A Ceramic Hip Replacement
A ceramic hip replacement will be made of either: -
In addition during June 2011 the FDA approved a new ceramic on metal system.
- a ceramic femoral head with a polyethylene cup lining (ceramic on poly)
- a ceramic femoral head and a ceramic lining (ceramic on ceramic)
In case your imagining that your hip will be made of some sort of pottery let me reassure you. The type of ceramic used in hip replacements is an oxide of a metal (oxide ceramics) and specifically alumina ceramic and zirconia ceramic. Ceramics are hard. In fact the only thing harder than aluminium oxide is diamond.
Ceramic Hip Replacement - AdvantagesNot only are ceramic implants very hard they are also extremely smooth and are therefore prone to less wear. As a result a ceramic-on-poly implant will significantly reduce the wear rate compared with a metal-on-poly implant but the lowest wear rates are achieved with ceramic-on-ceramic.
Wear is one of the most important factors to be considered in choosing a new hip. The process of wear generates small particles of debris and it is this debris which triggers a response from the body which, in turn, leads to the loosening of the implant. A loose implant will cause pain and, sooner or later, the need for revision surgery.
Its not just the amount of debris given off that is of concern but the type and here again a ceramic hip replacement has the advantage over a metal one. Not only does a metal implant wear out more quickly than a ceramic one but importantly the type of debris given off is in the form of metallic ions. These can spread throughout the body. A real issue is how the body will react to these sub-microscopic invaders. During 2010 Depuy issued a recall of it's ASR system which was linked to metallosis and a higher then normal rate of revision work. That recall alone affected 93,000 patients.
Of particular concern is the possible effect on a foetus and so women of child bearing age are advised not to have metal implants.
As the articulating surfaces of a ceramic hip replacement are non-metallic there is no issue around the release of metal ions and they are suitable for women who might want to start a family.
Finally, there is a relationship between the amount of wear and the size of the femoral head used. A larger sized femoral head is less likely to dislocate but will normally cause more wear. With the very low rate of wear associated with ceramic implants (particularly ceramic-on-ceramic) the surgeon is free to use a larger head and thus reduce the risk of dislocation.
Ceramic Hip Replacement - DisadvantagesA ceramic cup can not incorporate the lip that is a standard part of a plastic cup liner. This lip serves to lower the risk of dislocation. Therefore a ceramic on poly replacement has the advantage of the lip and a ceramic-on-ceramic has the advantage of being tougher and permitting the use of a larger femoral head.
In a few ceramic hip replacements there has a "catastrophic failure". Although ceramic is hard it is brittle and can break. Metals and plastics can deform under stress - ceramic can't. Improvements in the production of ceramics has significantly lowered this risk and it is now estimated to be about 1 in 25,000.
One other possible disadvantage is that ceramic-on-ceramic implants are more expensive. Whether this will affect you will depend on who is footing the bill for your treatment. Ceramic on poly come in a bit cheaper.
Who Are They For?Ceramic hip implants are aimed primarily at people who are likely to wear out their new hip and therefore need it to be replaced. Younger and more active people are the main target group.