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Supracondylar Humerus Fractures
Introduction
Supracondylar humerus (SCH) fractures are common injuries that account for 15% of all pediatric fractures. These injuries most commonly occur in children 5 to 7 years of age. The fractures are divided into extension- and flexion-type injuries, of which extension-type injuries make up 95% to 99%. Extension-type injuries occur after a fall onto an outstretched arm that drives the olecranon into the distal humerus and causes the anterior cortex of the distal humerus to fail in tension. Flexion-type injuries are thought to occur when the patient lands directly on the tip of their olecranon, causing a flexion-directed force at the elbow with the posterior cortex failing in tension. Neurovascular injuries can occur with these fractures due to the proximity of structures such as the brachial artery and the anterior interosseus and ulnar nerves. Careful history, physical exam, and imaging are critical when assessing these injuries. The mainstay of treatment for displaced SCH fractures is closed reduction and percutaneous pinning (CRPP). While our understanding of anatomy and surgical technique has improved, the clinician must be aware of complications that can arise throughout the perioperative course in order to optimize outcomes.
Preoperative Issues
The chief complications in the preoperative period chiefly concern neurovascular injury. SCH fractures are prone to injury-induced neurovascular injury. Complications arise when these are inadequately diagnosed or managed.
Assessment
Fractures are classified based on direction of displacement in both the coronal and the sagittal planes. The Modified Gartland classification is the most accepted classification system and aids in management and prognosis of these injuries ( Table 2.1 ). Understanding the Gartland classification can be helpful, as it provides information about the direction and magnitude of displacement of the fracture, which can predict certain types of associated injuries and serve as a guide for physical exam and surgical management.
Table2.1
Modified Gartland Classification
From Alton, TB, Werner, SE, Gee, AO. Classifications in brief: the Gartland classification of supracondylar humerus fractures. Clin Orthop . 2015;473:738–741; Flynn, K, Shah, AS, Brusalis, CM, Leddy, K, Flynn, JM. Flexion-type supracondylar humeral fractures: ulnar nerve injury increases risk of open reduction. J Bone Joint Surg Am . 2017;99:1485–1487.
| Fracture Type | Characteristics | Comments |
|---|---|---|
| I | Nondisplaced | Fat pad elevation may be seen on lateral radiographs |
| II | Displaced in one plane, posterior hinge intact (deformity in sagittal plane) | Anterior humeral line anterior to central capitellum |
| III | Displaced in two or three planes | No cortical contact |
| IV | Complete instability in flexion and extension | Diagnosed with exam under anesthesia |
| Medial comminution | Collapse of medial column | Loss of Baumann angle, leads to varus malunion |
| Flexion-type | Usually after direct fall onto olecranon | More likely to require open reduction |
While the patient may present with a painful and swollen elbow, initial assessment should be comprehensive to identify concurrent traumatic injuries. Urgent surgery is indicated when there are absent radial pulses, a pale and/or cool extremity, severe swelling, skin puckering in the antecubital fossa, open injury, and/or neurological deficits.
Preoperative complications can also arise from incorrect diagnosis of elbow injuries. While most orthopaedic surgeons can comfortably diagnose SCH, issues arise when more subtle injuries are missed. The two most important are medial epicondyle fractures and physeal separations. These will be discussed further in the “Imaging” section later.
Physical Exam
The history should determine the mechanism and energy level of injury. The affected extremity should be examined circumferentially for abrasions, skin tenting, bruising, or open wounds. Neurovascular injury is the most devastating complication SCH fractures. Therefore, a neurological and vascular exam should be carefully performed and documented both preoperatively and postoperatively. A proper and accurate physical exam will not only guide the urgency of surgery but will also determine whether any change in postoperative exam was potentially iatrogenic in nature.
Preoperative Nerve Injury
SCH fractures have a reported incidence of associated nerve injuries of 15% to 18%. Nerve injuries can be traumatic (primary) or iatrogenic (secondary) in nature. Care should be taken to assess the function of the radial, ulnar, and median (particularly the anterior interosseus nerve [AIN] branch) nerves. The AIN is at greatest risk for traumatic injury in extension-type fractures, while injury to the ulnar nerve occurs most frequently with flexion-type injuries.
Neurologic exams can be challenging in a pediatric patient. Instructing the child to perform certain maneuvers is often a pointless endeavor. Instead, careful observation of the child’s hand from the moment you enter the exam room can often bear fruit. The key things to observe are thumb interphalangeal extension or finger metacarpophalangeal extension (radial nerve) and thumb interphalangeal flexion (AIN/median nerve). Ulnar nerve examination is particularly challenging. Palpation of the first dorsal interosseous muscle can be helpful, as it is often possible to confirm ulnar motor function when you feel this firing. A sensory exam requires participation of the child. Sensation to the thumb, first dorsal web space, and small finger is checked. Care should be taken to document truthfully. In many patients “unable to assess” is the correct documentation. However, patience will often yield a thorough exam.
The era of electronic medical records (EMRs) has created a new type of complication. EMR templating may improve the completeness and documentation of neurological exams. However, the pretemplated “normal” physical exam, if not appropriately amended, may lead providers to document inaccurate findings or findings from assessments that were not actually performed. Vigilant documentation is critical for justification and defense of adequate medical care should any legal issues arise. Legal complications may arise, for example, if a pretemplated note is incorrectly filed that documents a functional AIN preoperatively, and then an AIN palsy is noted postoperatively. This may lead people to think the AIN injury was iatrogenic rather than due to the original trauma.
The role of exploring a primary nerve injury remains controversial. In most instances, primary nerve injuries in SCH fractures are neuropraxias that will resolve spontaneously over weeks to months. Observation is the preferred initial management. Prompt identification and appropriate management of nerve injuries has demonstrated good to excellent clinical outcomes. Primary nerve injuries that demonstrate no signs of clinical improvement at 5 to 7 months should be explored. Indications for early exploration include open fractures, vascular injuries, and irreducible fractures.
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