Design of anatomically locked plate for posterior malleolus by computer aided technique

Methods: The CT data of 20 normal ankles were imported into software Mimics in dicom format for three dimensional reconstruction of the ankle joint. The within the inside of the turn angle and the after the lateral varus angle of the posterior ankle, the twist height in the sagittal plane and the height of security zone for screw insertion in the posterior ankle cross—section were measured. The anatomic plate for the posterior ankle designed on the basis of 3 D reconstruction of the ankle joint using the software Mimics, CT and 3D printing The 3D printing was used to manufacture models of the anatomic plate which were tested and evaluated on the 15 fresh cadaver specimen.

Results: The measurements showed that the within the inside of the turn angle and the after the lateral varus angle of the posterior ankle increased gradually from the central axis of posterior ankle, while the twist height reduce from the external to the internal. The Computer aided technology design of the plate was achieved on the basis of the measurement data. The anatomic models of the plate fit the 15 fresh cadaver specimen of posterior ankle very well.

Conclusions: Design of anatomic plate can be carried out using CT data, software Mimics and 3D printing. This study provides some references and methods for Computer aided technology design of or internal fixation devices