Paediatric Supracondylar Fractures: Master the Bread and Butter

Visual Element: A 3D rotatable model of a Gartland Type III supracondylar fracture, showing the typical posteromedial displacement and the proximity of the neurovascular bundle.

If there is one operation a general orthopaedic surgeon must remain competent in, regardless of their subspecialty, it is the supracondylar humeral fracture. It is the most common admission to the paediatric ward and carries significant risks of compartment syndrome, nerve injury, and malunion.

This guide moves beyond the textbook basics to the practical realities of managing these injuries at 2 AM.

Part 1: Anatomy and Pathology

The distal humerus in a child is defined by the hourglass shape of the metaphysis (thin in the sagittal plane) and the robust ligamentous attachments.

• Mechanism: Fall on Outstretched Hand (FOOSH) with the elbow in extension (98% - Extension type).
• Deformity: The distal fragment typically displaces Posteriorly and rotates internally.

The Gartland Classification (Modified)

• Type I: Undisplaced. (Look for the Fat Pad Sign).
  • Tx: Cast/Splint.
• Type II: Displaced but posterior cortex intact.
  • IIA: No rotation.
  • IIB: Rotational deformity present.
  • Tx: Closed Reduction and Casting (if stable) OR Pinning (standard of care now for most IIB).
• Type III: Completely displaced. No cortical contact.
  • Tx: CRPP (Closed Reduction Percutaneous Pinning).
• Type IV: Instability in both flexion and extension (MDI - Multidirectional Instability). Periosteum stripped circumferentially. Diagnosed intra-op.

Part 2: The "Pink Pulseless" Hand

This is the most stressful clinical scenario. The child arrives, the elbow is grossly deformed. The hand is pink with good capillary refill (<2s), but the radial pulse is absent.

The Algorithm:

1. Do NOT panic. The collateral circulation around the elbow is robust. If the hand is warm and pink, the limb is viable.
2. Urgent Reduction: The artery is usually kinked over the proximal fracture spike. Perform a gentle closed reduction in the ER (or immediately in theatre).
3. Reassess: In most cases, the pulse returns immediately after reduction.
4. If Pulse Still Absent (but hand Pink):
   • Proceed to K-wire fixation.
   • Avoid hyper-flexion (which tamponades flow). Fix in 45-60 degrees of flexion if needed.
   • Admit for close observation (hourly vascular checks). Do not explore.
5. If Hand is White/Cold (Ischemic):
   • This is a vascular emergency.
   • Reduce -> Pin -> Explore. Open the antecubital fossa. Release the lacertus fibrosus. Often the artery is entrapped or in spasm (use papaverine). If transected (rare), call vascular.

Part 3: Nerve Injuries - The "OK" Sign

Nerve injuries occur in 10-15% of displaced fractures.

• AIN (Anterior Interosseous Nerve): The most common. Motor only.
  • Test: "Can you make an OK sign?" (Flex FPL and FDP to index).
  • Pathology: Neurapraxia from tenting over the proximal spike (posterolateral displacement).
• Radial Nerve: 2nd most common (with posteromedial displacement).
  • Test: "Thumbs up" or wrist extension.
• Ulnar Nerve: Usually Iatrogenic (from medial pin) or in Flexion-type fractures.
  • Test: "Cross your fingers."

Prognosis: 90% of nerve injuries are neurapraxias and resolve spontaneously over 3-6 months. Observation is the standard.

Part 4: Surgical Technique - Step-by-Step

The Goal: A stable reduction that restores the normal carrying angle (Baumann's angle).

1. The Setup

• Patient supine. Radiolucent board. C-arm coming in from the opposite side (or parallel to bed).
• Tip: Do not prep the arm yet. Do a trial reduction to see if it reduces easily or if there is soft tissue interposition (pucker sign).

2. The Reduction Maneuver

1. Traction: Longitudinal traction in slight flexion to unlock fragments.
2. Correction: Correct Coronal translation (Medial/Lateral shift) first.
3. Flexion: With the thumb on the olecranon, push the distal fragment anteriorly while flexing the elbow. Pronate (for posteromedial displacement) or Supinate (for posterolateral).
4. Lock: Hyperflex the elbow to lock the reduction.

3. The Pinning (CRPP)

Lateral vs. Crossed Pins:

• Lateral Only (2 or 3 pins): Safer. Eliminates risk of ulnar nerve injury. Biomechanically adequate if pins are divergent and engage the medial column.
• Crossed (Medial + Lateral): Stronger for torsional stability. Risk of ulnar nerve injury (3-5%).

My Technique:

1. Start with a lateral pin. Use a 1.6mm K-wire. Start on the lateral capitellum. Aim for the medial cortex proximal to the fracture.
2. Bicortical Purchase: You must feel the "bite" of the far cortex.
3. Place a second lateral pin. It must be divergent (spread apart at the fracture site) to create a mechanical "beam" effect.
4. Check stability. If unstable (Type IV), add a medial pin.
   • Medial Pin Safety: Extend the elbow to <90 degrees (nerve moves posterior). Make a small incision. Dissect down to bone. Use a drill guide/sleeves to protect the nerve. Don't guess.

4. Post-Op

• Long arm cast/splint in 70-90 degrees of flexion.
• Pull wires at 3-4 weeks in clinic.

Part 5: Complications

Malunion (Cubitus Varus)

• The "Gunstock Deformity."
• Cause: Failure to correct rotation or medial collapse.
• Significance: Mostly cosmetic. Function is usually preserved. Corrective osteotomy is difficult.

Volkmann's Ischemic Contracture

• The result of missed compartment syndrome.
• Fibrosis of the flexor muscle mass.
• Prevention: High index of suspicion. Low threshold to split casts. Measure pressures if unsure.

Conclusion

Supracondylar fractures are high-stakes poker. Follow the algorithm. Respect the soft tissues. Pin it right the first time. And never trust a pulse that disappears.

Operative Video

Watch a high-definition video of the 'mini-open' medial pinning technique.