Orthopedic Gadgets Practice Test

In joint prostheses, the surface that slides against the counterface needs to have a very low friction to minimize wear and heat. Ultra-high molecular weight polyethylene provides that combination. It’s a durable polymer with a very low coefficient of friction when articulating against metal or ceramic, and it resists wear under the repetitive loads of a moving joint. Because of this, UHMWPE is used as the bearing surface (the insert) in many metal-on-polyethylene or ceramic-on-polyethylene implants. The other materials listed are mainly used for structural components like stems or shells, and while metals can form bearings in some designs, they don’t offer the same low-friction wear performance as UHMWPE in the articulating pair.