Talus Fracture

Talus fractures are uncommon but potentially devastating because approximately 60% of the talus is covered by articular cartilage and its blood supply is vulnerable to disruption.

The talus participates in:

• Tibiotalar joint
• Subtalar joint
• Talonavicular joint

There are no muscular attachments to the talus.

Fractures are divided anatomically into:

• Talar head
• Talar neck
• Talar body
• Lateral process
• Posterior process

Talar neck fractures are particularly associated with osteonecrosis.

The most important immediate treatment principle is:

Displaced talar fracture dislocations require urgent reduction.

Definitive internal fixation can then be performed when soft tissues are suitable, provided reduction has restored threatened neurovascular and skin relationships.

Hawkins classification for talar neck fractures

Type I

Nondisplaced talar neck fracture.

Subtalar and tibiotalar joints remain reduced.

Lowest risk of osteonecrosis.

Type II

Talar neck fracture with subtalar subluxation or dislocation.

Tibiotalar joint remains reduced.

Type III

Talar neck fracture with both subtalar and tibiotalar dislocation.

The talar body may displace posteromedially and threaten the posterior tibial neurovascular bundle.

Type IV

Type III injury plus talonavicular dislocation.

This represents the greatest disruption of talar blood supply and carries the highest osteonecrosis risk.

Reported osteonecrosis risk rises markedly with increasing Hawkins grade. A systematic review found approximately 0% for type I, 16% for type II, 39% for type III and 55% for type IV injuries.

Sneppen classification for talar body fractures

A commonly used morphological classification includes:

Type I

Osteochondral or transchondral fracture.

Type II

Coronal, sagittal or horizontal shear fracture of the body.

Type III

Posterior tubercle fracture.

Type IV

Lateral process fracture.

Type V

Crush fracture of the talar body.

High energy trauma is typical for major neck and body fractures.

Patients present with:

• Severe ankle and hindfoot pain
• Swelling
• Inability to bear weight
• Restricted ankle and subtalar movement

Inspect carefully for:

• Medial skin tenting
• Open fracture
• Talar extrusion
• Neurovascular compromise
• Associated calcaneal, navicular, malleolar or tibial injury

Hawkins III injuries can compromise posterior tibial structures from posteromedial displacement of the talar body.

Lateral process fractures may be mistaken for ankle sprains, particularly after snowboarding or forced dorsiflexion with external rotation.

Obtain:

• AP ankle
• Mortise ankle
• Lateral ankle
• Foot views according to injury

A Canale view can improve visualisation of the talar neck.

CT: obtain for nearly all significant talar neck and body fractures.

CT defines:

• True displacement
• Comminution
• Subtalar articular involvement
• Talar body extension
• Associated foot fractures

A fracture appearing nondisplaced on radiographs should be confirmed with CT before committing to nonoperative treatment.

Urgent reduction

Immediately reduce any:

• Tibiotalar dislocation
• Subtalar dislocation
• Talonavicular dislocation
• Talar body threatening the skin
• Neurovascular compromise

Reduction restores alignment and reduces ongoing vascular and soft tissue injury.

If closed reduction fails, perform urgent open reduction.

Definitive fixation does not have to occur at the same moment if swelling or soft tissue compromise makes formal reconstruction unsafe. Urgent reduction followed by delayed definitive fixation after soft tissue recovery is an accepted strategy.

Hawkins I

A genuinely nondisplaced fracture confirmed on CT can be treated in a below knee cast or rigid immobilisation.

Maintain strict non weight bearing for approximately 6 to 8 weeks with serial imaging.

Displacement during follow up requires fixation.

Hawkins II to IV

Displaced talar neck fractures require anatomical reduction and internal fixation.

The objective is restoration of:

• Neck length
• Rotation
• Medial column
• Lateral column
• Subtalar congruity
• Tibiotalar congruity

Varus malreduction is particularly poorly tolerated.

Dual anteromedial and anterolateral approaches often allow direct assessment of both sides of the neck.

Use:

• Lag screws for simple fracture morphology
• Mini fragment plates for comminuted fractures

A medial plate can prevent varus collapse when the medial neck is comminuted.

Do not compress across comminuted areas in a way that shortens the talar neck.

Talar body fracture

Nondisplaced body fractures can occasionally be treated nonoperatively.

Displaced articular body fractures require anatomical reduction because both the ankle and subtalar surfaces may be involved.

Comminuted crush injuries carry high risks of:

• Osteonecrosis
• Post traumatic arthritis
• Malunion

Lateral process fracture

Small nondisplaced fragments may be treated in immobilisation.

A displaced fragment involving the subtalar articular surface requires fixation or excision depending on fragment size and reconstructability.

Missed lateral process fractures can lead to chronic subtalar pain.

Posterior process fracture

Small nondisplaced injuries can be immobilised.

Large displaced fragments causing posterior impingement or articular incongruity may require fixation or excision.

Extruded talus

An extruded talus should generally be thoroughly debrided, reduced and preserved when feasible rather than routinely discarded. Modern limb salvage favours reimplantation when contamination and tissue viability permit.

Osteonecrosis surveillance

The Hawkins sign is subchondral lucency of the talar dome appearing approximately 6 to 8 weeks after injury.

A positive Hawkins sign is reassuring for maintained vascularity.

Absence of the sign does not prove osteonecrosis. MRI can assist later when osteonecrosis remains suspected.

Do not diagnose inevitable talar collapse simply because radiographic osteonecrosis develops. Some talar bodies revascularise without collapse.

Postoperative care

Maintain non weight bearing for major displaced talar neck fractures, commonly approximately 10 to 12 weeks, depending on fracture healing and osteonecrosis concerns.

Begin ankle and subtalar range of motion once wounds and fixation permit.

Major complications include:

• Osteonecrosis
• Talar dome collapse
• Subtalar arthritis
• Tibiotalar arthritis
• Varus malunion
• Nonunion
• Infection
• Chronic stiffness
• Secondary subtalar or ankle fusion