三种单纯腰椎椎间融合并双侧椎弓根螺钉内固定后即刻稳定性的比较

背景：椎间融合术按照手术入路主要有前路椎间融合术、后路椎间融合术和椎间孔入路椎间融合术。3种融合术术中切除的结构不同，融合器置入的部位不同，其腰椎即刻稳定性也存在差异。 目的：比较前路椎间融合术、后路椎间融合术、椎间孔入路椎间融合术加用双侧椎弓根螺钉内固定后腰椎即刻稳定性的差异。 设计：对比观察。 材料：腰椎标本来自新鲜小牛15具。 方法：模拟临床手术建立前路椎间融合术、后路椎间融合术、椎间孔入路椎间融合术3种椎间融合术模型，先将所有标本作为正常对照组进行测试，然后将标本随机分为3组，每组5个标本，制成单纯椎间融合组，分别采用3种椎间融合术测试后，在此基础上再附加双侧椎弓根螺钉内固定进行测试。 主要观察指标：脊柱三维运动测试机上测试3种模型加用双侧椎弓根螺钉固定前后腰椎生物力学特性的变化。 结果：行3种单纯椎间融合后，腰椎的稳定性能明显下降，附加了双侧椎弓根螺钉固定后，腰椎的各项稳定性指标均增强，包括扭转力学指标也得到了很大增强，有效增加了腰椎的刚度。椎间孔入路椎间融合术各项稳定性指标都明显优于其他两种方法，说明椎间孔入路椎间融合术的即刻稳定性能在3者中最有优势。后路椎间融合术的刚度明显强于前路椎间融合术，应变和应力也较前路椎间融合术有优势，但是其扭转稳定性却不如前路椎间融合术。 结论：行单纯椎间融合术后，腰椎的稳定性较正常对照组均有明显下降，在加用双侧椎弓根螺钉内固定后能有效地提高其稳定性能。在3种椎间融合术中，椎间孔入路椎间融合术的腰椎即刻稳定性能最优。

Initial stability of lumbar spine following three types of interbody fusion and bilateral pedicle screw fixation

BACKGROUND: Operative approaches of lumbar interbody fusion include anterior (ALIF), posterior (PLIF) and transforaminal lumbar interbody fusion (TLIF). The resected structures and cage implantation sites are different, and the initial stability of lumbar spine is varied. OBJECTIVE: To compare the initial stability of lumbar spine following ALIF, PLIF or TLIF in combination with bilateral pedicle screw fixation. DESIGN: Comparative observation. MATERIALS: Fifteen samples of fresh calf lumbar spine were used. METHODS: Models of ALIF, PLIF and TLIF were simulated. After examination as normal group, the samples were randomly divided into three groups (n=5). Besides anterior, posterior and transforaminal lumbar interbody fusion include anterior, bilateral pedicle screw fixation was performed. MAIN OUTCOME MEASURES: Biomechanical characteristics of the lumbar spine before and after ALIF, PLIF or TLIF in combination with bilateral pedicle screw fixation. RESULTS: Following three approaches of lumbar interbody fusion, the stability of lumbar spine was significantly reduced, which was enhanced after bilateral pedicle screw fixation (torsion indexes were also increased). In addition, rigidity of the lumbar spine was enhanced. The stability indexes of lumbar spine following TLIF were significantly greater than the other approaches, indicating the initial stability of TLIF was the best. The rigidity, stress, and strain of lumbar spine following PLIF were greater than ALIF, but torsion indexes were smaller than ALIF. CONCLUSION: The stability of lumbar spine following lumbar interbody fusion was significantly reduced compared with normal sample. But bilateral pedicle screw fixation greatly increases the stability. Among three types of lumbar interbody fusion, the initial stability of lumbar spine following TLIF is the best.