Gissane's angle
Gissane angle, also known as the "critical angle", is an angular measurement made directly inferior to the lateral process of the talus. It is formed by the downward and upward slopes of the calcaneal superior surface. It is better seen on a lateral plain film of the calcaneus and hindfoot. Its normal value is usually between 120° and 145°.
Gissane’s angle, together with Böhler’s angle, are commonly used to evaluate the severity of a calcaneal fracture and the goal of a surgical treatment is to restore these angles to normal values.
History and etymology
William Gissane (1898-1981), an Australian by birth, was a professor of orthopedics, and is remembered as a pioneer of traumatology. He was the first clinical director of the Birmingham Accident Hospital, regarded as the first dedicated trauma center in the world .