Women more likely to have problems with hip joint replacements

By Lilian Anekwe

BMJ Group News

What do we know already?

There’s been a lot in the news recently about the safety of hip replacements. Recent studies looked at a type of hip joint replacement called a metal-on-metal prosthesis, which was wearing out more quickly than expected. These studies found that women are more likely than men to have problems with their replacement joint, and so to need another operation to repair or replace it.

Doctors aren’t sure why women are more likely to have problems with hip joint replacements than men. Other factors, such as people’s weight, other illnesses, the type of replacement hip joint used, and the experience of the surgeon, are also likely to affect whether people get problems. Researchers are trying to find out which factors are most important.

This latest study looked at what happened to more than 35,000 people who had a total hip replacement between 2001 and 2010 in 46 hospitals in the US. Researchers worked out whether women were more likely than men to have problems with their replacement hip joint in the years following their operation, after accounting for other factors.

What does the new study say?

After five years, around 29 in 1,000 women needed to have another operation compared with around 23 in 1,000 men. The most common reasons for needing a second hip operation were because the replacement joint became unstable, got infected, or became loose or fractured.

The researchers calculated that women were 29 percent more likely to have problems with replacement hip prostheses than men, after adjusting their figures to take account of other factors that could have affected the results.

How reliable is the research?

The researchers accounted for many of the factors that could affect how likely people were to need a replacement hip joint, such as differences in the hospital and the experience of the surgeon, and differences in the health of people having the operation. But there’s always the chance that something they didn’t account for affected women more than men, and that this affected the results.

During the course of the study, around 14 in 100 people either dropped out or died. This can sometimes affect the results of a study, but the researchers did account for this in their calculations. This study didn’t follow people for very long after their operation (the average was three years). Longer studies could give more useful information about how long hip replacements last for both men and women.

What does this mean for me?

Women seem more likely than men to have problems after hip replacement operations. But it’s important to note that this increased chance of problems is quite small. Overall, 29 in 1,000 women needed to have another operation compared with around 23 in 1,000 men - a difference of six in 1000 more women than men. If you are considering hip joint replacement surgery, your surgeon will be able to discuss the risks with you.