SUMMARY

• Calcaneus fractures are the most common fractured tarsal bone and are associated with a high degree of morbidity and disability.

• Diagnosis is made radiographically with foot radiographs with CT scan often being required for surgical planning. 

• Treatment is nonoperative versus operative based on fracture displacement and alignment, associated soft tissue injury, and patient risk factors.

EPIDEMIOLOGY

• Incidence

  • common

    • most frequent tarsal fracture

      • 60-75% of injuries are intra-articular fractures

      • 1-3% are calcaneal tuberosity fractures

• Anatomic location

  • 17% are open fractures

    • no significant increase in infection rates 

       

    • increased risk for wound complications 

       

  • calcaneal tuberosity fractures

    • peak incidence in women in seventh decade of life

ETIOLOGY

• Pathophysiology

  • mechanism

    • intra-articular fractures

      • traumatic axial loading is the primary mechanism of injury

        • fall from height

        • motor-vehicle accidents

    • calcaneal tuberosity fractures

      • poor bone quality/osteoporosis

        • violent contaction of the triceps surae with forced dorsiflexion

        • strong concentric contaction of the triceps surae with knee in full extension

      • intrinsic tightness of the gastrocnemius and achilles tendon

      • peripheral neuropathy leading to decreased pain sensation and proprioception resulting in recurrent microtrauma

    • calcaneal stress fractures 

      • increased physical activity in the setting of relative energy deficiency 

    • anterior process fractures

       

      • twisting injury mechanism

      • avulsion injury of the bifurcate ligament

  • pathoanatomy

    • intra-articular fractures

      • primary fracture line results from oblique shear and leads to the following two primary fragments

        • superomedial fragment (constant fragment)

          • includes the sustentaculum tali and is stabilized by strong ligamentous and capsular attachments

        • superolateral fragment

          • includes an intra-articular aspect through the posterior facet

      • secondary fracture lines

        • dictate whether there is joint depression or tongue-type fracture

    • extra-articular fractures

      • strong contraction of gastrocnemius-soleus with concomitant avulsion at its insertion site on calcaneus

      • more common in osteopenic/osteoporotic bone

    • anterior process fractures 

       

      • inversion and plantar flexion of the foot cause avulsion of the bifurcate ligament

• Associated injuries

  • orthopaedic

    • extension into the calcaneocuboid joint occurs in 63%

    • vertebral injuries in 10%

    • contralateral calcaneus in 10%

ANATOMY

• Osteology

  • articular facets 

    • superolateral fragment contains the articular facets 

    • superior articular surface contains three facets that articulate with the talus

    • posterior facet is the largest and is the major weight bearing surface

      • the flexor hallucis longus tendon is medial to the posterior facet and inferior to the medial facet and can be injured with errant drills/screws that are too long 

      • the flexor hallucis longus is also at risk of entrapment in the fracture site with marked posterior facet displacement 

         

    • middle facet is anteromedial on sustentaculum tali

    • anterior facet is often confluent with middle facet

  • sinus tarsi

    • between the middle and posterior facets lies the interosseous sulcus (calcaneal groove) that together with the talar sulcus makes up the sinus tarsi

  • sustentaculum tali

    • projects medially and supports the neck of talus

    • FHL passes beneath it 

       

    • represented by the constant fragment 

    • deltoid and talocalcaneal ligament connect it to the talus

    • contained in the anteromedial fragment, which remains "constant" due to medial talocalcaneal and interosseous ligaments 

       

  • bifurcate ligament

    • connects the dorsal aspect of the anterior process to the cuboid and navicular

CLASSIFICATION

• Extra-articular (25%) 

  • avulsion injury of

    • anterior process by bifurcate ligament 

    • sustentaculum tali

    • calcaneal tuberosity (Achilles tendon avulsion) 

       

• Intra-articular (75%)

  • Essex-Lopresti classification

    • the primary fracture line runs obliquely through the posterior facet forming two fragments

    • the secondary fracture line runs in one of two planes

      • the axial plane beneath the facet exiting posteriorly in tongue-type fractures 

        • when the superolateral fragment and posterior facet remain attached to the tuberosity posteriorly

      • behind the posterior facet in joint depression fractures 

  • Sanders classification

    • based on the number of articular fragments seen on the coronal CT image at the widest point of the posterior facet

      • Increasing number of fragments is associated with increased fracture severity and the development of post-traumatic arthritis