Particulate wear debris of artificial joints, metallic and plastic, and solutions of metals in body fluids are known to have adverse effects. Encapsulation of the articulating parts would prevent wear debris from entering the surrounding tissue and check tissue ingrowth into the joint. The capsule could contain an artificial lubricant to reduce friction and wear and increase the joint life. For the capsule material, several bioelastomers are being tested in an environment of body fluids and lubricants. Three fatigue rigs have been developed for these tests. Tests have shown that a bovine synovial fluid environment causes a tenfold increase in the fatigue life of silicone rubber. A special capsule shape for minimizing stresses due to creasing is being investigated. Electrophoresis has been explored as a method of filtration of wear debris. It has been shown that Co-Cr-Mo alloy wear particles are attracted to polymers having permanent negative surface charge.