Joint · Knee

Patellofemoral joint

Articulatio patellofemoralis

Where the kneecap glides in its groove on the front of the thigh bone. The patella is a sesamoid bone — it grew inside the quadriceps tendon — and it carries the thickest articular cartilage in the body, which tells you how much load passes through it. Its job is leverage: by holding the quadriceps tendon away from the joint's centre of rotation, it makes the muscle a more efficient knee straightener. It shares a capsule and joint cavity with the knee proper, so the two are effectively one space.