FRIDAY, June 26 (HealthDay News) -- A new drug to treat rheumatoid arthritis reduces joint inflammation in severe cases while causing only mild to moderate side effects, according to a report from the first clinical trial of the drug on humans.

Masitinib, which is being developed by AB Science pharmaceuticals, is supposed to halt the activity of mast cells, a part of the immune system believed to be involved in the start and progression of rheumatoid arthritis.

The results of the French trial, involving 43 people with arthritis that other treatments had failed to help, appears online in Arthritis Research and Therapy.

"We are encouraged from this study that masitinib not only appears to be effective, but that within the first three months of treatment, the worst of its side effects were over, possibly making it suitable for long-term treatment regimens," one of the researchers, Olivier Hermine, said in a news release from the journal's publisher. The next step will be placebo-controlled trials, he added.

More information

The Arthritis Foundation has more about rheumatoid arthritis  .

MONDAY, June 22 (HealthDay News) -- Total knee replacement is cost-effective in older adults with advanced osteoarthritis, a new U.S. study shows.

Researchers used a computer simulation model loaded with Medicare claims data and cost/outcomes data from national and international sources to project lifetime costs and quality-adjusted life expectancy (number of years remaining of good health) for a wide variety of patients.

The results showed that, overall, total knee replacement (arthroplasty) increased quality-adjusted life expectancy among Medicare patients (average age 74) from 6.822 to 7.957 years. The total cost for people receiving total knee replacement was $57,900, compared with $37,100 for those who didn't undergo knee replacement. That means the cost-effectiveness ratio of total knee replacement was $18,300 per quality-adjusted life year.

The researchers at Brigham and Women's Hospital in Boston and the Boston University School of Public Health concluded that total knee replacement is a highly cost-effective treatment for management of end-stage knee osteoarthritis compared with non-surgical therapies, and is within the range of accepted cost-effectiveness for other musculoskeletal procedures.

"This result is robust across a broad range of assumptions regarding both patient risk and hospital volume," the study authors wrote. "For patients who choose to undergo total knee arthroplasty, hospital volume plays an important role: regardless of patient risk level, higher-volume centers consistently deliver better outcomes. But the additional survival benefits associated with high-volume centers provide limited cost-effectiveness benefits for high-risk patients deliberating between medium- and high-volume centers."

The researchers concluded: "Clinicians, patients and policy makers should consider the relative cost-effectiveness of total knee arthroplasty in making decisions about who should undergo total knee arthroplasty, where and when."

The study appears in the June 22 issue of the Archives of Internal Medicine.

More information

The Arthritis Foundation has more about total knee replacement  .

(HealthDay News) -- Arthritis can cause pain and swelling in any joint, and the joints of the feet are no exception.

The American Podiatric Medical Association says the following triggers may contribute to foot arthritis:

• An injury to the foot, especially one that was left untreated.
• A bacterial or viral infection such as pnuemonia or Lyme disease.
• Bowel disorders such as ileitis or colitis.
• Use of certain prescription drugs or illicit drugs.
• Research has suggested that genetic history may also play a role in the development of arthritis.