Weisskopf M, Ohnsorge J A K, Martini F, Niethard F U, Birnbaum K
Wirbelsäulenchirurgie, Orthopädische Fachklinik Schwarzach.
Z Orthop Unfall. 2008 Jul-Aug;146(4):452-7. doi: 10.1055/s-2008-1038400.
Maintaining segmental motion is one of the most reported theoretical advantages of total disc replacement (TDR). Several inlay sizes are available for reconstruction of the physiological disc height. The influence of the implant height on the range of motion (ROM) was investigated in a biomechanical study.
A total of 10 human lumbar cadaver spines were subjected to biomechanical testing. Flexion/extension and side-bending moments were applied from 2.5-7.5 Nm on a spine load simulator allowing for all 6 degrees of freedom. Motion under different loads was monitored by the Zebris system in 3 dimensions. Initially intact specimens were tested in 3 load cycles. Then a total disc prothesis was implanted with an 8.5 mm inlay and the cycles were repeated. Finally in 5 cases a 1-mm larger inlay was inserted while in the remaining 5 cases the inlay was exchanged with a 2-mm larger implant. Neutral zone (NZ) and ROM were recorded under the different loads.
The average motion for the various loads showed no significant difference when the intact motion segment was compared to the specimen containing the 8.5-mm inlay. After the larger inlay had been mounted the average reduction of the ROM in flexion/extension was 25% under the load of 7.5 Nm, 26% under a torque of 5.0 Nm and 30% when 2.5 Nm were applied. The NZ was reduced by 37%. For side-bending the ROM was reduced by 21% under a load of 7.5 Nm, by 26% under 5.0 Nm and by 35% under a torque of 2.5 Nm. The NZ was decreased by 27%. The reduction of the ROM was significant (p=0.0057).
Segmental lumbar motion is maintained after TDR. The size of the inlay can significantly change the ROM in lumbar spine segments treated by TDR.
维持节段运动是全椎间盘置换术（TDR）最常被报道的理论优势之一。有几种嵌体尺寸可用于重建生理椎间盘高度。在一项生物力学研究中，研究了植入物高度对活动范围（ROM）的影响。
对10具人类腰椎尸体脊柱进行生物力学测试。在脊柱负载模拟器上施加2.5至7.5牛米的屈伸和侧弯力矩，允许所有6个自由度。通过Zebris系统在三维空间中监测不同负载下的运动。最初完整的标本在3个负载循环中进行测试。然后植入一个8.5毫米嵌体的全椎间盘假体，并重复循环。最后，在5例中插入一个大1毫米的嵌体，而在其余5例中，将嵌体换成一个大2毫米的植入物。记录不同负载下的中性区（NZ）和ROM。
将完整运动节段与含有8.5毫米嵌体的标本相比，各种负载下的平均运动无显著差异。安装较大嵌体后，在7.5牛米负载下屈伸ROM的平均降低率为25%，在5.0牛米扭矩下为26%，在施加2.5牛米时为30%。NZ降低了37%。对于侧弯，在7.5牛米负载下ROM降低了21%，在5.0牛米下降低了26%，在2.5牛米扭矩下降低了35%。NZ降低了27%。ROM的降低具有显著性（p = 0.0057）。
TDR后腰椎节段运动得以维持。嵌体尺寸可显著改变TDR治疗的腰椎节段的ROM。
