Division of Shoulder and Elbow Surgery, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
J Bone Joint Surg Am. 2019 Jul 17;101(14):1253-1260. doi: 10.2106/JBJS.18.00541.
The purpose of this paper was to determine whether acromial morphology influences anteroposterior shoulder stability. We hypothesized that a more horizontal and higher position of the acromion in the sagittal plane would be associated with posterior instability.
In this retrospective study, patients with unidirectional posterior instability were age and sex-matched to a cohort of patients with unidirectional anterior instability. Both cohorts were compared with a control group of patients with no instability and no degenerative glenohumeral (rotator cuff and/or joint surface) or acromial changes. Measurements on radiographs included posterior acromial tilt, anterior and posterior acromial coverage (AAC and PAC), posterior acromial height (PAH), and the critical shoulder angle (CSA).
The number of patients enrolled in each instability group was 41, based on a priori power analysis. The control group consisted of 53 shoulders. Of the measured anatomic factors, PAH showed the most significant association with posterior instability (odds ratio [OR] = 1.8; p < 0.001) in the logistic regression model. PAH was significantly greater in the posterior instability group compared with the anterior instability group (30.9 versus 19.5 mm; p < 0.001). With a cutoff value of PAH of 23 mm, the OR for posterior instability was 39. Shoulders with posterior instability were also significantly different from normal shoulders with regard to PAH (p < 0.001), AAC (p < 0.001), and PAC (p < 0.001) whereas, in the shoulders with anterior instability, all of these values except the AAC (p = 0.011) did not differ from those of normal shoulders.
Specific acromial morphology is significantly associated with the direction of glenohumeral instability. In shoulders with posterior instability, the acromion is situated higher and is oriented more horizontally in the sagittal plane than in normal shoulders and those with anterior instability; this acromial position may provide less osseous restraint against posterior humeral head translation. A steep "Swiss chalet roof-type" acromion virtually excluded recurrent posterior instability in an albeit relatively small cohort of patients. Additional investigation is needed to determine the relevance of these findings for future treatment.
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
本文旨在探讨肩峰形态是否会影响肩盂前后向稳定性。我们假设肩峰在矢状面中更为水平和高位，将与后向不稳定相关。
本回顾性研究将单向后向不稳定患者与单向前向不稳定患者进行年龄和性别匹配，并与无不稳定、无退行性肩盂（肩袖和/或关节面）或肩峰改变的对照组患者进行比较。X 线片上的测量包括肩峰后倾、肩峰前覆盖（AAC）和肩峰后覆盖（PAC）、肩峰后高（PAH）和临界肩角（CSA）。
根据先验的功效分析，每组不稳定患者的入组人数为 41 例。对照组包括 53 个肩。在测量的解剖因素中，PAH 在逻辑回归模型中与后向不稳定的相关性最显著（比值比[OR] = 1.8；p < 0.001）。与前向不稳定组相比，后向不稳定组的 PAH 值显著更高（30.9 毫米对 19.5 毫米；p < 0.001）。当 PAH 截断值为 23 毫米时，后向不稳定的 OR 为 39。与正常肩相比，后向不稳定的肩在 PAH（p < 0.001）、AAC（p < 0.001）和 PAC（p < 0.001）方面也有显著差异，而在前向不稳定的肩中，除了 AAC（p = 0.011）外，所有这些值均与正常肩无差异。
特定的肩峰形态与盂肱关节不稳定的方向显著相关。在有后向不稳定的肩中，肩峰在矢状面中更高，且更为水平，与正常肩和前向不稳定的肩相比，其位置可能对肱骨头后向平移的骨约束作用较小。在一个相对较小的患者队列中，陡峭的“瑞士木屋屋顶型”肩峰几乎排除了复发性后向不稳定。需要进一步研究以确定这些发现对未来治疗的相关性。
预后 III 级。请参阅作者说明以获取完整的证据水平描述。
