Friday, February 25, 2011 Half of Knee MRIs 'Unnecessary,' Say Researchers The vast majority of patients who are referred to orthopedic surgeons by primary care physicians do not need a magnetic resonance imaging (MRI) scan, according to a Medscape Medical News article based on a report recently presented at the American Academy of Orthopaedic Surgeons' 2011 annual meeting. For this study, researchers 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. For patients who had 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 statements were 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. The MRI findings had no effect on treatment outcome. MRI studies were judged 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. 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, says Medscape. Of the remaining 75 patients (69%) who did not have an MRI, only 4 required the test for evaluation, for a tentative diagnosis of a meniscal tear in 3 patients and osteonecrosis in 1 patient. According to the article, the most common final diagnosis for study participants was osteoarthritis (38%), followed by patellofemoral syndrome (13%) and meniscal tears (7%).