外置锁定钢板治疗胫骨近端骨折的有限元分析

Finite element analysis of external locking plate in treatment of proximal tibial fractures

目的探讨外置锁定钢板治疗胫骨近端骨折的生物力学可行性,为临床应用提供理论指导。方法采集1名志愿者下肢CT图像资料,分别进行正常胫腓骨、锁定钢板内固定及外置锁定钢板固定的虚拟三维模型重建。利用Abaqus软件,设定边界条件、施加150N纵向静态载荷以模拟60kg成人半负重站立时单侧下肢3种模型的受力分布及位移大小。结果正常胫腓骨模型半负重时最大应力值为7.7MPa,位于胫腓骨远端;锁定钢板内固定模型和外置锁定钢板固定模型的整体最大应力值分别为214.1MPa和351.8MPa,位于近端螺钉与钢板接触处。外置锁定钢板固定模型的整体位移大于锁定钢板内固定模型及正常胫腓骨模型,三者的最大位移分别为1.9mm、0.5mm和1.3mm,整体刚度分别为78.9N/mm、300.0N/mm和115.4N/mm。结论虽然外置锁定钢板使钢板承受了更大的应力,产生较大的位移,但其强度在安全范围之内,且刚度更接近于正常胫腓骨。因此,外置锁定钢板固定在生物力学方面具有一定可行性。

Objective To explore the biomechanical feasibility of external locking plate in the treatment of proximal tibial fractures, and to provide theoretical guidance for clinical application. Methods CT imaging data of the lower limbs of 1 volunteer were collected. The virtual three-dimensional model reconstruction of normal tibia and fibula, internal fixation with locking plate and external fixation with locking plate were performed, respectively. The Abaqus software was utilized to set the boundary conditions and apply 150 N longitudinal static load to simulate the stress distribution and displacement of three unilateral lower limb models when an adult weighed 60 kg was standing with half load.Results The maximum stress of the normal tibiofibular model was 7.7 MPa at half load, which was located at the distal end of tibiofibula. The overall maximum stress of the internal fixation model with locking plate and the fixation model with external locking steel plate were 214.1 MPa and 351.8 MPa, which were located at the contact site between the proximal screw and the plate. The overall displacement of the fixation model with external locking plate was larger than those of the internal fixation model with locking plate and the normal tibiofibular model. The maximum displacement of these three models was 1.9 mm, 0.5 mm and 1.3 mm, respectively. The overall stiffness was 78.9 N/mm, 300.0 N/mm and 115.4 N/mm, respectively.Conclusions Although the external locking plate bears greater stress and generates larger displacement, its strength is within a safe range and its rigidity is closer to that of normal tibia and fibula. Therefore, external locking plate fixation is a feasible approach in biomechanics.