Joint space narrowing: Meaning in a Radiology Report

Also written as: narrowed joint space, loss of joint space, reduced joint space, joint space loss

Joint space narrowing means the gap between two bones in a joint looks smaller than normal, usually because the cartilage has worn thin.

What it means

Cartilage does not show on an X-ray, so the space between the bones of a joint stands in for it. When cartilage thins, the bones sit closer together and the space shrinks. In the knee, a worn meniscus can add to it. It is the main X-ray sign of osteoarthritis, often seen with bone spurs (osteophytes) and denser bone under the cartilage (sclerosis). Inflammatory arthritis can narrow a joint too, usually more evenly.

When it matters

Some narrowing is very common with age, especially in the knees, hips and hands, and it does not always match how much a joint hurts. Doctors describe it as mild, moderate or severe, sometimes using the Kellgren-Lawrence grade. X-rays taken standing show narrowing in the knee more reliably. Your doctor may suggest exercise, weight management or pain relief. Severe narrowing with lasting pain may lead to a talk about joint replacement.

Questions to ask your doctor

How severe is the narrowing, and which part of the joint is affected?
Were my X-rays taken standing, and does that change the reading?
Does the amount of narrowing match the pain I have?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.