Velocity Workspaces of the Normal Human Knee

The human knee is a joint in the musculoskeletal system, and as such, its main function is to allow motion between the thigh and shank of the human lower limb. The development of an analysis technique that, given a set of constraints, maps out all possible knee motions, could offer much information and insight into studies of knee biomechanics. The study of the kinematics of the human knee is one discipline where the construction of this type of information could provide new perspectives on old problems, meaningful information on current questions, and possible direction to future work. Once a geometric model has been developed, the natural place to begin with respect to kinematic analysis is position analysis. The construction of all possible positions and orientations one rigid body may assume relative to some other rigid body is a general description of what displacement workspace analyses attempt to accomplish. It is highly probable that information useful to the study of the biomechanics of the human knee is inherently contained within workspace analyses based on the constraint systems of the joint. Investigation of a relatively simple model, including representations for constraints dictated by the four major ligaments, gives insight into many aspects of the joint biomechanics. For example, the addition and exclusion of ligaments to a workspace model showed noticeable changes in the shape, geometry and size of the two dimensional cross-sections of the displacement workspace. Such information may allow investigators to develop strategies for affecting the allowable displacements and trajectories in similarly constrained joints, in vivo (Fuller, et al., 2000).