EZ取钉器的生物力学测试和临床初步应用

Biomechanical test and clinical application of EZ extraction screws device

目的通过生物力学测试和临床初步应用验证EZ取钉器对断钉、打滑螺钉的取出效果。方法采用新鲜尸骨标本,股骨、胫骨、尺桡骨各4具,并随机分为两组:A组为起子取螺钉扭力组;B组为骨髓腔内灌骨水泥固定螺钉组,其中B1为螺钉打滑时最大扭力组;B2为EZ取钉器一个手柄时取钉器最大扭力组;B3为两个手柄时取钉器的最大扭力组,制成4种生物力学测试模型,内固定螺钉分为4.5mm和3.5mm两种类型。在万能材料试验机上测试实验标本,施加轴向载荷2kN,测量扭转拔出螺钉时的最大扭矩值、扭角及螺钉拔出时功耗大小和效率。实验数据经统计学处理,进行组间比较。并用EZ取钉器在12例患者中初步应用。结果 A组最大拔出扭矩为1.42～1.96N·m,B1组为2.87～3.27N·m,B2组为3.06～4.83N·m,B3组为4.12～8.36N·m,各组间均呈显著性差异(P<0.05)。其相对应各组的扭角均值分别为1.59毅、0.77毅、0.28毅和0.16毅,各组间有明显差异(P<0.05)。螺钉拔出(旋出)时,各组的功耗均值分别为12、21、32和45J;对应各组间的功率(机械效率)分别为0.20、0.35、0.53和0.75J/s,组间呈明显差异(P<0.05)。在12例临床断钉和打滑螺钉患者中初步应用,均成功取出,未出现术后并发症。结论 EZ取钉器具有足够的抗扭强度和刚度,夹持力大,拔钉稳定可靠,是取出骨骼中断钉和打滑螺钉较理想的工具。

Objective To evaluate the effect of EZ extraction screws device on screwing out the reduced screws,broken screws,skidded screws in biomechanical test and clinical application.Method 4 femurs,tibias,radius,ulnas of 4 fresh skeleton specimen were divided into two big groups randomly as Group A and Group B1,B2 and B3：In Group A the screws were taken out by screwdriver;In Group B,the screws were clamped in medulla cavity filled with the bone cement,;B1 was the group of measuring skidded screws with the biggest torsion;B2 was the group of measuring skidded screws with the biggest torsion by one handle;B3 was by two handles.Four mechanics test models were made,and the clamping screws were divided into two types of φ4.5 mm and φ3.5 mm each for 60.The experiment specimen were tested on the universal testing machines with exerting 2 kN axial loading,and surveyed the greatest torque,the torsion angle and the power loss as well as the efficiency when drawing out.The empirical datum after statistics processing were compared among the groups.And EZ was also used for 12 example patients in the preliminary clinical practice.Results Group A showed the biggest torque as 1.42～1.96 N·m for drawing out;Group B1 as 2.87～3.27 N·m;Group B2 as 3.06～4.83 N·m;Group B3 as 4.12～8.36 N·m.The significant difference（P0.05）was found in each group.The average value of torsion angle in each corresponding group is 1.59°,0.77°,0.28° and 0.16°,respectively with the obvious difference（P0.05）;The average value of power loss in each group is 12,21,32 and 45J respectively;and the power（mechanical efficiency） in each corresponding group is 0.20,0.35,0.53 and 0.75 T/s,respectively,which also showed the obvious difference（P0.05）.EZ used in 12 cases were successfully screwed out with all the broken screws and maintained the integrity of the bone without any postoperative complications.Conclusions EZ extraction screw device has sufficient torsional strength and stiffness with enough clamping force,and could pull out stably and reliably,which is an ideal tool for the stub screws,crooked screws and slipped screws in skeleton.