O’Brien Angulation: I (<30°), II (30–60°), III (>60°). Displacement/translation also matters; >3 mm or severe angulation predicts need for reduction/fixation. Metaizeau (elastic stable intramedullary nailing) classification is treatment-oriented with percutaneous leverage, intramedullary nail reduction, or open reduction for severely displaced injuries.
10 AI-generated high-yield questions by our AI engine
Overview — Paediatric Radial Neck Fractures
Radial neck fractures in children are injuries to the proximal radius at the level of the radial neck — the region between the radial head and the radial tuberosity. They account for approximately 5–10% of all paediatric elbow fractures and are distinct from adult radial head fractures (which involve the articular surface of the radial head proper). In children, the radial head is largely cartilaginous and rarely fractured in isolation — the injury more commonly involves the radial neck metaphysis or the proximal radial physis. The two most commonly used classification systems for these injuries are the O`Brien classification (describing the degree of angulation) and the Metaizeau system (further refining angulation thresholds and guiding surgical technique). The key challenge is that moderate-to-severe angulation significantly restricts forearm rotation and must be corrected to restore full pronation and supination.
Mechanism: a fall onto an outstretched hand (FOOSH) transmits an axial load up the radius; as the elbow is slightly supinated and in valgus, the radial head is driven against the capitellum; a valgus stress fractures the radial neck; alternatively, a Salter-Harris Type I or II fracture through the proximal radial physis produces a similar radiological appearance; the mechanism may also involve a combination of valgus loading and axial compression; occasionally, a radial neck fracture is associated with an elbow dislocation (the radial head may fracture or displace during the dislocation mechanism)
The critical measurement — angulation: the degree of angulation of the radial head relative to the radial neck axis is the primary determinant of treatment; normal is a straight line between the radial head and shaft (0° angulation — the radial head sits perpendicular to the radial neck in neutral rotation); angulation is measured on the AP or oblique view; for a given degree of angulation, the loss of forearm rotation is predictable: <30° angulation = little or no functional loss; 30–60° = moderate loss of rotation; >60° = severe restriction of forearm rotation; angulation >30° in children older than 10 years or >45° in younger children = surgical indication
O`Brien Classification
O`Brien Grade
Angulation
Translational Displacement
Treatment
Grade I
<30°
Minimal (<3 mm)
Non-operative — above-elbow cast for 3 weeks; good functional outcome expected; <30° angulation rarely causes significant functional restriction; no reduction required
Grade II
30–60°
Moderate (3–5 mm)
Closed reduction attempted first; if adequate reduction achieved (<30° residual angulation) → cast; if closed reduction inadequate → percutaneous or intramedullary reduction (Metaizeau technique)
Grade III
>60°
Significant (>5 mm) or complete displacement
Surgical intervention (Metaizeau intramedullary technique or open reduction); >60° angulation cannot be reliably reduced by closed manipulation alone; the Metaizeau technique achieves reduction without open surgery in most cases; open reduction reserved for failed Metaizeau
Metaizeau Classification & Surgical Technique
The Metaizeau classification is a modification of the O`Brien system that more precisely defines the surgical technique applicable to each grade. It also introduces the concept of `translational displacement` as an additional parameter. The Metaizeau intramedullary elastic nail technique is the most important advance in management of displaced paediatric radial neck fractures.
Closed manipulation under GA first; if residual angulation >30° → Metaizeau intramedullary elastic nail technique (percutaneous)
Grade III
60–90°
>5 mm; complete displacement
Metaizeau intramedullary technique (primary); the nail achieves reduction AND fixation simultaneously; most Grade III fractures can be reduced by this technique without opening the elbow joint
Grade IV
>90° (the radial head faces posteriorly — completely inverted)
Complete displacement; the radial head may be 180° rotated
Metaizeau attempted first; if unsuccessful → open reduction (lateral approach — Kocher or direct approach to radial head); AVOID vigorous closed reduction attempts in Grade IV as they may damage the articular cartilage and posterior interosseous nerve (PIN)
Metaizeau intramedullary elastic nail technique: a brilliant technique that reduces the angulated radial neck WITHOUT opening the elbow joint, thereby preserving the blood supply to the radial head and avoiding the risk of post-operative AVN, stiffness, and joint damage from direct surgical exposure; technique: (1) a flexible stainless steel or titanium elastic nail (2–2.5 mm diameter) is inserted through a small cortical window at the distal radial metaphysis (just proximal to the distal radial physis), directed proximally up the radial medullary canal; (2) the nail is advanced to the level of the fracture; (3) the tip of the nail engages the tilted radial head fragment; (4) the nail is then ROTATED (using a T-bar or chuck handle) — as it rotates within the medullary canal, the bent tip levers the radial head back into alignment (reducing the angulation); (5) the nail tip is rotated until the radial head is anatomically reduced under fluoroscopic control; (6) the nail is left in situ for 4–6 weeks and then removed; this technique avoids open joint surgery, reduces iatrogenic injury, and achieves anatomical or near-anatomical reduction in most cases
Closed Reduction Technique (Patterson Manoeuvre)
The Patterson (closed reduction) manoeuvre: for grade I–II injuries where closed reduction is attempted before considering Metaizeau; the surgeon stabilises the distal humerus with one hand; the elbow is extended and the forearm is supinated; a direct varus stress is applied at the elbow while the thumb applies direct pressure to the lateral radial head (pushing the head back into alignment); gentle supination and pronation during thumb pressure can `ratchet` the radial head back into position; requires fluoroscopic guidance; LIMIT manipulation attempts (3 attempts maximum) as aggressive manipulation increases AVN and PIN risk; if 3 attempts fail → proceed to Metaizeau
Percutaneous leverage technique (Israeli or `Joystick` technique): under fluoroscopy, a percutaneous K-wire or blunt elevator is inserted through the soft tissues at the lateral elbow to act as a lever or joystick against the tilted radial head; used as an adjunct to closed reduction for Grade II–III fractures; less elegant than Metaizeau but useful when the nail technique is not available
Complications
Avascular necrosis (AVN) of the radial head: the most feared complication; the blood supply to the radial head enters laterally (from the radial recurrent artery) and is vulnerable to disruption when the soft tissues are stripped from the radial head (as in OPEN reduction); the Metaizeau technique dramatically reduces AVN risk because the elbow is not opened; AVN presents as progressive sclerosis and collapse of the radial head on serial X-rays; management: observation if asymptomatic; radial head excision if symptomatic (rarely required in children); fortunately, children have significant remodelling potential and mild AVN may resolve
Posterior interosseous nerve (PIN) injury: the PIN passes through the radial tunnel (between the two heads of supinator) around the proximal radius; vigorous manipulation of displaced radial neck fractures (particularly closed reduction attempts with more than 3 passes) can stretch or injure the PIN; also at risk during open reduction if the posterior approach is used; clinical: weakness of finger and wrist extension (extensor digitorum, extensor carpi ulnaris); no sensory loss (PIN is pure motor); mostly neuropraxia; monitor for recovery; surgical exploration at 3–4 months if no recovery
Restriction of forearm rotation: the most common functional complication; directly related to residual angulation after treatment; >30° residual angulation in children over 10 years is associated with permanent loss of forearm rotation; the acceptable residual angulation is age-dependent: younger children (<10 years) may remodel more angulation; children >10 years have less remodelling potential — stricter reduction targets apply
Premature physeal closure: the proximal radial physis may close prematurely following injury or surgical fixation through the physis; results in asymmetric radial shortening; fortunately, the proximal radius contributes less than 20% of radial length (the distal radius contributes 80%), so the functional impact of proximal physeal arrest is limited
Exam Pearls
O`Brien classification: Grade I (<30° — non-op); Grade II (30–60° — closed reduction ± Metaizeau if fails); Grade III (>60° — Metaizeau or open); angulation = primary determinant of treatment and prognosis
Metaizeau grade: same angulation thresholds but adds Grade IV (>90° — Metaizeau first, open if fails); the Metaizeau intramedullary elastic nail technique is the key surgical advance
Metaizeau technique: elastic nail inserted distally up the radius; tip rotates to lever the radial head back into alignment; avoids open joint surgery; preserves the radial head blood supply; reduces AVN risk; nail left in situ 4–6 weeks; gold standard for Grade II–III displacement
Acceptable residual angulation after treatment: <30° in all ages; younger children (<10 years) may accept up to 45° (better remodelling); >30° in children over 10 years = permanent forearm rotation restriction; angulation >60° = surgical intervention regardless of age
Closed manipulation limit: maximum 3 attempts; more than 3 attempts = increased AVN and PIN risk; if 3 attempts fail → Metaizeau (not more manipulation); `three strikes and you`re out`
PIN injury: pure motor nerve (no sensory loss); passes around the proximal radius through supinator; injured by vigorous manipulation or open posterior approach; neuropraxia usually; recovers 3–6 months; EMG if no recovery at 3–4 months
AVN of the radial head: caused by open reduction disrupting the lateral blood supply; Metaizeau avoids this; open reduction reserved for failed Metaizeau; if open reduction needed → lateral (Kocher) approach; avoid stripping posterior soft tissue from the radial head
Associated injuries: elbow dislocation (check the radiohumeral and ulnohumeral relationships); medial epicondyle avulsion fracture (check for medial elbow tenderness); Monteggia equivalent (check the radiocapitellar line on all views)
