Bell Kevin M, Oh Adrianna, Cook Harold A, Yan Yiguo, Lee Joon Y
Ferguson Laboratory for Spine Research, Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
Ferguson Laboratory for Spine Research, Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
J Biomech. 2018 Mar 1;69:164-168. doi: 10.1016/j.jbiomech.2017.12.029. Epub 2018 Jan 5.
In-vitro biomechanical testing is widely performed for characterizing the load-displacement characteristics of intact, injured, degenerated, and surgically repaired osteoligamentous spine specimens. Traditional specimen fixture devices offer an unspecified rigidity of fixation, while varying in the associated amounts and reversibility of damage to and "coverage" of a specimen - factors that can limit surgical access to structures of interest during testing as well as preclude the possibility of testing certain segments of a specimen. Therefore, the objective of this study was to develop a specimen fixture system for spine biomechanical testing that uses components of clinically available spinal fixation hardware and determine whether the new system provides sufficient rigidity for spine biomechanical testing. Custom testing blocks were mounted into a robotic testing system and the angular deflection of the upper fixture was measured indirectly using linear variable differential transformers. The fixture system had an overall stiffness 37.0, 16.7 and 13.3 times greater than a typical human functional spine unit for the flexion/extension, axial rotation and lateral bending directions respectively - sufficient rigidity for biomechanical testing. Fixture motion when mounted to a lumbar spine specimen revealed average motion of 0.6, 0.6, and 1.5° in each direction. This specimen fixture method causes only minimal damage to a specimen, permits testing of all levels of a specimen, and provides for surgical access during testing.
体外生物力学测试广泛应用于表征完整、损伤、退变及手术修复的骨韧带脊柱标本的载荷-位移特性。传统的标本固定装置提供的固定刚度不明确，同时对标本造成的损伤量及可逆性以及对标本的“覆盖范围”各不相同，这些因素会限制测试过程中对感兴趣结构的手术操作，也排除了对标本某些节段进行测试的可能性。因此，本研究的目的是开发一种用于脊柱生物力学测试的标本固定系统，该系统使用临床可用脊柱固定硬件的组件，并确定新系统是否为脊柱生物力学测试提供足够的刚度。定制测试块安装在机器人测试系统中，使用线性可变差动变压器间接测量上固定装置的角偏转。该固定系统在屈伸、轴向旋转和侧弯方向上的整体刚度分别比典型的人体功能性脊柱单元大37.0倍、16.7倍和13.3倍，具有足够的刚度用于生物力学测试。安装到腰椎标本上时，固定装置在每个方向上的平均运动为0.6°、0.6°和1.5°。这种标本固定方法对标本造成的损伤极小，允许对标本的所有节段进行测试，并在测试过程中提供手术操作通道。
