Talus bone makes up the ankle joint, and navicular bone is a small bone found in the feet. Congenital vertical talus is a foot deformity in which the talus and navicular bones of the child's feet are abnormally positioned. This leads to rigid flat foot with a rocker-bottom appearance. The hind foot points downwards to the floor while the forefoot points upwards. It is usually present at birth and can occur with other conditions such as arthrogryposis and spina bifida. The exact cause for congenital vertical talus is unknown. One of the studies suggests that the abnormal pressure placed on the foot while the fetus is inside the uterus can cause the deformity. Other school of thought suggests muscle imbalance as the cause for the deformity. In both cases, stiffness in the hind foot causes the forefoot to ride on top of the talus and destabilize the entire foot.
The sole of foot appears convex and the normal arch of the foot is reversed. There is a crease on the upper portion of the foot. A callous may form on the sole of the foot at the place where the protruding talus bone touches the ground. If it is left untreated, it can cause pain in the foot which makes wearing shoes difficult and the child starts walking with a "peg leg gait".
This condition should be recognized and treated early because early, aggressive treatment gives better result. The treatment is started with manipulation and casting in order to stretch the foot. Surgery becomes necessary for complete correction of the deformity and should be performed before the age of two.
Surgery involves reduction of the dislocated bones of the foot and fusion of the joint between the talus and navicular bone. Achilles tendon or heel cord that has contracted may be lengthened. Complicated procedures such as fusing the talus to the bone in the heel may be required in older children.