Pediatric Chance Fracture

Pediatric Chance FracturesWe have discussed the potential hazards of being a child on numerous occasions (ex, Injury Prevention, Trampolines, Lawn Mowers, Submersions, Electricity, Firearms), but nothing leads to more injuries than motor vehicles (sometimes, even when they are standing still – Vehicle Hyperthermia). Certainly, the use of a seat belt can save a life; however, if positioned incorrectly, it can also lead to injury. Let us review one such injury- the Pediatric Chance Fracture:

 

Pediatric Chance Fracture: Basics

  • Due to a flexion-distraction injury.
    • Significant flexion of the lumbar spine leads to distraction of posterior segments.
    • Can lead to compression of the anterior segment as well.
  • Initially described as a purely osseous injury.
    • Fracture line passes through spinous processes, pedicles, and superior endplate of the vertebral body.
    • Involves all three columns of the spine.
    • But… now known to include several variants, one which is a purely soft-tissue injury involving the intervertebral disc and ligamentous structures.
  • Several classification systems:
    • Most are not appropriate for children as they do not account for the growth plates.
    • Use of MRI imaging can categorizing and defining Pediatric Chance Fractures. [de Gauzy, 2007]
      • Type I – Physeal injury of the superior growth plate
      • Type II – Osseous injury
      • Type III – Physeal injury of the inferior growth plate
  • Was thought to be rare, but is often initially missed initially.
    • Often misdiagnosed as compression fractures (even by spine surgeons). [Andras, 2016]
      • Pediatric Chance Fracture may have a compression component, but involves posterior elements as well.
      • Misdiagnosis can lead to suboptimal management and prolonged morbidity. [Andras, 2016]
    • Accounts for significant proportion of pediatric vertebral injuries – (42-100%). [Le, 2011]

 

Pediatric Chance Fracture: Different than Adult

Children have several anatomic features that alter the fracture pattern: [Le, 2011]

  • Presence of growth plates (weaker than bone, disc, & ligaments)
  • Healthy intervertebral discs (stronger than in adults)
  • Increased head-to-body ratio (changes center of gravity and torque angle => greater distraction forces)
  • Pelvis and femurs are smaller
    • Smaller iliac crest 
      • Difficult for lap restraint to secure the pelvis
      • Belt should be beneath the anterior inferior iliac crest, but difficult to secure in the young.
    • Shorter Femurs
      • If not in booster, shorter legs cause child to slouch in seat, aligning the lap belt with abdomen (which is bad!).
      • Child can slide under belt, even is align properly at first (this is why there is a crotch strap for very young children).

 

Pediatric Chance Fracture: Mechanism

  • Hyperflexion injury leading to either: [Le, 2011]
    • All 3 columns failing in tension (being pulled apart), OR
    • Middle and Posterior columns failing in tension and the Anterior column failing in compression.
    • Fracture pattern is dependent upon the axis of rotation.
    • Ligamentous and soft tissue injuries also occur.
  • Seen with children inappropriately restrained: [Le, 2011]
    • Lap belt (2-point restraint) only
      • Allows for hyperflexion
      • Since 2007, new cars sold in the US are mandated to have 3-point restraints in all seating positions.
    • Inappropriately worn 3-point restraint
      • Children who purposely sit with shoulder restraint behind the torso.
      • Children too small for lap belt to restrain the pelvis, allowing pelvis to slip under it and leading to flexion around the abdomen.

 

Pediatric Car Restraint Primer

  • Each car restraint device has manufacturer recommendations for positioning and child weights – follow them.
  • Infants and Toddlers should be rear-facing for as long as possible… but ~2 years of age is average (~40 lbs).
  • Car Seats should be used forward facing from 2-4 years of age (65-80 lbs … see manufacture guidelines).
  • Booster Seats (that help appropriately position the lap and should belts) should be used until ~ 8 years of age … when child’s legs are long enough to have feet flat on floor and hips at the back of the seat (preventing slouching).
  • Children under 13 years should continue to ride in the rear seat of the vehicle.

 

Pediatric Chance Fracture: Complications

  • Pediatric Chance Fractures are associated with concomitant injuries:
    • “Seat Belt Syndrome” 
      • Abdominal Wall Ecchymosis
      • Lumbar Spinal Injury
      • Visceral injury – ~66% will have intra-abdominal injury
    • Spinal cord injury
      • Paraplegia seen in ~15% of children (rare in adults)
    • Aortic Injuries also reported.

 

Moral of the Morsel

  • Seat Belts save lives… but inappropriately worn can cause damage!
  • Seat Belt Sign? Don’t just think about the intestines being injured. Look at that spine!
  • Compression fracture in a child? Scrutinize the potential for it being a Pediatric Chance Fracture. May need MRI.
  • Always discuss appropriate car safety and restraints at every opportunity! An ounce of Prevention… is worth a child’s spine!

 

References

Andras LM1, Skaggs KF, Badkoobehi H, Choi PD, Skaggs DL. Chance Fractures in the Pediatric Population are Often Misdiagnosed. J Pediatr Orthop. 2016 Dec 23. PMID: 28027145. [PubMed] [Read by QxMD]

Le TV1, Baaj AA, Deukmedjian A, Uribe JS, Vale FL. Chance fractures in the pediatric population. J Neurosurg Pediatr. 2011 Aug;8(2):189-97. PMID: 21806362. [PubMed] [Read by QxMD]

Arkader A1, Warner WC Jr, Tolo VT, Sponseller PD, Skaggs DL. Pediatric Chance fractures: a multicenter perspective. J Pediatr Orthop. 2011 Oct-Nov;31(7):741-4. PMID: 21926870. [PubMed] [Read by QxMD]

de Gauzy JS1, Jouve JL, Violas P, Guillaume JM, Coutié AS, Chaumoitre K, Launay F, Bollini G, Cahuzac JP, Accadbled F. Classification of chance fracture in children using magnetic resonance imaging. Spine (Phila Pa 1976). 2007 Jan 15;32(2):E89-92. PMID: 17224805. [PubMed] [Read by QxMD]

Sean Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renown educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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