Background:The open Latarjet procedure yields excellent results as a treatment for anterior shoulder instability. The position of the bony fragment and the insertion angle of the screw (the alpha angle) are critical factors for a successful procedure. The alpha angle is considered overangulated at >25°, which is associated with poor bone fixation and healing.Purpose:To assess preoperative patient anatomic factors that affect the alpha angle in the Latarjet procedure for anterior shoulder instability.Study Design:Case-control study; Level of evidence, 3.Methods:In this retrospective study, 76 patients who underwent the open Latarjet procedure between October 2009 and December 2023 were included. Postoperative computed tomography scans were reviewed for the alpha angle, and patients were classified into 2 groups: group 1 (alpha angle ≥25°) and group 2 (alpha angle <25°). Preoperative patient characteristics and radiological parameters obtained from preoperative computed tomography scans were analyzed and compared between groups 1 and 2. We developed a novel method to measure the depth of the chest and the angle between the deltopectoral interval and the plane of screw insertion. We also measured the thickness of the pectoralis major and subscapularis muscles.Results:Of the 76 patients in this study, 41 and 35 patients were included in groups 1 and 2, respectively. The mean alpha angles of groups 1 and 2 were 36° and 12°, respectively, and the body mass index was significantly higher in group 1 ( P < .001). In addition, group 1 had a significantly longer distance from the anterior edge of the glenoid to the skin margin of the deltopectoral interval ( P < .001). The angle between the deltopectoral interval and the plane of screw insertion (traction angle) was significantly larger in group 1 ( P < .001), and the pectoralis major and subscapularis muscles were thicker in group 1 ( P = .017 and P = .032, respectively).Conclusion:The alpha angle after the Latarjet procedure was strongly related to the patient's weight, body mass index, depth of the chest, and the angle between the deltopectoral interval and the plane of screw insertion. To our knowledge, this is the first study in which the preoperative factors that facilitate proper screw fixation in the Latarjet procedure are reported.

中文翻译：

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评估 Latarjet 开腹手术后影响螺钉插入 α 角的术前因素


背景： 开放 Latarjet 手术作为前肩不稳定的治疗效果极佳。骨碎片的位置和螺钉的插入角度（α 角）是手术成功的关键因素。α 角被认为在 >25° 处成角，这与骨固定和愈合不良有关。目的： 评估 Latarjet 手术中影响肩前不稳定 α 角的患者术前解剖因素。研究设计： 病例对照研究;证据水平， 3.方法： 在这项回顾性研究中，纳入了 2009年10月至 2023年12月期间接受开放性 Latarjet 手术的 76 例患者。回顾术后计算机断层扫描的 α 角，将患者分为 2 组： 第 1 组 （α 角 ≥25°） 和第 2 组 （α 角 <25°）。分析第 1 组和第 2 组之间术前患者特征和术前计算机断层扫描获得的放射学参数，并进行比较。我们开发了一种新方法来测量胸部的深度以及三角胸间和螺钉插入平面之间的角度。我们还测量了胸大肌和肩胛下肌的厚度。结果： 本研究的 76 例患者中，第 1 组和第 2 组分别包括 41 例和 35 例患者。第 1 组和第 2 组的平均 alpha 角分别为 36° 和 12°，第 1 组体重指数显著升高 （ P < .001）。此外，第 1 组从关节盂前缘到三角胸间的皮肤边缘的距离明显更长 （ P < .001）。 第 1 组三角胸间线与螺钉插入平面 （牵引角） 之间的角度显著较大 （ P < .001），第 1 组胸大肌和肩胛下肌较厚 （分别为 P = .017 和 P = .032）。结论： Latarjet 手术后的 α 角与患者的体重、体质量指数、胸部深度以及三角胸间与螺钉插入平面之间的角度密切相关。据我们所知，这是第一项报道了在 Latarjet 手术中促进正确螺钉固定的术前因素的研究。