Calcaneal Fractures -

Primary Fracture Line
- Starts at lateral wall near tarsal sinus
- Passes in coronal plane
- Passes obliquely across posterior facet
- Exits at medial wall posterior to sustentaculum tali
- Produces 2 main fragments
Tuberosity & Lateral wall with variable posterior facet
- Usually comminuted
- Usually displaces superior & lateral
Sustentaculum with anterior & middle facet
- Usually undisplaced
Secondary Fracture Lines
- May be numerous
- May be divided into two types
- Tongue & Depressed Joint types based on secondary fracture lines
- Tongue type
  - Secondary fracture line extends posteriorly from superior point of primary line
  - Produces posterior / superior lateral fragment
  - Contains part of posterior facet & dorsal cortex of tuberosity
  - Can seesaw down anteriorly
- Joint depression type
  - Secondary fracture line also extends posteriorly but deviates dorsally to exit posterior to posterior facet
  - Creates thalamic portion containing posterior facet
  - Thalamic fragment contains the major portion of the calcaneal surface

Coronal CT Classification
To aid reduction of 3 part fractures (96%, only 4% two-part fractures with only primary fracture line)
- Not prognostic
- Uses coronal cut at level lateral malleolus
3 main fragments with inverted “Y” fracture
- Lateral joint fragment – usually depressed, rotates into valgus
- Sustentacular fragment – rarely depressed due to soft tissues, rotates into varus
- Body fragment – non-articular, migrates proximally into defect

Type 1: lateral wall formed by lateral joint fragment (37%)
Type 2: lateral wall fragment formed by lateral joint fragment superiorly & body fragment inferiorly (45%)
Type 3: lateral wall formed by body fragment (18%)