摘要目的 探讨动态套筒式三翼钉治疗股骨颈骨折中的生物力学作用,为临床选择此内固定器治疗股骨颈骨折提供理论依据.方法 利用聚甲基丙烯酸甲酯(PMMA)制作人工股骨模型9个,分别以Pauwels角为30°、50°和70°于股骨颈中部,用手锯将模型锯断,每组3个,用动态套筒式三翼钉固定断端.标本摸拟人体单足站立位同定于英斯特朗-8874液压伺服力学实验机上,以速率10 mm/min线性载荷0～1 200 N分级加载,测定各组1 200 N载荷下股骨上段11个关键点的应变值以及不同载荷下头下沉位移、主压力侧的应变值和主张力侧的应变值.结果 1 200 N载荷下,3组均在6号电阻应变片的位置出现峰值,其数值差异有显著性意义(P＜0.01);在600～1 200 N,同一载荷下3组之间两两比较头下沉位移,差异均有显著性意义(P＜0.01);同一载荷下,Pauwels角度越大,股骨颈主压力侧和主张力侧的应变值越大,差异有显著性意义(P＜0.01).结论 Pauwels角角度越大,剪式应力越大,骨折断端间接触面积越小,骨折越不稳定;其角度越小,剪式应力就越小,骨折断端间接触面积则越大,骨折就越稳定.

abstractsObjective To explore the biomechanical stability of dynamic sleeve three-wing screw for treatment of femoral neck fracture and to provide theoretical basis for choosing the screw in clinical application.Methods Nine artificial PMMA femoral model were prepared and divided randomly into three groups (n=3),and the specimens were saw up with a hand saw at Pauwels angle of 30° ,50° and 70° in the central neck ,respectively and then fixed with dynamic sleeve three-wing screw.Specimens were fixed at simulated uniped standing position at Instron-8874 servo-hydraulic mechanical testing machine.Linear load of 0～1 200 N was loaded at the rate of 10 mm/min and strains at 11 key points under 1 200 N load were measured,as well as head sink displacement and the strain at principal pressure side and principal tension side under different loads.Results Strengthening peaks were observed at the number six resistance strain gage under the 1 200 N load in all tree groups,and the numerical difference of the three groups was statistically significant(P＜0.01).Under the load of 600～1 200 N,head sink displacement compare were performed in each two of the three groups under the same load,respectively,and showed statistically significant difference(P＜0.01) ;the strain of principal pressure side and principal tension side of the femoral neck was higher with the increasing Pauwels angle under the same load,the difference was significant(P＜0.01).Conclusion With the increasing Pauwel's angle,the shearing force was greater,the contact area of fracture line was smaller,and the fracture was more unstable;in contrast,the shearing force was smaller with the Pauwel's angle smaller,the contact area of fracture line was larger,and the fracture was more stable.