Supracondylar Humerus Fracture

Supracondylar humerus fracture is the commonest elbow fracture in children, usually occurring between approximately 5 and 7 years of age.

Most are extension type injuries following a fall onto an outstretched hand.

The distal fragment displaces posteriorly.

Less commonly, flexion type injuries occur after a direct fall onto a flexed elbow, with anterior displacement of the distal fragment.

The major threats are:

• Brachial artery injury
• Median or anterior interosseous nerve injury
• Radial nerve injury
• Ulnar nerve injury
• Compartment syndrome
• Volkmann ischaemic contracture
• Cubitus varus malunion

This article refers principally to the paediatric supracondylar fracture. Adult supracondylar injuries are managed as distal humeral fractures and follow different fixation principles.

Modified Gartland classification for extension type injuries

Type I

Nondisplaced or minimally displaced fracture.

Anterior humeral line remains appropriately related to the capitellum.

Stable.

Type IIA

Displaced fracture with posterior cortical hinge intact.

Angulation exists but there is minimal or no rotation or translation.

Type IIB

Posterior cortex remains partially intact, but there is rotational or translational instability.

Type III

Completely displaced fracture with no meaningful cortical contact.

Type IV

Multidirectional instability with complete periosteal disruption.

The fracture is unstable in both flexion and extension and is usually recognised during examination under anaesthesia or attempted reduction.

Displaced type II to IV fractures generally require closed reduction and percutaneous pin fixation.

The child presents with pain, swelling and refusal to move the elbow.

Severe displaced injuries can create an S shaped deformity.

Inspect for:

• Puckering of the antecubital skin
• Open wound
• Severe swelling
• Ecchymosis
• Skin tenting

Anterior skin puckering may indicate that the proximal fragment has buttonholed through brachialis and can predict a difficult closed reduction.

Neurological examination

Document function before and after reduction.

Anterior interosseous nerve

Test:

• Flexion of thumb IP joint
• Flexion of index finger DIP joint

Ask the child to make an \"OK\" sign.

AIN injury is particularly associated with posterolateral displacement of the distal fragment.

Median nerve

Test thumb opposition and palmar index sensation.

Radial nerve

Test wrist and finger extension and first dorsal web space sensation.

Ulnar nerve

Test finger abduction and little finger sensation.

Flexion type fractures are particularly associated with ulnar nerve injury.

Vascular assessment

Document:

• Radial pulse
• Hand colour
• Temperature
• Capillary refill
• Doppler signal where appropriate

Classify the limb conceptually as:

Pulseless and poorly perfused

Pale, cold hand with delayed capillary refill.

This is a vascular emergency.

Pulseless but well perfused

Warm pink hand with good capillary refill but no palpable radial pulse.

This requires urgent reduction and fixation followed by careful reassessment.

Obtain:

• AP elbow
• True lateral elbow

Anterior humeral line

On the lateral view, a line along the anterior humeral cortex should normally intersect the middle third of the capitellum in older children.

In extension type fractures it passes anterior to the capitellum.

Baumann angle

Assesses coronal alignment on the AP view.

Comparison with the opposite elbow can help when alignment is uncertain.

Posterior fat pad

A visible posterior fat pad after trauma should be treated as evidence of an occult intra articular elbow fracture until proven otherwise.

Routine CT is unnecessary.

Type I

Treat with long arm cast or posterior splint.

Immobilise the elbow generally around 60° to 90° flexion, avoiding excessive flexion when substantial swelling exists.

Duration is usually approximately 3 weeks.

Repeat radiographs according to fracture stability.

Type IIA

Selected stable type IIA fractures can be treated with carefully performed closed reduction and casting if:

• Reduction is anatomical or near anatomical
• No rotation exists
• Fracture remains stable without extreme elbow flexion
• Reliable radiographic follow up is available

Many surgeons favour percutaneous fixation when stability is uncertain.

Type IIB, III and IV

Perform closed reduction and percutaneous pinning.

Do not maintain reduction by forcing a massively swollen elbow into extreme flexion because this can compromise vascular flow and elevate compartment pressure.

Reduction principles

Restore:

• Coronal alignment
• Sagittal alignment
• Rotation
• Column continuity

For extension fractures, traction restores length, correction addresses translation and gentle flexion while directing the distal fragment restores sagittal alignment.

Avoid repeated traumatic manipulations.

Pin fixation

Two or three divergent lateral pins provide stable fixation for many fractures while avoiding iatrogenic ulnar nerve injury.

Pins should have wide separation at the fracture and engage both columns appropriately.

If lateral pins do not provide sufficient rotational stability, add a third lateral pin before defaulting to a medial pin.

A crossed medial and lateral pin construct provides strong stability but increases risk of iatrogenic ulnar nerve injury.

If a medial pin is required:

• Avoid hyperflexion during insertion
• Protect or directly identify the ulnar nerve when appropriate
• Use a small medial incision if needed

Open reduction indications

Open reduction is required when:

• Closed reduction fails
• Skin or brachialis interposition prevents reduction
• Vascular exploration is necessary
• Open fracture
• Irreducible fracture with suspected nerve entrapment

Pulseless, poorly perfused hand

Proceed emergently to fracture reduction and pin fixation.

Reassess immediately after reduction.

If the hand remains poorly perfused:

• Explore the brachial artery urgently
• Release entrapment
• Repair or reconstruct the vessel as necessary

Do not obtain routine angiography before correcting an obviously displaced fracture with an ischaemic hand. The fracture itself must be reduced immediately.

Pulseless but pink hand

Urgently reduce and pin the fracture.

If the hand remains:

• Warm
• Pink
• Capillary refill normal
• Neurologically stable

careful monitored observation may be appropriate despite absent palpable pulse.

However, deteriorating perfusion, absent Doppler flow, increasing pain or significant evolving median nerve findings should lower the threshold for vascular exploration.

This remains an area where management should be individualised because high quality evidence does not establish one mandatory approach for every well perfused pulseless hand.

Nerve palsy

Most traumatic nerve palsies are neuropraxias and recover spontaneously.

Observation is appropriate after satisfactory fracture reduction unless:

• Nerve entrapment is suspected
• Deficit develops after reduction
• Recovery fails to occur over expected follow up

Compartment syndrome

Avoid excessive cast flexion and monitor children with major swelling carefully.

Increasing pain, agitation, escalating analgesic requirement, pain with passive finger extension and increasing forearm tension should prompt urgent reassessment.

The traditional five Ps are unreliable early in children.

The three As can be particularly useful:

• Anxiety
• Agitation
• Increasing analgesic requirement

Established compartment syndrome requires emergency forearm fasciotomy.

Untreated ischaemia can cause Volkmann contracture.

Postoperative care

Immobilise the elbow with the pins protected.

Pin removal is commonly performed at approximately 3 to 4 weeks once sufficient healing is present.

Formal physiotherapy is usually unnecessary in uncomplicated children because elbow motion returns progressively after immobilisation ends.

Do not aggressively manipulate early elbow stiffness.

Cubitus varus

The classic gunstock deformity is usually caused by malunion rather than growth arrest.

It results principally from residual coronal malalignment.

It is primarily a cosmetic problem but can predispose to:

• Lateral condylar stress
• Tardy ulnar neuropathy
• Posterolateral rotatory instability

Prevention depends on obtaining correct coronal alignment at the initial reduction.

Other complications include:

• Cubitus valgus
• Pin tract infection
• Iatrogenic ulnar nerve palsy
• Loss of reduction
• Elbow stiffness
• Myositis ossificans after excessive manipulation