人工寰齿关节置换与Magerl经关节螺钉固定的生物力学比较

Biomechanical comparison between artificial atlanto-odontoid joint replacament and Magerl transarticular screw fixation

[目的]测试人工寰椎齿状突关节置换后寰枢椎的稳定性和功能,并与Magerl经关节螺钉固定进行比较。[方法]将12例新鲜的成人头颈部标本随机分为两组,第1组在齿状突切除术后使用人工寰齿关节置换;第2组在齿状突切除术后使用Magerl经关节螺钉固定。对两组的每一标本分别测定完整状态、人工关节置换术后或经关节螺钉固定后的运动范围和中性区。[结果]人工关节置换术后与完整状态相比前屈、后伸、左右侧屈的运动范围和中性区明显减小(P<0.05),左右旋转的运动范围无显著差异(P>0.05),中性区增大(P<0.05)。Magerl经关节螺钉固定后与完整状态相比前屈、后伸、左右侧屈及左右旋转的运动范围和中性区均明显减小(P<0.05)。人工关节置换术后及Magerl经关节螺钉固定后两组在前屈、后伸及左右侧屈的ROM稳定指数和NZ稳定指数相比均无显著差异(P>0.05)。[结论]实验证实在齿状突切除后,进行自行设计的人工寰椎齿状突关节置换可取得与Magerl经关节螺钉固定相似的前屈、后伸及左右侧屈稳定性,重要的是与完整状态相比左右旋转的运动范围无显著差异,最大限度的保留了寰枢复合体重要的旋转功能,对以往齿状突切除、脊髓减压后需要使用寰枢椎融合的患者,提供了另一种术式的选择。

[Objective]To determine the initial stability and function of a new artificial joint in a cadaveric cervical spine model by comparing it with a conventional method. [Methods]Twelve fresh human cadaveric cervical spines（C0~3） were randomly divided into 2 groups： group 1,resection of the odontoid with artificial atlanto-odontoid joint（AAOJ）,and group 2,resection of the odontoid with Magerl atlas and axis by transarticular screw fixation（Magerl）.For each specimen,the intact and resection of the odontoid underwent a flexibility test firstly,followed by the instrumented construct.Rotational angles of the C0~3 segment were measured to study the immediate stability and function of resection of the odontoid and AAOJ,compared with the intact and resection of the odontoid and Magerl.[Results]Compared to the intact state,resection of the odontoid and AAOJ resulted in a significant decrease in the range of motion（ROM） and neutral zone（NZ） during flexion,extension,and lateral bending（P0.05）;however,with regard to axial rotation,there was no significant difference in ROM（P0.05）.Compared to the intact state,resection of the odontoid and Magerl resulted in a significant decrease in the range of motion（ROM） and neutral zone（NZ） during all 6 degrees of freedom（P 0.05）.Compared with resection of the odontoid and Magerl,resection of the odontoid and AAOJ during flexion,extension,and lateral bending,showed no significant difference in ROM（P0.05）.[Conclusion]A new type of artificial atlanto-odontoid joint has been designed for correcting atlantoaxial instability resulted from C1、2 anterior decompression procedures.It can restore,to a great extent,the C1、2 axial rotation that is lost during current stabilization procedures.