不同融合方式对腰椎生物力学的影响

背景：腰椎融合已广泛应用于腰椎疾患，但腰椎融合后对邻近节段的影响尚存争议，不同融合方式的节段稳定性及对邻近节段的影响尚不清楚。 目的：利用动物模型研究腰椎融合节段生物力学稳定性及相邻上节段的生物力学特点。 方法：将新西兰大白兔随机分为前路椎体间融合组(切除L5~6椎间盘，终板去皮质化，自体髂骨移植)、后外侧融合组(L5~6双侧横突去皮质化后自体髂骨移植)、环状融合组(先行前路椎体间融合，1周后作后外侧融合)、对照组(不作手术)。术后12周处取标本作影像学检查、手触测试、生物力学测试。对融合标本分别施加屈伸，左右侧弯，左右旋转6个方向的纯力矩，比较不同融合方式融合节段的稳定性及邻近节段运动范围。 结果与结论：与对照组比较，前路椎体间融合组、环状融合组、后外侧融合组L5~6节段屈曲活动度分别下降86.24%(P < 0.05)，88.74%(P < 0.05)，73.10%(P < 0.05)，融合节段近上节段L4~5屈曲运动范围分别增加52.22%(P < 0.05)，55.89%(P < 0.05)，27.11%(P < 0.05)。说明3种融合方式均显著提高融合节段稳定性，环状融合提供的节段稳定性最高，后外侧融合提供的节段稳定性最低。3种融合方式均使融合节段邻近上节段运动范围显著增加。前路椎体间融合，360°融合使邻近上节段屈曲运动范围增加无统计学差异。后外侧融合使邻近上节段屈曲运动范围增加最少。

Effects of different lumbar fusion modes on lumbar spine biomechanics

BACKGROUND: Lumbar fusion has been widely used in treating lumbar diseases. However, the influence on adjacent segments is on debate, and the stability of fused segment and biomechanical effects on adjacent segments have not been well document. OBJECTIVE: To study the biomechanical properties of fused segments and adjacent segments. METHODS: New Zealand White rabbits were randomly assigned into anterior lumbar interbody fusion (ALIF) group (L5-6 discectomy, decortication of the vertebral end plates, autogeneuous iliac bone graft were performed), posterolateral fusion (PLF) group (autogeneuous iliac crest bone graft was placed over the bilateral decorticated L5-6 transverse processes), 360° fusion group (underwent ALIF firstly, and PLF L5-6 were performed after 1 week), or control group (treated without any operation). The spinal fusion was analyzed by radiography, manual palpation and mechanical testing at 12 weeks after operation. Each successful fusion specimen was tested in six pure moments (flexion and extension, left and right lateral bending, left and right axial rotation) to determine the stability of fused segments and the range of motion (ROM) of adjacent segments. RESULTS AND CONCLUSION: Compared with the control group, the ROM of flexion at L5-6 segment decreased significantly 86.24% (P < 0.05), 88.74% (P < 0.05), 73.10% (P < 0.05) for the ALIF group, 360° fusion group and PLF group, respectively. Accordingly, the ROM of flexion at L4-5 increased 52.22% (P < 0.05), 55.89% (P < 0.05), and 27.11% (P < 0.05). Three lumbar fusion methods can enhance the stability of fused segment significantly. The stability of 360° fusion is the highest, and that of PLF is the least. The ROM of flexion at proximal adjacent segment in ALIF and 360° fusion is no statistical difference, and that of the PLF is the least.