Inflammatory or degenerative arthritis of the subtalar joint, either idiopathic or posttraumatic. Pain is usually felt deep within the hindfoot, radiating medially and laterally. This is often exacerbated when walking on uneven ground. Examination will usually reveal normal pain-free ankle motion with limitation and pain on passive calcaneal abduction and adduction. Diagnostic injection of local anesthetic may be helpful in determining the source of pain where multiple joints in the ankle and hindfoot are affected by arthritis and may help predict the outcome of subtalar fusion.