Biomechanical Study Of A Numerical Modelling Of Locking Plates

Locking compression plates (LCPs) have been used to treat the comminutedfemoral shaft fracture, previous research have attempted to determine the best screwposition and the optimal number of screw for getting strongest fixation stability.Fixation stability is the most important factor to the success rate of fracture healing,the fixation stability of the LCP systems was significantly affected by differentnumbers、different positions of locking screws.The present study have a biomechanicsstudy of a numerical simulation of locking plates to determine the best screw positionand the optimal number of screw for getting strongest fixation stability.The present study uses CAD (computer aided design)、RE (reverse engineering)to develop a numerical models of the femur with an locking compression plate systemThe femur CT data imported in the Mimics software by DICOM format, generatefemur3D model, a twelve-hole locking plate, and locking screws were developed. Atransverse femoral shaft fracture with a fracture gap of10mm was assumed anddeveloped. To simulate clinical practice, the bone plate is placed on the tension sideof the fracture.The materials were assumed and assigned for both the femur and the LCP system.WORKBENCH software is applied to implement3D mesh model and analysis thefemur-LCP model, compute the femoral-LCP system model in each case, obtain stressand its distribution of bone plate, analysis the axial deformation of femoral system.The results showed the fixation stability of the LCP systems was significantlyaffected by different numbers、different positions of locking screws. Inserting alllocking screws into LCP system produces the strongest fixation stability. however, theinserting of the locking screws damags bone tissue and its adjacent muscles andhence，leads to the stress concentration and hence leads to plates failure, LCP systemswith the strongest fixation stability may lead to a stress shielding effect which will lead to osteoporosis and re-fracture. Fixation stability is stronger when screws arecloser to the fracture ends. Fixation stability is stronger when screws numbers aremore, the LCP system obtain the strongest fixation stability when all screws areinserted.