Hartman Robert A, Bell Kevin M, Quan Bichun, Nuzhao Yao, Sowa Gwendolyn A, Kang James D
Departments of *Physical Medicine and Rehabilitation †Bioengineering ‡Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA §Finance and Trade Hospital of Hunan Province, Tianxin, Changsha ∥The First Affiliated Hospital of University of South China, Xiangtan, Hunan, China.
J Spinal Disord Tech. 2015 Apr;28(3):E146-53. doi: 10.1097/BSD.0000000000000196.
An in vitro biomechanical study for rabbit lumbar functional spinal units (FSUs) using a robot-based spine testing system.
To elucidate the effect of annular puncture with a 16 G needle on mechanical properties in flexion/extension, axial rotation, and lateral bending.
Needle puncture of the intervertebral disk has been shown to alter mechanical properties of the disk in compression, torsion, and bending. The effect of needle puncture in FSUs, where intact spinal ligaments and facet joints may mitigate or amplify these changes in the disk, on spinal motion segment stability subject to physiological rotations remains unknown.
Rabbit FSUs were tested using a robot testing system whose force/moment and position precision were assessed to demonstrate system capability. Flexibility testing methods were developed by load-to-failure testing in flexion/extension, axial rotation, and lateral bending. Subsequent testing methods were used to examine a 16 G needle disk puncture and No. 11 blade disk stab (positive control for mechanical disruption). Flexibility testing was used to assess segmental range-of-motion (degrees), neutral zone stiffness (N m/degrees) and width (degrees and N m), and elastic zone stiffness before and after annular injury.
The robot-based system was capable of performing flexibility testing on FSUs-mean precision of force/moment measurements and robot system movements were <3% and 1%, respectively, of moment-rotation target values. Flexibility moment targets were 0.3 N m for flexion and axial rotation and 0.15 N m for extension and lateral bending. Needle puncture caused significant (P<0.05) changes only in flexion/extension range-of-motion and neutral zone stiffness and width (N m) compared with preintervention. No. 11 blade-stab significantly increased range-of-motion in all motions, decreased neutral zone stiffness and width (N m) in flexion/extension, and increased elastic zone stiffness in flexion and lateral bending.
These findings suggest that disk puncture and stab can destabilize FSUs in primary rotations.
使用基于机器人的脊柱测试系统对兔腰椎功能脊柱单元（FSU）进行体外生物力学研究。
阐明用16G针进行椎间盘穿刺对屈伸、轴向旋转和侧方弯曲力学性能的影响。
椎间盘穿刺已被证明会改变椎间盘在压缩、扭转和弯曲时的力学性能。在完整的脊柱韧带和小关节可能减轻或放大椎间盘这些变化的功能脊柱单元中，针刺对受生理旋转影响的脊柱运动节段稳定性的影响尚不清楚。
使用机器人测试系统对兔功能脊柱单元进行测试，评估其力/力矩和位置精度以证明系统能力。通过屈伸、轴向旋转和侧方弯曲的负载至破坏测试开发柔韧性测试方法。随后的测试方法用于检查16G针椎间盘穿刺和11号刀片椎间盘刺伤（机械破坏的阳性对照）。柔韧性测试用于评估环形损伤前后节段的活动范围（度）、中性区刚度（N·m/度）和宽度（度和N·m）以及弹性区刚度。
基于机器人的系统能够对功能脊柱单元进行柔韧性测试——力/力矩测量和机器人系统运动的平均精度分别<力矩-旋转目标值的3%和1%。柔韧性力矩目标为屈伸和轴向旋转时0.3N·m，伸展和侧方弯曲时0.15N·m。与干预前相比，针刺仅在屈伸活动范围、中性区刚度和宽度（N·m）方面引起显著（P<0.05）变化。11号刀片刺伤在所有运动中均显著增加活动范围，降低屈伸时的中性区刚度和宽度（N·m），并增加屈伸和侧方弯曲时的弹性区刚度。
这些发现表明，椎间盘穿刺和刺伤会使功能脊柱单元在主要旋转中不稳定。
