Jill Stein

February 18, 2011

February 18, 2011 (San Diego, California) — More than half of patients presenting to an orthopaedic surgeon with acute knee pain have had a magnetic resonance imaging (MRI) scan at the request of their referring physician that was not necessary, researchers reported here at the American Academy of Orthopaedic Surgeons 2011 Annual Meeting.

Dr. Harpal Khanuja

"[MRI] is useful in many diagnoses of knee pathology and can be a cost-effective means of decreasing the need for diagnostic arthroscopy and its risks when used appropriately," Harpal Singh Khanuja, MD, director of hip and knee replacement at the Rubin Institute for Advanced Orthopaedics at Sinai Hospital in Baltimore, Maryland, said.

"However, it is an expensive screening tool, and clinicians need to be up-to-date about the appropriate indications for its use," he asserted.

Dr. Khanuja and colleagues evaluated 108 consecutive patients with new-onset unilateral knee pain who were referred to 2 adult knee reconstruction surgeons over a recent 3-month period.

The investigators completed questionnaires for each patient that were intended to determine whether the MRI knee studies ordered by the primary provider were actually needed to obtain a diagnosis and select a treatment regimen.

Unnecessary Medical Tests Ordered More Often Than Not

The United States has the highest per capita healthcare expenditure worldwide, Dr. Khanuja points out. Healthcare costs currently account for 15% of the gross domestic product and have been projected to reach around 20% over the next decade. It is increasingly important for healthcare providers to identify ways to curb costs without compromising the quality of care, he says. The overuse of medical tests, and imaging studies in particular, has been frequently cited as a concern.

The diagnosis of knee conditions requires the use of an algorithm that calls for a combination of patient history, physical examination, and frequently, imaging studies. Although MRI can help diagnose knee pathology, cheaper imaging modalities are sometimes a reliable substitute, Dr. Khanuja notes.

MRI Necessity Criteria Not Heeded

In this study, for patients who presented with an MRI, the attending physician used specific criteria to determine whether an MRI was needed to establish the final diagnosis. MRI studies were considered unnecessary for patients at their initial presentation if any of the following was true:

  • the diagnosis could be established using plain X-rays alone,

  • the patient had patellofemoral pain with a normal ligamentous and meniscal exam,

  • the patient's knee pain resolved before he or she was seen by an orthopedic surgeon, or

  • the MRI findings had no effect on treatment outcome.

MRI studies were deemed necessary if they were indicated by history and/or physical examination to assess for meniscal, ligamentous, or osteochondral injury or osteonecrosis, or if the patient had an unexpected finding that affected treatment.

Overall, 66 patients (61%) were referred by their primary care physicians, 25 patients (23%) were referred by non–primary care physicians (eg, rheumatologists), 10 patients (9%) were self-referred, and the referring physician was unknown in 7 patients (6%).

MRI Overuse Problematic

Of the 33 patients (31%) who underwent MRIs, 18 scans (55%) were classified as unnecessary because it was possible to make the diagnosis with history, physical examination, and X-rays alone.

Two of 6 MRI studies ordered by referring orthopedic physicians were not necessary.

Of the remaining 75 patients (69%) who presented without an MRI study, only 4 required additional MRI evaluation, for a tentative diagnosis of a meniscal tear in 3 patients and osteonecrosis in 1 patient.

The most common final diagnosis for this cohort was osteoarthritis in 41 patients (38%), followed by patellofemoral syndrome in 14 patients (13%) and meniscal tears in 8 patients (7%).

Dr. Khanuja pointed out that potential study limitations include "a relatively small sample size with a short duration of data collection." In addition, the study examined practice patterns in a specific geographic area and urban setting, which may differ in other locations.

"This is exactly what we are seeing in our practices," Michael F. Schafer, MD, chairman of the Department of Orthopaedic Surgery at Northwestern University in Chicago, and chairman of the Communications Cabinet for the American Academy of Orthopaedic Surgeons, told Medscape Medical News. "In fact, I concur with the results of the study 100% — that the vast majority of patients who present to orthopaedic surgeons as referrals from primary care physicians do not need an MRI scan."

The tendency to overuse MRIs arguably "goes back" to medical school, he added. "There has been a decrease in the number of schools that even offer musculoskeletal education. However, when we have an opportunity to work with medical students, we can train them in a relatively short period of time."

He also pointed out that he favors the use of programs that teach primary care physicians about the appropriate use of diagnostic imaging.

Dr. Khanuja and Dr. Schafer have disclosed no relevant financial relationships.

American Academy of Orthopaedic Surgeons 2011 Annual Meeting: Abstract 299. Presented February 17, 2011.


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