Squeaking ceramic-on-ceramic hips may be due to stem
choice
Link
http://www.orthosupersite.com/view.asp?rid=34018
December 2008
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.
