椎弓根螺钉抗拔出强度的生物力学测试

Biomechanical study on the Pull-out strength of pedicle screws

目的:分析骨密度(bone mineral density,BMD)和植入角度对椎弓根螺钉拔出强度的影响。方法:6例新鲜尸体脊柱T_(10)～L_2椎骨,分解为单个椎体30个,共60个椎弓根。根据骨密度检查结果分组,每个标本脊椎左侧使螺钉在椎弓根平行植入,在脊柱右侧使螺钉在与椎弓根成7°角植入。将60个椎弓根分别进行拔出测试(5mm/min的速度垂直方向拔出)。结果:螺钉平行植入与椎弓根成7°角植入,后者其拔出力大20%(P<0.05)。骨密度对拔出力的影响,正常组与骨质疏松组相差57%(P<0.05)。结论:选择与椎弓根成角度植入螺钉有助于提高螺钉固定相对稳定性;对于骨质疏松的病例。

Objective： To evaluate the pull-out strength of pedicle screws in relation to the angle of the placement and the bone mineral density. Methods： Sixty fresh vertebral pedicles were obtained from 6 adult cadaver specimens（T10-L2）. According to the different bone mineral density （BMD）, the specimen were divided into two groups. The screw were parallelly placed on the left vertebral pedicle and with a angle （7° ） on the right. The axial pull-out strength of pedicle screw was measured. Results： The axial pull-out strength of pedicle screw were more great in the screw unparallelly placed than in the screw parallelly done （increased by 20%, P〈0.05）. Conclusions： The screws of fixture with unparallel placement help improve the relative stability of pedicle screw fixation;The pull-out strength of the serious osteoporosis should be paid more attention to.