Computer-assisted preoperative planning of a novel design of total ankle replacement

Computer-assisted preoperative planning are particularly sought for enhancing surgical implantation and improving clinical outcome of ankle joint replacement arthroplasty. A planning tool was designed to enhance the surgical implantation of a novel ligament-compatible three-component prosthesis. The tool includes a geometric and mechanical model of the ankle complex. The geometry of the articular surfaces and of main ligaments is defined from digitisation on a scanned lateral radiographs of the joint. From the expected movement arc and from component dimensions, a mechanical model of the ligaments is used to select the optimal size and the position the three prosthesis components. The planning is based on the minimisation of ligament change in length and of bone stock to be removed. The main output report is a detailed picture of the replaced ankle with indications of component locations and quantitative measure of bone cuts. An advanced report also superimposes the resulting prediction of prosthesis component kinematics at the replaced joint to the original radiographs.