Joint space narrowing

Written by Dr Sheila Strover on March 14, 2025

Joint space narrowing is when the bones of femur and tibia are closer together than normal, recognised on an X-ray taken from the front.

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Medial (M) joint space narrowing on both sides. The lateral (L) side is normal.
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X-ray demonstrating joint space narrowing on the one side of the knee.

What causes joint space narrowing?

Joint space narrowing is usually due to loss of the meniscus tissue which normally pads the space between these bones. It may also be due to thinning of the joint cartilage.

High tibial osteotomy, Unloader brace, Varus, Varus deformity