Methodology for Measurement in Vivo Ankle Joint Kinematics after Two Different Types of Total Ankle Arthroplasty

Revision surgery due to relatively high rates of loosening and implant subsidence is one of critical problems after total ankle arthroplasty (TAA). In Japan, ahead of the world, two types of TAA with differently shaped alumina ceramic implants are being used in recently. For one type, Standard TAA, an analysis of ankle joint kinematics after replacement has been performed. However, the method is specific to its implant for standard TAA, and ankle joint kinematics after the other type, Combined TAA, has not been analyzed or compared in terms of kinematics. In addition, the previous method has critical issue of reproducibility because it includes manual processes. The purpose of this study is to develop in vivo kinematics analysis method of ankle joint after Standard TAA and Combined TAA that can be used to compare them. Definition of reference systems using common implant shapes features enabled kinematics analysis independent of its shape. Also, calculating ankle joint kinematics using iterative closest point (ICP) algorithm enabled a uniform analysis without any manual processes. The proposed method allows comparison of ankle joint kinematics after Standard TAA and Combined TAA with automatically and reproducibility. The analysis results may lead to the development of optimal implant shapes.