Do I need an MRI for knee arthritis, or is an X-ray enough?

Why standing X-rays come first

Cartilage does not show on X-ray, but the gap between the bones does. When you stand, your body weight squeezes the joint, so a standing X-ray shows how much cartilage space is really left on each side of the knee. It also shows bone spurs, changes in the bone under the cartilage and the alignment of the leg. A view of the kneecap and sometimes a long-leg X-ray from hip to ankle complete the picture.

X-rays taken lying down can make the joint look healthier than it is, which is why your surgeon may ask for new standing views even if you have older images.

When an MRI adds useful information

• Symptoms are much worse than the X-ray suggests, or the X-ray looks normal
• A sudden change, such as new locking, could point to a torn fragment of meniscus or a loose body
• A meniscal root tear, a stress reaction in the bone or another problem is suspected
• A younger, active patient is being considered for osteotomy, cartilage surgery or a partial replacement and the other compartments need careful assessment

Reading an MRI report without alarm

MRI is very sensitive, and in knees with arthritis it usually lists many findings: cartilage thinning, a degenerative meniscus tear, bone marrow oedema, a cyst behind the knee. Many of these are part of the arthritis itself and are also found in people without pain. A degenerative meniscus tear in an arthritic knee, for example, rarely needs keyhole surgery, and arthroscopic washout is not recommended for osteoarthritis alone. The report is interpreted together with the examination, not on its own.

What to bring to your appointment

Bring any previous X-rays and MRI scans on disc or as a link, with the reports, and a list of treatments you have tried. At Aman Hospital, Dr. Gelber examines the knee, arranges the right standing views when needed and explains what the images show in plain terms, and whether any further test would actually change your treatment.