ABSTRACT
Objective To explore the necessity and function of the sustentaculum tali screw placement for the treatment of Sanders type Ⅱ calcaneal fracture.Methods The data of Dicom that CT scan with bone was input into Mimics 12.0 software and Ansys 13.0 software for construction of calcaneus three-dimensional finite element model.Then,this model was imported into Solidworks 2010 software.Type Ⅱ calcaneal fracture model was established according to Sanders type cutting of calcaneus.Geometric parameters of AO calcaneal plate and screws were imported to the Solidworks 2010 software.Two internal fixation simulations were established based on the calcaneal model.In one model,the steel was placed on the outside with bone and the cancellous' bone screws were infiltrated respectively into the vertical bone since two screw holes which under the articular surface behind the steel plate,two screw holes which rear of the steel plate,a screw hole of the below calcaneus,two screw holes which in front of steel plate.In another model,a cortical bone screw was infiltrated into the sustentaculum tali through the bottom screw hole of articular surface of the steel plate.The two internal fixation models were loaded under the same condition,and non linear finite element analysis was carried out.The stress distribution in the two internal fixation models was calculated respectively.Results The maximum principal stress focused on the cortical bone of sustentaculum tali in both of the models under the same condition of loading.Bone joint displacement,maximum principal stress of calcaneal and internal fixation system in the model with sustentaculum screw fixation were smaller than that in the model without sustentaculum screw fixation.The stress in the model with sustentaculum screw fixation was more dispersed.Conclusion The placement of sustentaculum tali screw is essential for fixation of type Ⅱ calcaneal fracture to achieve the biomechanical stability and can be used in clinical.