三维静态钉板系统固定对股骨上段骨质强度的影响

Influence of three-dimensional static screw-plate system on the strength of proximal femoral bone

目的:应用自行设计的用于股骨转子间骨折的新型内固定器械三维静态钉板系统与目前常用的动力髋螺钉及角钢板进行对比分析,观察其对股骨上段骨质强度的影响。方法:实验于2004-01在国防科技大学力学实验室完成。选取10副甲醛溶液固定1年以内的成对股骨标本(广东医学院解剖教研室提供),经X射线检查,排除有骨折、肿瘤、炎症、结核和明显骨质疏松等。随机分为三维静态钉-板系统及动力髋螺钉组和三维静态钉-板系统及角钢板组。每组采用三维静态钉-板系统及动力髋螺钉和三维静态钉-板系统及角钢板配对固定。随即取下,仅遗留钉道,制成模拟骨折愈合拆除内固定后的模型。然后将股骨安放于万能力学试验机上,以加载速度1mm/min作轴向加载至标本屈服(以载荷-位移曲线突然垂直下降为标志),并同步记录载荷位移曲线。利用统计软件进行数据分析。组间比较采用配对t检验。结果:①三维静态钉-板系统及动力髋螺钉组骨折愈合内固定拔出后模型极限载荷比较:本组模拟骨折愈合内固定取出后,垂直加载时三维静态钉-板系统组标本所承受的最大载荷明显强于动力髋螺钉组(6345.5,4538.6N,t=-4.980,P<0.05)。②三维静态钉-板系统及角钢板组骨折愈合内固定拔出后模型极限载荷比较:骨折“愈合”内固定拔出后,三维静态钉-板系统组标本最大载荷显著高于角钢板组(4187.6,3462.7N,t=-5.967,P<0.01)。结论:三维静态钉-板系统承载能力比动力髋螺钉和角钢板高,对股骨上段骨质强度的影响较小,可明显降低内固定取出后再骨折的风险。

AIM： To compare the static three-dimensional screw-plate system, a newtype internal fixation device that is self-designed for fixation of intertrochanteric fracture, with dynamic hip screw （DHS） or angled steel plate either of which is used commonly at present, and investigate their influences on strength of the proximal femoral bone. METHODS： Our experiment was conducted in the laboratory for mechanics, National University of Defense Technology in January 2004. Ten pairs of femoral bones fixed in formalin solution for less than 1 year were provided by Department of Anatomy, Guangdong Medical College. By X-ray examination, the femoral bones with fracture, tumor, inflammation, tubercle or obvious osteoporosis were excluded. The femoral bones were divided into two groups, which were fixated with the static threedimensional screw-plate system paired with dynamic hip screw （DHS） and static three-dimensional screw-plate system paired with angled steel plate respectively. The simulative fracture-healed models after removal of internal fixation were produced by inserting the three different devices and then pulling them out. The specimens were mounted on the all-round mechanical testing machine, and loaded vertically at 1 mm per minute till they were subdued （sudden vertical descending curve of load-displacement was regarded as the marker）, and the curves of load-displacement were recorded. The statistical software was used to analyze the data, and paired t test to perform inter-group comparison. RESULTS： ①The ultimate load of the fracture-healed models after pullout of internal fixation between the static three-dimensional screw-plate system group and the DHS group： The maximum vertical load of specimens in the former group was significantly more than that in the latter group （6 345.5 N vs 4 538.6 N, t=-4.980, P 〈 0.05）,②The ultimate load of the fracture-healed models after pull-out of internal fixation between the static three-dimensional screw-plate system group and the angled steel plate group： The maximum vertical load of the specimens was significantly more in the former group than in the latter group（4 187.6 N vs 3 462.7 N, t =-5.967, P 〈 0.01）. CONCLUSION： The static three-dimensional screw-plate system has more load than either DHS or angled steel plate has, and also has less impact on the strength of the proximal femoral bone. It can apparently decrease the re-fracture risk after internal fixation device is pulled out.