Non-accidental injury

Non-accidental injuries (NAI) represent both ethical and legal challenges to treating physicians.

Radiologists may be the first clinical staff to suspect non-accidental injuries when confronted with a particular injury pattern. Knowledge of these is essential if the opportunity to save a child from future neglect is not to be missed. At the same time, it is essential that suspicion is not raised inappropriately as the consequences for an innocent but accused parent or guardian are significant.

Over recent years, there have been a number of titles given to the constellation of injuries that are the result of the physical abuse of children. "Non-accidental injury" is the accepted most appropriate term to use in this setting. The modifier "inflicted" can be added for clarity e.g. inflicted non-accidental injury.

In 2001 an estimated 903,000 children were victims of maltreatment including:

  • neglect: 57%
  • physical abuse: 19%
    • cutaneous injury: most common
    • fractures are noted in ~30% (range 11-55%)
  • sexual abuse: 10%
  • psychological maltreatment: 7%
  • medical neglect: 2%

A number of features have been recognized as suspicious:

  • injury in the non-ambulatory/totally dependent child
  • injury and history given are inconsistent
  • delay in seeking medical attention
  • multiple fractures with no family history of osteogenesis imperfecta
  • retinal hemorrhage
  • torn frenulum
  • history of household falls resulting in fracture
    • despite falls being common, fractures are uncommon
  • abdominal injuries
  • thoracic injuries 10

A skeletal survey is performed in cases of suspected abuse to assess and document the extent of skeletal injuries. The so-called babygram (whereby the entire baby is imaged in one view) is not an acceptable substitute due to the overall lower quality that it produces; each anatomical region requires different radiographic exposures to accurately image.

Lead markers should be used in skeletal surveys and some institutions will repeat radiographs that do not have a lead marker within the primary field. 

Bone scans are performed in some institutions because of their ability to detect radiographically-occult fractures.

A number of fractures have been recognized as highly specific to non-accidental injuries (rather than accidental injury). They include:

Fractures which are moderately specific for NAI are 10:

  • bilateral fractures with fractures of differing ages
  • digital fractures in non-ambulant children
  • vertebral fractures or vertebral subluxation 
  • spiral humeral fractures 
  • separation of epiphysis
  • complex skull fractures 

Fractures which have low specificity for NAI are 10:

  • middle clavicular fractures 
  • linear simple fractures of parietal bone 
  • single fractures in diaphysis (spiral humeral fracture is an exception)
  • greenstick fractures

It is the most sensitive in detecting fractures of rib, scapula, spine, diaphysis and pelvis. The test becomes positive few hours after injury. Normally there is high uptake in the epiphyses of bones which should not be confused with a fracture 10.

The ability to date injuries is critical for medicolegal purposes and thus must be done carefully (please refer to specialist text for specific guidelines).

Traumatic periosteal injury can be seen up to 7 days post-injury (and therefore can be used for dating). Traumatic periosteal injuries can be seen on diaphyseal and rib injuries. Diaphyseal injuries start healing after one week. Healing should be complete by 12 weeks. Rib fractures are often missed, hence current practice is to repeat chest films in two weeks to observe for any healing fractures.

Metaphyseal (and costochondral junction) injuries do not heal with periosteal reaction and if visible are less than four weeks old. Skull fractures also do not heal with periosteal reaction and if seen are less than two weeks old.

  • skeletal dysplasias: one of the major, albeit uncommon pitfalls in diagnosing NAI (e.g. Schmid-type metaphyseal chondrodysplasia, osteogenesis imperfecta I and IV), which may lack the florid features of the full-blown disease and can be easily confused with NAI
    • features to differentiate osteogenesis imperfecta from NAI include
  • growth plates can also cause a degree of confusion, most notably at the hip, base of the fifth metatarsal, elbow and the acromion
  • birth injuries
  • rickets
Non-accidental injury
Postmortem and forensic imaging
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Article information

rID: 10133
Section: Signs, Gamuts
Synonyms or Alternate Spellings:
  • Non-accidental injury
  • Battered child syndrome
  • NAI
  • Non-accidental injuries (NAI)
  • Non accidental paediatric skeletal injuries
  • Child abuse
  • Non-accidental injury (NAI)
  • Non-accidental paediatric injuries
  • Non accidental trauma
  • Shaken baby syndrome (SBS)
  • Shaken infant syndrome
  • Stress-related infant abuse

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3: bilateral subdural hemorrhages
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  • Case 4
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  • Case 5: metaphyseal corner fracture
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  • Case 6: skull fracture with suspected NAI
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  • Case 7
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  • Zoomed in
    Case 7: with very subtle metaphyseal corner fracture
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  • Metaphyseal corne...
    Case 8
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