Rohlmann A, Bergmann G, Graichen F, Weber U
Orthopaedic Hospital, Free University of Berlin, Germany.
Med Eng Phys. 1997 Sep;19(6):539-46. doi: 10.1016/s1350-4533(97)00018-0.
The loads on internal spinal fixation devices were measured using modified, telemeterized AO-Dick internal fixators. The implants allow measurement of the three force components and the three moments acting on the implant. The modified fixators were mounted on cadaver spines, and the implant loads were measured in the intact and postcorpectomy spines for different loading modes, including axial compression force, flexion, extension, lateral bending, and torsion. The in vitro experiment did not consider muscle forces. Modified fixators were also implanted in three patients, and the implant loads were determined before and after anterior interbody fusion with autologous iliac-crest bone grafts. The results for different in vitro loading modes were compared with those in vivo in order to demonstrate the extent to which the in vitro loads represent the real situation in patients. In several cases, the implant loads in the in vitro experiment differed strongly from those measured in patients. For flexion and lateral bending, a tensile axial force occasionally was measured in the in vitro experiment, while in the patients the axial force was always compressive. Extension was predominantly associated with extension bending moments in the in vitro study but with flexion bending moments in the patients. When muscle forces are not considered in the in vitro experiment, the loads on the fixators may differ significantly from the situation found in patients.
使用改良的、带有遥测功能的AO-Dick内固定装置测量脊柱内固定装置上的负荷。这些植入物能够测量作用于植入物的三个力分量和三个力矩。将改良后的固定装置安装在尸体脊柱上，并在完整脊柱和椎体切除术后的脊柱上，针对不同的加载模式测量植入物负荷，包括轴向压缩力、前屈、后伸、侧弯和扭转。体外实验未考虑肌肉力量。改良后的固定装置还被植入三名患者体内，并在自体髂骨植骨进行前路椎间融合术前和术后测定植入物负荷。将不同体外加载模式的结果与体内结果进行比较，以证明体外负荷在多大程度上代表患者的实际情况。在一些情况下，体外实验中的植入物负荷与患者体内测量的负荷差异很大。在前屈和侧弯时，体外实验偶尔会测量到轴向拉力，而在患者体内轴向力始终是压缩力。在体外研究中，后伸主要与后伸弯矩相关，但在患者体内则与前屈弯矩相关。如果在体外实验中不考虑肌肉力量，固定装置上的负荷可能与患者体内的情况有显著差异。
