This procedure is designed to limit hyperpronation, an excessive range of motion of the subtalar joint typically caused by hereditary underdevelopment of the talus or the calcaneus. Hyperpronation can allow the foot to collapse inward and downward resulting in adult acquired flatfoot. During this procedure, a small device is implanted between the talus and calcaneus to correct this abnormal motion and stabilize the ankle. Several implant styles are available.