腰椎不同深度置入椎弓根螺钉对把持力的影响

Biomechanical analysis of imbedding pedicle screws on holding force in different lumbar vertebra depth

目的观察椎弓根螺钉在相同水平角度(TSA角为0°)、相同矢状角度(SSA角为0°)不同深度时置入单个椎体对把持力的影响,为临床置钉提供理论依据。方法采用6个月龄猪L2新鲜标本共16个椎体,将32侧椎弓根分4组,按不同深度分70%组、75%组、80%组、85%组分别置入椎弓根螺钉,自动记录仪记录下螺钉载荷-位移的变化曲线,测出最大轴向拔出力及最大拔出能量。结果 80%组椎弓根螺钉最大拔出力及最大拔出能量明显大于70%组(P<0.05),75%组与85%组椎弓根螺钉的最大拔出力及最大拔出能量与70%组比较差异无统计学意义(P>0.05)。结论不同深度置钉对椎弓根螺钉的把持力随置钉深度的增加而逐渐增大。

Objective To discuss the biomechanics of holding force on the pedicle screws after the screws were inserted into the pedicle of vertebral arch at same level angle（ TSA angle was 0°）,same sagittal angle（ SSA angle was0°） and different depth,and provide the basis for the clinical practice. Methods 16 new centrums（ L2） were adopted from pig with six months. According to different depth,the pedicle of vertebral arch（ 32 sides） were selected into4 groups： group of 70%,group of 75%,group of 80% and group of 85%. The changing curve of screw loading-displacement was recorded by automatic recording instrument. The maximum axial direction extraction force and extracting energy were examined. Results The 80% group of pedicle screws maximum output and pull out energy was bigger than 70% group（ P〈0. 05）,the 75% and 85% group of pedicle screws maximum output and pull out energy,were no statistically significant different compared with the 70% group（ P〉0. 05）. Conclusions When the screws are inserted into the pedicle of vertebral arch at different depth,the holding force will be increased as the depth augment.