Pronation and Supination

These are two normal movements, which take place in many joints of the body. In the foot the main joint where these movements occur is the sub-talar joint (or lower ankle joint). As we walk the heel hits the ground and the foot pronates, which causes it to roll inwards and the arch to lower. At the same time the leg bones twist inwards slightly. This is a shock absorbing movement and the midfoot is slightly unstable at this time. As weight is moved on to the ball of the foot, the opposite movement (supination) should occur at the subtalar joint (lower ankle). This makes the foot more stable, lifts the arch of the foot and creates a secure platform, which is important because the other foot is now swinging forwards to take the next step. Once this has occurred the heel can lift easily and we push ourselves forward from the ball of the foot and toes. These are normal movements; it is just that some of us have more or less of one than other people. The cycle of pronation and supination movement occurs with every step we take. In feet with lower arches it is often easier to see pronation because the Talus (ankle bone) tends to drop down further into the arch. In feet with high arches it is more difficult for the talus to drop and this causes the leg bones to twist inwards slightly more instead. Patients with lower arch feet who pronate too much are left with an unstable midfoot, no secure platform and no shock absorbency left. Patients with high arch feet who pronate too much tend to develop symptoms further up the leg. In fact, because it is so difficult for high arch feet to lower the arch they often tend to over supinate, which causes the arch to become even higher.