Metal-on-metal bearings for total hip replacement (THR) are becoming increasingly popular. Improved wear characteristics mean that these articulations are being inserted into younger patients in the form of THR and resurfacing procedures. This has led to concerns regarding potential carcinogenicity because of the increased exposure to metal ions that the procedure brings.

We have studied the serum cobalt and chromium concentrations in patients who had primary, well-fixed Ring metal-on-metal THRs for more than 30 years. The levels of cobalt and chromium were elevated by five and three times, respectively compared with those in our reference groups. Metal-on-metal articulations appear to be the source of metal ions throughout the life of the prosthesis. In three patients who had undergone revision of a previous metal-on-metal THR to a metal-on-polyethylene replacement the levels of metal ions were within the normal range. The elevations of cobalt and chromium ions seen in our study were comparable with those in patients with modern metal-on-metal THRs.

We performed a prospective randomised controlled trial of the A-V Impulse System in 82 patients treated by hemiarthroplasty for subcapital fracture of the femoral neck. The incidence of proximal deep-vein thrombosis as assessed by Doppler ultrasonography was 23% in the control group and 0% in those using the device (p less than 0.01). Calf and thigh circumferences were measured in both groups at seven to ten days after operation. In the treatment group there was a mean relative reduction of postoperative swelling of the thigh by 3.27 cm (p less than 0.001) and of the calf by 1.55 cm (p less than 0.001). The A-V Impulse System appears to be a safe and effective method of reducing the incidence of proximal deep-vein thrombosis, and of postoperative swelling.