Supracondylar Fractures: The Definitive Guide

The supracondylar humerus fracture is the "Appendicitis of Paediatric Orthopaedics"—common, potentially dangerous, and a rite of passage for every trainee. It is the most common elbow fracture in children (peaking age 5-7) and carries significant risks of nerve injury, vascular compromise, and malunion.

Visual Element: Cover image showing an "Anterior Humeral Line" and "Baumann's Angle" measurement guide (SVG).

1. Anatomy and Mechanism

The fracture occurs through the thin bone of the olecranon fossa.

• Extension Type (95%): FOOSH injury. Distal fragment displaced posteriorly.
• Flexion Type (5%): Direct blow to the elbow. Distal fragment displaced anteriorly. Danger: High rate of Ulnar nerve injury.

2. Assessment: The "Pink Pulseless Hand"

Neurology: You must test individual nerves.

• AIN (Anterior Interosseous Nerve): Most common palsy in Extension type (posterolateral displacement). Test: "Make an OK sign."
• Radial Nerve: Common in posteromedial displacement. Test: "Thumbs up."
• Ulnar Nerve: Common in Flexion type. Test: "Cross your fingers."

Vascular Status:

• Well Perfused: Warm, pink, refill <2s.
• Pink Pulseless: Warm, pink, but no radial pulse. (Collateral flow is adequate).
• White Pulseless: Pale, cold, ischemic. Surgical Emergency.

Clinical Pearl: The Pucker Sign. A dimple in the anterior skin/cubital fossa. It means the proximal fragment has buttonholed through the brachialis muscle and is subcutaneous. Warning: The neurovascular bundle is likely draped over the spike. Do not pull traction blindly!

3. Imaging Parameters

1. Anterior Humeral Line: On lateral view, should pass through the middle third of the capitellum. In extension fractures, it passes anteriorly.
2. Baumann's Angle: On AP view, angle between humeral axis and physeal line of capitellum. Normal ~70-75°. Assesses varus/valgus alignment.

4. Classification (Gartland)

• Type I: Non-displaced. (AHL intersects capitellum).
• Type II: Displaced, but posterior cortex intact (hinge).
• Type III: Completely displaced. No cortical contact.
• Type IV: Unstable in flexion AND extension (MDS - Multidirectionally Unstable). Diagnosed intra-op.

5. Management Strategy

Type I

• Cast immobilization (Long arm cast) for 3-4 weeks.

Type II

• The Debate: Some treat with cast (hyperflexion), others pin.
• Consensus: If significant extension (AHL misses capitellum) or any rotation -> Pin it. Hyperflexion casting increases compartment syndrome risk.

Type III & IV

• CRPP: Closed Reduction and Percutaneous Pinning.

6. Surgical Technique: The Reduction

The Maneuver (Extension Type):

1. Traction: Restore length (milking the soft tissues).
2. Correction: Correct Varus/Valgus and Rotation.
3. Flexion: Flex the elbow while pushing the olecranon forward.
4. Lock: Pronate (for posteromedial displacement) or Supinate (for posterolateral).

Pinning (The Construct):

• Lateral Divergent Pins: Two or three pins entering laterally.
  • Pros: Safest for Ulnar nerve.
  • Cons: Biomechanically weaker than crossed pins (but sufficient for most).
• Crossed Pins (Medial & Lateral):
  • Pros: Most stable construct.
  • Cons: Risk of iatrogenic Ulnar nerve injury (2-3%).
  • Technique: Extend elbow to <90° before placing medial pin to relax the nerve. Don't plunge.

7. Complications

• Cubitus Varus (Gunstock Deformity): Malunion due to failure to correct medial collapse/rotation. Cosmetic deformity mostly, but can cause tardy posterolateral instability.
• Volkmann's Ischemia: Compartment syndrome. Pain on passive extension of fingers.
• Stiffness: Usually resolves with time. Physiotherapy is rarely needed in kids.

Conclusion

The supracondylar fracture demands respect.

• Assessment: Check the pulse and the AIN.
• Reduction: Gentle, sustained traction. Don't fight the spasm.
• Fixation: Divergent lateral pins are safe and usually sufficient.
• Vigilance: Compartment syndrome is the enemy.

Treat the child, not the X-ray.