Supracondylar humerus fracture is the most common elbow fracture in children, accounting for 60-70% of pediatric elbow fractures with peak incidence at age 5-7 years. The fracture occurs through the thin, weak supracondylar metaphyseal region above the elbow trochlea-capitellum, just proximal to the olecranon fossa. Classification: Gartland (modified) describes extension-type fractures (97%): type I—non-displaced or minimally displaced (intact anterior humeral line through middle third of capitellum); type II—displaced with hinge of intact posterior cortex (anterior cortex disrupted, posterior intact); type III—completely displaced with no cortical contact; type IV—multidirectionally unstable (described intraoperatively when fragments translate in both flexion and extension positions). Flexion-type fractures (3%) result from fall on flexed elbow with anterior displacement of distal fragment.
Mechanism: extension-type from fall on outstretched hand with elbow extended causing posterior displacement of distal humeral fragment; flexion-type from fall on flexed elbow. The fracture is associated with high-energy trauma in older children, polytrauma evaluation indicated. Neurovascular injury occurs in 10-15%, with anterior interosseous nerve (AIN—a branch of median) most commonly injured (presents with inability to make 'OK sign'—FPL and FDP to index), median nerve (loss of forearm flexion, thumb opposition), radial nerve (less common), and ulnar nerve (especially with crossed pinning). Vascular injury (1-5%) involves brachial artery; absent radial pulse occurs in 10-20% (may indicate occult injury, requires reduction and reassessment, and angiography or vascular surgery if pulse not restored after reduction). Compartment syndrome of forearm is feared complication leading to Volkmann's ischemic contracture if missed.
Treatment is determined by Gartland type and presence of neurovascular compromise. Gartland I: long-arm cast at 90 degrees flexion for 3-4 weeks, then short-arm cast or removal. Gartland II: closed reduction (traction with elbow extended, then flexion with countertraction by surgeon's thumb on olecranon translating distal fragment anteriorly) and percutaneous pinning (CRPP)—two or three lateral K-wires (1.6 mm) preferred to avoid ulnar nerve, or crossed pin construct for unstable fractures with attention to small medial incision and direct visualization to avoid ulnar nerve. Gartland III/IV: CRPP standard; if reduction unsuccessful, open reduction via anterior, lateral, or medial approach. Pins removed at 3-4 weeks once callus visible, gradual range of motion. Indications for emergent surgery: open fracture, vascular compromise (pulseless and pale—revascularization within 6 hours), compartment syndrome, multilevel fractures of same limb (floating elbow). Postoperative care: long-arm cast 3-4 weeks with neurovascular monitoring; once pins removed, gentle range of motion; full ROM may take months; physical therapy occasionally needed for persistent stiffness. Complications: cubitus varus (gunstock deformity, varus and internal rotation of forearm—primarily cosmetic but some functional impairment, more common with malreduction; corrective osteotomy if symptomatic); Volkmann's ischemic contracture (delayed presentation with forearm contractures—prevention through prompt management of compartment syndrome); permanent neurologic injury (most AIN palsies recover spontaneously by 6 months, persistent deficits may need exploration); residual elbow stiffness (5-10% at 6 months but typically resolves by 1 year).