ADVANCED BEARING SURFACES
- The hip is a ball and socket joint. Traditional hip replacement replaces the ball with a metal head. The socket is replaced by a metal shell and a plastic liner is placed between the head and shell to allow for smooth gliding of the surfaces.
- While the metal on plastic joints have been used for many years, the plastic liner can wear out. Particles from plastic wear can cause osteolysis which damages the bone around the implant.
- Metal on metal bearings reduce the amount of wear that the joint experiences. This also leads to less osteolysis than metal on plastic replacements. However, there have been concerns about the production of free metal ions from the wear of the metal components against each other.
- Ceramic bearings also have less wear than metal on plastic, leading to less osteolysis. In the past there were problems with cracking of these hard, but brittle components. Newer generation ceramic components have avoided this problem. Squeaking of the implanted joint has been a problem reported in the newer ceramic replacements.
- The top image on this page is from Stryker's website, demonstrating a metal on metal bearing.
- The bottom image is an example of a traditional hip replacement from Zimmer with a plastic on metal bearing.
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