I tore the cartilage in my knee playing football. The X-ray report says there’s a chondral defect with a “knee mouse.” What does that mean?

Chondral is a term used to refer to the gristle or hyaline cartilage at the end of
the bones. When the cartilage is pulled away from the bone it can leave a tiny hole or crater. This is called a chondral defect. The joint surface is disrupted and no longer smooth at the point of injury.

When the cartilage pulls away from the bone it can take a piece of the bone with it. That piece of bone is a loose body, sometimes called a knee mouse.

Cartilage can’t repair itself, and these types of injuries can lead to arthritis. Early treatment to remove the loose body and repair the joint surface is often advised.