Kinematics measurement of mobile bearing total knee arthroplasty

The presented study describes a new method to measure kinematics of the polyethylene insert in mobile bearing total knee arthroplasty. The method estimates the three-dimensional position/orientation of the insert from a single-plane X-ray photograph using projected points of some metal balls which are embedded in the insert. The kinematics can be measured with an accuracy of 0.19 mm or better.