CANCER AND MORTALITY FOLLOWING METAL ON METAL HIP RESURFACING ARTHROPLASTY

Abstract

Introduction: Total hip replacement in one of the most commonly performed operation in orthopaedics in the UK with similar numbers being operated in other parts of the world (2). The main reasons for this magnitude are marked improvement in function and the quality of life. The hip prosthesis has evolved significantly over half a century and better prostheses are available today. These newer implants are required to have a survival of 90% for a minimum of 10 years. The improved survival of the implant tends to have effect on the quality of life as well as the life expectancy. There has been a continuous attempt to quantify this increased life expectancy and survival following total hip arthroplasty.

Materials and Methods: We compared the mortality figures of 3947 patients who had hip resurfacing arthroplasty with the national mortality figures of the UK. The cause of death was determined by telephone call to the next of kin and from the national death register.

Results: The average standardized mortality ratio of hip resurfacing patients compared to national figures over the nine year period was 0.524(99 percent C.I. 0.39 to 0.69). Individual SMR for each year is shown in Table. The number of observed deaths were 86 as compared to the expected deaths number 164. Out of the total 86 deaths over a nine year period, 36 deaths were due to cancer, 25 due to cardiovascular causes, eight due to respiratory conditions, four following accidents and 13 due to other causes such as suicide, old age. In the cancer group 7 patients died of lung cancer and 8 died of blood cell neoplasms. National figures for year 2007 were not yet compiled so SIR for cancer was not calculated.

Conclusion: The results of this study are comparable to other follow up studies on mortality following total hip replacement. This indicates that increased activity following hip resurfacing may help the patients maintain better fitness.

The incidence of cancer needs to be interpreted with caution and can only be ascertained by a prospective study.