Imaging of pediatric musculoskeletal trauma: Age-specific considerations and challenges

Table 1 Ossification occurs in a typically predictable order (Mnemonic: CRITOE: 1, 5, 7, 10, 10, 11)

Ossification centers	Average age that ossification occurs
Capitellum	1 year (ossifies first)
Radial head	5 years
Internal (medial) epicondyle	7 years-always ossifies before the trochlea
Trochlea	10 years
Olecranon	10 years
External (lateral) epicondyle	11 years (ossifies last)

Table 2 Gartland classification

Type	Description	Subtypes
I	Undisplaced or minimally displaced (< 2 mm)	Ia: Undisplaced in both projections; Ib: Minimal displacement, medial cortical buckle, anterior humeral line intersects capitellum
II	Displaced but with intact cortex	IIa: Posterior angulation, intact posterior cortex, anterior humeral line does not intersect capitellum; IIb: Rotatory or straight displacement, fracture ends remain in contact
III	Completely displaced	IIIa: Complete posterior displacement, no cortical contact; IIIb: Complete displacement with soft tissue gap (bone ends separated by soft tissue)
IV	Displaced, unstable in flexion and extension, periosteal disruption (diagnosed intra-operatively)	NA

NA: Not available.

Table 3 Advanced imaging modalities

Type1	Category	Subcategory and examples	Imaging modality indications
Acute trauma	Fractures	Physeal fractures: SH Type I-V; special adolescent variants: Tillaux (SH-III); Triplane (SH-IV). Incomplete fractures: Greenstick; torus/buckle; “Bowing”. Complete fractures: Transverse; comminuted; oblique. NAT fractures: Metaphyseal fractures; rib fractures; sternal fractures	Radiographs: Gold standard for initial evaluation. Advanced imaging: CT: For complex intra-articular or surgical planning MRI: Not for routine fracture detection; best for associated soft tissue, cartilage, or growth plate injury. Suspected NAT (based on RCH guidelines) < 2 years old: Primary: Full skeletal survey (mandatory). Follow-up: Limited skeletal survey after 14 days and no later than 28 days, to detect healing fractures. 2-5 years old: Assessment: Case-by-case depending on history, clinical signs and suspicion. Options: Skeletal survey; bone scan if expertise available. > 5 years old: Approach: Targeted imaging guided by clinical findings. Modalities: Radiographs o symptomatic areas; advanced imaging (CT/MRI) for specific injuries. Advanced imaging modalities: Bone scan: Only with appropriate expertise and when SS is limited/inconclusive. CT: Head CT for suspected abusive head trauma; CT chest/abdomen/pelvis only if unstable or visceral injury suspected. MRI: Brain/spine MRI for parenchymal, ischemic, ligamentous, or occult injury notes: US: May support abdominal or intracranial assessment but it’s not primary for skeletal injuries
	Soft tissue injuries. Note: These are less common than fractures as the bone is the weakest component in children	Ligaments: Sprains/partial tears; complete tears. Muscle-tendon unit: Apophyseal avulsions: Tendon ruptures (rarer). Cartilage. Osteochondral lesions	US: First-line for superficial injuries, effusions, apophyseal avulsions. MRI: Preferred for deep, complex, or preoperative assessment. CT: Only for polytrauma or when MRI unavailable
Chronic/overuse trauma		Overuse injuries: Stress fractures; Gymnast’s wrist. Little league shoulder; Little league elbow (medial epicondyle apophysitis). Sever’s disease (calcaneal apophysitis). Osgood Schlatter: Sinding larsen johanson	Radiographs: First-line in most cases due to accessibility and ability to detect physeal changes, fragmentation, and obvious stress reactions. MRI: Most useful modality for many overuse injuries in children. It detects early stress reactions, marrow edema, cartilage/physeal injury, and osteochondral involvement, without radiation exposure. CT: Largely supplanted by MRI in pediatrics due to radiation concerns. Still occasionally useful for surgical planning or equivocal cases. US: Limited but sometimes useful for superficial apophyseal or tendon-related pathology (e.g. Osgood-Schlatter, sever disease), especially when radiation avoidance is a priority. Note: CT is rarely needed; MRI avoids radiation and provides superior tissue contrast

¹Acute: Single, identifiable event; chronic/overuse: Repetitive trauma.

SH: Salter Harris; NAT: Non-accidental trauma; CT: Computed tomography; MRI: Magnetic resonance imaging; US: Ultrasound; SS: Skeletal survey; RHC: Royal children’s hospital.

Table 4 Non-accidental trauma vs accidental trauma

	Non-accidental trauma	Accidental trauma
Definition	Intentional physical harm inflicted by a caregiver (child abuse)	Unintentional injury (e.g. fall, sports, motor vehicle accident)
History/context	Inconsistent or changing history; delay in seeking care; injuries incompatible with child’s developmental stage (e.g., long bone fracture in a non-ambulatory infant)	Clear, consistent explanation of mechanism; injury matches developmental ability and timeline of presentation
Clinical clues	Bruises in atypical areas (torso, ears, neck-TEN rule; FACESp: Frenulum, angle of jaw, cheeks, eyelids, subconjunctiva); patterned bruises or burns; oral/sentinel injuries	Bruises over bony prominences (forehead, shins); abrasions/lacerations consistent with play or falls
Injury distribution	Multiple fractures at different healing stages; bilateral or symmetric injuries; high-specificity sites: Posterior ribs, classic metaphyseal lesions, scapula, sternum, pelvis	Usually single, isolated fracture; pattern matches mechanism (e.g., supracondylar humerus from FOOSH, toddler’s tibial spiral fracture, clavicle or buckle fracture)
First line imaging	Skeletal survey (< 2 years): Full series to detect acute, occult, and healing fractures; repeat limited survey at about 2 weeks increases sensitivity	Radiographs targeted to site of injury; sufficient in most cases
Other imaging	CT: Head CT for suspected abusive head trauma; chest/abdomen/pelvis CT only if unstable or high suspicion of internal injury. MRI: Brain MRI for parenchymal injury, ischemia, dating hemorrhage; spine MRI for occult fractures/Ligamentous injury in AHT; MSK MRI for complex/occult injuries	CT: Used when radiographs are insufficient or in severe head injury/neurological deficit. MRI: For selected complex fractures or suspected ligament/cartilage injury
Head trauma: Neuroimaging findings	Abusive head trauma: Subdural hemorrhage (often multiple or of varying ages), hypoxic-ischemic injury, spinal spinal subdural hemorrhage, retinal hemorrhages (clinical exam)	Isolated linear skull fractures, epidural hematoma with clear trauma history
Differential diagnoses	Bone fragility disorders (osteogenesis imperfecta, rickets, metabolic bone disease of prematurity, copper deficiency/Menkes, scurvy) can mimic fracture patterns; careful correlation with clinical and lab findings required	Consider NAT when the patterns/distributions are inconsistent (e.g. more than 3 bruises from a single event or bruises over opposite sides of the body). Note that accidental patterns rarely overlap with high-specificity injuries seen in NATs

TEN: Torso-ears–neck bruising rule; FACESp: Frenulum, angle of jaw, cheeks, eyelids, subconjunctiva; FOOSH: Fall on outstretched hand; CT: Computed tomography; MRI: Magnetic resonance imaging; MSK: Musculoskeletal; NAT: Non-accidental trauma; AHT: Abusive head trauma.