MRI Unnecessary for Diagnosing Osteoarthritis of the Knee

A new study found that patients seeking treatment for arthritic knees should be given a weight-bearing radiograph first.

Osteoarthritis (OA) is known as the "wear and tear” arthritis, which affects millions of people worldwide. Patients seeking relief from this disease are often sent for a magnetic resonance image (MRI) to diagnose their problem.

The study, presented in March 2008, at the 75th annual meeting of the American Academy of Orthopedic Surgeons (AAOS), held in San Francisco, CA, USA, highlighted the need for the primary-care physician to start with a patient's medical history, after that, a routine physical, and then focus on basic diagnostic skills.

"MRIs are being used in excess. Many doctors no longer talk to or examine their patients. Instead, they are going right for the technology,” said Wayne Goldstein, M.D., lead author on the study, who is a clinical professor of orthopedics at the University of Illinois at Chicago College of Medicine (USA). "This is another example of over-utilization of the healthcare system. It has become easier to go for the high-cost imaging. On average, an X-ray can cost less than US$150, while an MRI can cost around $2500. Many physicians are ordering MRIs for osteoarthritis of the knee, when all they need to make the diagnosis is that X-ray.”

Utilization of medical imaging is rising rapidly: in the United States, it now consumes 10-15% of U.S. Medicare payments to physicians, compared with less than 5% only 10 years ago. These costs are expected to continue growing at an annual rate of 20% or more. In 2008, U.S. Medicare will reimburse doctors more than $400 per MRI. A four-view X-ray, which works more effectively in showing osteoarthritis and is what most orthopedic surgeons use, will reimburse doctors just over $43.

In 2005, more than 533,000 total knee replacements (also known as total knee arthroplasties [TKA]) were performed in the United States. The most common reasons for this surgery are: severe pain and swelling and/or stiffness in the knee frequently caused by osteoarthritis, which cannot be satisfactorily treated with medications or other therapies.

Researchers in this study reviewed a random sample of 50 patients who had TKA for osteoarthritis to determine if they had an MRI of the knee within the two years before surgery. They discovered that 32 of the 50 patients did have an MRI scan that was ordered by their primary care or orthopedic physician, and that the MRI did not provide any additional diagnostic information that could not be provided by an X-ray. More than half did not have any X-rays performed before their surgical consultation.

Dr. Goldstein and his co-authors believe that the main reason for this over-utilization of the MRI is a lack of education on this diagnostic technique, particularly with family and primary care physicians. "Physicians need to look at why they are ordering an MRI and consider whether it is truly necessary.”


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University of Illinois at Chicago College of Medicine