Pediatric Supracondylar Humerus Fracture

Overview & Epidemiology

Supracondylar humerus fractures (SCHFs) are the most common elbow fractures in children, accounting for approximately 60% of all paediatric elbow fractures. They occur predominantly between 5–8 years of age, when the olecranon fossa is most prominent and the anterior humeral cortex is relatively thin. The clinical importance of this fracture is disproportionate to its frequency — it carries a well-defined risk of neurovascular injury, Volkmann ischaemic contracture, and malunion causing cubitus varus deformity (the `gunstock deformity`). All paediatric orthopaedic surgeons must have a thorough command of the classification, neurovascular assessment, reduction techniques, fixation principles, and complication management.

Mechanism: the vast majority (~97%) are extension-type fractures caused by a fall onto an outstretched hand (FOOSH) with the elbow hyperextended; the olecranon acts as a fulcrum, causing a transverse fracture through the distal humerus metaphysis just above the condyles; flexion-type fractures (~3%) result from a direct blow to a flexed elbow — these have a higher rate of ulnar nerve injury and are often more difficult to reduce and maintain
Anatomy: the distal humerus metaphysis is thin and the ossification centres of the elbow are incompletely developed in children (the CRITOE sequence of ossification); the radial nerve and anterior interosseous nerve (AIN) are at risk anterolaterally; the brachial artery runs directly anterior to the distal humerus and is at risk in displaced fractures; the ulnar nerve lies in the cubital tunnel posteromedially — at risk particularly in flexion-type fractures and during medial pin placement

Classification — Gartland Classification (Modified)

Type	Description	Anterior Humeral Line	Management
Type I	Undisplaced or minimally displaced; cortex intact or minor buckling; elbow fat pad sign may be present	Passes through middle third of capitellum (normal)	Conservative — collar and cuff or long arm backslab with elbow at 90° of flexion; 3–4 weeks immobilisation; review at 1 week to ensure no displacement
Type II	Displaced with intact posterior cortex — the posterior cortex is hinged and intact; the distal fragment tilts anteriorly (extension type) but does not completely displace; moderate displacement	Passes anterior to the capitellum (loss of normal anterior tilt)	Type IIA (no rotational deformity) — may be managed with closed reduction and above-elbow backslab; Type IIB (rotational deformity) — closed reduction and percutaneous K-wire fixation (CRPP); elbow hyperflexion to >120° is NOT safe (vascular compromise risk)
Type III	Completely displaced — both cortices disrupted; no cortical contact between proximal and distal fragments; posterolateral displacement most common (~75%); posteromedial displacement (~25%) — higher risk of anterior interosseous nerve (AIN) and brachial artery injury	Passes anterior to capitellum (completely disrupted alignment)	Closed reduction and percutaneous K-wire fixation (CRPP) — standard of care; urgent surgery in the setting of vascular compromise; open reduction for irreducible fractures or vascular repair
Type IV (Leitch modification)	Multidirectional instability — the fracture is unstable in both flexion and extension; the distal fragment can displace in any direction; typically a high-energy injury; previously called `floating elbow` when associated with forearm fracture	Disrupted	CRPP with careful attention to achieving stable fixation in multiple planes; may require medial pin for stability

Radiographic Assessment

Anterior humeral line (AHL): on a true lateral X-ray, a line drawn along the anterior cortex of the humerus should pass through the middle third of the capitellum; in extension-type SCHF, the distal fragment tilts posteriorly — the AHL passes anterior to the capitellum, or through its anterior third (indicating posterior displacement); the AHL is the most reliable single radiographic measurement for assessing reduction adequacy; post-reduction, the AHL should pass through the middle third of the capitellum
Baumann`s angle: on the AP view, the angle between the long axis of the humerus and a line through the physis of the lateral condyle; normal value 70–76° (mean ~72°); loss of Baumann`s angle indicates varus malposition of the distal fragment; post-reduction, compare Baumann`s angle with the contralateral normal side (it varies between patients, so comparison is more reliable than an absolute value); an asymmetry >5° from the contralateral side = unacceptable reduction
Fat pad signs: on a true lateral X-ray with the elbow at 90°, the anterior fat pad (sail sign) is normally visible as a thin sliver; the posterior fat pad is NEVER normally visible; a visible posterior fat pad = haemarthrosis = occult fracture until proven otherwise; a large anterior sail sign = significant haemarthrosis; in the context of a child with elbow pain after trauma and a visible posterior fat pad on X-ray (even without a visible fracture line), treat as a Type I SCHF or radial head/neck fracture until confirmed otherwise
CRITOE sequence: the order of appearance of the distal humeral ossification centres; Capitellum (1 yr), Radial head (3 yrs), Internal (medial) epicondyle (5 yrs), Trochlea (7 yrs), Olecranon (9 yrs), External (lateral) epicondyle (11 yrs); important because the medial epicondyle ossification centre can be entrapped in the elbow joint after dislocation — if it appears `missing` or displaced, it may be entrapped in the joint

Neurovascular Assessment — Critical

Structure at Risk	Fracture Pattern	Clinical Finding	Management
Anterior interosseous nerve (AIN) — branch of median nerve	Type III posteromedial displacement — the proximal fragment drives anteromedially, tenting the AIN; MOST COMMON nerve injury in SCHF	Inability to make `OK sign` — cannot flex the DIP of index finger and IP of thumb (flexor pollicis longus + FDP to index); sensory examination of the hand is NORMAL (AIN is purely motor)	Neuropraxia in most cases — observe; resolves in 2–4 months; if no recovery at 3 months → nerve exploration; rarely requires surgical intervention
Radial nerve / PIN	Type III posterolateral displacement — most common direction; proximal spike displaces anterolaterally into the radial nerve	Wrist drop (radial nerve) or inability to extend fingers at MCP joints (PIN — posterior interosseous nerve); sensory — dorsoradial hand (radial nerve); sensory normal with isolated PIN	Neuropraxia in most cases; observe; resolves; reduction and fixation typically relieves nerve tension; nerve exploration if no recovery at 3 months
Ulnar nerve	Flexion-type fractures; iatrogenic injury during medial pin placement; Type IV fractures	Clawing of ring and little fingers; weakness of intrinsics; sensory loss ulnar 1.5 fingers; assess carefully before and after medial pin placement; document pre-operative status	Iatrogenic — remove medial pin immediately if ulnar nerve symptoms develop post-operatively; consider lateral-only pin construct to avoid ulnar nerve risk altogether
Brachial artery	Type III fractures; posterolateral displacement drives proximal spike through brachialis and into the brachial artery anteriorly; tethered by the interosseous membrane at the bifurcation distally	Absent radial pulse; pale, cool, pulseless hand; compartment syndrome; assess capillary refill, colour, temperature, pulse oximetry on affected limb; a `pink pulseless hand` = hand is viable despite absent pulse (collateral circulation via anterior and posterior interosseous arteries — this is the critical concept); management differs based on hand perfusion	Pink pulseless hand — proceed with CRPP + reassess pulse (pulse typically returns after reduction); if pulse does not return post-reduction → surgical exploration of brachial artery; white pulseless hand (ischaemic) → EMERGENCY surgical exploration + vascular repair before or concurrent with fracture fixation

The pink pulseless hand — the most important concept in SCHF management: a hand that is pink, warm, with good capillary refill but no palpable radial pulse has adequate perfusion via collateral circulation (anterior and posterior interosseous arteries); this is NOT an emergency requiring immediate vascular exploration; the hand will survive; proceed with urgent (not emergency) CRPP to reduce the fracture (reduction often relieves arterial spasm or kinking and restores the pulse); after fixation, reassess the pulse and perfusion; if perfusion remains adequate (pink, warm hand) even without a return of radial pulse — close observation is appropriate; if perfusion deteriorates or remains compromised after reduction → vascular exploration; contrast: a white (pale), cold, pulseless hand = true vascular emergency requiring immediate exploration

Surgical Technique — Closed Reduction and Percutaneous Pinning (CRPP)

Reduction technique (extension-type): longitudinal traction in elbow extension to disengage the fragments and correct length; correct rotational deformity by palpating the medial and lateral condyles; apply pressure over the olecranon with the thumb while flexing the elbow — this `scoops` the distal fragment anteriorly and corrects the posterior tilt; the elbow is flexed to approximately 90–120°; check reduction on AP and lateral fluoroscopy images; the AHL must pass through the middle third of the capitellum on lateral view; Baumann`s angle must be within 5° of the contralateral side on AP view; medial and lateral cortical alignment (medial column) must be restored
Pin configuration: two main configurations — (1) two lateral pins (cross-lateral configuration) vs (2) one lateral + one medial pin (crossed pins); two lateral pins are generally preferred to avoid ulnar nerve injury from medial pin insertion; lateral-only pins have slightly less rotational stability than crossed pins but are safer; if a medial pin is placed, it should be done with the elbow at 20–30° of extension (NOT fully flexed) to move the ulnar nerve anteriorly, and with direct palpation of the medial epicondyle; three lateral pins provide excellent stability and are often used for Type III and Type IV fractures
Pin placement principles: pins should cross at or above the fracture site (not at the level of the fracture); pins should be divergent (not parallel) to maximise stability; pins should engage the medial and lateral columns of the distal humerus proximal to the fracture; pin diameter typically 1.6–2.0 mm (Kirschner wires); pins left protruding through the skin (percutaneous) for ease of removal; pin removal typically at 3–4 weeks in clinic under local anaesthetic
Immobilisation: full-length above-elbow backslab in the post-operative period; elbow at approximately 90° of flexion; mould the cast to maintain the reduction; formal cast applied at 2–3 days when swelling has subsided

Complications

Complication	Description	Management
Cubitus varus (gunstock deformity)	The most common late complication of SCHF; caused by malunion with medial rotation/tilt of the distal fragment; the carrying angle of the elbow is reduced or reversed; predominantly a cosmetic deformity — does not significantly affect elbow function in most children; also increases risk of lateral condyle fracture in future trauma (falls) and tardy posterolateral rotatory instability in adults; diagnosis — clinical + X-ray (decreased or negative carrying angle; abnormal Baumann`s angle)	Corrective osteotomy (lateral closing wedge supracondylar osteotomy) for significant cosmetic deformity or functional compromise; timing — typically after skeletal maturity or when deformity causes functional problems; NOT an urgent procedure in childhood unless functional impairment
Volkmann ischaemic contracture	Compartment syndrome of the forearm → muscle ischaemia → fibrosis → contracture of the flexor muscles; presents as pain on passive finger extension + tense forearm compartments + paraesthesia; the anterior (volar) compartment is most commonly affected; flexor muscle necrosis → `intrinsic minus` position of the hand (wrist flexion, MCP hyperextension, IP flexion); severity classified I–III (Tsuge grading)	Prevention — avoid excessive elbow flexion (>90°) if vascular compromise is suspected; recognise early; emergency forearm fasciotomy; established contracture → physiotherapy, splinting; severe (Grade III) → surgical release (muscle slide, Volkmann`s release), neuroplasty, free muscle transfer
Nerve injury (AIN, radial, ulnar)	See neurovascular table above; most are neuropraxia and recover spontaneously within 2–4 months; document neurological status before and after any surgical procedure	Observation; nerve exploration if no recovery at 3–4 months
Pin tract infection	Superficial infection around percutaneous K-wires; common (~5%); usually responds to oral antibiotics and early pin removal	Antibiotics; early pin removal if evidence of deep infection or >3 weeks post-op
Loss of elbow motion	Temporary stiffness is universal; full motion usually recovers within 3–6 months; prolonged physiotherapy is not recommended (children regain motion spontaneously); manipulation under anaesthesia is rarely required	Active use of the arm at play; supervised activity; physiotherapy not routinely needed in children

Exam Pearls

Most common elbow fracture in children (60%); peak age 5–8 years; extension type (97%) — FOOSH mechanism; flexion type (3%) — higher ulnar nerve risk
Gartland classification: I (undisplaced — conservative); II (intact posterior cortex, tilted — IIA conservative / IIB CRPP); III (completely displaced — CRPP); IV (multidirectional instability — CRPP)
Anterior humeral line (lateral view): should pass through middle third of capitellum; displacement = line anterior to capitellum; Baumann`s angle (AP view): normal ~72°; asymmetry >5° from contralateral = unacceptable reduction
Most common nerve injury: AIN (branch of median nerve); posteromedial displacement; intact sensation; unable to make `OK sign` (FPL + FDP to index — IP/DIP flexion); most resolve spontaneously
Pink pulseless hand: pink + warm + absent radial pulse = adequate collateral perfusion; NOT an emergency; proceed with CRPP; reassess pulse after reduction; white pulseless hand (ischaemic) = EMERGENCY vascular exploration
Lateral pins preferred over crossed pins: avoids ulnar nerve injury from medial pin; medial pin only if lateral-only construct provides inadequate stability; if medial pin used → elbow at 20–30° extension + palpate medial epicondyle
Volkmann`s ischaemic contracture: compartment syndrome → forearm muscle necrosis → fibrosis; `intrinsic minus` hand posture; prevent with early recognition and fasciotomy; avoid excessive elbow hyperflexion (>90°) in at-risk cases
Cubitus varus (gunstock deformity): most common LATE complication; medial rotational malunion; cosmetic predominantly; increased risk of lateral condyle fracture and PLRI in adults; corrective supracondylar osteotomy if indicated
Posterior fat pad sign: NEVER normally visible; visible = haemarthrosis = fracture until proven otherwise; treat as occult SCHF or radial head/neck fracture
CRITOE sequence: C(1), R(3), I(5), T(7), O(9), E(11) — medial epicondyle visible from age 5; if absent after dislocation → may be entrapped in joint (look for it in the joint space on X-ray)

Pediatric Supracondylar Humerus Fracture

References

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