BACKGROUND:From the point of view of human anatomy, the load of the spine is more. When the body moves, the range of activities, and activity are relatively large. After screws were implanted in the spine, if biomechanical properties and stability are not up to the standard, it easily leads to lack of grip force of screw and screw loosening so as to increase the incidence of complications after treatment. OBJECTIVE:To compare biomechanical properties and stability of the spine after insertion of pedicle screw and cervical vertebral screw into the spine. METHODS:100 vertebrae under human cervical spine specimens were analyzed and randomly divided into cervical vertebral screw fixation group and pedicle screw fixation group. Cervical vertebral screws and pedicle screws were implanted in lower cervical spine specimens. Electro Force 3510 material testing machine was used to test axial pul-out force, axial pul-out strength after the fatigue loading, and fixed stability. The biomechanical properties and stability were compared after two kinds of screws were implanted in the spine. RESULTS AND CONCLUSION:(1) Instantaneous pul out force and immediate pul out stiffness were significantly higher in the pedicle screw fixation group than in the cervical vertebral screw fixation group (P<0.05). (2) Fatigue pul-out strength and fatigue pul-out stiffness did not have significant differences in both groups, but statistical analysis showed significant differences (P<0.05). Fatigue pul-out strength and fatigue pul-out stiffness were significantly higher in the pedicle screw fixation group than in the cervical vertebral screw fixation group. (3) These results suggested that pedicle screw fixation after implantation in the spine provides sufficient fixation stability, has better fatigue resistance, elevates instantaneous pul-out force and fatigue pul-out strength, and presents strong stability.%背景：从人体解剖角度来说，脊柱承载的负荷较多，机体运动时活动幅度、活动量也比较大，螺钉置入脊柱后如果生物力学性能及稳定性达不到要求，容易导致螺钉的握持力不足发生松动，从而增加了患者治疗后并发症的发生率。 目的：对比内固定椎弓根螺钉与颈椎体螺钉置入脊柱后的生物力学性能及其稳定性。 方法：选取100个人体下颈椎椎体标本进行分析，随机分为颈椎体螺钉组与内固定椎弓根螺钉组。分别将内固定椎弓根螺钉与颈椎体螺钉置入人体下颈椎标本中，采用Electro Force 3510材料试验机对标本进行轴向拔出力、疲劳加载后轴向拔出力、固定稳定性等生物力学测试，比较2种螺钉置入脊柱后的生物力学性能及其稳定性。 结果与结论：①内固定椎弓根螺钉组即时拔出力、即时拔出刚度均显著高于颈椎体螺钉组(P<0.05)；②2组虽然疲劳拔出力和疲劳拔出刚度差别不大，但是经统计学分析二者差异有显著性意义(P<0.05)，内固定椎弓根螺钉组显著高于颈椎体螺钉组；③结果提示，内固定椎弓根螺钉置入脊柱后能够为机体提供足够的内固定稳定性，且具备较好的抗疲劳特性，可提高置入脊柱后的即时拔出力和疲劳拔出力，稳定性更强。
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