ABSTRACT
Rheumatoid arthritis and post-traumatic osteo-arthritis are very common conditions in the joints of the finger. They are often very painful and are also associated with deformity and a reduction in function. At present, flexible one-piece Silastic implants are the most popular solution to relieve the pain in the joint, correct deformity, restore function and improve the general look of the hand. These implants are designed primarily for flexion/extension but do allow some abduction/adduction as well. Long term studies show that these implants tend to fail after around 3-4 years, mostly due to fracture. This places further limits on the function, but the implants are not usually replaced, instead being left to act as simple spacers between the bones.
To improve the design of implants, kinematic and stress responses can be studied in computer models that closely mimic the functional environment. In this study, simple two and three dimensional finite element analyses of a prosthesis under load have been performed. The kinematic behaviour of the implants were simulated, and areas of undue stress and friction identified. Results were visualised using a novel interactive process that involved a Virtual Hand.
