Digital design of posterior anatomic plate for the distal tibia

Objective To report a digital design of posterior anatomic plate for the distal tibia by software Mimics and UG.Methods The CT data of 30 normal ankles were imported into software Mimics in.dicom format for three-dimensional (3D) reconstruction of the ankle joint.The posteromedial version angle of the distal tibia,the twist height in the sagittal plane and the height of security zone for screw insertion in the distal tibia cross-section were measured.The posterior anatomic plate for the distal tibia was designed on the basis of 3D reconstruction of the ankle joint using the software UG.Simulation of the virtual plating for the virtual fracture reduction was conducted to evaluate the digital plate.The rapid prototyping technique was used to manufacture models of the digital plate which were tested and evaluated in the preoperative virtual fracture reduction and actual surgery in 4 patients.Results The measuremeuts showed that the posteromedial version angle of the distal tibia increased gradually from the lateral to the medial while the twist height decreased from the lateral to the medial.The digital design of the plate was achieved on the basis of the measurement data.The models of the digital plate fit the distal tibia very well in the 4 patients with posterior ankle fracture in clinic.Conclusions Design of digital plate can be carried out using CT data,software Mimics and UG.This study provides a reference for digital design of orthopedic implants. Key words: Ankle joint; Computer-aided design;  Bone plates; Fracture fixation, internal