Critical Angle of Gissane
Other Names
- Gissane angle
- Angle of Gissane
- Crucial angle of Gissane
- Crucial angle
- Calcaneal crucial angle
Introduction
- The Critical Angle of Gissane is a radiographic measurement assessed on a lateral calcaneal radiograph
- Used primarily in the evaluation of calcaneal fractures and subtalar joint injury
- Formed by the downward and upward slopes of the calcaneal superior surface
- Commonly evaluated in trauma imaging following axial loading injuries
- Often interpreted together with Bohler’s angle during calcaneal fracture assessment
Description
- Measured on a lateral radiograph of the calcaneus
- Formed by the intersection of:
- The downward slope of the posterior facet
- The upward slope of the anterior calcaneal process
- Normal values are generally 120–145 degrees
- Best visualized just inferior to the lateral process of the talus
- Alteration of the angle may indicate disruption of calcaneal anatomy or subtalar joint depression
Pathology
- Calcaneus Fracture
- Posterior facet collapse
- Axial loading injuries
- Malunion of calcaneal fractures
- Hindfoot deformity
Evidence
- Knight et al[2]
- Poor interrater reliability, intraclass correlation coefficient (ICC) of only 0.52 (95% CI 0.43–0.60)
- Bohlers Angle, by contrast, had an ICC of 0.84 (95% CI 0.79–0.87).