The subtalar joint is a complex joint that is positioned below the ankle joint. The subtalar joint is comprised of the calcaneus (heel bone) and the talus, the bone that sits above it. Also known as the talocalcaneal joint, the subtalar joint is actually three separate articulations between the two bones.
The subtalar joint has three important functions:
- Adapting to changes in terrain while walking
- Pivoting your body on your feet
- Shock absorption as your feet hit the ground
When you twist your upper body while standing and look over your shoulder, the subtalar joints of your feet are moving along with your lower body. The two types of motion that the subtalar joint performs are supination and pronation. Pronation is a natural motion that occurs as your foot's instep rolls inward, toward the middle of the body. As this happens, your arch collapses to a degree. Supination is motion in the opposite direction -- the foot rolls outward and the arch height increases. When you twist your body and look over your shoulder, one foot pronates and one foot supinates.
Problems Associated with the Subtalar Joint
- Arthritis - Can be caused by excessive wear and tear on the subtalar joint over time or by a history of previous injury, such as a fracture of the talus or calcaneus.
- Flat Feet - A subtalar joint that allows too much pronation can contribute to a flat foot.
- Cavus Foot - Also known as a high arch foot, a cavus foot has a restricted range of motion at the subtalar joint, making it a more inflexible foot type.
- Tarsal Coalition - A tarsal coalition is a fusion of bones that can cause restricted range of motion, pain, and a rigid flat foot.
- Tarsal Tunnel Syndrome - This is a pinched nerve in the area of the subtalar joint that can cause shooting pain, burning, and tingling sensations.