Residency · Residency · Orthopedic Surgery
Pediatric Supracondylar Humerus Fractures
Introduction
Supracondylar humerus fractures are the most common elbow fracture in children, accounting for approximately 60% of all pediatric elbow fractures. They occur most frequently between ages 5 and 7 years. These injuries demand urgent evaluation because of their association with neurovascular compromise, and management errors can lead to devastating complications including malunion, stiffness, and Volkmann ischemic contracture.
Anatomy and Mechanism
The supracondylar region of the distal humerus is the thinnest portion of the bone, making it vulnerable to fracture. The anterior humeral line normally passes through the middle third of the capitellum on a lateral radiograph. Extension-type fractures (95 to 98% of cases) result from a fall on an outstretched hand with the elbow in extension, displacing the distal fragment posteriorly. Flexion-type fractures (2 to 5%) result from a fall onto a flexed elbow, displacing the distal fragment anteriorly. The brachial artery and median nerve are tethered anteriorly and are at risk in extension-type injuries.
Classification (Gartland)
| Type | Displacement | Key Features | Treatment |
|---|---|---|---|
| I | Nondisplaced | Anterior humeral line normal; posterior fat pad sign | Long arm cast 3-4 weeks |
| IIA | Angulated, no rotation | Intact posterior cortex (hinge); no rotational malalignment | Closed reduction and casting |
| IIB | Angulated with rotation | Intact posterior cortex with rotational malalignment | Closed reduction and percutaneous pinning |
| III | Completely displaced | No cortical contact; highest neurovascular risk | Urgent closed reduction and percutaneous pinning |
| IV | Multidirectional instability | Circumferential periosteal disruption | Pinning in slight extension; may need open reduction |
Type I
Type I fractures are nondisplaced or minimally displaced. The anterior humeral line passes through the middle third of the capitellum, and only a posterior fat pad sign may be visible on the lateral radiograph. Treatment consists of a long arm cast in 60 to 90 degrees of flexion for 3 to 4 weeks.
Type II
Type II fractures are angulated with an intact posterior cortex (hinge). The anterior humeral line passes anterior to the middle third of the capitellum. Type IIA has no rotation, while Type IIB has rotational malalignment. Type IIA may be managed with closed reduction and casting, while Type IIB typically requires closed reduction and percutaneous pinning (CRPP).
Type III
Type III fractures are completely displaced with no cortical contact, representing the most severe injury pattern with the highest risk of neurovascular compromise. They are subdivided by the direction of displacement: posteromedial (more common, associated with radial nerve injury) and posterolateral (associated with median nerve and AIN injury). Treatment requires urgent closed reduction and percutaneous pinning.
Type IV (Modified Gartland/Leitch)
Type IV fractures have multidirectional instability with circumferential periosteal disruption. They require pinning in slight extension and may require open reduction.
Neurovascular Assessment
Nerve Injuries
Nerve injuries occur in approximately 10 to 15% of displaced fractures. The anterior interosseous nerve (AIN) is the most commonly injured nerve overall, tested with the "OK sign" (FPL and FDP to the index finger). The radial nerve is more commonly injured with posteromedial displacement and is tested with wrist and finger extension. The median nerve is more commonly injured with posterolateral displacement. The ulnar nerve is at risk during medial pin placement. The vast majority are neurapraxias that recover spontaneously within 3 to 6 months, and acute exploration is rarely indicated.
Vascular Injuries
The brachial artery may be stretched, kinked, or entrapped by the fracture. A pulseless, well-perfused hand ("pink, pulseless hand") may occur due to arterial spasm or kinking, with the hand perfused via collateral circulation. A pulseless, poorly perfused hand is a surgical emergency requiring immediate reduction and vascular exploration. After reduction, the pulse is reassessed; if the hand remains pink with capillary refill under 2 seconds, observation with serial examinations is acceptable in the pink-pulseless scenario. Persistent ischemia after reduction mandates vascular exploration and possible repair.
Surgical Technique: Closed Reduction and Percutaneous Pinning
Reduction Maneuver (Extension Type)
The reduction sequence begins with longitudinal traction applied with the elbow in slight extension and the forearm supinated. Coronal plane displacement (medial or lateral translation) is corrected next. Rotational deformity is then corrected (internal rotation for posteromedial, external rotation for posterolateral). Finally, the elbow is flexed while a posteriorly directed force is applied on the olecranon to correct the sagittal plane deformity, and reduction is maintained in flexion and pronation.
Pin Configuration
Lateral entry pins consist of two or three divergent pins from the lateral condyle, avoiding ulnar nerve risk. Crossed pins (lateral and medial) are biomechanically more stable for rotation, but the medial pin places the ulnar nerve at risk. If using a medial pin, a small incision should be made, the ulnar nerve palpated, and the elbow flexed to less than 90 degrees before pin insertion. Modern evidence supports three lateral divergent pins as an alternative providing comparable stability to crossed pins. Pins are cut outside the skin and removed in clinic at 3 to 4 weeks.
Complications
Compartment Syndrome (Volkmann Ischemic Contracture)
This is the most feared complication, resulting from prolonged ischemia to the forearm compartments. Signs include escalating pain, pain with passive extension of the fingers, and a tense forearm. Excessive elbow flexion during casting can exacerbate vascular compression. Treatment requires urgent fasciotomy; delayed diagnosis leads to irreversible contracture.
Malunion
Cubitus varus (gunstock deformity) is the most common late complication of malunion, resulting from malreduction in the coronal plane (internal rotation and varus angulation). It is primarily a cosmetic concern but may predispose to lateral condyle fractures in the future. Corrective osteotomy may be performed for severe deformity.
Other Complications
Pin tract infection is superficial and usually managed with oral antibiotics. Elbow stiffness usually resolves with time and activity in children; physical therapy and passive stretching should be avoided. Myositis ossificans is rare and associated with repeated manipulation attempts.
Clinical Pearls
A posterior fat pad sign on the lateral radiograph is always pathologic at the elbow and indicates an occult fracture; if no fracture line is visible, it should be treated as a nondisplaced supracondylar fracture. The anterior interosseous nerve is the most commonly injured nerve in extension-type supracondylar fractures, so the "OK sign" should always be tested before and after reduction. A pink, pulseless hand after reduction with intact capillary refill may be observed with serial neurovascular checks, while a white, pulseless hand requires emergent vascular exploration. Three divergent lateral pins provide adequate stability for most fractures and avoid the risk of iatrogenic ulnar nerve injury associated with medial pin placement.
References
- Gartland JJ. Management of supracondylar fractures of the humerus in children. Surg Gynecol Obstet. 1959;109:145-154.
- Babal JC, Mehlman CT, Klein G. Nerve injuries associated with pediatric supracondylar humeral fractures: a meta-analysis. J Pediatr Orthop. 2010;30(3):253-263.
- Skaggs DL, Cluck MW, Mostofi A, Flynn JM, Kay RM. Lateral-entry pin fixation in the management of supracondylar fractures in children. J Bone Joint Surg Am. 2004;86(4):702-707.
- White L, Mehlman CT, Crawford AH. Perfused, pulseless, and paralyzed: a systematic review of vascular injuries in pediatric supracondylar humerus fractures and results of a POSNA questionnaire. J Pediatr Orthop. 2010;30(4):328-335.