Paediatric Fractures & Growth Plate Injuries

Children's bones are not simply small adult bones — a thick periosteum, growing physis (growth plate), and remodelling potential give them unique fracture patterns and healing behaviour. This topic is a perennial NEET PG favourite, with Salter-Harris classification, supracondylar humerus fractures and pulled elbow appearing almost every year.

Why the paediatric skeleton behaves differently

The immature skeleton differs from the adult skeleton in several exam-relevant ways:

• Physis (growth plate): A radiolucent cartilaginous zone, the weakest link in the child's bone. Ligaments are stronger than the physis, so forces that would sprain an adult ligament instead fracture the growth plate in a child.
• Thick, biologically active periosteum: Acts as a hinge, limits displacement, and accelerates callus formation — paediatric fractures unite faster.
• High remodelling potential: Angulation in the plane of joint movement remodels well; rotational deformity does not remodel.
• Soft, porous bone: Permits incomplete fractures (greenstick, torus/buckle) and plastic bowing unique to children.

High-yield: The physis is weaker than the surrounding ligaments and joint capsule. Therefore in a child, what looks like a "sprain" is often a Salter-Harris fracture until proven otherwise.

Zones of the physis

The growth plate has four zones from epiphysis to metaphysis. Knowing the zone of weakness explains the classic Salter-Harris fracture line.

Zone	Function	Notes
Resting (germinal)	Stem cells / reserve	Closest to epiphysis
Proliferative	Cell division, longitudinal growth	Best blood supply
Hypertrophic	Cell enlargement, matrix calcification	Weakest zone — fractures occur here
Provisional calcification / metaphysis	Ossification	—

High-yield: Fractures classically propagate through the zone of provisional calcification within the hypertrophic zone — the area of least matrix and most cellular hypertrophy. Slipped capital femoral epiphysis (SCFE) also occurs here.

Salter-Harris classification of physeal injuries

This is the single most tested item in paediatric orthopaedics. About 15–30% of all paediatric fractures involve the physis. The classification predicts prognosis: higher types → higher risk of growth arrest.

Mnemonic — "SALTER":

• S = Slipped (Type I) — through physis
• A = Above (Type II) — fracture exits above into the metaphysis
• L = Lower (Type III) — fracture exits below into the epiphysis
• T = Through / Transverse / Together (Type IV) — through metaphysis, physis and epiphysis
• ER = ERasure / crUsh (Type V) — compression/crush of the physis

(An older mnemonic "SALTR" maps to Slip, Above, Lower, Through, Rammed.)

Type	Fracture path	Frequency	Thurston-Holland fragment	Prognosis / growth arrest risk
I	Through physis only	~5%	No	Excellent; rarely growth arrest
II	Physis + metaphysis	~75% (most common)	Yes (metaphyseal)	Good
III	Physis + epiphysis (intra-articular)	~8%	No	Guarded — needs anatomical reduction
IV	Metaphysis + physis + epiphysis (intra-articular)	~10%	Yes	Poor — high arrest risk
V	Crush of physis	Rare	No	Worst — growth arrest common, diagnosed retrospectively

High-yield: Type II is the commonest Salter-Harris fracture. The metaphyseal fragment in Type II is the Thurston-Holland fragment (also seen in Type IV).

High-yield: Types III and IV are intra-articular and require anatomical (often surgical) reduction to restore the joint surface and physeal alignment. Types I and II are usually treated by closed reduction and immobilisation.

High-yield: Type V is the most dangerous — initial X-rays may look normal, and the diagnosis is often made retrospectively when growth arrest or angular deformity appears. It carries the worst prognosis.

Flow of increasing severity: Type I → II → III → IV → V means increasing involvement of the epiphysis/joint and increasing risk of growth arrest.

Complications of physeal injury include complete growth arrest (limb-length discrepancy), partial/asymmetric arrest (angular deformity, formation of a physeal bony bar / bridge), and joint incongruity (for intra-articular types). Treatment of an established physeal bar may involve bar resection with interposition of fat or silastic (Langenskiöld procedure).

Incomplete (paediatric-specific) fracture patterns

Because immature bone is porous and the periosteum thick, children sustain incomplete fractures rarely seen in adults.

Pattern	Mechanism	X-ray appearance	Key point
Greenstick	Bending force — fracture of one cortex, other cortex intact	Cortical break + bend on convex side; concave cortex intact	May need to "complete" the fracture to correct angulation
Torus / buckle	Axial compression at metaphysis	Cortical "buckle" / bulge, no clear lucent line	Stable; common at distal radius; treated with splint/cast
Plastic / bowing deformity	Microfractures, no cortical break	Bowed bone, no fracture line	Often ulna/fibula; may need correction if cosmetically/functionally significant
Toddler's fracture	Twisting in ambulating toddler	Subtle spiral fracture of distal tibia	Limp/refusal to bear weight; X-ray may be subtle

High-yield: Greenstick = incomplete fracture, one cortex broken, one intact (like snapping a green twig). Torus/buckle = compression buckle of the metaphyseal cortex, inherently stable, classically at the distal radius.

Supracondylar fracture of the humerus

The commonest elbow fracture in children and the commonest paediatric fracture requiring operative management; peak age 5–8 years.

Mechanism & types

• Extension type (~95–98%): Fall on an outstretched hand (FOOSH) with the elbow extended; the distal fragment displaces posteriorly.
• Flexion type (rare): Fall on a flexed elbow; distal fragment displaces anteriorly.

Gartland classification (extension type)

Gartland type	Displacement	Treatment
I	Undisplaced	Above-elbow cast in ~90° flexion
II	Displaced, posterior cortex/hinge intact	Closed reduction + percutaneous K-wire fixation (or cast if stable)
III	Completely displaced, no cortical contact	Closed reduction + percutaneous K-wire fixation; open reduction if irreducible/vascular compromise
IV (some texts)	Multidirectional instability	Reduction + K-wiring under fluoroscopy

High-yield: Standard surgical treatment of displaced supracondylar fractures is closed reduction and percutaneous pinning (CRPP) with K-wires. Lateral-entry pins are preferred to reduce iatrogenic ulnar nerve injury from a medial pin.

Nerve injuries

• Anterior interosseous nerve (AIN, branch of median): The commonest nerve injured in extension-type supracondylar fractures. AIN is purely motor — tests with the "OK" sign / pinch grip; weakness of flexor pollicis longus (FPL) and flexor digitorum profundus to index finger. No sensory loss.
• Radial nerve: Often injured with posterolateral displacement.
• Median nerve / ulnar nerve: Median with posterolateral; ulnar is more often injured iatrogenically by a medial K-wire, or in flexion-type fractures.

High-yield: AIN palsy → loss of the "OK" sign (cannot flex IP joint of thumb and DIP of index). It is the most common neural injury in extension-type supracondylar fractures and usually recovers spontaneously (neuropraxia).

Vascular injury & compartment syndrome

The brachial artery may be injured or kinked. Assess the radial pulse and hand perfusion.

Approach to the pulseless supracondylar fracture → Reduce and pin first → reassess perfusion → if the hand is pink and perfused but pulseless, observe closely → if the hand is white/pale and pulseless (poorly perfused), proceed to urgent vascular exploration.

High-yield: The dreaded late complication is Volkmann's ischaemic contracture — fibrosis of forearm flexor compartment muscles from missed compartment syndrome/ischaemia, producing a fixed flexion claw hand. The cardinal early warning is pain on passive extension of the fingers (the most sensitive sign of compartment syndrome), not absence of pulse.

Malunion — cubitus varus

• Cubitus varus ("gunstock deformity") is the commonest late complication, due to malunion (not growth arrest), classically from a Gartland fracture healing in varus/internal rotation.
• It is mainly a cosmetic deformity; functional loss is usually minimal. Correction is by corrective (lateral closing-wedge / French) osteotomy of the distal humerus.

High-yield: Cubitus varus after a supracondylar fracture = malunion (cosmetic, "gunstock"). Cubitus valgus is more typically a sequel of lateral condyle fracture nonunion, and can cause tardy (delayed) ulnar nerve palsy.

Pulled elbow (Nursemaid's elbow / radial head subluxation)

A classic OPD scenario and a frequent single-best-answer MCQ.

• Definition: Subluxation of the radial head from beneath the annular ligament.
• Age: Typically 1–4 years (peak 2–3); the annular ligament is lax/weak at this age.
• Mechanism: Sudden longitudinal traction on a pronated, extended forearm — e.g., an adult yanking a toddler up by the hand.
• Presentation: Child holds the arm pronated, slightly flexed, refuses to use it ("pseudoparalysis"); not distressed at rest, no swelling/deformity.
• X-ray: Usually normal; imaging is not required if the history and presentation are classic.
• Reduction: Two manoeuvres — (1) Supination of the forearm followed by full flexion of the elbow; or (2) hyperpronation (often equally or more effective). A palpable/audible click signals reduction; the child resumes use within minutes.

High-yield: Pulled elbow = annular ligament subluxation over the radial head from axial pull on a pronated extended arm; X-ray normal; reduce by supination + flexion (or hyperpronation). No immobilisation needed if reduction is successful.

Other high-yield paediatric fractures (quick contrasts)

• Lateral condyle humerus fracture: Intra-articular (often Salter-Harris IV physeal equivalent); prone to nonunion, cubitus valgus, and tardy ulnar nerve palsy. Often needs ORIF.
• Medial epicondyle avulsion: May entrap within the joint after dislocation; watch for ulnar nerve symptoms.
• Distal radius (torus/greenstick): Commonest paediatric fracture overall (FOOSH).
• Femoral shaft fracture in a non-ambulatory infant / multiple fractures of differing ages / metaphyseal "corner" (bucket-handle) fractures / posterior rib fractures: Raise suspicion of non-accidental injury (child abuse) — a recurring exam theme.

High-yield: Metaphyseal "corner"/bucket-handle fractures and multiple fractures at different stages of healing are highly suggestive of non-accidental injury.

Investigation of choice

• Plain radiographs (X-ray) in two orthogonal views (AP + lateral) are the first-line investigation for all suspected paediatric fractures.
• Comparison views of the contralateral (normal) side are sometimes obtained because paediatric ossification centres can mimic or mask fractures.
• CT for complex intra-articular fractures (Type III/IV) and pre-operative planning.
• MRI is the most sensitive for occult physeal injury, cartilage and Type V/early growth-arrest assessment; ultrasound can detect radiocapitellar relationships and effusions in infants where the epiphysis is not yet ossified.

Elbow ossification centres — CRITOE

Crucial for not mistaking an ossification centre for a fracture fragment.

Mnemonic — CRITOE (appearance ages, roughly): Capitellum (1 yr) → Radial head (3) → Internal (medial) epicondyle (5) → Trochlea (7) → Olecranon (9) → External (lateral) epicondyle (11).

High-yield: Order of appearance = CRITOE at roughly 1-3-5-7-9-11 years. The internal (medial) epicondyle appears before the trochlea; if you see a "trochlear" ossific centre without a medial epicondyle, suspect an entrapped/avulsed medial epicondyle within the joint.

Management principles (overview)

1. ABCDE / trauma assessment first; exclude open fracture, neurovascular injury and compartment syndrome.
2. Document distal neurovascular status before and after every manipulation (AIN "OK" sign, radial pulse, capillary refill, sensation).
3. Undisplaced / stable (Salter I–II, torus, Gartland I) → closed reduction + cast/splint.
4. Intra-articular / unstable / displaced (Salter III–IV, Gartland II–III, lateral condyle) → anatomical reduction, frequently operative (CRPP or ORIF).
5. Pulseless, poorly perfused limb → urgent reduction + pinning, then vascular exploration if perfusion not restored.
6. Avoid hardware across the physis where possible; if pins must cross, use smooth K-wires (threaded screws across the physis risk arrest).
7. Follow up for growth arrest, angular deformity and length discrepancy.

Complications — summary

• Growth arrest (complete → shortening; partial → angular deformity / physeal bar) — worst with Salter IV & V.
• Malunion → cubitus varus (supracondylar), angular deformity.
• Nonunion → lateral condyle fracture → cubitus valgus → tardy ulnar nerve palsy.
• Neurovascular → AIN palsy, radial/median/ulnar injury, brachial artery injury.
• Volkmann's ischaemic contracture (compartment syndrome sequel).
• Joint stiffness, myositis ossificans (especially with forceful repeated manipulation around the elbow).

Key differentials

• Pulled elbow vs supracondylar fracture vs lateral condyle fracture: History (traction vs FOOSH), swelling/deformity (absent in pulled elbow), and X-ray distinguish them.
• "Sprain" vs Salter-Harris I: In children with point tenderness over the physis and normal X-ray, treat as a physeal injury.
• Non-accidental injury vs accidental fracture: Mismatch between history and injury, multiple ages of healing, specific patterns.
• Septic arthritis / osteomyelitis vs toddler's fracture: A limping toddler with fever needs infection excluded (raised CRP/ESR, joint aspiration) before assuming occult fracture.

Recently asked / exam angle

• Salter-Harris: "Most common type?" → Type II. "Worst prognosis / crush injury?" → Type V. "Intra-articular types needing anatomical reduction?" → III & IV. Identify the type from a diagram showing the fracture line relative to the physis (a recurring image-based MCQ).
• Thurston-Holland fragment = metaphyseal fragment in Salter-Harris II (and IV).
• Supracondylar fracture: "Commonest nerve injured (extension type)?" → AIN (tests "OK" sign / FPL). "Commonest late complication?" → cubitus varus (malunion). "Treatment of displaced fracture?" → CRPP with K-wires.
• Cubitus valgus + tardy ulnar nerve palsy → think lateral condyle nonunion.
• Pulled elbow: age, mechanism (pull on pronated arm), reduction (supination-flexion / hyperpronation), normal X-ray.
• CRITOE order and ages; medial epicondyle entrapment clue.
• Weakest zone of physis → zone of hypertrophic / provisional calcification.
• Most sensitive sign of compartment syndrome → pain on passive stretch.

Rapid revision

1. Physis is weaker than ligaments → children fracture where adults sprain.
2. Fracture line runs through the hypertrophic / provisional calcification zone of the physis.
3. SALTER: I-Slipped, II-Above, III-Lower, IV-Through, V-cRush/Erasure.
4. Salter-Harris II is the commonest; V has the worst prognosis (crush, retrospective diagnosis).
5. Thurston-Holland fragment = metaphyseal piece in Salter II (and IV).
6. Greenstick = one cortex broken; torus/buckle = compression bulge at distal radius (stable).
7. Supracondylar fracture: peak 5–8 yrs, extension type ~98%, FOOSH, posterior displacement.
8. Gartland I-cast, II/III-CRPP with K-wires; lateral-entry pins spare ulnar nerve.
9. AIN palsy is the commonest nerve lesion → loss of "OK" sign; usually recovers.
10. Cubitus varus (gunstock) = malunion = commonest late complication; cubitus valgus = lateral condyle nonunion → tardy ulnar palsy.
11. Pulseless pink/perfused hand → observe after pinning; pale/poorly perfused → vascular exploration; beware Volkmann's contracture.
12. Pulled elbow (1–4 yrs): pull on pronated extended arm; X-ray normal; reduce by supination + flexion or hyperpronation. CRITOE = 1-3-5-7-9-11 yrs.