人工颈椎间盘置换术与融合术的生物力学比较

目的 分析颈前路植骨融合术（anterior cervical discectomy and fusion，ACDF）与颈椎间盘置换术（total disc replacement，TDR）后颈椎生物力学特性。方法 采用12具人体颈椎标本，通过三维非接触式光电测量系统及位移控制方式，测试原始状态（intact）、TDR及ACDF术后各节段在前屈与后伸、左侧弯与右侧弯、左旋转与右旋转6种独立工况的运动和载荷分布，并探讨颈椎正常生理运动规律及植入器械特点。结果TDR术后，颈椎各节段运动保留效果明显，能恢复接近正常的运动，并以屈伸、旋转工况为优；同等工况下ACDF术后手术节段运动丢失达73.41%，其他节段运动也存在明显改变。侧弯工况两者均存在较大运动改变，TDR达45.92%，ACDF达108.06%。试验发现，颈椎正常生理运动为空间三轴耦合运动，以侧弯工况耦合程度最大，绕X轴运动分量达35%，TDR术后，颈椎能恢复接近正常的耦合运动规律。结论TDR术能使颈椎恢复更接近正常的生理运动，在屈伸、旋转工况效果最好，侧弯次之。本研究为TDR与ACDF的临床手术提供理论依据和定量参考。

In vitro study on biomechanical comparison between cervical arthroplasty and fusion

Objective To analyze biomechanical properties of cervical spine after anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR) surgery. Methods Twelve cadaveric cervical spines (C2-T1) were adopted, and the motion and load distributions of the cervical segments under intact state and after ACDF and TDR surgery were tested using a three-dimensional (3D) optoelectronics measurement system. All the tests were carried out with displacement control in directions of flexion (Flex), extension (Ext), left bending (LB), right bending (RB), left rotation (LR) and right rotation (RR). Motion characteristics of the normal cervical spine and the implant were also discussed. Results In TDR-treated specimens, range of motion (ROM) was well preserved and could restore to the normal ROM distributions, especially in Flex/Ext and LR/RR direction. While in ACDF-treated specimens, ROM presented a large decrease as much as to 73.41% under the same condition compared with TDR, and ROM distributions were also changed obviously in other motions for the segments. Significant changes of ROM in LB/RB direction occurred in both TDR and ACDF group, which were up to 45.92% and 108.06%, respectively. The experimental data indicated that the normal motion of cervical spines was a 3D coupled motion, especially in LB/RB direction, where a 35% rotation around X-axis existed. The cervical spine could recover close to normal coupled motion after TDR surgery. Conclusions TDR surgery can restore the physiological motion of cervical spines more close to the normal state, especially in Flex/Ext and LR/RR direction. The study provides a theoretical basis and quantitative reference for TDR and ACDF surgery in clinic.