Computer-aided design of anatomic locking plate for the posterior malleolus / 中华创伤骨科杂志

ABSTRACT

Objective To design an anatomic locking plate for the posterior malleolus using 3D reconstruction CT of the ankle joint and software Mimics.Methods The CT data of 20 normal ankles were imported into software Mimics in.dicom format for 3D reconstruction of the ankle joint.The angles of posteromedial and posterolateral varus,the twist height on the sagittal plane and the height of safe screw placement zone,the width of the posterior malleolus were measured for the posterior malleolus.After the anatomic locking plate was designed using the anatomic data measured and software Ungraphics NX5.0,it was 3D printed in a proportion of 11.Next,the model plate was tested and evaluated in 15 fresh cadaveric specimens of the ankle all the soft tissues of which were removed to fully expose the bony structure of the posterior malleolus.Results The anatomic measurements showed that the angles of postemmedial and posterolateral varus increased gradually towards the medial and lateral sides along the central axis of the posterior malleolus while the twist height reduced from the lateral to the medial side,and that the width of the posterior malleolus increased gradually from the superior to the inferior.It was found that after placement in the 15 fresh cadaveric specimens the anatomic model plate fit the posterior malleolus very well,fulfilling all the designed requirements for the anatomic locking plate for the posterior malleolus.Conclusion A novel anatomic locking plate for the posterior malleolu has been successfully designed and manufactured using 3D reconstruction CT of the ankle joint,software Mimics and 3D printing.