• BACKGROUND
    • Low polyethylene wear rate and low incidence of osteolysis after total hip arthroplasty using annealed and remelted highly cross-linked polyethylene have been reported. However, there is no previous report that directly compared both types of highly cross-linked polyethylene. We therefore performed a retrospective study on a series of highly cross-linked polyethylene, in order to: (1) compare wear rates and the incidence of osteolysis between annealed and remelted highly cross-linked polyethylene at 7-10 years; (2) identify the frequency of complication related to annealed and remelted highly cross-linked polyethylene.
  • HYPOTHESIS
    • There is no difference in the linear wear rate and the incidence of osteolysis between the annealed and remelted highly cross-linked polyethylene in total hip arthroplasty.
  • PATIENTS AND METHODS
    • Two hundred and sixteen cases of cementless total hip arthroplasties with annealed or remelted highly cross-linked polyethylene, which were performed between January 2003 and December 2006 in one institution, were followed for 7-10 years and received computed tomography scan, in addition to radiography at the latest follow-up. Annealed and remelted highly cross-linked polyethylene was used in 91 cases and 125 cases, respectively. A 26-mm cobalt-chromium head was used in all cases. Penetration rates from 1 year to the last evaluation were used to estimate the yearly linear wear rate. Existence of osteolysis was evaluated by plain radiography and computed tomography.
  • RESULTS
    • There were no significant differences in patients' background between the two groups. The linear wear rate of annealed and remelted group was 0.031±0.022mm/year and 0.032±0.020mm/year, respectively (P=0.91). Two cases of small femoral osteolysis were found in the annealed group. Any complication related to highly cross-linked polyethylene was not found in both groups.
  • DISCUSSION
    • There was no significant difference in the linear wear rate and the incidence of osteolysis between the annealed and remelted group at postoperative 7 to 10 years. Excellent results of both types of highly cross-linked polyethylene were revealed by this study.
  • LEVEL OF EVIDENCE
    • Level III retrospective case control study.