Aims This study aimed to quantify the shoulder kinematics during an apprehension-relocation test in patients with anterior shoulder instability (ASI) and glenoid bone loss using the radiostereometric analysis (RSA) method. Kinematics were compared with the patient's contralateral healthy shoulder. Methods A total of 20 patients with ASI and > 10% glenoid bone loss and a healthy contralateral shoulder were included. RSA imaging of the patient's shoulders was performed during a repeated apprehension-relocation test. Bone volume models were generated from CT scans, marked with anatomical coordinate systems, and aligned with the digitally reconstructed bone projections on the RSA images. The glenohumeral joint (GHJ) kinematics were evaluated in the anteroposterior and superoinferior direction of: the humeral head centre location relative to the glenoid centre; and the humeral head contact point location on the glenoid. Results During the apprehension test, the centre of the humeral head was 1.0 mm (95% CI 0.0 to 2.0) more inferior on the glenoid for the ASI shoulder compared with the healthy shoulder. Furthermore, the contact point of the ASI shoulder was 1.4 mm (95% CI 0.3 to 2.5) more anterior and 2.0 mm (95% CI 0.8 to 3.1) more inferior on the glenoid compared with the healthy shoulder. The contact point of the ASI shoulder was 1.2 mm (95% CI 0.2 to 2.6) more anterior during the apprehension test compared to the relocation test. Conclusion The humeral head centre was located more inferior, and the GHJ contact point was located both more anterior and inferior during the apprehension test for the ASI shoulders than the healthy shoulders. Furthermore, the contact point displacement between the apprehension and relocation test revealed increased joint laxity for the ASI shoulder than the healthy shoulders. These results contribute to existing knowledge that ASI shoulders with glenoid bone loss may also suffer from inferior shoulder instability.

中文翻译：

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肩前部不稳定和关节盂骨丢失患者恐惧-重新定位试验期间的盂肱关节运动学。


目的 本研究旨在使用放射立体测量分析 （RSA） 方法量化肩关节前不稳定 （ASI） 和关节盂骨丢失患者在恐惧-重新定位试验期间的肩部运动学。将运动学与患者的对侧健康肩部进行比较。方法 共纳入 20 例 ASI 和 > 10% 关节盂骨丢失和健康的对侧肩关节患者。在反复忧虑-重新定位测试期间对患者肩部进行 RSA 成像。骨体积模型由 CT 扫描生成，用解剖坐标系标记，并与 RSA 图像上数字重建的骨骼投影对齐。盂肱关节 （GHJ） 运动学在前后和上下方向进行评估：肱骨头中心相对于关节盂中心的位置;以及肱骨头接触点在关节盂上的位置。结果 在恐惧试验期间，与健康肩部相比，ASI 肩关节盂头中心在关节盂上低 1.0 毫米 （95% CI 0.0 至 2.0）。此外，与健康肩关节相比，ASI 肩关节的接触点前部高 1.4 毫米 （95% CI 0.3 至 2.5），关节盂下部低 2.0 毫米 （95% CI 0.8 至 3.1）。与重新定位试验相比，在恐惧试验期间，ASI 肩关节的接触点向前多 1.2 毫米 （95% CI 0.2 至 2.6）。结论 在 ASI 肩部的恐惧试验中，肱骨头中心的位置更靠下，GHJ 接触点的位置比健康肩膀更靠前和更靠下。 此外，担忧和重新定位试验之间的接触点位移显示 ASI 肩关节松弛度高于健康肩部。这些结果有助于现有知识，即伴有关节盂骨丢失的 ASI 肩也可能患有下肩关节不稳定。