Screw Fixation of Medial Epicondyle Fractures

Collin May

Mininder S. Kocher

Fractures of the medial epicondyle are a common pediatric injury, representing 12% to 20% of all pediatric elbow fractures (1, 2, 3). The typical mechanism is a fall onto an outstretched hand, creating a valgus load at the elbow leading to avulsion of the epicondyle from pull of either the flexor-pronator mass or ulnar collateral ligament. This injury is most frequent in children between the ages of 9 and 14 and is 4 times more likely in boys (4, 5, 6, 7). Medial epicondyle fractures are associated with elbow dislocation in about 50% of cases, and incarceration of the epicondylar fragment in the elbow joint occurs in 15% to 18% (8). Ulnar nerve dysfunction is reported to occur nearly 10% of the time (9). Multiple treatments have been described including nonoperative treatment, single screw fixation (the focus of this chapter), fixation with a single or multiple K-wires, suture repair, and excision of the fragment and suturing of the flexor-pronator mass to the humeral periosteum.

INDICATIONS/CONTRAINDICATIONS

Optimal management of medial epicondyle fractures is controversial, with good outcomes demonstrated after both operative and nonoperative treatment. Historically, most treatment has been nonsurgical, with immobilization in a long-arm cast until healing. Despite a relatively high nonunion rate with displaced fractures (around 60%), good functional results from nonoperative treatment can be expected. Recent trends have been toward more aggressive operative management, with stable fixation allowing early mobilization and assurance of anatomic reduction and healing. Consensus exists in the literature regarding just two absolute indications for surgery: open fractures, and fractures with an incarcerated medial epicondyle that is irreducible by closed means. Fractures associated with ulnar nerve dysfunction, with gross elbow instability, or in patients participating in high-demand athletics are considered relative indications for surgery. No agreement exists in the literature regarding the degree of displacement of the epicondylar fragment that warrants surgical fixation, with recommendations for surgery with as little as 2 mm of displacement and recommendations for nonoperative management with as much as 15 mm of displacement on plain radiographs. We have settled on 5 mm of displacement as a criterion for operative intervention, particularly in an athlete who places significant valgus stress on the elbow (Table 3-1).

Comminution of the epicondylar piece and fractures in very young patients are both relative contraindications to screw fixation. If fixation is indicated in these patients, alternative strategies may be employed, including K-wire or suture repair.

TABLE 3-1 Indications for Open Reduction and Internal Fixation of Medial Epicondyle Fractures

Absolute
	Open fracture Incarcerated medial epicondyle
Relative
	Ulnar nerve injury Gross elbow instability High-demand athletics or employment Displacement >5 mm

PREOPERATIVE PLANNING

Anatomy

The medial epicondyle is an apophysis located on the posteromedial aspect of the distal humerus. It is the origin of the flexor-pronator mass and the ulnar collateral ligament. The ulnar nerve enters the cubital tunnel posterior to the medial epicondyle and is at risk of injury with medial epicondyle fractures. The vascular supply to the medial epicondyle is via the inferior ulnar collateral artery and the medial arcade, formed by anastomoses of the superior and inferior ulnar collateral arteries with the posterior ulnar recurrent branch of the ulnar artery.

Clinical Presentation and Physical Exam

Patients with a medial epicondyle fracture typically present with a history of fall onto an outstretched hand. Findings on exam are varied and may include soft-tissue swelling, crepitus, and ecchymosis on the medial elbow, decreased range of motion, or frank elbow dislocation. Examination in the reduced elbow should include testing of elbow stability, and valgus stress testing may be performed clinically or with radiographs to give the provider a sense of the degree of ligamentous injury. Neurovascular testing should be performed, paying particular attention to the ulnar nerve-innervated structures. It is important to document the status of ulnar nerve function prior to any intervention.

Imaging

Standard AP and lateral radiographs of the elbow should be obtained to assess for epicondylar fragment displacement as well as rule out an entrapped fragment in the elbow joint. The accuracy and precision of displacement measurements from AP and lateral images have recently been brought into question. Pappas and colleagues showed poor inter- and intraobserver agreement in displacement measurement among surgeons of various levels of training in reviewing AP, lateral, and oblique images (10). They suggest measuring displacement on standardized AP radiographs at the point of maximal displacement. Even with a standardized protocol, displacement measurements on radiographs may grossly underestimate the amount of true displacement as shown by CT scan (11). It has been recently suggested that internal oblique x-rays may give a more accurate indicator of displacement if used with a standard multiplier value (12). Stress radiographs can be used to assess for elbow instability, particularly in the setting of a minimally displaced fracture that may otherwise be treated nonoperatively.

Classification

No validated classification system exists for medial epicondyle fractures, though many different systems have been described. Most classification schemes are descriptive in nature, with fractures noted to be acute or chronic, nondisplaced or displaced, and stable or unstable and the presence of associated factors such as elbow dislocation or entrapped fragment within the joint.