A random sample of patients who had total knee arthroplasty suggests magnetic resonance imaging (MRI) is being overused when a simple, inexpensive x-ray image would be an effective tool for diagnosis of osteoarthritis, an investigator reported in a poster presentation here at the American Academy of Orthopaedic Surgeons (AAOS) 75th Annual Meeting.

Wayne Goldstein, MD, Clinical Professor of Orthopaedics, University of Illinois, and Chair, Illinois Bone and Joint Institute, both in Chicago, Illinois, said a careful history and exam coupled with an old-fashioned radiograph of the knee is sufficient to diagnose osteoarthritis of the knee.

For their study, Dr. Goldstein and colleagues obtained data by phone and chart review. Of the 50 patients sampled, 32 had an MRI image of the knee prior to visiting Dr. Goldstein, who said he routinely orders knee radiographs that include weight-bearing and Rosenberg notch views. More than half of the patients had not had an x-ray prior to surgical consultation.

Dr. Goldstein said that patients referred by primary care physicians for torn meniscus expect arthroscopy and often are irate if a surgeon does not consult an MRI.

"A $42 x-ray shows you [more] than an MRI does at 10 times the price, and [the MRI] adds nothing to the care of the patient," said Dr. Goldstein. "You don't do an MRI if the history and exam show you arthritis."

"There is no or minimal benefit to MRI obtained in patients with osteoarthritis of the knee that is obviously apparent on weight-bearing and skyline patella-view x-rays," the researchers noted in their poster.

But Dr. Goldstein noted that elderly women sometimes present with sudden onset of knee pain -- especially on bearing weight -- coupled with localised tenderness, that can look normal on a radiograph. In such cases, MRI can be useful to diagnose spontaneous osteonecrosis or a stress fracture.

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