Supracondylar Fractures of the Elbow in Children

Introduction

Supracondylar humerus fractures are the most common elbow fracture in children and have the highest complication rate for elbow fractures in this age group. These compelling facts continue to arouse the interest and hold the attention of orthopedists who treat pediatric patients. Since the last edition of this text, clinical practice guidelines have been developed to guide fracture management and are included within this chapter. These guidelines highlight the lack of high-quality evidence available to direct supracondylar humerus fracture treatment but can be used as a starting point for making treatment decisions and for designing future research. Issues that continue to generate discussion regarding supracondylar fracture treatment include timing of reduction and treatment, as well as pin configuration used for fracture stabilization.

Incidence and Etiology

Supracondylar humerus fractures almost exclusively affect the immature skeleton. Eliason reported that 84% of supracondylar fractures occurred in patients younger than 10 years. The peak age for supracondylar humerus fracture has been reported to be between the ages of 6 and 7 years, and the left arm is injured more frequently than the right. ^a

a References .

Previous reports have suggested that supracondylar fractures are common in boys, but more recent studies have documented an equal sex distribution. ^b

b References .

Traditional teaching has held that the peak incidence for extension-type supracondylar humerus fractures occurs at approximately 7 years of age because that is the age of maximum elbow flexibility and hyperextension. This mechanism has been confirmed by research suggesting that a fall on a hyperextended elbow produces a supracondylar humerus fracture, whereas a fall on an outstretched arm without elbow hyperextension is more likely to cause a distal radius fracture. Hyperextension converts what would be an axial loading force to the elbow into a bending moment. The tip of the olecranon acts as a fulcrum, causing the fracture to occur through the relatively thin bone of the olecranon fossa ( Fig. 27.1 ). The distinctive shape of the humeral metaphysis with the medial and lateral condyles and columns and the narrow midpoint of the olecranon fossa add to the instability of the fracture, particularly when there is rotation and tilting of the distal fragment.

Knowledge of elbow anatomy is important to understand the cause of the injury and corresponding treatment principles. The stability of the elbow is derived from bony and soft tissue structures. Soft tissue stability on the lateral aspect of the elbow is provided by an expansion of the triceps, anconeus, brachioradialis, and extensor carpi radialis longus. The thickened periosteum of a young child, both medially and laterally, is an important additional stabilizer of the fracture fragment and provides a medial or lateral hinge during reduction ( Fig. 27.2 ). Research by Khare et al. has confirmed the importance of the triceps tendon acting as a tension band to achieve fracture stability in the flexed elbow.

Because angular deformity is a common complication of these fractures, the normal variations in pediatric anatomy should be understood. The carrying angle of the elbow joint is the angle formed by the intersection of the longitudinal axis of the arm and the forearm ( Fig. 27.3 ). The normal elbow is usually in slight valgus alignment, but this feature varies among children. Smith noted that, of 150 children aged 3 to 11 years, the carrying angle in boys averaged 5.4 degrees and ranged from 0 to 11 degrees, whereas in girls, it averaged 6 degrees and ranged from 0 to 12 degrees. Aebi observed that the measurements were not constant and changed as the child matured, tending to decrease in magnitude and in variation between children with growth.

Although not commonly associated with abuse in the past, a recent report found that 36% of patients younger than age 15 months at the time of their supracondylar fracture sustained the fracture as a result of abuse. Clinicians must exclude “nonaccidental trauma” as a potential cause of injury whenever an infant presents with a supracondylar humerus fracture.

Classification

A classification system should guide treatment, provide information on prognosis, and facilitate research by ensuring that similar injuries are compared in the literature. The vast majority of supracondylar humerus fractures can be classified as either flexion or extension injuries, a distinction based on the radiographic appearance and the mechanism of injury. The distinction is important for treatment because the reduction maneuvers are essentially opposite for the two fracture types, with flexion-type fractures considerably more difficult to reduce by closed means. A small minority of fractures exhibit multidirectional instability and do not fit into either flexion or extension types. Recognition of multidirectional instability is also helpful in formulating an effective treatment strategy.

Flexion-Type Fractures

Flexion-type fractures are the result of a direct fall onto a flexed elbow in which a powerful flexion force is applied to the distal humerus, usually through the olecranon. The distal humeral fragment is displaced anteriorly, and the fracture line crosses the humerus from the distal posterior to the proximal anterior aspect ( Fig. 27.4 ). Flexion-type fractures are frequently completely displaced and are difficult to reduce by closed means. The reduction maneuver for flexion-type fractures involves elbow extension or using the forearm to apply a posterior-directed force to the anteriorly displaced distal fracture fragment with the elbow flexed 90 degrees.

Extension-Type Fractures

Extension-type fractures typically occur as the result of a fall onto an outstretched arm with the elbow in a hyperextended position. The fracture line traverses the distal humerus from the proximal posterior to the distal anterior aspect. Numerous classification systems have been devised for extension-type supracondylar humerus fractures, but the classification system attributed to Gartland is the most commonly accepted system in use today. As described by Gartland, the classification system is simple, reproducible and helpful in guiding treatment and provides information on prognosis and potential complications. A similar fracture classification system was published in the German literature of the early 20th century by Felsenreich.

Type I

Type I fractures are nondisplaced ( Fig. 27.5 ). In many patients, the fracture line may not be visible on injury radiographs, but the presence of a posterior fat pad sign, palpable tenderness in the supracondylar region, and an appropriate mechanism of injury allows the physician to establish a correct diagnosis. The diagnosis is often confirmed when periosteal callus is seen on radiographs taken 3 weeks after the injury. If recognized and treated appropriately, type I fractures should never be associated with neurovascular injury or malunion.

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