Abstract
Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. This study reviews AP and lateral radiographs for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).
Reduced implant survivorship due to aseptic loosening has prompted research into alternative bearing materials. Simulator testing is useful but clinical studies are the gold standard to evaluate the wear characteristics of new bearing materials.
On hundred and twelve patients matched for sex, age, body mass index, primary pathology, Charnley grade, and follow up underwent uncemented total hip replacement using an identical implant. Group One (sixty-four patients) had a RAM extruded liner (GUR 4150 HP) and Group Two (forty-eight patients) had a compression molded liner (Montell H 1900). HMWPE sterilisation regimes were identical. AP and lateral radiographs were analysed for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).
Preliminary data show a linear and volumetric wear rate in Group One of 0.067 mm/yr and 26 mm3/year respectively between two years to maximum follow up. Similarly, the wear rates for Group Two were 0.132 mm/yr and 45 mm3/year respectively. There was no statistical difference in acetabular osteolysis between Group One (16.3%) and Group Two (15%) patients at maximum follow up.
Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. Quality of the wear debris is more likely to be important in producing aseptic loosening than actual wear rate.
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
