Talus fractures are relatively uncommon.
Talus fractures can be associated with significant complications.
The talus is involved in about 2% of all lower extremity injuries and about 5-7% of foot injuries.
The talus bone of the foot is the most important to stabilize and mobilize soon after injury.
Talus fractures are usually associated with hyperdorsiflexion of the ankle as the talar neck impacts the anterior margin of the tibia.
The talus articulates superiorly with the tibia and fibula in the ankle mortise and the calcaneous and navicular inferiorly.
Body weight is transmitted through the tibia to the superior surface of the talus.
The anterior portion of the body of the talus is wider than the posterior portion allowing for stability of the ankle.
The neck of the talus connects to the head which connects to the navicular and calcaneous and is the most vulnerable to fracture.
The talus has no muscular or tendinous attachments, has a groove for the flexor hallicus longus tendon, and is mostly covered by articular cartilage, articulates with the spring ligament inferiorly, the sustentaculum tali posteroinferiorly and the deltoid ligament medially.
The major blood supply to the body is from the artery of the tarsal canal from the posterior tibial artery.
Other blood supply to the talus by arteries from the peroneal and dorsalis pedis arteries, the posterior tibial artery and the anterior tibial artery.
Classification system is the Hawkins classification of talar neck fractures:
Type I – nondisplaced talar neck fracture
Type II – displaced with subluxation or dislocation of subtalar joint
Type III – displaced with dislocation of body from ankle mortise
Type IV – displaced with subluxation or dislocation of talonavicular joint
Other types of fractures include talar head fractures, talar body fractures, lateral process fractures, and posterior process fractures.
Patients clinically present with foot pain with painful range of motion, swelling, tenderness and crepitus following injury.
Patients with talus fracture mat have other fractures of the foot and ankle.
Patients with talus fractures may have dislocation.
Imaging studies include: AP, lateral and mortise x-rays of the ankle and AP, lateral and oblique views of the foot.
CT scan of the ankle is useful for assessing fracture pattern, displacement, and articular involvement.
Occult fractures may be identified by CT, MRI and Technetium bone scan.
Avascular necrosis of the talus may be identified by MRI scan.
Hawkins Type I fracture tretment involves a short leg cast or boot for 8-12 weeks, with non weight-bearing for 6 weeks.
Hawkins Type II-IV fractures are treated with ORIF (open reduction and internal fixation).
Lateral process fracture treatment is determined by the extent of displacement: with less than 2mm displacement a short leg cast or boot for 6 weeks and non weight-bearing for 4 weeks, and with more than 2mm displacement, ORIF is recommended.
Posterior process fracture treatment with nondisplacement or minimal displacement are treated with a short leg cast for 6 weeks and non weight-bearing for 4 weeks, while for displaced fractures, ORIF is recommended.
Non displaced talar head fractures are treated with a short leg cast molded to preserve the longitudinal arch and partial weight-bearing is recommended for 6 weeks.
Displaced talar head fractures are treated with ORIF.
Prognosis for talus fractures is related to the degree of damage to its blood supply, while the complication rate is related to the degree of displacement.
One of the most common complications of talus fractures is avascular necrosis due to injury to the artery of the tarsal canal which supplies the body, and branches of the dorsalis pedis and peroneal arteries which supply the head and neck. Risk of avascular necrosis is stratified according to the Hawkins classification:
Hawkins Type I: 0-15% Hawkins Type II: 20-50% Hawkins Type III Hawkins Type IV: 100% Open fractures can occur in up to 15-25% of injuries reflecting the high-energy mechanism of injury. There is an infection rate of up to 40% in open talus fractures. Post-traumatic arthritis occurs in 40-90% of cases. Delayed union or nonunion occurs in approximately 15% of cases and malunion is also a concern. Other complications include skin slough secondary to prolonged dislocation, interposition of the long flexor tendons, and foot compartment syndrome.
Outcomes ORIF results in lower rates of nonunion, shorter time to union, earlier weight-bearing, better anatomical reduction, and lower rate of avascular necrosis than closed treatment.