I have rheumatoid arthritis in my hips and will probably have one of them replaced in the spring. I’ve gotten the impression that we are fairly rare and that most patients who need hip replacements have the other kind of arthritis. Just how rare is my situation?

Keeping track of number and type of joint replacements can be done in several different ways but in the United States, we don’t have every patient entered into a database like some other countries do. We can get information from hospital discharge data and Medicare part B that is helpful. Many times, this is limited to patients over the age of 65. It doesn’t include younger patients or people who have their replacements done in private orthopedic surgical clinics.

Some of the other countries such as Finland do have a national registry. This type of information is routinely collected and has been a clinical feature for over 30 years. Because their patient population isn’t so different from ours (socioeconomic, educational background, lifestyle), we can often make comparisons that could easily apply to our country.

A recent report was published using data from the Finish Registry that might answer your question. They ran a software program that pulled out how many hip replacements were done just for patients with rheumatoid arthritis. The time period information was collected from was from 1980 to 2006.

There were a total of 132,540 primary (first-time) hip replacements in the whole study (all diagnoses such as osteoarthritis, traumatic arthritis, rheumatoid arthritis). Breaking that down by age, the majority of those (86 per cent) were in adults 55 years old or older. That’s approximately 114,600 of the 132,540. And of the people in the 55 years and up group, only five per cent (about 6,000 patients) had rheumatoid arthritis as their main diagnosis. So you can see, this isn’t a rare group but fairly uncommon.

Those overall figures are lower than in the United States where over half a million hip replacements done each year. About five per cent of those will be in patients with a primary (main) diagnosis of rheumatoid arthritis (RA).

With the new, more effective medications to control the progression of joint destruction associated with RA, this percentage may not increase over time — even though more adults with RA are living longer with their disease. Over time, better control will yield better results and outcomes with less invasive treatment.