Ansaripour Hossein, Ferguson Stephen J, Flohr Markus
Institute for Biomechanics, D-HEST, ETH Zurich, Gloriastrasse 37/39, 8092 Zurich, Switzerland.
CeramTec GmbH, CeramTec-Platz 1-9, 73207 Plochingen, Germany.
Bioengineering (Basel). 2024 Aug 22;11(8):857. doi: 10.3390/bioengineering11080857.
(1) Background: The kinematic characteristics of disc prosthesis undergoing complex motion are not well understood. Therefore, examining complex motion may provide an improved understanding of the post-operative behavior of spinal implants. (2) Methods: The aim of this study was to develop kinematic tests that simulate multiplanar motion and combined rotational-translational motion in a disc prosthesis. In this context, five generic zirconia-toughened alumina (BIOLOX, CeramTec, Germany) ball and socket samples were tested in a 6 DOF spine simulator under displacement control with an axial compressive force of 100 N in five motion modes: (1) flexion-extension (FE = ± 7.5°), (2) lateral bending (LB = ± 6°), (3) combined FE-LB (4) combined FE and anteroposterior translation (AP = 3 mm), and (5) combined LB and lateral motion (3 mm). For combined rotational-translational motion, two scenarios were analyzed: excessive translational movement after sample rotation (scenario 1) and excessive translational movement during rotation (scenario 2). (3) Results: For combined FE-LB, the resultant forces and moments were higher compared to the unidirectional motion modes. For combined rotational-translational motion (scenario 1), subluxation occurred at FE = 7.5° with an incremental increase in AP translation = 1.49 ± 0.18 mm, and LB = 6° with an incremental increase of lateral translation = 2.22 ± 0.16 mm. At the subluxation point, the incremental increase in AP force and lateral force were 30.4 ± 3.14 N and 40.8 ± 2.56 N in FE and LB, respectively, compared to the forces at the same angles during unidirectional motion. For scenario 2, subluxation occurred at FE = 4.93° with an incremental increase in AP translation = 1.75 mm, and LB = 4.52° with an incremental increase in lateral translation = 1.99 mm. At the subluxation point, the incremental increase in AP force and lateral force were 39.17 N and 38.94 N in FE and LB, respectively, compared to the forces in the same angles during the unidirectional motion. (4) Conclusions: The new test protocols improved the understanding of in vivo-like behavior from in vitro testing. Simultaneous translation-rotation motion was shown to provoke subluxation at lower motion extents. Following further validation of the proposed complex motion testing, these new methods can be applied future development and characterization of spinal motion-preserving implants.
(1) 背景：对于经历复杂运动的椎间盘假体的运动学特征，目前尚未完全了解。因此，研究复杂运动可能有助于更好地理解脊柱植入物的术后行为。(2) 方法：本研究的目的是开发能够模拟椎间盘假体多平面运动以及旋转 - 平移复合运动的运动学测试方法。在此背景下，在一台6自由度脊柱模拟器中，对五个通用的氧化锆增韧氧化铝（BIOLOX，德国CeramTec公司）球窝样本进行测试，在位移控制下施加100 N的轴向压缩力，测试五种运动模式：(1) 屈伸运动（FE = ± 7.5°），(2) 侧弯运动（LB = ± 6°），(3) 屈伸 - 侧弯复合运动，(4) 屈伸与前后平移复合运动（AP = 3 mm），以及(5) 侧弯与侧向运动复合运动（3 mm）。对于旋转 - 平移复合运动，分析了两种情况：样本旋转后过度平移运动（情况1）和旋转过程中过度平移运动（情况2）。(3) 结果：对于屈伸 - 侧弯复合运动，与单向运动模式相比，合力和力矩更高。对于旋转 - 平移复合运动（情况1），在屈伸角度为7.5°时发生半脱位，前后平移增量增加 = 1.49 ± 0.18 mm，侧弯角度为6°时发生半脱位，侧向平移增量增加 = 2.22 ± 0.16 mm。在半脱位点，与单向运动相同角度时的力相比，屈伸和侧弯时前后力和侧向力的增量分别为30.4 ± 3.14 N和40.8 ± 2.56 N。对于情况2，在屈伸角度为4.93°时发生半脱位，前后平移增量增加 = 1.75 mm，侧弯角度为4.52°时发生半脱位，侧向平移增量增加 = 1.99 mm。在半脱位点，与单向运动相同角度时的力相比，屈伸和侧弯时前后力和侧向力的增量分别为39.17 N和38.94 N。(4)结论：新的测试方案有助于从体外测试更好地理解类似体内的行为。结果表明，同时进行的平移 - 旋转运动会在较低的运动幅度下引发半脱位。在对所提出的复杂运动测试进行进一步验证之后，这些新方法可应用于未来脊柱运动保留植入物的开发和特性研究。
