Proximal Ulnar Fractures in Children

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CHAPTER 18 Proximal Ulnar Fractures in Children

Anthony A. Stans, Bernard F. Morrey

INTRODUCTION

Proximal ulnar fractures in children and adolescents are uncommon, accounting for between 4% and 7% of pediatric and adolescent elbow fractures.^1,^2,^6,⁸ As a result, (1) they are often completely missed, (2) the variation in growth centers makes the radiographic interpretation confusing, (3) the precise fracture line is often not appreciated, and (4) the potential for a poor outcome occurs if the displacement is not appreciated. In this chapter, we review fractures of the physis, metaphysis, and coronoid (Table 18-1).

TABLE 18-1 Types of Proximal Ulnar Fracture in the Pediatric Age Group

Type	Incidence
Apophyseal (physeal, epiphyseal)	Very rare
Metaphyseal	5% of elbow fractures
Coronoid	Less than 1% of elbow fractures

GROWTH AND DEVELOPMENT

As noted in Chapter 1, at birth none of the articular elements of the ulna, including the coronoid and olecranon, are ossified. At age 9, the secondary center of ossification appears at the olecranon (Fig. 18-1). The ossification center may be bipartite and eccentric, and as the proximal ulna grows, the growth plate orientation alters from transverse to oblique. Closure of the physis begins at the articular surface and progresses toward the extensor surface of the bone. Just before fusion of the growth plate, the metaphyseal bone develops a sclerotic margin and may be widely separated from the apophysis, resembling a fracture. These vagaries can make it difficult to recognize a fracture of the olecranon in a child, and comparative views of the opposite side are often valuable.² Although a secondary center may appear in the olecranon tip, there is no secondary ossification center of the coronoid. This helps explain the fracture pattern observed in the proximal ulna of the various age groups (Fig. 18-2).

FIGURE 18-1 Schematic of ossification of the proximal ulna observed at birth (A) and at adolescence (B). This explains the fracture patterns seen in the young and the adolescent age groups.

FIGURE 18-2 Fracture of the apophysis may (open arrow) or may not (closed arrow) include the coronoid process.

APOPHYSEAL FRACTURE

Apophyseal fractures are extremely rare. Reviewing his experience and that of the literature up to 1991, Wilkins ¹⁷ identified only 16 such cases. As a matter of fact, a review of the literature of the less rare olecranon or proximal ulnar fracture resulted in the identification of 192 cases but no mention of a fracture of the apophysis.¹⁷

The fracture may or may not include the coronoid as the fracture line passes between the growth center and the proximal ulna (see Fig. 18-2). This is because the coronoid does not develop from a separate growth center; thus, the fracture line in this rarest of fractures may be rather variable (Fig. 18-3).

FIGURE 18-3 A 13-year-old boy slipped and fell onto his left arm and presents with point tenderness over his olecranon. (A) Lateral radiograph suggests an olecranon apophysis fracture, which is confirmed by comparison with the contralateral uninjured elbow (B). At the time of his olecranon fracture, the patient was using crutches because he had sustained a left femur fracture 1 month earlier in a motor vehicle accident. The decision was made to perform open reduction with tension band internal fixation (C).

TREATMENT

The extreme rarity of this fracture makes it difficult to make definitive recommendations for treatment. If the fracture is displaced, basic principles apply; that is, reduce the fracture anatomically. Smooth K-wires, possibly supplemented with a figure-of-eight wire as recommended by the Arbeitsgemeinschaft für osteosynthese fragen (AO) technique for olecranon fractures, appears to be adequate, based on the limited reports from the literature. The major challenge, of course, is to diagnose the displacement. Today, computed tomography (CT) scanning, magnetic resonance imaging (MRI), and ultrasonography are useful for this purpose.

METAPHYSEAL FRACTURE

Metaphyseal fractures, although more common than fracture of the apophysis, still account for only approximately 5% of elbow injuries.^3,^11,¹⁵ Wilkins¹⁷ identified only 230 cases among 4,684 proximal ulnar fractures reported in the child before 1991. It appears that there is a biphasic frequency by age, with the greatest early frequency occurring between 5 and 6 years¹² and a second incidence observed in the adolescent. The first peak probably relates to the growth and development of the bone. The second peak relates to the growth and development of the individual participating in activity with increasing propensity for injury.

The mechanism of injury is similar to that described for many injuries about the elbow, including supracondylar, condylar fractures, and dislocations. Although proximal ulna fractures may be caused by direct impact, a more common mechanism is a fall onto an outstretched hand with transmission of the force proximally to the elbow. Differences in injury pattern probably relate to the precise degree of elbow flexion, possibly the rotation of the forearm, and the manner in which the muscles contracted at the time of impact. With fracture of the metaphysis, a varus or valgus force often occurs, causing additional fractures about the elbow. In four large series of proximal ulnar fractures, 20% had a documented associated fracture.¹⁷ In some reports, as many as 50% to 70% had an additional injury, most commonly involving the radial head with a valgus stress at the time of impact (Fig. 18-4).^2,^14,¹⁶

FIGURE 18-4 The metaphyseal fracture involves the ossified proximal ulna. Varus or valgus angulation patterns assist in documenting the mechanism of injury.

CLASSIFICATION

In 1981, Matthews ¹⁰ offered a classification based on radiographic appearance, degree of displacement, and associated injury (±4 mm being the limit). Wilkins¹⁷ considered these by the mechanism of the fracture: (A) flexion; (B) extension; (1) valgus; (2) varus; and (C) shear injury. More recently, Graves and Canale⁷ classified the fracture according to (1) displacement greater or less than 5 mm and (2) presence of compounding. This classification was subsequently modified by Gaddy and coworkers,³ with a type I fracture being less than 3 mm and a type II greater than 3 mm. Evans and Graham² have proposed a classification system based on anatomic site, fracture configuration, intra-articular displacement, and associated injuries, with approximately 18 subtypes. Thus, this fracture has the interesting characteristic of having almost as many classifications as episodes of occurrence.

Although metaphyseal fractures are extremely uncommon, as noted, they are more frequent than the physeal injury is, and they account for approximately 5% of all elbow injuries. Of these, only 10% to 20% require surgical management. Rarely, proximal ulna fractures may be associated with ipsilateral fractures in the distal humerus,⁹ ulnar shaft,¹³ or radial head.⁴

DIAGNOSIS

Because the fracture involves ossified tissue, the metaphyseal fracture is relatively easily identified on the radiograph. Abrasion of the skin or open wound gives some idea of the mechanism; that is, direct or indirect trauma, respectively. A further means of determining the extent of displacement and hence the need for open reduction and internal fixation is to observe whether the fracture separates with flexion and extension under fluoroscopy. If an excessive amount of motion is observed at the fracture site (3 to 4 mm), then open reduction and internal fixation are carried out.

TREATMENT

As implied from the above-mentioned classification, the approach to treatment is based primarily on fracture displacement. Fortunately, approximately 80% of these fractures are minimally displaced, requiring open reduction and internal fixation in only 15% to 20% of individuals.²

Reduction may be accomplished in most instances by reversing the mechanism, which provides some justification for Wilkins’ mechanistic classification noted earlier.

For those fractures that are minimally displaced, simple immobilization for approximately 3 weeks appears to be adequate and is the universal recommendation. For displacement of greater than 3 mm, depending on the classification, surgical treatment is indicated. It is uncommon to have greater than 4 mm displacement in patients under the age of 10 years; thus, open reduction and internal fixation are generally observed in the older age group. Several authors have noted that displacement found intraoperatively is often significantly greater than displacement appreciated on plain radiographs.^3,⁷ Typically, the AO technique with smooth K-wire with circumferential tension band wire is adequate (Fig. 18-5). Recently, there have been several reports successfully using heavy absorbable suture in tension band technique instead of wire.^2,⁵ Absorbable suture was prominent, less likely than wire to become symptomatic and did not need to be removed. Metal internal fixation is typically removed 6 to 12 months postoperatively to ensure that premature closure of the proximal ulnar physis does not occur, and to relieve symptoms of proximal hardware. There have been no reported cases of premature proximal ulnar physeal closure using this internal fixation technique.

FIGURE 18-5 A 10-year-old girl fell 3 feet from a desk directly onto her left elbow, sustaining a proximal ulnar fracture (A) and transcondylar humerus fracture associated with an intra-articular loose bone fragment. Four weeks after open reduction and internal fixation of the proximal ulna and distal humerus, anatomic alignment and periosteal healing are demonstrated (B). Two years following her fracture and 18 months following removal of the tension band wire, the fractures have completely healed, elbow motion is full and without limit, and the patient is entirely asymptomatic (C).

RESULTS

Graves and Canale ⁷ reported the results of 39 fractures treated over 30 years at the Campbell Clinic. Twenty-eight of 30 patients treated nonoperatively were classified as satisfactory after closed treatment. Of the nine treated by open reduction and internal fixation, seven (78%) developed a satisfactory result. Gaddy and colleagues³ reported 35 fractures occurring in patients ranging from 2 months to 15 years. Of these, all 23 treated nonoperatively were considered satisfactory. The criterion for nonoperative treatment was displacement of less than 3 mm. Furthermore, 10 of 10 patients with greater than 3 mm of displacement underwent open reduction and internal fixation, and all developed a satisfactory outcome.

Evans and Graham ² reported the results of 40 proximal ulna fractures treated surgically. In the text of their article a detailed treatment algorithm is provided, outlining their indications for surgical treatment. In summary, fractures greater than 4 mm were always treated surgically, fractures with less than 2 mm of displacement were never treated surgically, and treatment of fractures with displacement between 2 and 4 mm was determined by anatomic site, fracture configuration, and associated injuries. Thirty-six of 40 fractures were managed by tension band technique; 28 using wire and eight using absorbable suture.

In the end, following a simple classification based on the degree of displacement appears to be a reliable guide to surgical intervention and good outcome.