Burton Douglas, McIff Terence, Fox Tyler, Lark Richard, Asher Marc A, Glattes R Chris
Department of Orthopedic Surgery, University of Kansas Medical Center, Kansas City 66160-7387, USA.
Spine (Phila Pa 1976). 2005 Dec 15;30(24):2765-71. doi: 10.1097/01.brs.0000190814.11514.5e.
A biomechanical study to assess the ability of posterior fixation techniques to stabilize a functional spine unit (FSU) after insertion of an anterior load-sharing device.
The objective of this study is to compare various posterior fixation techniques in combination with an anterior load-sharing implant.
Pedicle screws and translaminar facet screws have been shown to improve the stiffness of an FSU in combination with an anterior load-sharing device. No published studies, to our knowledge, have compared translaminar facet screw fixation versus bilateral and unilateral pedicle screw fixation used with an anterior load-sharing device.
Ten cadaveric FSUs were potted using methylmethacrylate and attached to a spine simulator mounted to an MTS Mini-Bionix testing machine. The simulator was configured to control compressive loading, axial torque, flexion, extension, and lateral bending. Each specimen was tested in the intact state and following the application of each of four stabilization techniques: custom cage alone, cage plus translaminar facet screw fixation, cage plus unilateral pedicle screw and plate fixation, and cage plus bilateral pedicle screw and rod fixation with transverse coupling. Compressive stiffness and total range of motion (ROM) between +/-8 Nm of torque were extracted from the raw data.
Each fixation method decreased ROM in torsion, flexion-extension, and lateral bending compared with the intact state. Unilateral pedicle fixation offered less stability than either of the other posterior fixations in all modes of testing except axial loading, where it was equivalent. Translaminar facet screw fixation was equivalent to bilateral pedicle screws in all modes tested.
Using a load-sharing interbody implant, translaminar facet screws are equivalent to bilateral pedicle screws in resisting motion in all three planes. Translaminar facet screws and bilateral pedicle screws offer greater stabilization in all three planes compared with unilateral pedicle screws and a single plate.
一项生物力学研究，旨在评估在前路负载分担装置植入后，后路固定技术稳定功能性脊柱单元（FSU）的能力。
本研究的目的是比较各种后路固定技术与前路负载分担植入物联合使用的情况。
已表明椎弓根螺钉和经椎板小关节螺钉与前路负载分担装置联合使用时可提高FSU的刚度。据我们所知，尚无已发表的研究比较经椎板小关节螺钉固定与与前路负载分担装置联合使用的双侧和单侧椎弓根螺钉固定。
使用甲基丙烯酸甲酯将10个尸体FSU制成标本，并连接到安装在MTS Mini-Bionix试验机上的脊柱模拟器上。模拟器配置为控制压缩载荷、轴向扭矩、屈伸和侧弯。每个标本在完整状态下以及在应用以下四种稳定技术中的每一种之后进行测试：单独使用定制椎间融合器、椎间融合器加经椎板小关节螺钉固定、椎间融合器加单侧椎弓根螺钉和钢板固定，以及椎间融合器加双侧椎弓根螺钉和带横向连接的棒固定。从原始数据中提取扭矩在+/-8 Nm之间时的压缩刚度和总活动范围（ROM）。
与完整状态相比，每种固定方法均降低了扭转、屈伸和侧弯时的ROM。在除轴向加载（在此情况下二者等效）之外的所有测试模式中，单侧椎弓根固定提供的稳定性均低于其他两种后路固定方法中的任何一种。在所有测试模式中，经椎板小关节螺钉固定与双侧椎弓根螺钉等效。
使用负载分担椎间植入物时，经椎板小关节螺钉在抵抗所有三个平面的运动方面与双侧椎弓根螺钉等效。与单侧椎弓根螺钉和单块钢板相比，经椎板小关节螺钉和双侧椎弓根螺钉在所有三个平面上均提供更大的稳定性。
