Department of Orthopedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
Institute for Sports & Reconstructive Surgery (ICR), Nice, France.
J Shoulder Elbow Surg. 2024 May;33(5):1169-1176. doi: 10.1016/j.jse.2023.09.026. Epub 2023 Oct 27.
Lateralization and distalization in reverse shoulder arthroplasty (RSA) can be measured on anteroposterior (AP) radiographs using 2 previously described angles: lateralization shoulder angle (LSA) and distalization shoulder angle (DSA). However, these 2 angles measure global lateralization and distalization but do not allow to differentiate how much lateralization or distalization are attributable to the glenoid and the humerus. We hypothesized that new angles could allow us to separately measure glenoid vs. humeral lateralization and distalization. A more precise understanding of independent glenoid and humeral contributions to lateralization and distalization may be beneficial in subsequent clinical research.
Retrospective analysis of postoperative AP radiographs of 100 patients who underwent primary RSA for cuff-tear arthropathy, massive cuff tear, or glenohumeral osteoarthritis were analyzed. The new angles that we proposed use well-known bony landmarks (the acromion, glenoid, and humerus) and the most lateral point of the glenosphere, which we termed the "glenoid pivot point" (GPP). For lateralization, we used the GPP to split LSA into 2 new angles: glenoid lateralization angle (GLA) and humeral lateralization angle (HLA). For distalization, we introduced the modified distalization shoulder angle (mDSA) that can also be split into 2 new angles: glenoid distalization angle (GDA) and humeral distalization angle (HDA). Three orthopedic surgeons measured the new angles, using the online tool Tyche. Mean values with overall and individual standard deviations as well as intraclass correlation coefficients (ICCs) were calculated.
Because the angles form a triangle, the following equations can be made: LSA = GLA + HLA, and mDSA = GDA + HDA. All angles showed excellent inter- and intraobserver reliability (ICC = 0.92-0.97) with low means of individual standard deviations that indicate a precision of 2° for each angle.
Use of the most lateral part of the glenosphere (termed glenoid pivot point) allows us to separately measure glenoid vs. humeral lateralization and distalization. The 4 new angles (HLA, GLA, GDA, HDA) described in the present study can be used on true AP radiographs, routinely obtained after shoulder replacement, and the measured angles may be used with all types of reverse prostheses available.
在反式肩关节置换术（RSA）中，可以使用两种先前描述的角度在前后位（AP）射线上测量侧向和远移：侧向肩角（LSA）和远移肩角（DSA）。然而，这两个角度仅能测量整体的侧向和远移，而不能区分侧向和远移有多少是由肩盂和肱骨引起的。我们假设新的角度可以使我们分别测量肩盂和肱骨的侧向和远移。更精确地了解肩盂和肱骨对侧向和远移的独立贡献，可能对后续的临床研究有益。
回顾性分析了 100 例因肩袖撕裂性关节炎、巨大肩袖撕裂或肩肱关节炎而行初次 RSA 的患者的术后 AP 射线照片。我们提出的新角度使用了已知的骨标志（肩峰、肩盂和肱骨）和最外侧的肩盂窝点，我们称之为“肩盂旋转点”（GPP）。对于侧向，我们使用 GPP 将 LSA 分为两个新角度：肩盂侧向角（GLA）和肱骨侧向角（HLA）。对于远移，我们引入了改良的远移肩角（mDSA），它也可以分为两个新角度：肩盂远移角（GDA）和肱骨远移角（HDA）。三位骨科医生使用在线工具 Tyche 测量了新的角度。计算了平均值、整体和个体标准差以及组内相关系数（ICC）。
由于角度形成三角形，因此可以得出以下等式：LSA=GLA+HLA，而 mDSA=GDA+HDA。所有角度的观察者间和观察者内可靠性均非常好（ICC=0.92-0.97），个体标准差的平均值较低，表明每个角度的精度为 2°。
使用肩盂窝的最外侧部分（称为肩盂旋转点）可以使我们分别测量肩盂和肱骨的侧向和远移。本研究中描述的 4 个新角度（HLA、GLA、GDA、HDA）可以在真正的 AP 射线照片上使用，这些射线照片通常是在肩部置换后获得的，并且可以在所有类型的反式假体中使用测量得到的角度。
