Werner Brian C, Lenters Timothy R, Thakur Siddhant, Knopf David, Metcalfe Nick, Tokish John M
Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, USA.
Trinity Health, Grand Rapids, MI, USA.
J Shoulder Elbow Surg. 2025 Jan;34(1):147-153. doi: 10.1016/j.jse.2024.04.011. Epub 2024 Jun 4.
Preoperative 3-dimensional (3D) computed tomography (CT)-based planning for anatomic total shoulder arthroplasty (TSA) has grown in popularity in the past decade with the primary focus on the glenoid. Little research has evaluated if humeral planning has any effect on the surgical execution of the humeral cut or the positioning of the prosthesis.
Three surgeons performed a prospective study using 3D-printed humeri printed from CTs of existing patients, which were chosen to be -3, -1, 0, 1, and 3 standard deviations of all patients in a large database. A novel 3D printing process was used to 3D print not only the humerus but also all 4 rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicone shoulder, with printed musculature and skin, and with tensions similar to human tissue requiring standard retraction and instruments to expose the humerus. Three phases of the study were designed. In phase 1, humeral neck cuts were performed on all specimens without any preoperative humeral planning; in phase 2, 3D planning was performed, and the cuts and implant selection were repeated; in phase 3, a neck-shaft angle (NSA) guide and digital calipers were used to measure humeral osteotomy thickness to aid in the desired humeral cut. All humeri were digitized. The difference between the prosthetic center of rotation (COR) and ideal COR was calculated. The percentage of patients with a varus NSA was calculated for each phase. The difference in planned and actual cut thickness was also compared.
For both 3D change in COR and medial to lateral change in COR, use of preoperative planning alone and with standard transfer instrumentation resulted in a significantly more anatomic restoration of ideal COR. The deviations from planned cut thickness decreased with each phase: phase 1: 2.6 ± 1.9 mm, phase 2: 2.0 ± 1.3 mm, phase 3: 1.4 ± 0.9 mm (P = .041 for phase 3 vs. phase 1). For NSA, in phase 1, 7 of 15 (47%) cases were in varus; in phase 2, 5 of 15 (33%) were in varus; and in phase 3, 1 of 15 (7%) cases was in varus (P = .013 for phase 3 vs. phase 1).
Use of preoperative 3D humeral planning for stemless anatomic TSA improved prosthetic humeral COR, whether performed with or without standard transfer instrumentation. The use of an NSA cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.
在过去十年中，基于术前三维（3D）计算机断层扫描（CT）的解剖型全肩关节置换术（TSA）规划越来越受欢迎，主要侧重于肩胛盂。很少有研究评估肱骨规划是否会对肱骨截骨的手术操作或假体的定位产生任何影响。
三位外科医生对从现有患者的CT扫描中3D打印出来的肱骨进行了一项前瞻性研究，这些肱骨被选为大型数据库中所有患者的-3、-1、0、1和3个标准差。一种新颖的3D打印工艺不仅用于3D打印肱骨，还用于打印所有4条肩袖肌腱。对于每个手术过程，将打印好的肱骨安装在一个带有打印肌肉组织和皮肤的硅胶肩部内，其张力类似于需要标准牵开和器械暴露肱骨的人体组织。该研究设计了三个阶段。在第1阶段，对所有标本进行肱骨颈截骨，术前不进行任何肱骨规划；在第2阶段，进行3D规划，并重复截骨和植入物选择；在第3阶段，使用颈干角（NSA）导向器和数字卡尺测量肱骨截骨厚度，以辅助进行理想的肱骨截骨。所有肱骨都进行了数字化处理。计算假体旋转中心（COR）与理想COR之间的差异。计算每个阶段内翻NSA患者的百分比。还比较了计划截骨厚度与实际截骨厚度之间的差异。
对于COR的三维变化以及COR的内侧到外侧变化，单独使用术前规划以及与标准转移器械一起使用，均能显著更接近理想COR地恢复解剖结构。与计划截骨厚度的偏差在每个阶段都有所减小：第1阶段：2.6±1.9毫米，第2阶段：2.0±1.3毫米，第3阶段：1.4±0.9毫米（第3阶段与第1阶段相比，P = 0.041）。对于NSA，在第1阶段，15例中有7例（47%）为内翻；在第2阶段，15例中有5例（33%）为内翻；在第3阶段，15例中有1例（7%）为内翻（第3阶段与第1阶段相比，P = 0.013）。
对于无柄解剖型TSA，使用术前3D肱骨规划可改善假体肱骨COR，无论是否使用标准转移器械。使用NSA截骨导向器和卡尺测量截骨厚度可显著降低肱骨内翻截骨的百分比以及与计划截骨厚度的偏差。
