The best screening tool for knee pain is X-ray, not MR, according to a new study that was published in the Journal of American Academy of Orthopaedic Surgeons. If it’s conducted first, it can reduce both time and cost.

"There is a perception amongst the public and many physicians that MR is better than X-ray, but MR is just a different type of test," Dr. Muyibat Adelani, lead author of this study and an orthopedic surgeon at Washington University, told HCB News. "Most knee problems that middle-aged or older patients have — namely, arthritis — can be identified by X-ray."

Researchers from Washington University analyzed 100 MR knee exams from patients age 40 years and older. The most common diagnoses were osteoarthritis and meniscal tears, which is when the wedge-shaped pieces of cartilage in the knee joint tear.

Nearly one in four of the MR exams were conducted before the patient first underwent a weight-bearing X-ray. Only half of the MRs conducted before meeting with an orthopedic surgeon lead to diagnosis and treatment for osteoarthritis.

X-ray findings can reveal if a patient has significant arthritis, which is more important than MR findings like meniscus tears because the amount of arthritis often determines the treatment.

"MR can identify other problems, such as meniscus tear or ligamentous injury," said Adelani. "However, because arthritis often dictates treatment in this patient population, it is important to identify the amount of arthritis present in a joint before going any further."

The researchers recommend that patients older than 40 years should always get a standing X-ray before getting an MR to screen for knee pain.

"The current standard for evaluating knee pain is to start with weight-bearing X-rays," said Adelani. "The amount of arthritis in a knee dictates further treatment options, so it is important to identify that by taking regular X-rays."