Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.
Laboratory of Biomechanical Orthopedics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
J Shoulder Elbow Surg. 2018 Oct;27(10):1800-1808. doi: 10.1016/j.jse.2018.04.023. Epub 2018 Jun 27.
This study proposes a method for inferring the premorbid glenoid shape and orientation of scapulae affected by glenohumeral osteoarthritis (OA) to inform restorative surgery.
A statistical shape model (SSM) built from 64 healthy scapulae was used to reconstruct the premorbid glenoid shape based on anatomic features that are considered unaffected by OA. First, the method was validated on healthy scapulae by quantifying the accuracy of the predicted shape in terms of surface distance, glenoid version, and inclination. The SSM-based reconstruction was then applied to 30 OA scapulae. Glenoid version and inclination were measured fully automatically and compared between the original OA glenoids, SSM-based glenoid reconstructions, and healthy scapulae.
Validation on healthy scapulae showed a root-mean-square surface distance between original and predicted glenoids of 1.0 ± 0.2 mm. The prediction error was 2.3° ± 1.8° for glenoid version and 2.1° ± 2.0° for inclination. When applied to an OA dataset, SSM-based reconstruction restored average glenoid version and inclination to values similar to the healthy situation. No differences were observed between average orientation values measured on SSM-based reconstructed and healthy scapulae (P ≥ .10). However, the average orientation of the reconstructed premorbid glenoid differed from the average orientation of OA glenoids for Walch classes A1 (version) and B2 (version, inclination, and medialization).
The proposed SSM can predict the premorbid glenoid cavity of healthy scapulae with millimeter accuracy. This technique has the potential to reconstruct the premorbid glenoid cavity shape, as it was prior to OA, and thus to guide the positioning of glenoid implants in total shoulder arthroplasty.
本研究提出了一种从解剖学上推断受肩关节炎（OA）影响的肩胛骨的术前肩胛盂形状和方向的方法，以便为修复手术提供信息。
使用从 64 个健康肩胛骨构建的统计形状模型（SSM），基于被认为不受 OA 影响的解剖学特征来重建术前肩胛盂形状。首先，通过量化预测形状在表面距离、肩胛盂倾斜角和肩胛盂倾斜角方面的准确性，来验证该方法在健康肩胛骨上的有效性。然后，将 SSM 重建应用于 30 例 OA 肩胛骨。完全自动测量原始 OA 肩胛盂、SSM 重建肩胛盂和健康肩胛骨的肩胛盂倾斜角和倾斜角。
对健康肩胛骨的验证表明，原始和预测肩胛盂之间的均方根表面距离为 1.0 ± 0.2mm。预测误差为肩胛盂倾斜角 2.3°±1.8°，肩胛盂倾斜角 2.1°±2.0°。当应用于 OA 数据集时，SSM 重建恢复了平均肩胛盂倾斜角和倾斜角，使其接近健康情况。在 SSM 重建和健康肩胛骨上测量的平均方向值之间未观察到差异（P≥.10）。然而，重建的术前肩胛盂的平均方向与 OA 肩胛盂的平均方向（Walch 分类 A1 和 B2）的肩胛盂倾斜角、倾斜角和内移存在差异。
提出的 SSM 可以以毫米精度预测健康肩胛骨的术前肩胛盂形状。这项技术有可能重建术前肩胛盂形状，从而为全肩关节置换术中肩胛盂植入物的定位提供指导。
