Radial Head Subluxation

Radial head subluxation, or nursemaid’s elbow, is a common injury that affects children between the ages of 6 months and 5 years. It results from hyperextension with subluxation of the radial head and acute interposition of the annular ligament into the radiocapitellar joint. A history of longitudinal traction may not be obtained because the caretaker may not be aware of a particular event or may feel guilty about causing the child’s injury. A concern about wrist or shoulder injury may be reported because inadvertent manipulation of the injured elbow caused pain.

Presenting Signs and Symptoms

Children refuse to use the affected arm and hold it close to the body and in slight flexion. They do not appear to be in particular distress but may be fearful that examination will elicit pain. There is no tenderness with palpation or bony or soft tissue abnormality. Radiographs are unnecessary unless another particular injury is suspected. Edema and tenderness are present with supracondylar fractures.

A number of reduction techniques are used, including the hyperpronation method and the supination-flexion method. The hyperpronation method has proved more effective and appears to be less traumatic.¹ With the arm held in extension, the wrist is hyperpronated and a click is sometimes heard. In the supination-flexion approach the examiner places the thumb of one hand over the radial head and provides countertraction. Next, while holding the wrist, the elbow is pulled into extension. The final phase is supination and flexion at the elbow. Most children return to full functioning within 15 minutes, and the child should be observed until full range of motion is regained.

When multiple reductions fail, radiography should be considered. In a child with failed reduction and negative radiographic findings, a sling or posterior splint is necessary with close orthopedic follow-up.

Fractures

Trauma to immature and incompletely ossified bones results in unique pediatric orthopedic injuries, including torus, greenstick, bowing, and physeal fractures. These patterns do not occur in dense adult bone. Because the radiographic findings of some of these abnormalities are incredibly subtle, comparison views are particularly helpful. Trauma that would result in sprains and strains in structurally mature individuals causes the thick periosteum to be torn from the bony cortex and resultant avulsion fractures. Ligamentous tears are uncommon in children because their ligaments are stronger than the neighboring bones.

Children’s bones are apt to bend with a fracture on only one side of the periosteum. Callus formation and remodeling are extensive in pediatric injuries and contribute to the faster healing found in children. The goal of reduction should always be nearly perfect alignment, and growing bones have a dramatic potential for spontaneous correction.

Pediatric bones are less dense and therefore more prone to compression or bending when an axial load is applied. Falls onto an outstretched arm may result in torus or buckle fractures (Fig. 25.1). Greenstick fractures are incomplete, with the cortex remaining intact on one surface. To obtain complete reduction, completion of the fracture is necessary. Bowing fractures result when the force is insufficient to cause a complete break but results in deformation of the osseous structure (Fig. 25.2). Cosmetic deformity and functional abnormality will result without complete reduction. Repair is often difficult because both cortices remain intact.

Fig. 25.1 Torus fracture of the distal end of the radius.

Fig. 25.2 Radial bowing fracture with the normal contralateral side shown for comparison.

The physis or growth plate is a weak area of cartilage present in developing bone. Trauma that causes strains or joint dislocations in skeletally mature individuals frequently results in growth plate fractures in children. Anatomic alignment of such fractures is critical for optimal growth.

Salter-Harris Classification of Fractures

The most commonly used system to identify physeal injuries is the Salter-Harris classification. Fractures are categorized as types I through V, with the higher numbers having the greater risk for growth abnormalities. All such injuries require pediatric orthopedic follow-up.²

Type I fractures result from a longitudinal force through the physis that splits the epiphysis from the metaphysis. Radiographs may reveal a widened growth plate. Identification can be difficult, particularly when the displacement is minimal, and a fracture should be suspected in children with tenderness along the physis even in the absence of radiologic findings. Type I fractures rarely result in growth disturbances and can be treated effectively with immobilization.

Type II fractures, the most common type, occur when a piece of the metaphysis remains attached to the epiphysis (Fig. 25.3). They require splinting and generally carry a good prognosis. Types III and IV are intraarticular fractures that also involve the growth plate. In a type III injury, the fracture line extends through the epiphysis into the physis. In type IV, the fracture passes through the epiphysis, physis, and metaphysis. Types III and IV carry a risk for growth retardation, altered joint mechanics, and functional impairment and thus require urgent orthopedic evaluation. Type V fractures are compression injuries and are difficult to visualize on radiographs. The diagnosis is often made retrospectively following a case of growth arrest.