Simple X-Ray Best for Diagnosing Knee Pain in Patients Aged Older Than 40

Plain x-rays are the best first-line screening tools for knee pain among middle-aged patients, according to a study published in the September issue of the Journal of American Academy of Orthopaedic Surgeons (JAAOS).

Whether a patient will need surgery for knee problems depends on how much arthritis he or she has.

“If an x-ray shows that a person has significant arthritis, the MRI [magnetic resonance imaging] findings — like a meniscus tear — are less important because the amount of arthritis often dictates the treatment,” said lead author Muyibat Adelani, MD, Department of Orthopedics, Washington University, St. Louis, Missouri. “Therefore, patients should always get a standing x-ray before getting an MRI to screen for knee pain in patients aged older than 40 years.”

The study looked at 100 MRIs of knees from patients aged 40 years and older and found that the most common diagnoses are osteoarthritis (39%) and meniscal tears (29%).

Nearly 1 of 4 MRIs was taken prior to the patient’s first having obtained a weight-bearing x-ray; and only half of those MRIs obtained prior to meeting with an orthopaedic surgeon actually contributed to a patient’s diagnosis and treatment for osteoarthritis.

“Patients should always get weight-bearing x-rays before getting an MRI because MRIs are not always needed to diagnose knee problems,” said Dr. Adelani.

In cases where arthritis is suspected, weight-bearing x-rays often are more than enough for orthopaedists to complete the diagnosis and treatment plan. An appropriately timed consultation with an orthopaedic surgeon can be more cost effective than first obtaining MRI scans.