经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性

目的评价双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性。方法将6具新鲜尸体颈椎标本（包括枕骨基底部和C1-C4颈椎节段）置于1．5Nm载荷下，测量C1，2节段的三维运动范围（range of motion，ROM）。标本依Gallie内固定、双侧经寰枢关节间隙螺钉和Gallie内固定、双侧经寰枢关节间隙螺钉内固定、双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定、双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定的顺序实施固定，每次固定后测量三维运动范围。结果包含经寰枢关节间隙螺钉的内固定组在旋转和侧屈方向上具有最小的ROM，其中双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定组在屈伸运动方向上也具有最小的ROM。寰椎侧块螺钉和枢椎椎弓根螺钉内固定组在旋转方向上ROM大于单纯经寰枢关节间隙螺钉内固定组，但在侧屈和屈伸方向上接近经寰枢关节间隙螺钉，差异无统计学意义；其在侧屈和旋转方向上ROM均小于Gallie内固定组，差异有统计学意义。结论双侧经寰枢关节间隙螺钉和寰椎椎板钩“三点”内固定具有最强的生物力学稳定性。虽然双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定在生物力学稳定性上不及“三点”内固定，但明显优于Gallie内固定。

The biomechanical in vitro research of novel posterior atlantoaxial fixation techniques using bilateral atlas laminar hook combined with transarticular screws

Objective To evaluate the immediate three-dimensional biomechanical stability of the novel posterior atlantoaxial fixation using bilateral atlas laminar hook combined with transarticular screws in vitro. Methods Six human specimens C0-C4 were loaded nondestructively with 1.5 Nm in the unconstrained testing apparatus and specimens were respectively instrumented with each of the following techniques: Gallie fixation, transarticular screws fixation and Gallie fixation, transarticular screws, transarticular screws combined with atlas laminar hook fixation, lateral mass screws in the atlas combined with isthmic screws in the axis connected with rods. After each operation, the range of motion (ROM) at the level of C1-C2 was measured in flexion-bending, lateral bending, axial rotation directions. Results The data indicated that destabilization via intact significantly increased ROM of C1-C2. All screws techniques significantly decreased ROM of C1-C2, as compared with the Gallie wiring method in lateral bending and axial rotation (P< 0.05). In fixation techniques with transarticular screws fixation, the largest difference of ROM happened in the anterior-posterior direction (P< 0.05), the differences in other directions were not statistically significant (P >0.05). As lateral mass screws in the atlas combined with isthmic screws in the axis fixation was compared to different fixation techniques with transarticular screws fixation, the most noticeable difference of ROM happened in axial rotation with 1.5 Nm load (P< 0.05 ), and lateral mass screws in the atlas combined with isthmic screws in the axis fixation presented much smaller value of ROM than Gallie fixation in lateral bending, axial rotation direction (P< 0.05). Conclusion The novel transarticular screws combined with atlas laminar hook fixation technique provides the best biomechanical stability. Although lateral mass screws in the atlas combined with isthmic screws in the axis connected with rods fixation is not as stable as the transarticular screws fixation, it provides a much excellent biomechanical stability than Gallie fixation.