in 60°, 90°, and 120° of abduction with 90° of external rotation without an external load. Subsequently, 3D virtual models were created of the humerus and the scapula to create a glenoid coordinate system to identify poster-anterior, inferior-superior, and lateral-medial position of the humeral head relative to the glenoid. Joint space thickness was defined as the average distance between the subchondral bone surfaces of the humeral head and glenoid. Fifteen consecutive patients were included. In supine position, the humeral head was positioned more anteriorly (p = 0.004), inferiorly (p = 0.019), and laterally (p = 0.021) in the injured compared to the uninjured shoulder. No differences were observed in any of the other positions. A joint-space thickness map, showing the bone-to-bone distances, identified the Hill-Sachs lesion footprint on the glenoid surface in external rotation and abduction, but no differences on average joint space thickness were observed in any position.
摘要：
在不稳定的肩膀上，肱骨头相对于关节盂的过度前下位置可导致脱位。因此，测量肱骨头位置在量化肩部松弛方面可能很有价值。这项研究的目的是测量（1）肱骨头相对于关节盂的位置，以及（2）被动运动过程中由创伤性前脱位引起的不稳定肩部和对侧未受伤肩部的关节间隙厚度。对单侧肩前不稳定的患者进行了前瞻性横断面CT研究。患者在仰卧位（0°外展和0°外旋）和60°位置接受了受伤和未受伤侧的CT扫描，90°,在没有外部负载的情况下，外旋90°外展120°。随后，3D虚拟模型被创建的肱骨和肩胛骨创建一个关节盂坐标系来识别前，劣等-优等，肱骨头相对于关节盂的外侧-内侧位置。关节间隙厚度定义为肱骨头软骨下骨表面与关节盂之间的平均距离。包括15例连续患者。仰卧位,肱骨头定位得更靠前（p=0.004），向下（p=0.019），与未受伤的肩膀相比，受伤的肩膀和侧面（p=0.021）。在任何其他位置没有观察到差异。关节空间厚度图，显示骨骼到骨骼的距离，确定了外旋转和外展中关节盂表面的Hill-Sachs病变足迹，但是在任何位置均未观察到平均关节间隙厚度的差异。
