Subtalar arthritis is characterized by pain in the hindfoot that is aggravated by standing and walking, particularly on uneven ground. It is likely to be associated with stiffness when attempting to move the foot from side to side. The location of the pain is commonly just below the level of the inside and outside ankle bones (medial and lateral malleoli). The most common cause of subtalar arthritis is a previous injury – usually a calcaneal fracture, or abnormal alignment of the heal bone.
Patients with subtalar arthritis will complain of pain on one or both sides of the foot, just below the ankle bones (malleoli). This is commonly illustrated by the patient encircling the affected foot with their fingers, just below the level of the bony prominence on either side of the ankle (malleoli). The hollow just in front of the outside ankle bone (the sinus tarsi) is another common location of pain. The sinus tarsi is a space surrounded by the three contact areas between the talus and calcaneus, that comprise the subtalar joint. The subtalar joint is largely responsible for allowing the foot to accommodate uneven terrain by moving the hindfoot from side to side (inversion and eversion). Walking on uneven surfaces places a great deal of stress on the subtalar joint and may be difficult, if not impossible, to accomplish in patients with subtalar arthritis.
Most subtalar arthritis is caused by a previous trauma, usually a calcaneal fracture, although certain fractures involving the talar body may also cause subtalar arthritis. Other causes include rheumatoid arthritis, or the abnormal loading of the subtalar joint associated with malalignment of the heel bone (calcaneus). The load applied to the subtalar joint can be unevenly distributed in cases where the heel bone turns in (varus alignment seen with a high arched foot) or out (valgus alignment associated with a flat foot).