Grubb M R, Currier B L, Stone J, Warden K E, An K N
Department of Orthopaedics and Rehabilitation, Penn State University College of Medicine, Milton S. Hershey Medical Center, Hershey, USA.
Spine (Phila Pa 1976). 1997 Sep 1;22(17):1948-54. doi: 10.1097/00007632-199709010-00002.
In vitro biomechanical investigation with nondestructive and destructive testing in a human cadaveric model simulating a wide postlaminectomy condition.
To determine the relative stability conferred by a posterior cervical spinal rod system and posterior cervical plating.
Posterior cervical plate fixation has been shown to be biomechanically superior to wiring techniques, but lateral mass screws may injure neurovascular structures or facet joints if they are inserted improperly. A cervical rod system has been developed to enhance the safety of lateral mass instrumentation.
The cervical spines of 12 cadavers underwent biomechanical testing. After completion of the nondestructive intact testing, a wide laminectomy with subtotal facetectomies from C4 to C6 was performed. The specimens in two subgroups (group A, cervical spine rods with unicortical fixation, and group B, reconstruction plates with bicortical fixation) were tested in flexion, lateral bending, and torsion. Finally, destructive testing in flexion was performed. Stiffness, neutral zone, failure moment, energy to failure, and mechanism of failure were determined for each specimen. The data were analyzed using paired t tests and ANOVA.
Group B had a greater mean screw torque value. The instrumented constructs had a greater stiffness ratio (instrumented/intact) than the intact specimens in flexion, lateral bending, and torsional testing. Group A had a significantly greater flexural stiffness than Group B. Neutral zone ratio values were significantly lower during flexural testing for the cervical rod construct. Destructive testing resulted in significantly greater failure moment and energy-to-failure values for group A. In the cervical rod construct, failure occurred primarily by superior screw loosening with pull-out from the lateral mass. Reconstruction plates consistently failed with fracture of the lateral mass and superior screw loosening.
Significantly greater stability was noted in the cervical rod construct during nondestructive and destructive flexural testing.
在模拟广泛椎板切除术后状况的人体尸体模型中进行无损和破坏性测试的体外生物力学研究。
确定颈椎后路脊柱棒系统和颈椎后路钢板固定所赋予的相对稳定性。
颈椎后路钢板固定在生物力学上已被证明优于钢丝技术，但如果侧块螺钉植入不当，可能会损伤神经血管结构或小关节。已开发出一种颈椎棒系统以提高侧块器械操作的安全性。
对12具尸体的颈椎进行生物力学测试。在完成无损完整测试后，从C4至C6进行广泛的椎板切除术并部分切除小关节。将两个亚组（A组，单皮质固定的颈椎棒；B组，双皮质固定的重建钢板）的标本进行屈曲、侧弯和扭转测试。最后，进行屈曲破坏性测试。确定每个标本的刚度、中性区、破坏力矩、破坏能量和破坏机制。使用配对t检验和方差分析对数据进行分析。
B组的平均螺钉扭矩值更大。在屈曲、侧弯和扭转测试中，植入器械的结构比完整标本具有更高的刚度比（植入器械/完整）。A组的弯曲刚度明显大于B组。颈椎棒结构在弯曲测试期间的中性区比值明显更低。破坏性测试导致A组的破坏力矩和破坏能量值明显更大。在颈椎棒结构中，失效主要是由于上方螺钉松动并从小关节侧块拔出。重建钢板始终因小关节侧块骨折和上方螺钉松动而失效。
在无损和破坏性弯曲测试中，颈椎棒结构的稳定性明显更高。
