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Squeaking ceramic-on-ceramic hips may be due to stem choice
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ORLANDO, Fla. — Reports of squeaking coming from ceramic-on-ceramic hip prostheses have been documented in the medical literature and have become somewhat of a conundrum in the orthopedic community.
However, a Tufts University investigator says the squeaks are the result of a specific titanium alloy stem used with the ceramic bearings.
“Appropriately designed alumina ceramic-on-ceramic bearings have been used in our institution over 1,100 times for more than a decade by nine surgeons, none of whom ever had a patient come into their office with a squeak,” Stephen B. Murphy, MD, said. “Our experience is that the loud, reproducible, common squeaking is associated with one specific hip implant combination.”
Murphy commented on the topic in an Orthopaedic Crossfire presentation at the 25th Annual Current Concepts in Joint Replacement Winter Meeting, here.
He said the combination of ceramic components mounted on a beta titanium alloy stem causes the squeaks.
In investigating the squeaking prostheses, Murphy and colleagues focused on the influence of design and found two main groupings: one with flush mounted liners and one with an elevated metal rim.
“We subdivided the elevated metal rim group into those with stems made from conventional titanium alloy and those with stems made out of a beta titanium alloy that included molybdenum, zirconium and iron,” he said.
Murphy said the beta titanium alloy was significantly problematic in terms of squeaking. The researchers then looked at the prostheses used in the literature reports of squeaking and found that most if not all of the implants used the beta titanium stems with recessed liners.
“Overall, alumina ceramic-on-ceramic bearings have had superb outcomes in 10-year studies, and the results are as good as or better as anything in young patients that has ever been published,” he said. “In the two FDA investigational device exemption (IDE) studies, there were no complaints of squeaking and no revisions for squeaking. This problem seemed to happen after the FDA clearance when any femoral component was able to be used with them.”
For more information:
- Murphy SB. Ceramic-ceramic: For the hard of hearing and lives alone — opposes. Paper #5. Presented at the 25th Annual Current Concepts in Joint Replacement Winter Meeting. Dec. 11-13, 2008. Orlando, Fla.