AAOS study: MRI overused for knee osteoarthritis

SAN FRANCISCO - MRI scans are being overutilized in diagnosing osteoarthritis of the knee, a practice that inflates healthcare costs and sacrifices patient care standards, according to a study presented Wednesday at the American Academy of Orthopaedic Surgeons (AAOS) meeting.

"Ordering an MRI to diagnose osteoarthritis of the knee, when a simple $42 weight-bearing x-ray is what's needed to make a diagnosis, reflects a lack of education about imaging technologies on the part of referring primary care doctors," said Dr. Wayne Goldstein, lead author of the study. Goldstein is a clinical professor of orthopedics at the University of Illinois in Chicago.

In a study conducted by Goldstein and colleagues at the Illinois Bone and Joint Institute, the researchers prospectively reviewed a random sample of 50 patients who had undergone primary total knee arthroplasty in their practice within the last two years. After chart review, they found that 32 of the 50 patients had an MRI prior to a consultation for knee osteoarthritis, and more than half of the 50 patients had not had an x-ray prior to the MRI.

"MRIs are simply being used excessively. There are patients who you can see from across the room have deformed knees, and clearly have osteoarthritis, yet they are being referred for MRIs," Goldstein said.

MRIs are of minimal benefit in diagnosing osteoarthritis, but the disease is often clearly evident on weight-bearing and skyline-patella view x-rays, he said. MRIs are also vastly more expensive than x-rays. In 2008, Medicare reimburses physicians more than $400 for MRIs, while it reimburses physicians just over $43 for four-view x-rays.

In the study, most patients were referred out to radiology or hospital centers for their MRIs, and the MRIs were performed on whole-body MRI systems, making them even more expensive than dedicated extremity musculoskeletal MRI scanners, Goldstein said. While dedicated extremity scanners could reduce costs for diagnosing knee injuries, the fact remains that for patients with clear indications of osteoarthritis they are virtually useless, according to Goldstein.

"For a soft-tissue problem, MRIs are just great. But for a simple and basic bone condition like osteoarthritis of the knee, x-rays are the best diagnostic tool," Goldstein said. "Every adult with a knee problem should first have an x-ray, before an MRI is considered. Doctors should ask whether MRIs are really medically necessary."

If an elderly patient with knee pain does present with a normal x-ray, then a diagnosis other than osteoarthritis should be considered, according to Goldstein. "There are cases where an MRI is warranted," he noted, "for instance, for spontaneous osteonecrosis of the knee," in which blood loss to the knee area causes the bones to break down.

In Goldstein's study, the referring doctors were primary care physicians, and a small percentage were orthopedic specialists. "I really think that the overutilization of MRI reflects a lack of musculoskeletal education on the part of some physicians, and for others, a lack of knowledge about the capabilities of MRI. Most physicians practicing in Illinois today are over 55, and when they were training in medical school, MRIs were unknown. Now they're considered a premier diagnostic tool -- and sometimes we jump into using technology before we do the necessary basics of taking a history, a good physical exam, and an x-ray," Goldstein said.

The incentive for utilizing MRIs can also be financial. In Goldstein's study, the average reimbursement for a knee MRI to physicians varied from $471 (Medicare) to just under $1,290 from preferred provider organizations (PPOs) and contracting medical organizations. By contrast, the reimbursement rate for four-view knee x-rays to physicians varied from $43 (Medicare) to a range of $60 to $183 from PPOs and provider contracting organizations.

Medical imaging now consumes 10% to 15% of Medicare payments to physicians, compared to less than 5% 10 years ago, Goldstein said. And these costs are expected to grow at an annual rate of 20% or more.

Goldstein noted that because of the rising cost of medical imaging, insurance companies may soon begin tracking physicians to ensure that they order x-rays before MRIs for osteoarthritis cases. "In the future, reimbursement for physicians may be determined based on whether or not their use of imaging is appropriate," Goldstein said.

Goldstein said he doesn't plan any further studies on the question of medical imaging. "I did this study to highlight a significant point -- that we often use technology before it's needed. We need to be diagnosticians first, and just do the basics," he said.

For his part, Goldstein intends to ensure that the medical students working under him at the University of Illinois understand the appropriate utilization of diagnostic imaging. "In an era of skyrocketing health costs, when the emphasis is on saving money and taking care of the uninsured, we need to educate physicians about the appropriate utilization of imaging technologies," he said.

By Barbara Boughton
AuntMinnie.com contributing writer
March 6, 2008

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