Radial Neck Fractures Pediatric

Radial neck fractures make up 5-10% of paediatric elbow fractures. The peak age is 9-10 years, boys and girls are affected equally, and the usual story is a fall in the playground or at sport. This page is the radial-neck deep-dive; the olecranon fractures, elbow dislocations and medial-epicondyle injuries that accompany it are covered on the companion Pediatric Elbow Injuries page, and the two are read together.

Why the neck and not the head. In a child the radial head is largely cartilaginous, and the physis and neck are weaker than the annular ligament. The force that fractures the head in an adult therefore breaks the neck in a child. The ossification centre of the radial head appears at 3-5 years.

Mechanism. A fall on the outstretched hand with the elbow extended, delivering a valgus force with an axial load.

Associated injuries. 50% of these children have another elbow injury, and around 10% have an elbow dislocation. A Monteggia variant may carry a radial neck injury.

• Elbow dislocation
• Olecranon fractures
• Ulna fractures (Monteggia variant)
• Medial epicondyle fractures
• Capitellum injuries

The radiocapitellar joint. The radial head articulates with the capitellum, and the joint allows both flexion-extension and rotation. The annular ligament stabilises the radial head; its disruption allows dislocation. In forearm rotation the radius turns around the ulna, and an angulated neck limits pronation and supination.

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Blood supply. The radial head is fed mainly by periosteal vessels around the neck; intramedullary flow is minimal. Disrupting those vessels during open reduction can cause avascular necrosis, and stripping the annular ligament is how that supply is lost, so any operation preserves the soft tissues and the ligament.

The posterior interosseous nerve. The PIN is the deep branch of the radial nerve. It runs anteriorly around the radial neck and enters supinator at the arcade of Frohse, which puts it at risk both from the injury and from percutaneous and open procedures. It is purely motor, supplying the finger extensors (EDC, EIP) and the thumb extensors (EPL, EPB).

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Two systems are in use. O'Brien grades angulation alone, measured against the shaft axis on the lateral radiograph (see Investigations). Judet combines angulation with translation and is used for prognosis; O'Brien is the angulation number, Judet is what you operate on. Judet IV is the head off the neck, divided into IVa, where the head still contacts the metaphysis, and IVb, where it is free. Judet III-IV fractures are the ones that climb the closed, percutaneous, Metaizeau ladder. An O'Brien type IV is a completely displaced head at 90°, which describes displacement; it is not a comminuted head.

Read the treatment column alongside Management: open reduction is reached when closed, percutaneous and intramedullary techniques have failed, or for the other indications listed there.

O'Brien and Judet describe the deformity, but the examiner also expects the physeal anatomy of the injury and what a growth disturbance would cause.

The fracture pattern. Most injuries are either a physeal separation through the proximal radial physis, Salter-Harris type I or, more often, type II, or a purely metaphyseal (subcapital) neck fracture just distal to it.

Growth. The proximal radial physis contributes only about 20-25% of the radius's length; the distal physis does the bulk. Pure longitudinal growth loss from a proximal injury is therefore usually modest.

Remodelling. Children remodel these fractures well, helped by the physis's contribution to growth and a robust blood supply, and the correction comes largely from the physis re-orienting the tilted head. Because remodelling depends on remaining growth, the younger child remodels best and the older child less, which is why the acceptable angle tightens with age and why modest residual angulation is accepted in young children. That, alongside the case against excision below, is why a conservative, head-preserving strategy is favoured.

Premature physeal arrest. Severe injury or open reduction can close the proximal radial physis early. The result is radial head and neck deformity, relative radial shortening with positive ulnar variance, and altered radiocapitellar congruity.

History. A fall on the outstretched hand with a valgus mechanism, followed by lateral elbow pain and difficulty rotating the forearm. Ask whether the elbow dislocated.

Examination. Tenderness is lateral, with swelling over the radiocapitellar region and limited pronation and supination. Test elbow stability and PIN function, and look for the associated injuries listed above.

Radiographs. AP and lateral views of the elbow. Angulation is measured on a true lateral, not a rotated film:

1. Draw a line through the axis of the radial shaft
2. Draw a line through the centre of the radial head, perpendicular to its articular surface
3. The angle between them is the angulation; normally the two lines are nearly collinear, less than 15°

That number, not an impression that the head "looks a bit off", sets the classification and the treatment, and puts the child on the 30° or the 45° pathway. Check the same films for an elbow dislocation, an ulna fracture or an olecranon fracture.

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The fat pads. A visible posterior fat pad after trauma is an intra-articular fracture until proven otherwise; if the supracondylar region is clean, look at the radial neck. The sail sign is the anterior pad lifted by the same effusion and is not a diagnosis on its own.

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The painful, swollen, rotation-restricted child's elbow has several mimics. On plain film the radiocapitellar line and the radial neck angle on a true lateral separate them.

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What is acceptable. In a child under 10 years, angulation of less than 30° needs no reduction; over 10 years, and in adolescents, less than 45° is accepted. The difference is the remodelling capacity described above. Both numbers are conventions rather than trial-derived values, and the evidence behind them is discussed in the Evidence Base and Controversies sections.

Above the threshold, the angle sets the first step. The table applies the under-10 threshold; in a child over 10 the 30-45° row lies within the accepted range.

Non-operative. For angulation within the threshold and a stable elbow: an above-elbow cast or splint for 2-3 weeks, early range-of-motion exercises after that, and full activity at 6 weeks. These fractures remodel well.

Closed reduction. In outline: flex the elbow, valgus the forearm, supinate, and put a thumb on the head. Under sedation, the Patterson manoeuvre applies valgus stress while supinating the forearm, with direct thumb pressure over the radial head. The Israeli technique relies on direct thumb pressure over the radial head while reducing. If the head comes down to less than 30° in a young child or 45° in an older one, stop there. An above-elbow cast follows for 3-4 weeks, with a radiograph to confirm the reduction is maintained.

Percutaneous K-wire reduction. Indicated after a failed closed reduction, for angulation of 30-60°. A K-wire at the fracture site is used as a joystick to reduce the angulated head (technique below).

Intramedullary reduction (Metaizeau). Its indications are significant angulation, over 60°, and failed percutaneous reduction. A flexible nail passed up from the distal radius, avoiding the physis, is advanced to the radial head and reduces it by lever action, achieving reduction without opening.

Open reduction. Reserved for failure of all closed techniques, an incarcerated fragment, or associated injuries that need surgery in their own right.

Percutaneous K-wire reduction. The child lies supine under sedation or general anaesthesia, with fluoroscopy. A 1.5-2mm K-wire goes in from the lateral side into the fracture site beside the tilted radial head and is used as a joystick, levering the head back into position under gentle supination. The wire may be left for stability or removed; an above-elbow cast follows, and the wire is removed at 2-3 weeks.

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Metaizeau intramedullary reduction. A pre-bent elastic nail goes in from the distal radius and its tip is engaged in the tilted epiphysis. Rotating the nail about 180° swings the head onto the neck, so the nail is both the reducer and the splint. A percutaneous K-wire joystick may help the head onto the nail, and that is still not an open reduction. Leave the nail until the neck has united: pulling it early is how the head tilts back.

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Open reduction. The Kocher approach (posterolateral), between ECU and anconeus, is the most common. Identify the radial head, preserve the annular ligament if intact, minimise soft-tissue stripping to keep the periosteal blood supply, and fix, usually with K-wires or a small fragment screw if the fragment is large enough.

Why open reduction is the last resort. Open reduction has 2-3x the complication rate of closed methods. Stiffness reaches up to 50% after open reduction against 10-20% after closed, and AVN and radioulnar synostosis occur almost exclusively after open procedures. Post-traumatic radiohumeral arthritis is a further complication of open reduction.

By treatment. A fracture of less than 30° treated non-operatively has an excellent prognosis, with full range of motion expected and complete remodelling. After a successful closed reduction the outcome is good; some minor loss of motion is common but rarely functional. Percutaneous and Metaizeau reductions give intermediate results, better than open reduction, which carries the higher complication rate and the risk of AVN.

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With elbow dislocation. Reduce the dislocation first, then assess the position of the radial head. Fixation may be needed if the head is unstable once the dislocation is reduced.

Monteggia-like injuries. An ulna fracture with a radial head or neck injury. Assess the PRUJ and radiocapitellar alignment on every forearm radiograph. Anatomic reduction of the ulna usually reduces the radial head; direct reduction may be needed if it stays displaced.

In the skeletally immature child, excising the radial head is contraindicated, or at most a true last resort, whereas in adults it is an accepted option for an unreconstructable head. That contrast is a classic adult-versus-child examiner discriminator, and the rule is to preserve the child's radial head whenever possible.

If the head is genuinely unreconstructable, with severe avascular necrosis or fragmentation, delay any excision until skeletal maturity if at all possible.