Equinus calcaneus Hindfoot equinus Equinus deformity of the calcaneus Abnormal plantar flexion of the calcaneus relative to the longitudinal axis of the tibia. This results in the angle between the long axis of the tibia and the long axis of the heel bone (calcaneus) being greater than 90 degrees. UMLS:C1860449 HP:0008138 Abnormality of the calcaneus