Serum-cobalt levels with metal-on-metal bearings in the cement-free total hip arthroplasty results covering two years; prospective study

80 patients, age 34- 82, with primary osteoarthritis or avascular necrosis of the femoral head, were placed into one of two THA treatment groups to test the effectiveness of different bearing types: The first group, metal-on-metal, was given a metal-on-metal bearing following surgery, while the second group was given a ceramic-on-ceramic bearing. Results showed that radiologically and clinically there was no difference between the groups, but the metal-on-metal group had significantly higher medium cobalt serum levels 2 years after treatment.