In the context of joint replacement, what is polyethylene?

Polyethylene is a type of plastic specifically used for bearing surfaces in joint prosthetics, particularly in total joint replacement surgeries such as hip and knee replacements. This material is favored because it has excellent wear resistance and a good track record for biocompatibility, which means it can coexist with human tissue without causing adverse reactions.

In joint replacements, polyethylene is often used in the insert that sits between metal components, allowing for smooth movement while minimizing friction and wear over time. Its ability to absorb some impact and its relative light weight make it a suitable choice for long-term joint function.

Given the other options, metals play a role in joint prosthetics, but they are not the same as polyethylene. Natural tissue grafts, known as autografts or allografts, serve different purposes in surgeries, particularly in reconstructive goals rather than as bearing surfaces. Ceramics are also used in some joint replacements, but they serve different mechanisms such as providing hardness and are typically not used interchangeably with polyethylene. This makes the choice of polyethylene as a type of plastic used for bearing surfaces the most accurate and relevant answer.