Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
Am J Sports Med. 2019 Aug;47(10):2464-2468. doi: 10.1177/0363546519858418. Epub 2019 Jun 27.
It has been believed that a Hill-Sachs lesion (HSL) is created with the arm in abduction and external rotation at the time of dislocation. However, no studies have clarified the arm position in which an HSL is created.
To determine the arm position in which an HSL is created.
Descriptive laboratory study.
The computed tomography images of 100 shoulders of 100 patients (72 males and 28 females; mean age, 30 years old) with recurrent anterior dislocation of the shoulder were investigated using an image analyzing software. Three-dimensional surface bone models of the scapula and humerus were created separately. The humerus was moved so that the HSL perfectly fit the anterior rim of the glenoid. This arm position was recorded 3-dimensionally.
Considering the scapulohumeral rhythm, the average arm position in which the HSL and the anterior glenoid rim best fit was 74° of abduction, 27° of external rotation, and 3° of horizontal flexion relative to the trunk.
The arm position when an HSL and the anterior glenoid rim best fit is 74° of abduction, 27° of external rotation, and 3° of horizontal flexion, which seems to be the arm position when the HSL has been created. This result suggests 2 possibilities: dislocation occurred in this midrange position or HSL was not created at the time of dislocation but later in the mid-range of motion. However, as we have no information on the arm position at the time of dislocation, we cannot conclude which of these possibilities is true in our study.
This study gives us a better understanding of the timing of HSL occurrence. Shoulder dislocation may occur at the end range of motion or in the mid-range of motion, but an HSL is created in the mid-range of motion.
人们一直认为 Hill-Sachs 损伤（HSL）是在肩关节脱位时手臂处于外展和外旋位时形成的。然而，尚无研究阐明形成 HSL 的手臂位置。
确定形成 HSL 的手臂位置。
描述性实验室研究。
使用图像分析软件研究了 100 例（72 名男性和 28 名女性；平均年龄 30 岁）复发性肩关节前脱位患者的 100 个肩部的计算机断层扫描图像。分别创建肩胛骨和肱骨的三维表面骨骼模型。使肱骨移动，使 HSL 与关节盂前缘完全吻合。将该手臂位置以三维方式记录下来。
考虑到肩肱节律，HSL 和前关节盂缘最吻合的平均手臂位置是相对于躯干外展 74°、外旋 27°和水平屈曲 3°。
HSL 和前关节盂缘最吻合的手臂位置是外展 74°、外旋 27°和水平屈曲 3°，这似乎是 HSL 形成的手臂位置。该结果提示了两种可能性：脱位发生在这个中间范围位置，或者 HSL 不是在脱位时形成的，而是在中间运动范围后期形成的。然而，由于我们没有关于脱位时手臂位置的信息，我们无法在我们的研究中得出哪种可能性是正确的结论。
本研究使我们更好地理解 HSL 发生的时机。肩关节脱位可能发生在末端运动范围或中间运动范围，但 HSL 是在中间运动范围形成的。
