Roch Paul Jonathan, Hemprich Constantin, Klockner Friederike, Meier Marc-Pascal, Jäckle Katharina, Lehmann Wolfgang, Wachowski Martin Michael, Weiser Lukas
Department of Trauma Surgery, Orthopaedics and Plastic Surgery, University of Göttingen, Göttingen, Germany.
DUO - Duderstadt Trauma Surgery and Orthopaedics, Duderstadt, Germany.
Global Spine J. 2025 Mar;15(2):445-458. doi: 10.1177/21925682231193642. Epub 2023 Aug 17.
In vitro human cadaveric biomechanical analysis.
Optimization of prostheses for cervical disc arthroplasties (CDA) reduces the risk of complications. The instantaneous helical axis (IHA) is a superior parameter for examining the kinematics of functional spinal units. There is no comprehensive study about the IHA after CDA considering all 3 motion dimensions.
Ten human functional spinal units C4-5 (83.2 ± 7.9 yrs.) were examined with an established measuring apparatus in intact conditions (IC), and after CDA, with 2 different types of prostheses during axial rotation, lateral bending, and flexion/extension. Eccentric preloads simulated strains. The IHA orientation and its position at the point of rest (IHA-position) were analyzed.
The results confirmed the existing data for IHA in IC. Lateral preloads showed structural alterations of kinematics after CDA: During axial rotation and lateral bending, the shift of the IHA-position was corresponding with the lateral preloads' applied site in IC, while after CDAs, it was vice versa. During lateral bending, the lateral IHA orientation was inclined, corresponding with the lateral preloads' applied site in the IC and oppositely after the CDAs. During flexion/extension, the lateral IHA orientation was nearly vertical in the IC, while after CDA, it inclined, corresponding with the lateral preloads' applied site. The axial IHA orientation rotated to the lateral preloads' corresponding site in the IC; after CDA, it was vice versa.
Both CDAs failed to maintain physiological IHA characteristics under lateral preloads, revealing a new aspect for improving prostheses' design and optimizing their kinematics.
体外人体尸体生物力学分析。
优化颈椎间盘置换术（CDA）的假体可降低并发症风险。瞬时螺旋轴（IHA）是检查功能性脊柱单元运动学的一个优越参数。目前尚无关于CDA后考虑所有三个运动维度的IHA的全面研究。
使用既定测量设备对10个C4 - 5节段的人体功能性脊柱单元（83.2±7.9岁）在完整状态（IC）下进行检查，并在CDA后，使用2种不同类型的假体在轴向旋转、侧弯和屈伸过程中进行检查。偏心预载荷模拟应变。分析IHA的方向及其在静止点的位置（IHA位置）。
结果证实了IC中IHA的现有数据。侧向预载荷显示CDA后运动学的结构改变：在轴向旋转和侧弯过程中，IHA位置的偏移与IC中侧向预载荷的施加部位相对应，而在CDA后则相反。在侧弯过程中，侧向IHA方向倾斜，与IC中侧向预载荷的施加部位相对应，而在CDA后则相反。在屈伸过程中，侧向IHA方向在IC中几乎垂直，而在CDA后则倾斜，与侧向预载荷的施加部位相对应。轴向IHA方向在IC中旋转到侧向预载荷的对应部位；在CDA后则相反。
两种CDA在侧向预载荷下均未能维持生理IHA特征，揭示了改善假体设计和优化其运动学的一个新方面。
