Patients arrive in clinic having been told their knee is bone on bone. It sounds final. It is usually said kindly, and it is usually meant as shorthand. But it is worth knowing what it actually describes, because the phrase drives a lot of unnecessary fear and a lot of unnecessary surgery.

What the X-ray is showing

Cartilage does not appear on an X-ray. What you see is the gap between the thigh bone and the shin bone, and that gap is cartilage you cannot see. When radiologists write joint space narrowing, they mean that gap has reduced. Bone on bone means the gap has effectively disappeared in at least one part of the joint.

That is a real finding. It is also only one finding. A standing X-ray loads the knee and shows the gap honestly. A lying down X-ray can make a knee look better than it is. If you have been told bone on bone from a non weight bearing film, the picture is incomplete.

Why it does not settle the question

Severity on film and severity of symptoms track each other loosely at best. There are patients with grade four changes who walk two kilometres daily and want nothing done. There are patients with grade two changes who cannot sleep. Both are common. Neither is unusual.

So a knee replacement is not indicated by an X-ray. It is indicated by what the knee is doing to your life, with the X-ray confirming that the cause is structural and not something else.

What usually matters more than the film

How far you can walk before you stop. Whether night pain wakes you. Whether stairs have become a planning problem. Whether the knee has started to bend outward or inward. Whether simple measures have been tried properly and have stopped working.

Those five answers carry more weight in my decision than the grade written on the report.

If you have been told bone on bone

It does not mean you need surgery this month. It does mean the non-surgical options have a narrower ceiling than they did five years ago, and that you should understand what is left in that toolbox before you commit to anything.

Read further here: https://www.mayurajcc.com/knee-arthritis-guides/severe-knee-arthritis-bone-on-bone and https://www.mayurajcc.com/knee-arthritis-guides/stages-of-knee-arthritis and https://www.mayurajcc.com/knee-arthritis-guides/knee-arthritis-diagnosis-xray-mri