SAN FRANCISCO — Magnetic resonance imaging is often ordered before patients are referred for total knee arthroplasty, yet MRI confers minimal or no benefit, compared with taking weight-bearing and skyline patella-view x-rays of patients with osteoarthritis of the knee, according to Dr. Wayne M. Goldstein.
In a random sample of 50 patients referred for total knee arthroplasty within the past 2 years, Dr. Goldstein and his associates found that 32 had MRI of the knee. Most patients got no x-rays prior to the MRI. Given that knee MRI costs approximately 10 times more than x-rays, this is an example of wasteful spending in the health care industry, according to Dr. Goldstein, who reported the study results in a poster presentation at the annual meeting of the American Academy of Orthopaedic Surgeons.
“Possibly due to lack of musculoskeletal education, or possibly as a result of financial incentive due to ownership, MRI is sometimes ordered instead of x-rays. This study suggests the need for strict guidelines or credentialing of those who order musculoskeletal MRIs,” said Dr. Goldstein of the University of Illinois, Chicago, and the Illinois Bone and Joint Institute, Morton Grove, Ill.
In their review, Dr. Goldstein and his associates determined whether patients had undergone MRIs by reviewing chart data and by calling the referring physicians. Patients in the study all had x-ray evidence of bone-on-bone articulation in one or more compartments.
“The patient is often referred by the primary care physician with the finding of 'torn meniscus,' and many patients expect an arthroscopy and seem upset that the orthopedic surgeon does not use the MRIs to make the diagnosis and direct treatment,” he said.
An MRI can be useful in rare cases, usually in elderly women, to diagnose spontaneous osteonecrosis of the knee or a stress fracture. An example would be an elderly woman with a history of sudden onset of knee pain, especially on weight bearing, with localized tenderness on physical examination and normal findings on a complete series of x-rays.
This narrow usefulness of knee MRI “is, unfortunately, not apparent to a very small segment of orthopedic surgeons,” who were among the referring physicians in the study, Dr. Goldstein said.
Dr. Goldstein routinely obtains radiographs of patients with knee osteoarthritis, including weight bearing and Rosenberg notch views. At his private group practice in Illinois, the charge for an MRI in 2007 was $1,116 (CPT code 73721), compared with $136 for a four-view x-ray series of the knee for arthritis (CPT code 73564). Medicare in 2007 reimbursed $471 for knee MRI and $42 for the x-ray series. In 2008, Medicare decreased reimbursement for the knee MRI to $457 and increased reimbursement for the radiographs to $43. Reimbursement for knee MRI can be significantly higher from commercial insurers.
Medical imaging comprises 10%–15% of Medicare payments to physicians today, compared with 5% a decade ago, and Medicare imaging costs are expected to keep growing at an annual rate of 20% or higher—outpacing the growth in cost for prescription drugs, Dr. Goldstein noted. “Overutilization of MRI contributes to cost, especially in a radiographically proven osteoarthritic knee,” he said.
Osteoarthritis of the knee is a poor indication for MRI when a series of radiographs (example radiograph shown) will suffice. Courtesy Dr. Wayne M. Goldstein