HRT helps to prevent repeat knee and hip replacement surgery

Taking Hormone Replacement Therapy (HRT) regularly for six months following a knee or hip replacement appears to reduce the risk of repeat surgery becoming necessary by up to 40%, a large new study has shown.

Existing data for England and Wales reveals that more than 2% of surgical procedures to replace the knee or hip have to be repeated within three years. In the majority of cases this is due to osteolysis, which is a condition that occurs when particles from the implant leak into surrounding tissue causing an inflammatory response that then destroys the bone around the implant.

The team of scientists carrying out the study assessed the likelihood of repeat joint replacement surgery among women who required a first knee or hip replacement between 1986 and 2006. The women's details had been entered into the primary care General Practice Research Database (GPRD), which holds millions of anonymised medical records for patients across the UK.

More than 21,000 eligible women who met the criteria had not used HRT, while more than 3500 had done so for at least six months, providing matched samples of 2700 HRT users and 8100 women who had not used HRT. The risk of repeat surgery was tracked in both sets of women for a minimum of three years.

Those women who had taken HRT regularly for six months or more after their surgery were 38% less likely to require repeat surgery than were those who had not done so. In addition, those who regularly took HRT for 12 months or more after their procedure were more than 50% less likely to need further surgery during the three year monitoring period. These findings held true even after taking other factors into account such as the use of drugs that can impair bone turnover. However, taking HRT before surgery made no difference to the risk of implant failure, the findings showed. Low levels of the female hormone oestrogen have been implicated in bone thinning and loss, while HRT is thought to help conserve bone thickness.

The authors of the study, which was published online in the Annals of the Rheumatic Diseases, say that this is the first study to show that HRT can help to prevent repeat surgery in women who have undergone knee or hip replacement.