A capsule is a container which surrounds and protects something.

In the knee, the capsule is a waterproof lining around the knee joint, enclosing the internal structures.


Enclosing the articulating part of the knee joint is a water-tight capsule made of a strong fibrous material lined on the inside with a thin layer of secretory cells.

Knee capsule

Quick overview of the outer casing of the knee joint.