Prosthetic joint replacement design methods to restore kinematics and stability while preventing material overload

Abstract

Using computer aided design tools, new total joint prostheses and surgical procedures have been designed to restore normal mechanics and thereby offer hope for improved patient outcome, To obtain improved outcome at a reduced cost, new total joint implant systems must allow the surgeon to restore joint mechanics without overloading prosthetic or skeletal materials. Current techniques often fail to restore normal joint function, Many replacement arthroplasties have experienced an unacceptable rate of loosening. Normal joint mechanics depend on recreation of the joint's kinematic mechanism, In our work average kinematic parameters are used to define mathematical models of the joint surfaces. Duplication of the normal joint is accomplished, However, a series of kinematically correct surfaces can be designed for any given joint. Surface and interface geometries can be varied to take into account the strengths and weaknesses of the prosthetic and biologic materials. New hand prosthetic design alternatives are discussed in detail. The importance of surface asymmetry in stabilizing normal and prosthetic joints, and the processes used to create and analyze specific joint models are also highlighted.