- Metal Ball and Polyethylene Liners
- Ceramic Ball and Polyethylene Liner
- Metal Ball and Metal Liner
- Ceramic Ball and Ceramic Liner
The standard metal ball and polyethylene cup have been in use since the early 1960s. Scientific studies indicate the use of improved polyethylene liners, called ‘highly crosslinked’ bearings, result in overall decreased wear of the implant.
Because of its durability and performance, Metal-on-Polyethylene has been the leading artificial hip component material chosen by surgeons since hip replacement surgeries have first been performed. The metal ball is cobalt chrome alloy and the liner is polyethylene. Polyethylene is the most understood and used of all the liner materials, offering the surgeon a range of options to obtain stability in the body while the operation is underway.
This ability to adapt and customize during the surgical procedure is an important attribute of polyethylene. It is also the least expensive bearing.
All implants shed wear debris. Your body has to cope with any wear debris that is released when you use your hip implant, unlike your car engine that has special filters to remove the wear products. Currently, wear resistant polyethylene liners, called “highly crosslinked polyethylene” are in use which, during the manufacturing process, have been treated with a short burst of radiation to help the cup resist wear.
Over time, the body may see polyethylene wear particles as invaders or a source of infection. As the body starts to attack them, this leads to osteolysis, a “dissolving of the bone”, which may result in having to replace the implant (known as revision).
Metal-on-Polyethylene implants wear at a rate of about 0.1 millimeters each year.
In the next three days, I will post the other options and then will look at the studies surrounding the wear debris associated with the metal on poly since is seems to be the option of choice over the others.