Abstract
Ceramic-on-polyethylene (COP) bearings have traditionally been reserved for younger patients that were at high risk of polyethylene wear requiring revision. With the 1999 advent of highly crosslinked polyethylene (XLP), wear with XLP has not been a cause for revision. Simulator studies have not shown a difference in wear comparing COP to metal-on-polyethylene (MOP). Therefore, and considering the additional cost of COP, we have until recently not needed COP. However, a 2012 report of 10 cases that developed an adverse reaction to metal debris generated by head neck corrosion has resulted in COP becoming the most common bearing surface as reported by the American Joint Replacement Registry. This reactionary change has occurred despite the fact that we do not understand the cause, do not know the frequency, if it is more common in some implants than others, and we do not know the additional cost or markup of ceramic heads. One study reported a 3.2% revision prevalence caused by mechanically assisted crevice corrosion (MACC) at the head neck junction of a single manufacturer's implant. Other studies have estimated the frequency to be less than 5%. COST IS THE CONCERN in a value based healthcare environment. Models for and against the wholesale use of COP have been proposed and are based on variables that are unknown, including estimated frequency of the problem and the incrementally higher cost of a ceramic head. I use COP in younger patients that I believe will use their hip for more than 15 years. This is based on my personal experience. I have prospectively followed a series of MOP patients for 5 years and not seen cobalt elevations. I have placed new metal femoral heads on corroded femoral tapers without subsequent failure. I have evaluated the taper junctions of postmortem retrievals and found them virtually free of corrosion. A query of our institutional database for MOP primary hips identified 3012 cases between 2006–2017. Eighty revisions (2.7%) were identified. 2 of the 80 were for MACC representing 2.5% of revisions done on our own patients and 0.07% of our MOP cases. Further, evaluating our most recent all cause 350 revisions (7/2015–10/2017) there were 3 revisions for MACC (0.9%). Each one of us needs to EVALUATE OUR OWN PRACTICE AND MAKE AN EDUCATED, VALUE BASED DECISION whether or not to use COP in all patients.
