一种新型椎弓根螺钉内固定系统对不稳腰椎的稳定性效果评价

目的评价一种新型椎弓根螺钉内固定系统对不稳定腰椎的稳定性效果。方法取12具新鲜尸体腰椎标本,随机分为2组,每组6例。测量每组腰椎在8.0 N·m载荷下L2~L5节段的运动范围(range of motion, ROM)后将两组腰椎制成腰椎三柱不稳模型,A组以椎弓根螺钉固定,B组以SOCON椎弓根螺钉固定,再分别测量两组ROM并进行比较。结果新型的椎弓根螺钉内固定系统和SOCON椎弓根螺钉均能显著降低腰椎各方向上的ROM,尤其对前屈、后伸提高其稳定程度最大,前屈时新型的椎弓根螺钉内固定系统可降低62.8%,SOCON螺钉可降低63.9%,后伸时则分别降低54.9%和51.0%。A、B固定腰椎后ROM在6个方向上无明显差异,两种螺钉的稳定作用相近。结论新型的椎弓根螺钉内固定系统有较好的生物力学稳定作用,能有效提高损伤腰椎各方向上,尤其是前屈和后伸方向上的稳定程度。

A new internal fixation system using vertebral pedicle screw for unstable lumbar spine: an in vitro biomechanical stability evaluation

Objective To evaluate the effect of a new internal fixation system utilizing vertebral pedicle screw in fixing unsta-ble lumbar spine in vitro. Methods Twelve lumbar spine specimens (L 2~5 ) obtained from fresh human cadavers were randomly divided into 2 equal groups, namely groups A and B. All intact specimens were subjected to nondestructive testing in 6 load-ing modalities on a universal testing machine, before complete L 2~5 instability was produced by means of a wedge fracture in-duced by resection of the posterior ligamentous structures. Specimens in group A were fixed with the new internal fixation system, and group B with SOCON pedicle screw. The same nondestructive testing was repeated to determine the structural stability of the spine after fixation in both groups. Results The injured spines fixed with implants in both groups were signifi-cantly more stable than the intact specimens in all modes of tests (P<0.05), especially in flexion and extension tests, in which a stability increase by 62.8% for flexion and 63.9% for extension was recorded in group A, and 54.9% for flexion and 51.0% for extension in group B. The two fixation systems exhibited similar effect in stabilizing the injured lumbar in all the 6 loading modalities (P>0.05). Conclusion This internal fixation system with vertebral pedicle screw is capable of providing biome-chanical stability for unstable lumbar spine.