Three-dimensional Finite Element Analysis Of Three Internal Fixation Of Distal Femur Fractures

PurposeDynamic condylar screw (DCS), femoral retrograde interlocking intramedullary nail(GSH) and distal femoral locking plate (LCP) are the most clinically applied internalfixation of distal femur fractures. However, owing to the complexity of distal femoralfractures and the healing efficacy differences of various internal fixations, scholars carry adifferent controversy.By using the three-dimensional finite element method, this study comparativelyevaluates the fixation effect of three internal fixations(DCS, GSH and LCP) for dynamiccondylar distal femur A, B types of fractures, and compares their advantages anddisadvantages in order to offer reasonable recommendations for the clinical selection ofinternal fixations.MethodsThis paper establishes ideal finite element model of both type A and type B distalfemur fractures and three internal fixation finite element models, assembles the fracturemodels separately. Moreover, simulating the situation of a weighing60Kg of normal gait,with one foot in neutral position, and loading the gravity of the assembled model, itanalyses the displacement of the distal femur on the model, the displacement of the internalfixation, the stresses of the fracture section and the fixed components, so as to compare themechanical characteristics and the pros and cons of the three internal fixation models forthe type A and type B fractures.Results(1) For fractures of type A, the mechanical stability of femur retrograde interlockingintramedullary nail was the best for its minimal loading-point displacement, internal fixation displacement and internal fixation stress, followed by distal femoral locking plate,and finally for the dynamic condylar screw.(2) As for fractures of type B, the distal femoral locking plate has the minimal stress,followed by the dynamic condylar screw, while the femur retrograde interlockingintramedullary nail is not fittable for such type of fractures.Conclusions(1) In this study, the established models are authentic, which can be used forbiomechanical analysis.(2) It is feasible to use the three-dimensional finite element method to compare thebiomechanical properties of dynamic condylar screw, femoral retrograde interlockingintramedullary nail and distal femoral locking plate in fixing distal femur fractures.(3) All the three internal fixations are feasible for fractures of type A. However, themechanical stability of femur retrograde interlocking intramedullary nail is the best,followed by distal femoral locking plate, and finally for the dynamic condylar screw.(4) As for fractures of type B, the distal femoral locking plate is the stablest, followedby the dynamic condylar screw, while the femur retrograde interlocking intramedullary nailis not fittable for such type of fractures.