Abstract:

BACKGROUND: Total hip prosthesis with polyethylene liner has been widely applied in the total hip arthroplasty by the reason of stable quality and relatively low price. Nevertheless, polyethylene wear particles can induce periprosthetic osteolysis, and then lead to aseptic loosening, it is still the main reason influencing prosthesis survival rate.
OBJECTIVE: To measure the polyethylene linear wear of metal-on-polyethylene and ceramic-on-polyethylene bearing by computer-aided method and to compare the difference of antiwear ability.
METHODS: Forty-eight patients (58 hips) with Zweymuller uncemented total hip arthroplasty were selected from Nanfang Hospital of Southern Medical University from 1997 to 2005, and all the patients were followed-up. The migration in the femoral head center relative to the axis of acetabulum opening plane on digital consecutive radiographs were examined to determine direction and degree of polyethylene linear wear. The experiment was divided into two groups according to different weight-bearing interface combinations: metal-on-polyethylene group (36 hips) and ceramic-on-polyethylene group (22 hips), and then the liner wear rate of two groups was compared.
RESULTS AND CONCLUSION: The average polyethylene linear wear rate of metal-on-polyethylene group after 6.3 years follow-up was (0.20±0.11) mm/year, the average polyethylene linear wear rate of ceramic-on-polyethylene group after 4.6 years follow-up was (0.11±0.03) mm/year. After controlling for potential confounding factors, such as age, follow-up time, bilateral femoral eccentricity and the linear wear direction, the covariance analysis showed that the linear wear rate of ceramic-on-polyethylene group was higher than that of metal-on-polyethylene group (P = 0.017). The study showed that ceramic-on-polyethylene bearing got lower wear rate in total hip arthroplasty, and it was beneficial to long-term result.