For Knee Pain, It Could Pay to Ask for an X-ray, Not an MRI

X-rays may be a better diagnostic tool for arthritis, a study finds, and MRIs are much costlier.

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Good news for people with bad knees: A study released last week found that an old-fashioned X-ray may be better at diagnosing osteoarthritis than a much more costly magnetic resonance imaging, or MRI, test. Since you may very well be responsible for paying a chunk of the cost of these diagnostic tests, that's useful information to keep in mind.

The study examined a random sample of 50 knee replacement patients at the Illinois Bone and Joint Institute. It found that MRI tests didn't provide any diagnostic information that wouldn't have been seen on a "standing" or "weight bearing" X-ray. But the sophisticated imaging test sure costs a lot more: about $2,500, compared with just $150 for the X-ray, according to the study.

Too often, though, primary-care physicians order up MRIs for patients who come in complaining of achy knees, says Wayne Goldstein, the study's lead author and a clinical professor of orthopedics at the University of Illinois-Chicago's School of Medicine. For most patients, he maintains, a standing X-ray that shows what a patient is actually experiencing while on his or her feet is a better choice. "It tells me how much space there is between the bones and the alignment of the bones," he says.

Osteoarthritis, which afflicts more than 20 million Americans, occurs when the cartilage that cushions the ends of our bones breaks down, leading to pain and loss of movement in our joints. More than 533,000 people had knee-replacement surgery in 2005, up from just under 300,000 in 2000.

The study findings, presented at the American Academy of Orthopaedic Surgeons' annual meeting last week, provide more grist for critics who claim that expensive imaging tests are overused. Doctors with financial interests in imaging centers or equipment probably make the problem worse, say experts. A McKinsey & Co. study last year reported that "self-referring" physicians order two to eight more CT and MRI scans annually than the average physician and cited research that 30 to 40 percent of diagnostic imaging in the United States is inappropriate or unnecessary. The study concluded that excess imaging capacity costs the healthcare system some $40 billion annually.

Big-picture concerns aside, if your doctor orders an MRI when an X-ray would do just as well, you may end up paying more for it. Employers have been shifting more healthcare costs onto their employees' shoulders for years, and imaging tests are no exception. If I need an X-ray or an MRI, for example, my plan will expect me to pay 10 percent of the cost. If you're in a high-deductible health plan and haven't met your deductible for the year, you may owe the entire amount of the test. So it could pay to ask your doctor to consider whether going the lower-tech route is an option in your case. You might also ask if he or she has seen the study. Here's the link.