Overview — The Most Common Paediatric Elbow Fracture
Supracondylar humerus fractures (SCH fractures) are the most common elbow fracture in children, accounting for approximately 60–70% of all paediatric elbow fractures and 3% of all paediatric fractures. They occur predominantly in children aged 5–8 years during the peak period of elbow hypermobility. The extension-type fracture (caused by a fall onto an outstretched hand — FOOSH) accounts for 97–99% of all supracondylar fractures. The Gartland classification of the extension-type SCH fracture is the universal system that guides clinical decision-making, surgical indications, and urgency of intervention. These fractures carry significant risks of neurovascular injury, malunion (cubitus varus — the `gunstock deformity`), and the devastating complication of Volkmann`s ischaemic contracture.
- Anatomy: the fracture occurs at the thin, weak metaphyseal region immediately proximal to the condyles — the supracondylar region; in children, this area consists of thin cortical bone with little cancellous support; it is inherently mechanically weak in the AP direction; in extension-type fractures, the distal fragment displaces posteriorly and the periosteum tears anteriorly; the neurovascular structures at risk are in the antecubital fossa — the anterior interosseous nerve (AIN — the branch most commonly injured), the radial nerve (lateral injuries), the brachial artery, and the median nerve
- Key vascular anatomy: the brachial artery passes directly anterior to the supracondylar region; in displaced SCH fractures, the proximal fragment spike may tent the brachial artery or the artery may be entrapped, kinked, or lacerated; the brachial artery is at highest risk in Gartland Type III posterolaterally displaced fractures; a pulseless hand after SCH fracture = vascular emergency; the `pink but pulseless` hand is the most important management dilemma in paediatric orthopaedics — pulseless but perfused hand may be managed with reduction and fixation before formal vascular exploration
Gartland Classification (Extension Type)
| Type | Description | Radiological Features | Treatment |
|---|---|---|---|
| Type I — Undisplaced | The fracture line is present but there is NO displacement of the distal fragment; the periosteum is intact on both sides; the cortex is disrupted but the fragments remain in anatomical alignment | The fracture line may be subtle on plain X-ray; the anterior humeral line (a line drawn along the anterior surface of the humeral shaft on a true lateral X-ray) should pass through the middle third of the capitellum in a normal elbow — in Type I, this relationship is preserved; the posterior fat pad sign (posterior fat pad visible on the lateral X-ray = haemarthrosis = fracture present, even if the fracture line is not visible); a visible posterior fat pad in a child with elbow pain after trauma = occult supracondylar fracture until proven otherwise | Non-operative — above-elbow posterior slab or collar and cuff for 3 weeks; no reduction required; excellent prognosis; neurovascular status documented and monitored; return to activity at 3–4 weeks |
| Type II — Displaced with intact posterior cortex | The distal fragment is displaced POSTERIORLY; the posterior cortex remains in contact (intact — the `intact posterior hinge`); the anterior cortex is disrupted; there is angulation (the distal fragment tilts posteriorly) but the posterior periosteum/cortex provides a hinge that partially limits displacement; there may be rotational malalignment (medial or lateral displacement of the distal fragment in addition to the posterior displacement) | The anterior humeral line now passes through the ANTERIOR third (or anterior to) the capitellum — indicating posterior displacement of the distal fragment; the distal fragment is tilted posteriorly; the posterior fat pad is visible; the posterior cortex contact distinguishes Type II from Type III; Type IIA = posterior angulation only; Type IIB = posterior angulation + rotation | Controversial — many centres treat all Type II with closed reduction + percutaneous K-wire fixation (as for Type III) to avoid late loss of reduction; some centres treat undisplaced/minimally displaced Type IIA with above-elbow cast in flexion after gentle reduction; Type IIB (with rotational malalignment) should be treated operatively (closed reduction + K-wire fixation); neurovascular assessment is mandatory |
| Type III — Completely displaced (no cortical contact) | The distal fragment is COMPLETELY displaced posteriorly; there is NO cortical contact between the proximal and distal fragments; the posterior periosteum is disrupted; the distal fragment may be posterolateral (most common — 70%) or posteromedial (30%); posteromedial displacement is associated with radial nerve injury; posterolateral displacement is associated with anterior interosseous nerve (AIN) injury and brachial artery injury | Complete loss of cortical contact; the anterior humeral line passes ANTERIOR to the capitellum; the distal fragment is completely separated from the proximal humerus; the fracture `bayonet` alignment on AP view; significant soft tissue injury; neurovascular structures at high risk; the proximal fragment spike can be seen medially (posteromedial displacement) or anterolaterally (posterolateral displacement) | SURGICAL — urgent closed reduction + percutaneous K-wire fixation (CRPP) under general anaesthesia; the gold standard treatment for all Gartland Type III and most Type II fractures; reduces within 24 hours for neurovascularly intact fractures; IMMEDIATE if neurovascular compromise; post-operative above-elbow cast for 3–4 weeks; K-wires removed in outpatient clinic at 3–4 weeks |
- Leitch modification of Gartland: some centres use a modified classification that adds Type IV — a completely displaced fracture with multidirectional instability (the distal fragment can be displaced in any direction due to complete periosteal disruption); these fractures are particularly unstable and may require open reduction if closed reduction is unsuccessful or if there is significant soft tissue interposition
Radiological Assessment — Key Lines & Angles
| Line / Angle | How to Assess | Normal | Abnormal |
|---|---|---|---|
| Anterior humeral line | On true lateral X-ray: a line drawn along the ANTERIOR surface of the humeral shaft; the line is extended distally to the capitellum | Should intersect the MIDDLE THIRD of the capitellum | Passes through the ANTERIOR third or anterior to the capitellum = posterior displacement of the distal fragment = Type II or III SCH fracture; even subtle posterior displacement shifts the capitellum posterior to this line |
| Baumann`s angle | On AP X-ray: the angle between the growth plate of the lateral condyle and the axis of the humeral shaft; the angle between the long axis of the humerus (shaft) and a line drawn along the physis of the lateral condyle | Normal: 70–75° (some texts cite 64–81°); comparison with the contralateral side is essential as there is normal variation between individuals | Decreased Baumann`s angle (<70°) = increased carrying angle = cubitus valgus; increased Baumann`s angle (>75°) = decreased carrying angle = cubitus varus; Baumann`s angle is the best intraoperative guide to achieving anatomical reduction of the carrying angle — each 5° change in Baumann`s angle ≈ 2° change in the carrying angle |
| Carrying angle (clinical) | Measured with the elbow in full extension and forearm in full supination; the angle of valgus between the long axis of the humerus and the long axis of the forearm | Normal: 11–16° valgus (slightly greater in girls) | Cubitus varus (`gunstock deformity`): the most common malunion after SCH fracture; the medial cortex collapses giving progressive varus; the carrying angle is reduced or reversed (varus); appears as a `gunstock` deformity on profile; causes cosmetic deformity and increased risk of lateral condyle fracture (from increased lateral force transmission); corrected by lateral closing-wedge supracondylar osteotomy when established |
| Posterior fat pad sign | On lateral X-ray: the posterior fat pad is normally not visible (it lies within the olecranon fossa); a haemarthrosis (from ANY intra-articular fracture) displaces the fat pad posteriorly out of the olecranon fossa → it becomes visible | Posterior fat pad NOT visible = normal | VISIBLE posterior fat pad = haemarthrosis = intra-articular fracture (most commonly occult SCH fracture in a child); treat as SCH fracture (collar and cuff for 3 weeks) even if no fracture line is visible; a visible anterior fat pad alone (anterior sail sign) can be normal or indicate a small effusion; the POSTERIOR fat pad is the more specific sign |
Neurovascular Assessment & Complications
- Anterior interosseous nerve (AIN) palsy: the most common nerve injury in SCH fractures (~7–16%); the AIN is the deep motor branch of the median nerve; it innervates: flexor pollicis longus (FPL), flexor digitorum profundus to the index and middle fingers (FDP 2&3), and pronator quadratus; AIN palsy produces: inability to flex the interphalangeal joint of the thumb (FPL) and the DIP joint of the index finger (FDP) — the patient cannot make an `OK sign` (pinch); no sensory deficit (AIN is pure motor); associated with posterolaterally displaced Gartland Type III SCH fractures; typically a neuropraxia — most recover within 3–6 months; surgical exploration at 3–4 months if no recovery
- Brachial artery injury: occurs in approximately 10–20% of Gartland Type III fractures; the `pink pulseless hand` is the most challenging management problem; (1) Pulseless hand with adequate perfusion (pink, warm, capillary refill <2 seconds, good oxygen saturation) = `pink pulseless hand` = the brachial artery is in spasm or kinked but the collateral circulation (via the anterior and posterior recurrent radial and ulnar arteries) is maintaining perfusion; management: closed reduction + K-wire fixation FIRST — reduction alone restores the pulse in 60–80% of cases; if pulse returns after reduction → observe; if pulse does not return after reduction → Doppler assessment; if adequate perfusion on Doppler despite absent palpable pulse → observe (collateral flow sufficient); if inadequate perfusion → vascular surgical exploration; (2) Pulseless hand with poor perfusion (pale, cold, prolonged capillary refill, SpO2 drop) = VASCULAR EMERGENCY → immediate OR; K-wire fixation first (stabilises the fracture and may restore flow), then vascular exploration and repair
- Volkmann`s ischaemic contracture: the most devastating complication; results from unrecognised forearm compartment syndrome (from tight dressings, delayed reduction, or vascular injury); leads to fibrosis and contracture of the forearm flexor muscles; results in a fixed wrist flexion + intrinsic-minus hand deformity; PREVENTED by: (1) urgent reduction of displaced fractures; (2) avoiding tight bandaging or plaster (posterior slab ONLY — not circumferential cast in the acute phase); (3) frequent neurovascular monitoring; (4) low threshold for fasciotomy; the BOAST 11 guideline (British Orthopaedic Association) mandates that all Gartland Type III fractures undergo reduction within 8 hours
Surgical Technique — CRPP (Closed Reduction + Percutaneous K-Wire Fixation)
- Reduction technique (Swenson technique): the patient is supine under general anaesthesia; fluoroscopy available; the surgeon applies traction in the line of the humerus with the elbow in slight flexion (to unlock the fracture fragments from the muscle mass); traction + disimpaction; then the forearm is pronated (for posterolateral displacement — pronation brings the medial spike medially, avoiding the ulnar nerve); the elbow is then flexed acutely (90–120°) while maintaining longitudinal pressure on the olecranon (Dunlop`s manoeuvre); the position is checked on both AP and lateral fluoroscopy views; the reduction is confirmed by: (1) anterior humeral line passing through the middle third of the capitellum on the lateral view; (2) Baumann`s angle within normal limits (comparison with contralateral side); (3) medial cortex interlocking (the medial column is reduced with the slight pronation)
- K-wire configuration — lateral vs crossed: (1) Two or three lateral K-wires (all inserted from the lateral side): this is the SAFEST technique for the ulnar nerve — the ulnar nerve lies medially in the cubital tunnel and is at risk of direct injury if a medial K-wire is inserted without an incision; two lateral wires provide good stability but slightly less rotational control than crossed wires; (2) Crossed K-wires (one lateral + one medial): provides maximum rotational stability but the medial wire risks the ulnar nerve; if a medial wire is used, it must be placed through a small stab incision with the elbow in extension (the ulnar nerve subluxes anteriorly in flexion — the common position for wire insertion — and is directly in the path of a medially inserted wire in elbow flexion); Level I evidence (Kocher et al.) suggests that lateral-only configuration is as mechanically stable as crossed wires and avoids the ulnar nerve risk
Exam Pearls
- Gartland classification: Type I = undisplaced (cast); Type II = displaced with intact posterior cortex (consider CRPP for Type IIB); Type III = completely displaced (CRPP); extension type is 97–99% of all SCH fractures; ages 5–8 years peak
- Anterior humeral line: on lateral X-ray → should pass through MIDDLE third of capitellum; through anterior third = Type II; anterior to capitellum = Type III; the single most useful radiological line for SCH fractures
- Baumann`s angle: AP X-ray; humeral shaft axis vs lateral condyle physis; normal 70–75°; each 5° change ≈ 2° change in carrying angle; intraoperative guide to correct reduction; compare with contralateral side
- AIN palsy: most common nerve injury (7–16%); pure motor (no sensory loss); inability to flex thumb IP joint + index DIP (no OK sign); posterolateral displacement; mostly neuropraxia, recovers 3–6 months
- Pink pulseless hand: reduce + K-wire fix first → pulse returns 60–80%; if pulse does not return after reduction → Doppler; if perfused → observe; if ischaemic → vascular exploration; NEVER send a pink pulseless hand to angiography — immediate OR
- Cubitus varus (gunstock deformity): most common malunion; medial cortex collapse in varus; cosmetic deformity + increased risk of lateral condyle fracture; prevents cubitus valgus (not the same as cubitus valgus OA); treat with lateral closing-wedge osteotomy when established
- K-wire safety: lateral-only wires (2–3) are as stable as crossed wires AND avoid ulnar nerve risk; if medial wire used → small stab incision + elbow in EXTENSION (not flexion) to avoid ulnar nerve subluxation into the path of the wire; BOAST 11 mandates reduction of Gartland III within 8 hours
- Posterior fat pad sign: pathognomonic of haemarthrosis = fracture present; treat as occult Type I SCH fracture even if no fracture line visible; above-elbow collar and cuff for 3 weeks; anterior fat pad alone is less specific