Patients did as well as those with osteoarthritis, but same did not hold true for hip replacement.

THURSDAY, June 20, 2013 (HealthDay News) — The common belief that rheumatoid arthritis patients don't benefit from knee replacement surgery as much as those with the more common osteoarthritis has been challenged by the findings from a pair of studies by New York City scientists.

Researchers from the Hospital for Special Surgery also found, however, that rheumatoid arthritis patients who underwent a total hip replacement didn't fare as well as those with osteoarthritis, though they did experience improvements in pain and function.

"One thing that we can clearly pull out of this research is that the levels of pain and function among those with rheumatoid arthritis were so much worse preoperatively at the point they approached joint replacement," explained rheumatologist Dr. Susan Goodman, the lead author of both studies. "They may be postponing or not getting to surgery until they're really in a much worse state. Perhaps that's one of the explanations for the results . . . perhaps it's their generalized disease. We really just don't know yet."

Goodman presented the research last week at the European League Against Rheumatism's annual meeting in Madrid, Spain. Research presented at scientific conferences has typically not been peer-reviewed or published and is considered preliminary.

Affecting one of every five adults, along with 300,000 children, arthritis is the leading cause of disability in the United States, according to the Arthritis Foundation. Osteoarthritis, the most prevalent form, progressively breaks down cartilage in the joints due to wear and tear, while rheumatoid arthritis is an autoimmune disease marked by inflammation of the membranes surrounding joints. Along with bringing chronic pain, both types can result in joint destruction.

Historically, rheumatoid arthritis patients have had worse outcomes after joint replacement surgeries than osteoarthritis patients, according to the study authors, but more effective drugs developed over the last two decades have helped them to better control their disease.

In the first study, Goodman and her team analyzed joint replacement registry data to identify 178 rheumatoid arthritis patients and more than 5,200 osteoarthritis patients who underwent knee replacement surgery. Though rheumatoid arthritis patients had worse pain and function before surgery, patients in both groups had similar satisfaction rates after surgery.

The second study compared outcomes of 202 rheumatoid arthritis patients and more than 5,800 osteoarthritis patients who underwent hip replacement, finding that those with rheumatoid arthritis started out with worse function before surgery and also had worse pain and function scores after surgery. However, rheumatoid arthritis patients were as likely as those with osteoarthritis to experience an overall improvement after hip replacement, though the gains didn't erase the disparity between the two groups.

"The advice to rheumatoid arthritis patients is, really, that you will have significant pain relief [from joint replacement surgery]," Goodman said. "It is an area that needs more study. We're looking forward to assessing more rheumatoid-specific factors."

The research, which looked at participants with active rheumatoid arthritis, is consistent with what Dr. Olivia Ghaw, an assistant professor of medicine in rheumatology at Mount Sinai Medical Center in New York City, sees in her practice.

But Ghaw said she felt the study's two-year follow-up period was perhaps not long enough to confirm if the joint replacement outcomes remained positive for rheumatoid arthritis patients.

"For some of my patients, if their joint is severely destructed, I still do recommend joint replacement," she said. "Ideally, we would love to get their underlying disease under better control. If we can bring their inflammation down, perhaps they can have better results with joint replacement."