As a result of the increased popularity of metal-on-metal bearings for total hip arthroplasty, concerns have been expressed about patient exposure to increased serum metal ion levels.

We therefore performed a retrospective review of patients with metal-on-metal, uncemented Ring total hip replacements with a minimum follow up of thirty years.

After allowing for prosthesis revision and patient mortality, 6 hips in 5 patients were reviewed and serum ion levels measured. Similar cohorts of patients with other combinations of bearings were compared with an age-matched osteoarthritic control group.

Serum cobalt and chromium levels in the metal-on-metal hip arthroplasty group were significantly higher than in all other groups and approximately five and three times greater respectively than in the group with no implants. Unlike the stainless steel-on-plastic group, the cobalt/chrome-on-plastic group showed significantly raised serum cobalt levels compared with the control group. It is of interest that patients who have had their metal-on-metal hip replacements revised to metal-on-plastic, have metal ion levels that are not statistically different to those of the osteoarthritic control group.

Though we acknowledge the small numbers of patients studied, no identifiable harmful effects were found.

We conclude that serum metal ions remain elevated throughout the life of the metal-on-metal articulation. Metal bearing hip arthroplasty is being used in ever younger patients and together with increased life expectancy we are exposing our patients to potentially harmful levels of metal ions throughout the life of the implant.

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.