Approximate Method for Determining the Axis of Finite Rotation of Human Knee Joint

The aim of this paper is to present an approximate method for determining the position and orientation of the axis of finite rotation with regard to human knee joint. The method includes data acquisition of anatomical angles and landmarks, which are considered as known inputs. Three position components of the origin of reference frame (Ot), secured to the sensor in the absolute coordinate system, and three Euler-angles between the reference frame and the absolute coordinate system are needed for the calculation. By the use of basic vector and quaternion theory, the determination of the axis of finite rotation can be carried out.