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BMJ Case Reports 2012; doi:10.1136/bcr.10.2011.5028
  • Rare disease

Paediatric talus fracture

  1. Michael Stephens
  1. Department of Paediatric Orthopaedics, The Children’s University Hospital, Temple Street, Dublin, Ireland
  1. Correspondence to Ms Ann-Maria Byrne, ann_maria_byrne{at}hotmail.com

Summary

Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

Background

Fractures of the talus are rare injuries with an estimated prevalence of 0.008% of all childhood fractures compared with 0.3% in adults.1 It is thought that the paediatric foot is flexible and skeletally immature bone less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur.2 3 The talar neck is the most common fracture site, followed by the talar body. Cast immobilisation is sufficient treatment for non-displaced fractures; however displaced fractures of the talus require surgical intervention to minimise the risk of trauma-related avascular necrosis due to disruption of the vascular supply originating from the talar neck.1 3,,5

Case presentation

A 7-year-old girl was brought to the emergency department following a fall of between 8 and 10 feet from a climbing wall. She was unable to weightbear on her right foot and her anterior ankle region was swollen, with no open wounds or abrasions. She had no other injury and no medical or surgical history. Following triage, she was sent for mortise and lateral radiographs of her ankle (figure 1a,b), which the emergency physician felt showed no bony nor physeal injury. However, her foot was increasingly swollen and bruised during her time in the emergency department. She was still unable to weightbear following intravenous paracetamol and morphine, these analgesics being titrated to her weight. Repeat examination of the child demonstrated pain of the right ankle and foot region, with no associated neurovascular compromise. She was sent for foot radiographs, at this stage, to delineate any distal injury, and an opinion from the orthopaedic service was sought.

Investigations

On review of the ankle and foot radiographs, she was noted to have a right neck of talus fracture (figures 1 and 2). Her CT images demonstrated a Hawkins Type 1 neck of talus fracture with no displacement of the fracture or subtalar dislocation (figure 3a). 3-D CT reconstruction views demonstrated talar neck compression where the anterior tibial plafond was driven into the neck of the talus when the foot was loaded in dorsiflexion (figure 3b,c).

Figure 1

(a) Mortise and (b) lateral radiographs of right ankle; the neck of talus fracture was initially missed in the emergency department on these views.

Figure 2

Oblique radiograph of right foot (non-weight bearing) clearly demonstrating a neck of talus fracture, but without adquate visualisation of the subtalar joint.

Figure 3

(a) Sagittal CT image demonstrating Hawkins Type 1 neck of talus fracture with evidence of collapse where anterior tibial plafond was driven into the neck of the talus when the foot was loaded in dorsiflexion; (b) and (c) 3-D reconstruction CT images to aid with planning of treatment.

Treatment

Initial treatment involved a plaster of paris backslab with the ankle in a neutral position. Her right leg was elevated on pillows and treated with ice to alleviate swelling. She was admitted to the hospital for analgesia, limb elevation and further imaging with CT to delineate the nature of the fracture and to plan definitive management. Due to the relatively undisplaced nature of the fracture, the acceptable position of the comminuted fragments, and the congruency of the subtalar joint, the decision was taken to treat her conservatively with a non-weightbearing below knee cast for 6 weeks, and follow her clinically and radiographically for at least 2 years following union to assess for avascular necrosis of the talus.

Discussion

In 1919, Anderson described talus fractures as ‘aviator’s astragalus’ and identified the dorsiflexion mechanism of injury.6 Research focusing on paediatric talar fractures identified road traffic accidents and falls from a height as the most frequent injury mechanisms.3 4 Smith et al7 studied 29 children with talus fractures sustained at an average age of 13.5 years. They reported that displaced paediatric talus fractures and those associated with high-energy trauma resulted in more complications including avascular necrosis (7%), arthrosis (17%), delayed union (3%), neurapraxia (7%) and the need for further surgery (10%). They also found that talus fractures were more common and occurred with more severity among older boys.7 These findings were supported by Eberl et al3 in their comparison of children and adolescents sustaining talus fractures. Furthermore, they observed no persistent osteonecrosis in patients younger than 12 years, and reported favourable outcomes in the majority of cases irrespective of the mode of treatment.3 Jensen et al2 reported an excellent long-term prognosis of minimally displaced and undisplaced fractures of the talus in the paediatric population. Avascular necrosis of the body of the talus has been reported in children after minimally displaced fractures8 but usually occurs following fracture-dislocations of the talus.2 8 9 Definitive guidelines regarding treatment and incidence of avascular necrosis following talar fractures in the paediatric population has yet to be eludicated. However, awareness of this rare fracture can help early identification of injured children, expedite treatment, followed by clinical and radiological follow-up, assessing for avascular necrosis of the talus.

Learning points

  • Paediatric talus fractures are rare injuries and a high index of suspicion can avoid misdiagnosis.

  • Mechanism of injury includes axial loading of the talus against the anterior tibial plafond with the foot in dorsiflexion.

  • Conservative and surgical treatment outcomes are similar.

  • Avascular necrosis following paediatric talus fractures is rare but has been reported with displaced fractures.

Footnotes

  • Competing interests None.

  • Patient consent Obtained.

References

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