EULAR 2009: New Diagnostic Recommendations for Knee Osteoarthritis

Alice Goodman

June 12, 2009

June 12, 2009 (Copenhagen, Denmark) — New EULAR recommendations for the diagnosis of knee osteoarthritis unveiled here focus on simple measures — clinical examination and plain radiography.

"These recommendations should be especially helpful for primary care physicians in providing them a firm foundation of diagnostic criteria," said lead author Weiya Zhang, associate professor at the University of Nottingham in the United Kingdom.

The guidance was released here during EULAR 2009: The Annual European Congress of Rheumatology.

Dr. Zhang pointed out that these EULAR recommendations differ from American College of Rheumatology (ACR) criteria by focusing on clinical diagnosis rather than classification, and they are more generalizable to different populations because they were based on a thorough evidence-based review of studies from 1950 to 2008 as well as expert consensus from different countries.

The task force was made up of 17 osteoarthritis experts from 12 countries. The expert panel developed 10 key recommendations, and then tested the diagnostic accuracy of these recommendations on 2 separate study populations: one from the United Kingdom and one from the Netherlands.

Three Recommendations Presented

At EULAR, Dr. Zhang presented 3 of the new recommendations — one on risk factors, one on clinical diagnosis, and one on radiography. The full document that includes all 10 recommendations will be published soon.

Risk factors for knee osteoarthritis were identified as follows: female sex, aging, overweight, joint injury, malalignment, joint laxity, occupational and recreational use, family history, and Heberden's nodes (bone overgrowth) at the distal finger joints.

The recommendation for clinical diagnosis focused on 3 symptoms (pain on use, short-lived morning stiffness, and functional limitation) and 3 signs (crepitus, restricted movement, and bony enlargement). The panel found that the 3 signs and 3 symptoms could correctly identify 99% of patients with knee osteoarthritis.

A validation study in the UK sample using the 6 criteria identified a prevalence of knee osteoarthritis of 44%. The probability of making the diagnosis increased with increasing use of the 6 features.

"This performance test tells us that the clinical diagnosis of knee osteoarthritis can be made with confidence based on these factors," Dr. Zhang said. "These 6 criteria apply even if the radiographs appear normal."

The third recommendation called for plain radiography of the knees, with a weight bearing, semi-flexed view, plus a lateral and skyline view. Classical features of osteoarthritis on radiography are space narrowing, osteophytes, and subchondral bone sclerosis.

"There is no gold standard for knee osteoarthritis, as there is for gout, but using the 3 views increases the probability of a correct diagnosis," Dr. Zhang explained. "Other imaging modalities, such as MRI, sonography, and scintigraphy, are seldom needed.

"We call radiography a reference standard, not a gold standard," he pointed out. "Some patients with radiographic damage may not have symptoms, and some patients with symptoms may not have evidence of radiographic damage."

This is the first formal EULAR recommendation for diagnostic imaging for knee osteoarthritis. Imaging may also be needed for management, Dr. Zhang noted.

Consider Recommendations Within Context

The new EULAR recommendations should be considered within the context of the many new treatments available for osteoarthritis and the need to have a consensus for training purposes, according to Andrew Cope, MD, from King's College in London, United Kingdom.

"These are recommendations, not fixed guidelines. The idea is to guide clinicians according to the evidence base. There is no question that some patients won't fit the parameters, which is always a weakness of population-based recommendations. The long-term, far-off goal for rheumatologists is patient-specific targeted management," Dr. Cope said.

The recommendations should be helpful for primary care physicians, he continued. "Keep it simple, keep it safe," he said.

Dr. Zhang, the other panel members, and Dr. Cope have disclosed no relevant financial relationships.

EULAR 2009: The Annual European Congress of Rheumatology: Abstract OP-0209. Presented June 12, 2009.

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