Abstract：
BACKGROUND: Preoperative three-dimensional 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.
METHODS: Three surgeons performed a prospective study utilizing 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 utilized to 3D print not only the humerus, but also all four rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicon 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: Phase 1: Humeral neck cuts were performed on all specimens without any preoperative humeral planning, Phase 2: 3D planning was performed, and the cuts and implant selection were repeated, Phase 3: A neck shaft angle 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 neck shaft angle (NSA) was calculated for each phase. The difference in planned and actual cut thickness was also compared.
RESULTS: 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 = 0.041 for Phase 3 vs Phase 1). For NSA, in Phase 1: 7/15 (47%) cases were in varus, in Phase 2: 5/15 (33%) were in varus and Phase 3: 1/15 (7%) were in varus (p =0.013 for Phase 3 vs Phase 1).
CONCLUSIONS: Use of preoperative 3-D humeral planning for stemless anatomic TSA improved prosthetic humeral center of rotation, whether performed with or without standard transfer instrumentation. The use of a neck-shaft angle cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.
METHODS: Three surgeons performed a prospective study utilizing 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 utilized to 3D print not only the humerus, but also all four rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicon 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: Phase 1: Humeral neck cuts were performed on all specimens without any preoperative humeral planning, Phase 2: 3D planning was performed, and the cuts and implant selection were repeated, Phase 3: A neck shaft angle 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 neck shaft angle (NSA) was calculated for each phase. The difference in planned and actual cut thickness was also compared.
RESULTS: 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 = 0.041 for Phase 3 vs Phase 1). For NSA, in Phase 1: 7/15 (47%) cases were in varus, in Phase 2: 5/15 (33%) were in varus and Phase 3: 1/15 (7%) were in varus (p =0.013 for Phase 3 vs Phase 1).
CONCLUSIONS: Use of preoperative 3-D humeral planning for stemless anatomic TSA improved prosthetic humeral center of rotation, whether performed with or without standard transfer instrumentation. The use of a neck-shaft angle cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.
摘要：
背景：在过去的十年中，基于三维CT的解剖全肩关节置换术（TSA）术前计划越来越受欢迎，主要集中在关节盂上。很少有研究评估肱骨规划是否对肱骨切口的手术执行或假体的定位有任何影响。
方法：三名外科医生利用现有患者的CT打印的3D打印肱骨进行了一项前瞻性研究，在大型数据库中选择所有患者的-3、-1、0、1和3个标准偏差。一种新颖的3D打印工艺不仅用于肱骨的3D打印，还有四个肩袖肌腱.对于每个外科手术，印刷的肱骨安装在硅肩内，印有肌肉组织和皮肤，并且具有类似于人体组织的张力，需要标准的牵开和仪器来暴露肱骨。设计了三个阶段的研究：第一阶段：在没有任何术前肱骨规划的情况下对所有标本进行肱骨颈切割，阶段2：进行3D规划，重复切割和植入物的选择，阶段3:使用颈轴角导向器和数字卡尺来测量肱骨截骨厚度以辅助期望的肱骨切割。所有肱骨都被数字化了。计算假体旋转中心（COR）与理想COR之间的差异。计算每个阶段内翻颈轴角（NSA）患者的百分比。还比较了计划和实际切割厚度的差异。
结果：对于COR的3D变化和COR的内侧到外侧变化，单独使用术前计划和标准转移器械可显著改善理想COR的解剖恢复.与计划切割厚度的偏差随每个阶段而减小：第1阶段：2.6±1.9mm，阶段2:2.0±1.3mm,阶段3:1.4±0.9mm(阶段3与阶段1的p=0.041)。对于国安局来说,在第一阶段：7/15(47%)病例出现内翻，在第2阶段：5/15（33％）为内翻，第3阶段：1/15（7％）为内翻（第3阶段与第1阶段的p=0.013）。
结论：术前三维肱骨计划用于无茎解剖TSA可改善假体肱骨旋转中心，无论是否使用标准转移仪器进行。使用颈轴角度切割导向器和卡钳测量切割厚度显着降低了肱骨内翻切割的百分比和与计划切割厚度的偏差。
方法：三名外科医生利用现有患者的CT打印的3D打印肱骨进行了一项前瞻性研究，在大型数据库中选择所有患者的-3、-1、0、1和3个标准偏差。一种新颖的3D打印工艺不仅用于肱骨的3D打印，还有四个肩袖肌腱.对于每个外科手术，印刷的肱骨安装在硅肩内，印有肌肉组织和皮肤，并且具有类似于人体组织的张力，需要标准的牵开和仪器来暴露肱骨。设计了三个阶段的研究：第一阶段：在没有任何术前肱骨规划的情况下对所有标本进行肱骨颈切割，阶段2：进行3D规划，重复切割和植入物的选择，阶段3:使用颈轴角导向器和数字卡尺来测量肱骨截骨厚度以辅助期望的肱骨切割。所有肱骨都被数字化了。计算假体旋转中心（COR）与理想COR之间的差异。计算每个阶段内翻颈轴角（NSA）患者的百分比。还比较了计划和实际切割厚度的差异。
结果：对于COR的3D变化和COR的内侧到外侧变化，单独使用术前计划和标准转移器械可显著改善理想COR的解剖恢复.与计划切割厚度的偏差随每个阶段而减小：第1阶段：2.6±1.9mm，阶段2:2.0±1.3mm,阶段3:1.4±0.9mm(阶段3与阶段1的p=0.041)。对于国安局来说,在第一阶段：7/15(47%)病例出现内翻，在第2阶段：5/15（33％）为内翻，第3阶段：1/15（7％）为内翻（第3阶段与第1阶段的p=0.013）。
结论：术前三维肱骨计划用于无茎解剖TSA可改善假体肱骨旋转中心，无论是否使用标准转移仪器进行。使用颈轴角度切割导向器和卡钳测量切割厚度显着降低了肱骨内翻切割的百分比和与计划切割厚度的偏差。
