Xray and MRI for knee arthritis

Xrays and MRI are common tests in orthopaedic surgery. Why do we obtain an xray, and when do we need an MRI to make a diagnosis? In this Ask Dr. Geier video, I explain the role of each for one of the more common problems orthopedic surgeons see – knee osteoarthritis.

Matt asks:
Do you often see an MRI and x-ray contradict each other? For instance, a patient that presents with lateral knee pain has an MRI that shows severe cartilage degeneration of the lateral compartment, but the X-rays still show a gap. How does a physician go about figuring which one is correct?

An xray just shows bone, but they don’t show soft tissue structures like the meniscus, articular cartilage, tendons and ligaments. If performed in certain ways, xrays can demonstrate arthritis changes. In this video, I explain why xrays and MRIs can show what appear to be conflicting results.

Also read:
Ask Dr. Geier – Should I get an x-ray or MRI?
Ask Dr. Geier – Is an MRI necessary to diagnose an ACL injury?

MRI image of a degenerative medial meniscus tear