Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Talus Fracture

Basics
Description
  • The talus, a small bone in the hindfoot:
    • Articulates with the calcaneus and the remainder of the midfoot bones
    • Supports the body’s weight and distributes the body’s forces to the foot
    • Is critical to proper function of the foot
    • Is covered (~60%) with articular cartilage
    • Is vascularly supplied by vessels through a small area of the talar neck
  • Because of its the tenuous blood supply, the talus is predisposed to posttraumatic osteonecrosis.
    • Fractures of the talus may be difficult to diagnose, and the clinician must understand the presenting features of this injury because of the high rate of osteonecrosis.
    • The talus may fracture in different anatomic locations, including the talar neck, the talar body, and the processes of the talus.
    • Another common talus fracture is the talar dome osteochondral fracture.
  • Classification of fracture patterns:
    • Talar neck fractures: Modified Hawkins system :
      • Type I: Nondisplaced vertical fracture of the talar neck
      • Type II: Displaced fracture of the talar neck with subluxation or dislocation of the subtalar joint; ankle joint is normal
      • Type III: Displaced fracture of the talar neck, associated with dislocation of the ankle and subtalar joints
      • Type IV: Extrusion of the talus
    • Talar body fractures:
      • Type I: Coronal or sagittal fractures
      • Type II: Horizontal fractures
    • Talar process fractures:
      • Posterior process fractures
      • Lateral process fractures
Pediatric Considerations
Because children have a higher cartilage-to-bone ratio than do adults, the pediatric talus is more prone to bend and thus better tolerates deforming forces.
Epidemiology
No age- or gender-related associations
Incidence
  • Talar fractures represent 3% of all foot fractures, and 50% are in the talar neck .
  • Talar body fractures are less common, accounting for 7-8% of all tarsal fractures .
Risk Factors
  • Motor vehicle collisions
  • High-energy falls
  • Snowboarding
Pathophysiology
  • Neck fractures occur with impaction of the neck of the talus against the distal anterior tibia during severe dorsiflexion of the foot.
  • Among snowboarders, lateral process fractures are common, with external rotation forces applied to the booted, dorsiflexed foot.
  • Body fractures occur from axial compression between the tibia and calcaneus.
Etiology
The cause is high-energy trauma with forefoot hyperextension.
Associated Conditions
Talar neck fractures commonly are associated with medial malleolar fractures.
Diagnosis
Signs and Symptoms
  • Extreme pain about the talus and hindfoot, associated with high-energy trauma
  • Ecchymosis and swelling
  • Deformity
History
  • Commonly caused by motor vehicle accidents and falls from a height.
  • Historically associated with pilots because they place their feet against the rudder controls (aviator’s astragalus).
Physical Exam
  • Check the ankle and hindfoot for:
    • Focal tenderness
    • Deformity
    • Ankle and subtalar motion
  • Clinicians should carefully examine patients with mid- or hindfoot sprains and maintain a high index of suspicion for radiographic and CT findings.
  • Talar process fractures may be missed easily.
Tests
Imaging
  • Radiography:
    • AP and lateral radiographs of the ankle and foot are the baseline studies.
    • An oblique view of the talar neck can be helpful.
      • The foot is held in maximal equinus (plantarflexion) and 15° of pronation for this view.
  • CT is required to delineate fracture displacement.
Pathological Findings
Occasionally, fractures occur through cysts or bone tumors.
Differential Diagnosis
  • Ankle fractures
  • Ankle dislocation
  • Talar dislocation
  • Calcaneus fracture
  • Navicular fracture
Treatment
Initial Stabilization
  • Ice, immobilization, and elevation are indicated.
  • Immediate reduction of displaced fragments is recommended to reduce risk of skin necrosis and secondary infection.
General Measures
  • Nondisplaced fractures may be treated with a below-the-knee cast for 12 weeks and nonweightbearing for 6 weeks.
  • Type II talar neck fractures require reduction by closed or open (surgical) means.
  • Type III talar neck fractures almost always require surgery to obtain an adequate reduction.
  • Talar body fractures:
    • Have a higher incidence of osteonecrosis than do talar neck fractures
    • Should be treated surgically for the best reduction, if possible
  • Established osteonecrosis of the talus is very difficult to treat, given the bone’s minimal blood supply.
  • Displaced fractures that cannot be reduced require open reduction and internal fixation.
  • Displaced fractures are more predisposed to skin necrosis and infection because of the lack of protective subcutaneous tissue, especially dorsally.
    • Displaced fragments can distort surrounding tissues, which may lead to necrosis and secondary infection.
  • A talar process fracture <1 cm in size and displaced <2 mm is treated with a nonweightbearing cast for 6 weeks .
Pediatric Considerations
  • Nondisplaced fractures are treated in an above-the-knee plaster cast for 6-8 weeks.
  • With the remodeling potential of pediatric patients, displacement of <5 mm and <5° of malalignment on an AP view are acceptable after reduction.
Activity
Nonweightbearing for at least 4-6 weeks
Special Therapy
Physical Therapy
ROM exercises are begun after removal of the cast.

Medication
Pain can be controlled with opioid analgesics as appropriate, with transition to NSAIDs or acetaminophen as appropriate.
Surgery
  • Open or closed reduction
  • Open reduction of the talus and the talar neck is performed through incisions over the medial or lateral aspects of the hindfoot.
    • Incision placement depends on the precise fracture geometry.
    • Displaced fractures generally require 2 incisions to ensure precise reduction.
  • Fractures are reduced using intraoperative fluoroscopy.
    • Cannulated screws are used for fixation and can be placed in an anterograde or retrograde manner.
    • Comminuted fractures of the talar neck have little support for screw fixation, and plate fixation may be preferred.
  • Talar body fractures are more difficult to approach than are talar neck fractures.
    • A medial malleolar osteotomy often is required for visualization.
    • Screw heads should be buried into the articular surface.
  • Process fractures >1 cm in size or displaced >2 mm are thought to have a better outcome with open reduction and internal fixation.
    • Either small cannulated screws or Kirschner wires may be used .
  • After surgery, swelling should be monitored carefully for signs of compartment syndrome.
    • If necessary, compartment pressure should be measured in the foot.
    • Fasciotomies should be performed if compartment syndrome exists.
  • Postoperatively, a well-modeled splint should be placed and then converted to a below-the-knee, nonweightbearing cast after swelling is reduced.
Follow-up
Disposition
  • Pain should be well controlled.
  • Radiographic follow-up should continue for at least 18-24 months for nondisplaced fractures and for longer periods for displaced fractures and those complicated by posttraumatic osteonecrosis.
Prognosis
  • Prognosis is directly related to the degree of initial injury, often regardless of anatomic reduction and fixation .
  • Talar body fractures have a poor prognosis and often are associated with posttraumatic osteonecrosis and/or arthritis; 1 series reported that 88% of patients had 1 or both entities .
Complications
  • Osteonecrosis
  • Skin necrosis and infection
  • Delayed union is common, given the relatively poor blood supply.
  • Nonunion leads to chronic pain and may require bone grafting or fusion procedures.
  • Malunion can redistribute forces on the foot and cause chronic foot pain.
  • Posttraumatic arthritis:
    • Can occur with or without associated osteonecrosis
    • Subtalar or pantalar fusion may be required as a salvage procedure.
Patient Monitoring
  • The integrity of the talar vascular supply can be confirmed with follow-up radiographs.
    • The Hawkins sign is a subchondral lucency (talar dome subchondral bone osteopenia) that results from bone resorption after a talus fracture with an intact blood supply.
    • The presence of a Hawkins sign excludes osteonecrosis of the talus.
  • Diagnosis of osteonecrosis can be confirmed with MRI.

Miscellaneous
Codes
ICD9-CM
825.21 Talus fracture
Patient Teaching
  • Inform patients of the high incidence of talar osteonecrosis.
  • Teach proper cast care and stress the importance of nonweightbearing during the healing period.
  • Inform patients about the severity of the injury and the often poor long-term results.
  • Review the potential need for later hindfoot fusion.
Activity
  • Crutch walking and nonweightbearing until instructed otherwise.
  • Physical therapy to increase ROM and strength after cast removal
FAQ
Q: How soon should a displaced talar fracture be reduced?
A: Talar fractures of the neck or body should be reduced as soon as possible to prevent soft-tissue complications. Some authors believe that emergent surgery is not necessary because the risk of posttraumatic arthritis is far greater than that of osteonecrosis.
Q: How likely am I to return to full activities after a talar fracture?
A: After a displaced fracture, osteonecrosis may occur. The rate of osteonecrosis depends on the severity of the initial injury. If osteonecrosis occurs, a high likelihood exists that a fusion will be required. Hindfoot fusion results in ankle stiffness and difficulty in walking on uneven ground and in climbing. Most patients with displaced talar neck or body fractures have arthritis and chronic pain.

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