Supracondylar Humerus Fracture - Closed Reduction Percutaneous Pinning

Indication. A displaced extension supracondylar humerus fracture in a child that is unstable or completely displaced. In practice this means a Gartland Type IIB (angulated and rotated, unstable despite appearing aligned on a single view) and every Gartland Type III (completely displaced, no cortical contact). A non-displaced Type I is treated non-operatively in an above-elbow backslab, and a stable Type IIA (angulated but with an intact posterior cortex and no rotation) is often managed non-operatively if the Baumann angle is maintained — although many surgeons pin it for reliability. Timing. A Gartland III fracture is urgent — operate within 6-8 hours — because the completely displaced fragment threatens the anterior neurovascular bundle and carries a compartment syndrome risk of 0.5-1%. Severe swelling at presentation and any delay to reduction are independent red flags for compartment syndrome, even with an intact pulse. The pulseless hand — one decision that changes everything. Perfusion, not the presence of a pulse, drives management:

Pre-operative neurovascular exam (medicolegal essential). Before touching the fracture, examine and document all five territories and the vascular status, because nerve injuries at presentation are common and must not later be attributed to the operation: - Anterior interosseous nerve (AIN) — most common, 10-20% — test the OK sign (FPL) and index DIP flexion (FDP); pure motor, no sensory loss; mechanism is stretching over the anterior spike of the proximal fragment.

• Median nerve — 3-5% — thumb-index pinch, thenar bulk, sensation to the radial three and a half fingers.
• Radial nerve — 3-5% — wrist and thumb extension, first webspace sensation.
• Ulnar nerve — 1% at presentation — finger abduction, Froment sign, small-finger sensation (iatrogenic risk rises to 2-4% only if a percutaneous medial pin is used).
• Vascular — radial pulse (present, diminished, absent), capillary refill, hand colour and temperature: pink versus white. Consent for the reduction maneuver, the pin choice (lateral-entry versus crossed) and its ulnar nerve risk, compartment syndrome and the small possibility of re-operation for loss of reduction, late cubitus varus, and the expected stiffness that improves over 6-12 months. Setup. Supine on a radiolucent hand table with the whole arm prepped and free. General anaesthesia with muscle relaxation is mandatory — reduction is impossible against muscle tone. Position the image intensifier so you can shoot true AP and lateral views of the elbow without moving the arm (rotate the tube, not the limb). A tourniquet is rarely needed.

The goal: re-establish length, coronal alignment and sagittal alignment by a systematic closed maneuver, lock the reduction against the intact posterior periosteal hinge, hold it with divergent K-wires, and immobilise in safe flexion. There is no open surgical exposure for the standard case — the "exposure" is the pin entry-point anatomy, where the radial and ulnar nerves live, and that anatomy is laid out in Steps 7 and 9 below.

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Rehabilitation | Phase | Timing | Immobilisation | Activity | |-------|--------|----------------|----------| | 1 | 0-3 weeks | Above-elbow backslab, elbow less than 90 degrees | Finger active range of motion only | | 2 | 3-4 weeks | Pin removal in clinic; removable splint | Begin active elbow motion | | 3 | 4-8 weeks | Splint for protection only | Active ROM, no passive stretching | | 4 | 2-6 months | None | Progressive activity; full motion returns gradually | Pins are removed at 3-4 weeks as a clinic procedure (no anaesthesia if left proud; local anaesthetic and a small incision if buried). Active range of motion begins immediately after removal — never passive stretching, which seeds myositis ossificans. About 80-90% regain full extension by six months; 5-10% keep a small (greater than 10 degrees) extension loss that is cosmetic, not functional. A delayed ulnar nerve cubital tunnel syndrome can appear months to years later in 5-10% of cubitus varus deformities. Complications

Epidemiology. Supracondylar fractures are among the most common elbow fractures in children. The mechanism is almost always a fall onto an outstretched hand, and the vast majority — about 98% — are extension-type (the distal fragment displaces posteriorly), with only about 2% flexion-type. The neurovascular risk that drives every management decision is concentrated in the displaced fractures: nerve injury at presentation in roughly 15-20% and vascular compromise in 10-15% of Gartland III injuries, with compartment syndrome in about 0.5-1%. Pathomechanics. An extension injury fails the anterior periosteum but leaves the posterior periosteal hinge intact; that hinge is what a closed reduction re-engages when the elbow is hyperflexed, locking the fragments like closing a book. The sharp anterior spike of the proximal fragment is what threatens the anterior neurovascular bundle — the AIN, median and radial nerves and the brachial artery are stretched or impaled across it. A flexion-type injury (2%) is the mirror image: the posterior periosteum fails and the anterior hinge is preserved, so reduction and immobilisation are in extension.

Radiographic assessment. Two lines do most of the work. On the lateral view, the anterior humeral line (drawn along the anterior humeral cortex) should bisect the middle third of the capitellum; passing through the anterior third or anterior to the capitellum indicates extension deformity and is unacceptable after reduction. On the AP view, the Baumann angle (between the humeral shaft axis and the capitellar physis) is normally 70-75 degrees (range 64-81) and should be within 5 degrees of the contralateral side; a Baumann less than 64 degrees, or more than 10 degrees from the contralateral, predicts cubitus varus. Also check medial and lateral column alignment and the Gordon line (the anterior cortex line should point to the capitellar ossification centre) — disruption of either indicates rotation. Key evidence. Skaggs showed lateral-entry-only pinning held reduction in all 124 displaced fractures with zero ulnar nerve injuries. Brauer's systematic review (2054 children) quantified the trade-off: crossed pinning makes iatrogenic ulnar nerve injury 5.04 times more likely, but loss of reduction only 0.58 times as likely. Choi established that perfusion, not pulse, drives management — every well-perfused pulseless hand did well with reduction alone, while the poorly perfused hand was high risk. Ramachandran showed that severe swelling and delay (mean 22 hours) herald compartment syndrome even with an intact pulse. Gottschalk's synthetic-bone work found rotational stiffness is driven by a capitellar start and larger pin diameter, with a third 1.6mm pin adding no measurable stiffness in a perfectly reduced fracture.