Engineering a new wrist joint replacement prosthesis - A multidisciplinary approach

The wrist joint is highly complex and there remain unresolved problems to be overcome in designing a successful wrist joint prosthesis. Consequently, the results of total wrist joint replacements have been poor compared to those for hip and knee joint replacements. A multidisciplinary team of orthopaedic surgeons and engineers is working at Bath to tackle some of the key issues in the engineering of a new wrist joint prosthesis. Following a brief background to the work being undertaken by the group, this paper describes two ongoing research activities. Firstly, an assessment is being made of the optimum geometry for a wrist replacement through the use of a geometric constraint modeller. The second activity is the development of a mechanical simulator to assess wrist prosthesis function and loading. A computer algorithm controls articulation of the wrist using cables that mimic normal wrist tendons. This system allows for full movement of the hand and can also simulate external loading. The forces transmitted at the prosthesis/bone interfaces can be monitored using sensors attached adjacent to the prosthesis.