By Pat Anson, PNN Editor

Two new studies are raising doubts about a commonly used treatment for knee osteoarthritis, a progressive and painful condition found in many older adults. Corticosteroid injections in the knee are often used to relieve osteoarthritis pain by reducing inflammation in the joint, with the relief lasting for days, weeks or sometimes months.

But a new long-term study by researchers at the University of California, San Francisco (UCSF) found that corticosteroid injections appear to worsen the progression of knee osteoarthritis compared to patients who received injections of hyaluronic acid, a polymer gel that acts as a lubricant and shock absorber.

UCSF researchers followed 210 patients with knee osteoarthritis (OA). Seventy of the patients received injections of either corticosteroids or hyaluronic acid, while the rest received no injections and served as a control group. MRI scans were performed on all participants at the start of the study and again two years later, focusing on the meniscus, bone marrow lesions, cartilage, joint effusion and ligaments.

“This is the first direct comparison of corticosteroid and hyaluronic acid injections using the semi-quantitative, whole organ assessment of the knee with MRI,” said Upasana Upadhyay Bharadwaj, MD, a research fellow in the Department of Radiology at UCSF.

In findings presented this week at the annual meeting of the Radiological Society of North America (RSNA), Bharadwaj reported that corticosteroid injections were significantly associated with the progression of knee OA, specifically in the lateral meniscus, lateral cartilage and medial cartilage.

Hyaluronic injections were not associated with the progression of knee OA. Patients who received hyaluronic acid showed a decreased progression of osteoarthritis, specifically in bone marrow lesions, compared to the control group. 

The findings are important because osteoarthritis is the most common form of arthritis, causing progressive joint damage and thinning of cartilage.  Over 32 million U.S. adults have knee OA, and about 10% of them receive corticosteroid or hyaluronic injections.

“While both corticosteroid and hyaluronic acid injections are reported to help with symptomatic pain relief for knee osteoarthritis, our results conclusively show that corticosteroids are associated with significant progression of knee osteoarthritis up to two years post-injection and must be administered with caution,” Bharadwaj said. “Hyaluronic acid, on the other hand, may slow down progression of knee osteoarthritis and alleviate long term effects while offering symptomatic relief.

“Knowing the long-term effects of these injections will help osteoarthritis patients and clinicians make more informed decisions for managing the disease and the pain it causes.”

In a second study presented at the RSNA’s annual meeting, researchers at the Chicago Medical School compared X-ray images of 50 patients with knee OA who received injections of corticosteroids to 50 patients who received injections of hyaluronic acid. Another 50 patients who had no injections served as a control group. Like the UCSF study, X-rays of all patients were taken at the start of the study and again two years later.

The findings mirrored those found in the first study. Patients injected with corticosteroids had significantly more osteoarthritis progression, including medial joint space narrowing, a hallmark of the disease.

“Even though imaging findings for all patients were similar at baseline, the imaging hallmarks of osteoarthritis were worse two years later in patients who received corticosteroid injections compared to patients who received hyaluronic acid injections or no treatment at all,” said Azad Darbandi, a researcher and medical student.

“The results suggest that hyaluronic acid injections should be further explored for the management of knee osteoarthritis symptoms, and that steroid injections should be utilized with more caution.”

The Mayo Clinic recommends that corticosteroid injections be limited to once every six weeks, and that knee OA patients receive injections no more than three or four times a year.

There was a third long-term study presented at the RSNA meeting that debunked another common treatment for knee OA: non-steroidal anti-inflammatory drugs (NSAIDs). UCFS researchers found that NSAIDs worsen inflammation and weaken cartilage in patients with osteoarthritis, contributing to a painful joint condition called synovitis. MRI imaging at the start of the study found joint inflammation and cartilage quality were worse in patients taking NSAIDs, and their knee joints deteriorated even more after four years.