单纯腰椎前路椎间融合器即刻与疲劳稳定性的研究

Instant and fatigue stability analysis of anterior lumbar interbody fusion with stand-alone cage

目的研究单纯植入椎间融合器（Cage）进行腰椎前路椎间融合的即刻与疲劳稳定性。方法6副人腰椎标本（L3-S1），L4以上和S1以下包埋固定，保留L4／L5和L5／S1两个间隙活动。首先作为空白组测试，随后于L5／S1间隙植入Cage作为实验组测试。即刻稳定性测试L4／L5、L5／S1椎体间在前屈、后伸、侧屈3个方向相对活动度。疲劳稳定性测试屈伸5万次后，Cage在L5／S1椎间隙中的相对位移。结果L5／S1植入Cage后在前屈、后伸、左侧屈3种运动下，椎间相对活动度分别为（0．83±0．26）°、（1．60±0．19）°和（0．72±0.20）°，明显小于空白组的活动度（3．60±0．30）°、（4．82±0．34）°和（3．80±0．28）°，差异均有统计学意义（均P〈0．01）。同时L4／L5椎间相对活动度代偿性增加，分别为（5．82±0.36）°、（5．38±0．30）°和（4.96±0．29）°，明显大于空白组（4．16±0．33）°、（4．02±0．30）°和（3．48±0．34）°，差异均有统计学意义（均P〈0．01）。5万次屈伸疲劳运动后，Cage与S1椎体间的相对位置无明显变化，相对位移为0。结论单纯应用Cage进行腰椎前路椎间融合，具有良好的即刻稳定性与疲劳稳定性。

Objective To investigate the spinal segment instant and fatigue stability of anterior lumbar interbody fusion with stand-alone cage. Methods The vertebrae L4 and S1 of 6 human lumbar specimens （ L3 - S1 ） were embedded with dental base acrylic resin powder and fixed on mechanical machine, and the L4/L5 and L5/S1 disk spaces were left active. The 6 specimens underwent mechanical test as control group first, and then used as experimental group with a cage implanted in L5/S1. Instant instability was tested in three directions： flexion, extension, and lateral bend. The relative movement of L4/L5 and L5/S1 was recorded. Fatigue instability was tested after 50 000 times of flexion-extension movement, and the relative displacement between the cage and S1 was recorded. Result In the three directions of flexion, extension, and lateral bend, the relative movements of L5/S1 in the experimental group were 0. 83 ± 0. 26°, 1.60 ± 0. 19°, and 0. 72 ± 0. 20° respectively, all significantly decreased than those of the control group （3. 60 ± 0. 30°, 4. 82 ± 0. 34°, and 3.80 ± 0. 28° respectively, all P 〈 0. 01 ）. The relative movement of L4/L5 of the experimental group were 5. 82 ± 0. 36°,5.38 ±0. 30°, and 4. 96 ±0. 29°in the three directions respectively, all significantly higher than those of the control group （4. 16 ±0.33°, 4.02 ±0.30°, and 3. 48 ±0. 34° respectively, all P 〈 0. 01 ）. After 50 000 times of flexion-extension fatigue movement, the relative displacement between the cage and S, was zero. Conclusion Anterior lumbar interbody fusion with a stand-alone cage has excellent instant and fatigue stability, which can provide enough stability for clinical bone fusion without other internal fixation.