Wear rate slower in crosslinked than conventional polyethylene for total hip arthroplasty
First-generation crosslinked polyethylene is more resistant to wear than conventional polyethylene during the first 13 years after total hip arthroplasty (THA), a new randomized controlled trial (RCT) follow-up reveals.
In 16 patients who were followed up for 13 years following THA, the yearly wear rate of the crosslinked polyethylene (n=8; 0.04±0.02 mm/year) was significantly lower than the conventional polyethylene (n=8; 0.08±0.03 mm/year; p=0.007).
Similarly, femoral head penetration in the conventional polyethylene group (1.046 mm; 0.549 to 1.428) was significantly higher than in the crosslinked polyethylene group (0.622; 0.361 to 1.037; p=0.013).One case of osteolysis was reported in the conventional polyethylene group. At 13.7 years, the femoral head penetration was 1.4 mm and the wear rate was 0.104 mm/year.
In terms of clinical outcomes, there were no significant differences between the two groups. Mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores at 13 years in the crosslinked and conventional polyethylene were comparable to each other (69.2 vs 67.9; p=0.92).
Similarly, corresponding scores in the Harris Hip Score (85.6 vs 89.5; p=0.51) and SF-12 mental score (57.5 vs 54.2; p=0.45) indices were not significantly different from each other.
Patients were from an initial prospective RCT including 100 THA patients randomized to receive either conventional polyethylene (n=50) or crosslinked polyethylene (n=50). The current cohort consists of 16 of the original patients who returned for radioisometric analysis and clinical outcome assessment after 13 years.
The current cohort had a mean duration of 13.6 years since implantation, a mean BMI of 28.4 kg/m2 and a mean age of 67.5 years at the time of the procedure. There were no significant demographic differences between the two polyethylene groups.