空心加压螺钉治疗股骨颈骨折的轴向拔出实验研究

目的通过实验,研究影响空心钉在股骨头内稳定性的重要因素,为临床中空心钉治疗股骨颈骨折选择理想的手术方案提供理论依据。方法31枚股骨头标本,空心螺钉按照治疗股骨颈骨折的方法植入股骨头。记录年龄、测量股骨头直径、测量股骨头骨密度、测量钉尖到关节面软骨的距离;同时固定股骨头和螺钉帽,通过实验机进行空心钉轴向拔出实验,记录最大拔出负荷。用SPSS11.5软件包对实验数据进行多元逐步回归分析。结果股骨头骨密度和钉尖到关节面软骨的距离与最大拔出负荷相关,前者呈正相关(P=0.002),而后者呈负相关(P=0)。钉尖到关节面大于8mm组和小于8mm组的最大拔出负荷之间有显著差异(P=0.004)。结论股骨头骨密度越高,一定范围内螺钉植入越深,越有利于内固定的稳定。

Axial pullout tests of cannulated cancellous screws used for femoral neck fracture

Objective The purpose of this experimental study was to find the important factors affecting the stability of cannulated cancellous screws in femoral head and provide experimental basis in clinical use on femoral neck fracture using internal fixation with cannulated cancellous screws.Methods 31 femoral heads were from the patients of femoral neck fracture,then cannulated cancellous screws were embedded into them by the method for the treatment of femoral neck fracture.We recorded the ages of the patients,the diameters of the femoral heads,the BMDs of the femoral head,the distances from the tips of the screws to the articular surfaces of femoral heads.we fixed up femoral head and screw extremity into the mechanical experimental apparatus and carried out the tests.We got the stress-strain curves and the maximal pullout stresses of the screws.The data were analysed by multiple regression of SPSS for windows 11.5.Results The difference of the femoral head's BMDs and the depths of the screws which were embedded into the femoral heads brought about the difference of the maximal pullout stresses.By multiple regression,we found that the maximal pullout stresses of the screws were correlated with the femoral head's BMDs and the distances from the tips of the screws to the articular surfaces of femoral heads,the maximal stresses positively were correlated with the fore(P=0.002) and negatively correlated with the latter(P=0).Conclusions We should choose the higher BMD's patients of femoral neck fracture to treat them with cannulated cancellous screws and embed cannulated screws into the special depth of femoral head.