ACEP ID:

Pediatric Emergency Medicine

Pearls & Pitfalls - CAST Fractures: Accidental or Child Abuse?

Larry Mellick, MD, MS, FAAP, FACEP
Professor of Emergency Medicine
Medical College of Georgia

Pearl:
Spiral tibial fractures are common long bone fractures in children that are most commonly accidental and rarely are associated with non-accidental trauma.

Presentation: A 19-month-old female presented to the emergency department for evaluation of her refusal to bear weight on her leg. Earlier in the month, the toddler had been diagnosed with toxic synovitis of her hip, and the mother was concerned that the condition had returned. However, she also reported that her daughter tripped over a vacuum cleaner hose the evening before and fell to the floor. Since the fall, she had refused to bear weight. The physical examination demonstrated full range of motion of her hip, knee, and ankle and no evidence of tenderness. The patient crawled around on the examination table without any apparent pain, but adamantly and consistently refused to bear weight on her leg. The patient's distal tibia demonstrated distinct tenderness and mild swelling. The radiographs demonstrated a non-displaced distal spiral tibial fracture that was seen best on oblique views. The orthopedic service was consulted, a long leg cast was placed on the lower extremity, and follow-up in a week was arranged.

Discussion: This patient sustained a spiral tibial fracture following a relatively minor fall. Originally, the fracture was described as an obscure distal, spiral tibial fracture occurring in ambulating toddlers 9-36 months of age. The original article published by Dunbar, et al. in 1964 described the need for oblique views of the tibia to make the diagnosis.1 Subsequent and larger series have suggested that the fracture also occurs in older children, is frequently accidental, and is not radiology obscure.2,3,4 The originally described toddler's fracture is now considered to be a subset of the Childhood Accidental Spiral Tibial (CAST) fracture.4 In one retrospective study, patients with isolated spiral tibial fractures ranged in ages from 12 months to 94 months (7 years 10 months). The mean age was 50.7 months. Only one-third of children classified with CAST fractures were younger than 36 months. Most CAST fractures involve the distal half of the tibia, not just the distal third.4 The fracture typically is treated with a long leg cast for 5-6 weeks.

Unfortunately, the history of a minor trauma and the presence of spiral tibial fracture often seem incongruent. This raises the specter of non-accidental trauma. However, several case series and a review of the literature would suggest that the condition is much more commonly accidental in origin.5,6 An animal model of an accidental spiral tibial fracture has also been described.7  

See Figure 1: Radiograph of a Non-displaced Distal Spiral Tibial Fracture 

References:  

  1. Dunbar JS, Owen HF, Nogrady MM, et al. Obscure tibial fracture of infants the toddler's fracture. J Canad Assoc Radiol 1964;15:136-144.
  2. Mellick LB, Reesor K. Spiral tibial fractures of children: A commonly accidental spiral long bone fracture. Am J Emerg Med 1990;8:234-237.
  3. Mellick LB, Reesor K, Demers D, et al. Tibial fractures of young children. Pediatr Emerg Care 1988;4:97-101.
  4. Mellick LB, Milker L, Egsieker E. Childhood accidental spiral tibial (CAST) fractures. Pediatr Emerg Care 1999;15:307-309.
  5. http://emj.bmj.com/cgi/content/full/23/6/473  
  6. http://www.bestbets.org/bets/bet.php?id=134  
  7. Mellick LB, Mellick DL. An animal model of the childhood accidental spiral tibial fracture. Letters to the Editors. Pediatr Emerg Care 2004;20:864.

 

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