Paediatric Fractures

Definition

In the paediatric skeleton the soft bone tends to bend and partially break (greater elasticity)

• Greenstick fracture: the bone cortex and periosteum break on the convex side of a long bone only

• Torus fracture: the bone cortex buckles on the concave side

• Plastic bowing: a long bone bends, rather than breaks (multiple oblique microfractures are present) ▸ in the forearm, a non-bowed bone may fracture or dislocate

Definition

Injuries are graded according to the Salter–Harris classification (types I–V) ▸ injuries become more serious as the grade rises, with an associated risk of growth disturbance or avascular necrosis ▸ there is a worse prognosis within the lower limb than the upper limb

• Types I and II: the epiphysis remains intact ▸ good prognosis

• Types III and IV: the epiphysis is fractured ▸ poorer prognosis

• Type V: a very rare crushing injury of the physeal cartilage ▸ it is usually associated with types 1–IV injuries

Definition

This is the most common elbow fracture in children ▸ it is a transverse fracture of the distal humerus (proximal to the humeral condyles)

Definition

This is an avulsion injury (due to contraction of the forearm flexor muscles during a fall on an outstretched arm or an impaction injury from a fall onto the olecranon)

• A medial condylar fracture extends to the trochlear articular surface (an epicondylar injury is extra-articular)

• Valgus stress causes displacement of the medial epicondylar epiphysis inferiorly ▸ it may be associated with ulnar nerve injury

Pearl

‘Little leaguer's elbow’: chronic apophysitis around the medial epicondyle due to low energy repetitive traction forces

Definition

An undisplaced oblique fracture of the middle/distal tibial diaphysis in young children ▸ it may not be seen on an initial XR (perform delayed XR or scintigraphy – periosteal reaction + sclerosis)

• This is not suspicious for NAI (in isolation) if the toddler is ambulant

Definition

• Children's physes are more likely to fail than the ankle ligaments ▸ those of the distal tibia and fibula fuse at the same time (if only one is fused suspect an epiphyseal injury)

• Triplane and Tillaux fractures tend to occur in adolescence around the time of distal tibial epiphyseal fusion ▸ CT is used for assessment prior to reduction

Tillaux fracture

A Salter–Harris type III injury due to avulsion of the anterior tibiofibular ligament: the fracture line runs through the anterolateral aspect of the distal tibial physis until it reaches the part that has fused, and then passes downwards through the epiphysis and into the joint ▸ no fracture component in the coronal plane (cf. triplane fracture)

• As the majority of the epiphysis has already fused there is no growth arrest (but the fracture must be reduced to restore joint congruity)

Clinical impact guidelines: the I in CRITOL

From Raby, N. Paediatric elbow. In: Accident and Emergency Radiology Survival Guide, 3rd edition. Bailliere Tindall, 1995. © 2015, Elsevier Limited. All rights reserved.

The ossification centre for the internal (i.e. medial) epicondyle is the point of attachment of the forearm flexor muscles. Vigorous muscle contraction may avulse this centre. The most common injury mechanism is a fall on an outstretched hand. Avulsions also occur in children who are involved in throwing sports, hence the term “little leaguer's elbow”. When a major displacement of the internal epicondyle occurs the bone can become trapped within the elbow joint. This is a well recognised complication of a dislocated elbow, occurring in 50% of cases following an elbow subluxation or dislocation. A major avulsion is easy to overlook when an elbow has been transiently dislocated and then reduces spontaneously because the detached epicondyle may, on the AP radiograph, be mistaken for the normally positioned trochlear ossification centre. I before T. Though the CRITOL sequence may vary slightly there is a constant: the trochlear (T) centre always ossifies after the internal epicondyle. Therefore apply this rule: if the trochlear centre (T) is visible then there must be an ossified internal epicondyle (I) visible somewhere on the radiograph. If the internal epicondyle is not seen in its normal position then suspect that it is trapped within the joint.

Clinical presentation

• This ranges from vague minor symptoms to life-threatening shock