A metal–on-poly implant wears out about 10 times faster than a metal-on-metal one (0.1 and 0.01 mm per year respectively). In either case this is higher than found in ceramic-on-ceramic implants. The table below shows the comparative wear rates. So Why not chose a ceramic on ceramic hip…or why not use the newest poly with metal? Seems like an easy choice doesn’t it? I thought I would look at the medical studies on these options.
Wear rate per year
Metal ball and poly liner
.1mm (highest wear rates)
.01 with highly crosslinked polyethylene. Polyethylene has been the dominant bearing surface for many years.Highly crosslinked polyethylene, an advancement in this material, is now one of the preeminent alternative bearing
materials available today. This advanced material is highly wear-resistant. It also
offers flexibility and options for surgeons not found in other liner materials
Marathon ploy liners had average wear rates of 15.4 mm over 3 years in some studies. Enduron poly had average wear rates reported as 55.5 mm over the same time frame. That is, the marathon poly had average wear rates 73% below the Enduron poly.
The highest proportion of loosening occurs due to osteoylysis produced by the ultra high molecular weight poly.
Ceramic ball and poly liner
Less prone to fracture vs the older ones
More likely to require removal of healthy bone due to size limitations.
Metal ball and metal liner
Depuy Hip with Ion wear debris found locally and systemically. Recalled from the market.
Ceramic ball and ceramic liner
.0001 mm (least wear rates)
While early ceramic implants tended to chip and break more easily, they now have dramatically lower fracture rates.
Squeaking noise present which is troublesome to patients in many studies I read from 2010