Ankle morphometry for development of ankle prosthesis

Abstract

The goal standard treatment of ankle osteoarthritis is arthrodesis. Alternatively, total ankle arthroplasty can improve function. No ideal design for this operation. The novel systerms are developing. The fundamental data to achieve that is ankle morphology. This study measure of 32 ankle by MRI which is 3D modality. The appropriate section was selected and measure the parameters the important to creat the ankle prosthesis. The parameters include the anteroposterior, mediolateral diameter of talus and distal tibia, sagitl radius of talus, malleolar width and malleolar axis. Some parameters can not measure directly. Because external rotation of normal ankle distort the true length, the adjust method by trigonometrical equation modify the parameters closed to reality. The comparison of the true talar AP length and the adjusted sagital talar length demonstrate no statistical and clinical significant. This modification method will applied to some parameters. The results shows the detail of 10 ankle parameters. Female group has smaller size than male group significantly except malleolar axis that is not different. The non adjusted parameters compare with the current data from Europe show sample population have smaller parameters except tibial width. If compare with data from China, the sample have no statistical significant except sagital radius of talus. But if compare both Europe and China with adjusted parameters, all parameters except tibial width, sample population are smaller significantly. The reasons of this phenomenon are different in race, the different measurement tool (2D or 3D) and the effect of external rotation of ankle. Ankle parameters play an important role to design and size the novel total ankle prosthesis. No system design for Thai people available now. This study shows that TNK (from Japan) is the most compatible one for Thai population