Non-Accidental Injury

Non-Accidental Injury (NAI) is physical abuse of a child, often by a caregiver.

• Epidemiology:
  • Peak age: under 2 years (especially under 1 year).
  • Boys slightly more affected.
  • Mortality: 10-30% in severe cases (shaken baby syndrome).
• Risk Factors:
  • Young, single parents.
  • Substance abuse, mental health issues.
  • Previous history of NAI in family.
  • Colicky or difficult child.
  • Low socioeconomic status (although occurs in all groups).
• Importance for Orthopaedic Surgeons:
  • Fractures are the second most common manifestation of NAI (after bruising).
  • Early recognition can save lives.

Mechanisms of Injury in NAI

• Shaking: Causes subdural hematoma, retinal hemorrhages. In infants, the head is large and the neck muscles are weak.
• Gripping/Squeezing: Causes posterior rib fractures (thumbs on spine, fingers on ribs).
• Twisting/Pulling: Causes metaphyseal corner fractures (avulsion at the chondro-osseous junction).
• Direct Blows: Long bone shaft fractures, skull fractures.

Why Metaphyseal Corner Fractures are Specific

• The metaphysis is weaker than the shaft.
• Twisting or pulling forces cause avulsion at the periosteal-bone junction.
• This mechanism rarely occurs in accidental falls.

History Red Flags:

• Delayed Presentation: Caregivers wait before seeking help.
• Inconsistent History: Explanation doesn't match injury severity or pattern.
• Changing Story: Different versions from different caregivers.
• No History: "I don't know how it happened."
• Inappropriate Affect: Caregiver not appropriately concerned.

Physical Exam:

1. Full Body Inspection: Look for bruises (especially non-accidental patterns like grip marks, loop marks, bite marks).
2. Bruises in Non-Mobile Infants: Any bruise in a non-mobile infant is suspicious.
3. Skeletal Tenderness: Palpate all limbs and axial skeleton.
4. Head Circumference: Increasing head size may indicate subdural hematoma.
5. Fontanelle: Bulging fontanelle is concerning.

HIGH SPECIFICITY (When present, NAI is highly likely):

• Metaphyseal Corner Fractures (Bucket-Handle): Classic. Caused by twisting/pulling.
• Posterior Rib Fractures: Caused by squeezing (thumbs on back).
• Scapula Fractures: Very unusual in children (requires significant force).
• Spinous Process Fractures: Direct blow or hyperflexion.
• Sternum Fractures: Direct blow.

MODERATE SPECIFICITY:

• Multiple Fractures at Different Healing Stages: Indicates repeated trauma.
• Bilateral Fractures: Statistically unlikely from single accident.
• Complex Skull Fractures: Multiple fracture lines, depressed.

LOW SPECIFICITY (Common in accidental trauma):

• Clavicle Fractures: Common in birth and falls.
• Long Bone Shaft Fractures: Can be accidental or non-accidental.
• Linear Skull Fractures: Common in falls.
• Toddler's Fractures: Common accidental injury.

Skeletal Survey (MANDATORY):

• Full body X-rays (AP and lateral of all limbs, chest, abdomen, skull, spine).
• Repeat at 10-14 days if initial is negative (allows healing fractures to become visible).

Head Imaging:

• CT Head: Urgent if any neurological signs.
• MRI Brain: More sensitive for subtle injury.

Ophthalmology:

• Dilated Fundoscopy: Retinal hemorrhages (especially multilayer) are highly specific for shaken baby syndrome.

Laboratory:

• Bleeding studies (PT, APTT, platelet count) to rule out bleeding disorders.
• Metabolic bone disease screen (calcium, phosphate, ALP, vitamin D) to rule out rickets, OI.

Documentation:

• Meticulous notes, diagrams, photographs.
• Your documentation may be used in court.

Clinical tip: Investigate mimics thoroughly, but a negative medical workup does not exclude abuse - and a confirmed medical condition (e.g. OI) does not exclude coexisting inflicted injury. Report if the clinical picture is suspicious.

• Vitamin D deficiency as a cause of fractures: A recurring courtroom argument. Subclinical vitamin D insufficiency is common and does not, by itself, produce the fracture patterns of abuse; radiographic rickets is required before metabolic bone disease can plausibly explain fractures. This remains a contested medico-legal area.
• "Temporary brittle bone disease": A proposed entity used in some defences to explain multiple infant fractures. It is not accepted as a validated diagnosis in mainstream paediatric and radiological practice and lacks a reproducible evidence base.
• The biomechanics of abusive head trauma: The relative contribution of shaking versus impact, and the specificity of the "triad" (subdural haemorrhage, retinal haemorrhage, encephalopathy), remain debated. Current consensus is that the triad raises strong suspicion but is interpreted alongside the whole clinical and radiological picture rather than as standalone proof.
• Dating of fractures and bruises: Radiological fracture dating is broad (ranges, not precise days) and bruise colour does not reliably date injury; over-precise dating in reports is a frequent source of challenge.
• Whole-skeleton imaging in older children: The yield of routine skeletal survey falls sharply after 2 years, so imaging in the 2-5 year group is selective and guideline-dependent rather than uniform.

Fracture Management in NAI Context:

• Priority is Child Safety: Fracture treatment is secondary to ensuring the child is protected.
• Conservative Treatment Preferred: Most NAI fractures can be treated non-operatively.

When Surgery is Required:

• Open fractures (rare in NAI)
• Unstable fractures requiring fixation
• Neurosurgical intervention for intracranial hemorrhage

Important Considerations:

• Always document pre-operative findings with photographs.
• Ensure child protection clearance before discharge.
• Post-operative follow-up must be coordinated with social services.

Physical Complications:

• Fracture Malunion/Nonunion: Rare with appropriate treatment.
• Growth Disturbance: Physeal injuries may cause limb length discrepancy.
• Neurological Sequelae: Brain injury from shaking can cause permanent disability.
• Visual Impairment: Retinal hemorrhages may lead to visual problems.

Psychological Complications:

• Post-Traumatic Stress Disorder (PTSD): Common in abused children.
• Attachment Disorders: Difficulty forming healthy relationships.
• Developmental Delay: Physical and cognitive delays.
• Behavioral Problems: Aggression, anxiety, depression.

Long-Term Outcomes:

• Without intervention, abuse typically escalates.
• Early recognition and intervention can be life-saving.
• Children who remain in abusive environments have high mortality rates.

Fracture-Related Care:

• Standard fracture aftercare applies (cast care, weight-bearing status).
• Follow-up imaging to confirm healing.
• Physiotherapy if indicated for stiffness or weakness.

Child Protection Aspects:

• Do Not Discharge Without Clearance: Social services must approve discharge plan.
• Safe Placement: If home is unsafe, alternative placement must be arranged.
• Follow-Up: Coordinated between orthopaedics, pediatrics, and social services.
• Sibling Assessment: Other children in the household must also be assessed.

Documentation:

• Complete discharge summary with all findings.
• Clear follow-up plan documented.
• Communication with GP and community health services.

Fracture Outcomes:

• Most fractures heal well with appropriate treatment.
• Growth disturbance is possible with physeal injuries.
• Functional outcomes are generally good if recognized early.

Child Protection Outcomes:

• With Intervention: Children removed from abusive environments have better long-term outcomes.
• Without Intervention: Mortality rate is 10-30% in severe cases; morbidity approaches 100%.

Prognostic Factors:

• Age at recognition (younger children more vulnerable)
• Severity of injuries (especially neurological)
• Quality of intervention and follow-up
• Availability of safe alternative placement

Key Message: Early recognition by the orthopaedic surgeon can save lives. Even if uncertain, report suspected NAI - you are protected from liability when acting in good faith.

• Mandatory Reporting: Legal obligation. You are protected from liability if acting in good faith.
• Documentation: Your notes may be subpoenaed. Be factual, objective, and comprehensive.
• Avoid Speculation: Document what you observe, not your opinion on who caused it.
• Chain of Custody: If specimens or photographs are taken, maintain proper procedures.
• Expert Witness: You may be called as a witness. Be prepared to explain findings objectively.

• Recognition: Identify suspicious fracture patterns.
• Reporting: Notify appropriate authorities.
• Documentation: Meticulous records.
• Treatment: Treat fractures appropriately (usually conservative).
• Court Attendance: May be required as a factual or expert witness.
• Ongoing Monitoring: If child returns with new injuries, re-escalate.

Global epidemiology

• Child maltreatment is reported worldwide; physical abuse disproportionately affects infants, with the highest fracture and fatal-head-injury rates in the first year of life.
• Fractures are a common manifestation of physical abuse and are second only to bruising; up to a third of physically abused children have a fracture, and the proportion is highest in non-ambulant infants.
• Risk is increased by young/sole caregivers, parental substance misuse and mental illness, intimate-partner violence, social isolation and prematurity/disability of the child - but abuse occurs across all socioeconomic groups and no profile is diagnostic.

Side-by-side guideline comparison

Practice variation: high- vs limited-resource settings

• High-resource: dedicated child-protection paediatric teams, on-site paediatric radiology, ophthalmology and forensic input, statutory multi-agency pathways.
• Limited-resource: skeletal survey may be substituted by targeted/limited radiography; ophthalmology and CT/MRI may be unavailable; reporting frameworks and social-care infrastructure vary widely. The clinical threshold for suspicion and the duty to protect the child remain the same regardless of available investigations.
• Reporting is mandatory by law in many countries (e.g. across the US, Australia, parts of Europe and Asia) and professionally expected elsewhere; clinicians must know the local pathway, but the duty to act on reasonable suspicion is universal.

Why is my child being investigated? When a child has an injury that doctors cannot easily explain, they have a legal and ethical duty to make sure the child is safe. This does not mean they are accusing you of anything - it means they are being thorough.

What investigations will be done?

• X-rays of the whole body (skeletal survey) to check for other injuries.
• A scan of the brain if there is any concern.
• An eye examination to look for signs of bleeding.
• Blood tests to rule out medical conditions.

What happens next? A team of doctors, social workers, and sometimes police will review the findings. Their goal is to ensure your child is safe.

What are your rights? You have the right to legal representation. Cooperating with the investigation is in your child's best interest.