Researchers puzzled by results of anti-inflammatory medications for osteoarthritis

Researchers in the US are calling for a re-evaluation of the way some well known painkillers are prescribed after research showed they may actually lead to a worsening of inflammation over time in osteoarthritis-affected knee joints.

NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) such as ibuprofen and naproxen are designed to reduce inflammation for the estimated 2.2 million Australians suffering from the sometimes debilitating effects of osteoarthritis.

Osteoarthritis is a degenerative condition affecting joints in the body – most commonly hips, knees, ankles, spine and hands – which results from the degradation of cartilage on the ends of bones within the joints. As the cartilage wears away, the bones rub together resulting in swelling, pain and restricted movement.

To combat this pain and swelling, NSAIDs are commonly prescribed, however the long-term impact of this type of medication is unclear, including its effect on the progression of the condition.

“To date, no curative therapy has been approved to cure or reduce the progression of knee osteoarthritis,” said the study’s lead author, Johanna Luitjens, from the Department of Radiology and Biomedical Imaging at the University of California, San Francisco. “NSAIDs are frequently used to treat pain, but it is still an open discussion of how NSAID use influences outcomes for osteoarthritis patients.

Read more: What is osteoarthritis?

Osteoarthritis in hip joint on x-ray
Arthritis often affects the hip joint . Film x-ray show inflamed of hip joint and blank area at right side. Credit: Stockdevil/Getty Images

Surprisingly the report says: “…the impact of NSAIDs on synovitis, or the inflammation of the membrane lining the joint, has never been analysed using MRI-based structural biomarkers.”

The study compared 793 participants with moderate to severe osteoarthritis of the knee who did not use NSAIDs, with 277 patients who received sustained treatment with NSAIDs for more than a year. Each patient underwent Magnetic Resonance Imaging (MRI) scans of the joint, which were then repeated after four years.

The researchers were able to assess the images for indications of inflammation and arthritis progression including cartilage thickness and composition.

Osteoarthritis in knee shown in mri
The fat pad adjacent to the kneecap (Hoffa’s fat pad, infrapatellar fat pad) can change in signal on MRI when the knee is inflamed. (A) Normal knee without signs of inflammation. (B) Arrow pointing on a circumscribed area with higher signal (bright lines) in the area of the fat pad (normally dark), which is indicative of a beginning inflammatory reaction. (C) The whole fat pad has a higher signal (light grey color with white lines), which is a sign of progressive inflammation of the knee joint. Credit: RSNA/Johanna Luitjens

The data showed the group using NSAIDs, had worse joint inflammation and cartilage quality than those not using NSAIDs, at the time of the initial MRI scan. And the follow-up imaging showed the conditions had worsened for the NSAID group.

“In this large group of participants, we were able to show that there were no protective mechanisms from NSAIDs in reducing inflammation or slowing down progression of osteoarthritis of the knee joint,” said Luitjens.

According to Luitjens, the common practice of prescribing NSAIDs for osteoarthritis should be revisited as there doesn’t appear to be any evidence they have a positive impact on joint inflammation nor do they slow or prevent synovitis or degenerative changes in the joint.

There is also a possibility that NSAIDs simply mask the pain. Despite adjusting the study’s model for individual levels of patient physical activity, “patients who have synovitis and are taking pain-relieving medications may be physically more active due to pain relief, which could potentially lead to worsening of synovitis,” said Luitjens.

Luitjens hopes future studies will better characterise NSAIDs and their impact on osteoarthritic inflammation. With one in three people over the age of 75 in Australia suffering from osteoarthritis and an estimated one in 10 women and one in 16 men set to develop it in the future, unlocking treatment options for this crippling condition is an imperative.

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