Your knee is the largest and most complex joint in your body. It consists of three bones: the femur (thigh bone), the tibia (shin bone) and the patella (your kneecap). Knee movement is powered by the muscles in your thighs, with the biggest muscle being your quadriceps.
Your thigh muscles and the shin bones are connected by tendons and ligaments which work together to maintain your normal knee function and provide the stability required for you to get moving.
The surfaces on your kneecap, thigh, and shin bones, are coated with a smooth tissue called cartilage. This cartilage, together with a substance called synovial fluid acts as a protective ‘cushion’ in the knee, preventing your bones from rubbing against each other and stopping them from wearing down and becoming damaged.