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Highly crosslinked polyethylene hips show no evidence of wear
Investigators also found no evidence of osteolysis among patients who underwent THA.
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Results of a recently presented study indicate that highly crosslinked polyethylene demonstrates low wear for as long as 11 years after total hip replacement, with no indication of femoral head penetration increasing over time.
“Total hip replacement patients continue to do well with the use of highly crosslinked polyethylene and have no evidence of wear of the articulation or particle induced periprosthetic osteolysis,” Charles R. Bragdon, PhD, told Orthopedics Today.
“This data helps validate the continued use of this material for total joint replacement surgery,” added Bragdon, an instructor of orthopedics at Harvard Medical School and research scientist at the Harris Orthopaedic Laboratory at Massachusetts General Hospital in Boston.
He presented these study results at the 12th EFORT Congress 2011 held in Copenhagen, Denmark.
Multicenter study
Bragdon and colleagues conducted a retrospective, multicenter, clinical outcome study to evaluate long-term wear of the ultra-high molecular polyethylene inserts (Longevity; Zimmer Inc.) in a large group of patients.
Seven academic centers participated in the study and identified patients who had radiographs taken at multiple times since surgery. At a minimum, patients included in the study needed to have postoperative films at 1 year, 2 years to 4 years, 5 years, and have at least one film taken longer than 5 years postoperatively.
Patients received a primary total hip replacement at least 6 years prior to the study. The study incorporated 235 of the 250 hips that were under active analysis, with 3,160 film comparisons.
No increase in wear
Results showed that the average wear rate was not significantly different during the early and late periods.
“An exciting finding of this study was that while the wear of the highly crosslinked-polyethylene was essentially not measurable out to 11 years after surgery, there was no evidence of osteolysis,” he said. “Previous studies on standard polyethylene have reported a high incidence of osteolysis at 7 to 10 years after surgery.”
The researchers are conducting follow-up studies to focus on the performance of this material in patients’ second decade of use. – by Tara Grassia
Reference:
- Bragdon C, Martell J, Jarrett BV, et al. A multi-center study of the mid-term wear results of highly crosslinked polyethylene THR components. Presented at the 12th EFORT Congress 2011. June 1-4. Copenhagen, Denmark.
- Charles R. Bragdon, PhD, can be reached at The Harris Orthopaedic Laboratory, Massachusetts General Hospital, Fruit Street, Jackson Building 1126, Boston, MA 02114, 617-726-3886; email: cbragdon@partners.org.
- Disclosure: Bragdon is co-inventor of the highly crosslinked polyethylene reported in this study. The patent is held by Massachusetts General Hospital, and Bragdon receives royalties from the license.