|
Cross-Linked Plastic Better Than
Conventional Polyethylene for Hip Replacement: Presented
at AAOS
SAN FRANCISCO March 6, 2008 - A cross-linked
polyethylene hip replacement surface holds up better to
wear over 6 years compared with the polyethylene product
that is used conventionally.
Investigator Michael J. Anderson, MD, Adjunct Faculty,
Columbia St. Mary's Hospital, Milwaukee, Wisconsin,
presented findings from a prospective, randomised trial
here on March 5 at the American Academy of Orthopaedic
Surgeons (AAOS) 75th Annual Meeting.
The study enrolled 171 patients (181 hips) who had
received either the cross-linked or conventional plastic
part, and the results showed 110% reduced wear for
cross-linked versus conventional polyethylene at 6 years
of follow-up.
Four centres were involved in the trial. Evaluations
included x-ray reading by clinicians who were blinded to
the type of hip device used in each patient, and a
validated, computer-assisted edge-detection method, as
well as a rating of joint function.
Analysis of wear by the blinded and a computer-assisted
method was performed at 6-month and 1-year intervals,
which allowed for bedding-in of the joint replacement
over the first year. The 2-dimensional wear rate was
0.01 mm/year for the cross-linked plastic joint and 0.17
mm/year for the conventional joint replacement (P =
.002).
Mean weight of patients in the study was 140 lbs, but
Dr. Anderson noted that a patient's weight, height, or
activity level "is not an issue" for preferring the
cross-linked plastic product. "It helps for everybody,"
Dr. Anderson said.
No clinical differences have appeared so far between the
two hip replacement methods in terms of Harris hip
score, Western Ontario and McMaster Universities (WOMAC)
score, 12-item Short Form Health Survey score, or
University of California, Los Angeles Activity score.
Cross-linked polyethylene is created by irradiating the
material, breaking carbon bonds which can then be
re-linked. The process produces a more wear-resistant
plastic. It also allows use of larger femoral heads,
which leads to greater joint stability.
Dr. Anderson said that cross-linked polyethylene is now
the standard of care for hip replacement. "This may
represent the most cost-effective change in years" to
hip replacement surgery, he concluded.
Funding for this study was provided by Zimmer.
[Presentation title: A Prospective Randomized Wear Study
Comparing Highly Crosslinked vs. Conventional
Polyethylene. Abstract 026]
|
