Osteolysis is a term used to describe a problem common to artificial joint replacements. It refers to an active process of bone breaking down and dissolving. Particles called debris wear off the implant. This starts a process of bone degeneration.
As the body tries to clean up the loose particles of plastic or metal, the bone grows away from the implant, causing it to loosen. A second or revision surgery may be needed. The surgeon will remove the damaged implant, smooth the bone, and reinsert another (new) implant.
Osteolysis caused by wear debris occurs for a variety of reasons. Patient activity is probably the most important one. Increased activity puts greater load over time on the joint replacement.
The implant itself is part of the problem. Manufacturers are working to improve implant materials and design. And finally, the surgery is a factor. Balancing the ligaments and restoring normal joint alignment are important in the long-term wear and tear on the joint.