I had a joint hip replacement for severe arthritis three years ago. The doctor tells me that “third-body wear” is likely the cause of some uneven wear in the joint. What does this mean?

When patients with hip joint replacements are compared, there are very different results in wear patterns of the new joint. This is true even when the same replacement parts are used from patient to patient.

In fact, one study looked at patients with both hips replaced using the same implant. The researchers compared one side to the other and found that the wear pattern was different from side to side. One of the reasons for this is third-body wear.

This is the presence of tiny particles in the joint. These pieces may be bits of bone or fragments of glue or cement used to hold the new joint in place. Even metal debris from the coating around the joint implant can cause the joint liner to be scratched and roughed up. Joint wear and tear is increased when the surfaces are roughened.