Elbow fractures are more common in children than adults, and treatment can differ greatly from adults because of the healing and remodeling potential of pediatric fractures. Occult fractures are also more common in children, in part because not all of the damaged bone may be ossified. Detecting unossified fractures on plain radiographs can be difficult, and many of the epiphyses in the elbow region ossify late. Comparison radiographs of the uninjured elbow often help in identifying subtle fracture lines and displaced fracture fragments. Any child who presents with a history of fall or injury, tenderness to palpation about the elbow, and a fat pad sign on plain radiographs should be treated for an occult fracture and immobilized in a splint or cast for a minimum of 3 weeks. New callus formation at the presumed fracture site will typically be present on plain radiographs at this time to allow the diagnosis to be confirmed.
Supracondylar Fracture Of Humerus
Supracondylar fractures of the humerus are the most common elbow fracture in children and are much more common in children and adolescents than in adults. In children, the fracture typically involves the thin bone between the coronoid fossa and the olecranon fossa of the distal humerus, proximal to the epicondyles, and the fracture line angles from an anterior distal point to a posterior proximal site. In adults, supracondylar fractures are not usually confined to the extra-articular portion of the distal humerus, as in children, but extend into the elbow joint.
The most frequent cause of supracondylar fractures of the humerus is a fall on the outstretched hand with the elbow extended. By far the most common fracture pattern is an extension-type injury with posterior displacement of the distal fragment; only 5% to 10% of supracondylar fractures are flexion-type injuries with anterior displacement of the distal fragment. Extension-type supracondylar fractures are classified as nondisplaced (type I), partially displaced with the posterior cortex still intact (type II), and completely displaced with no cortical contact between the fragments (type III).
In the evaluation of any fracture, careful assessment of the neurovascular status is important, but this assessment is even more critical in supracondylar fractures of the elbow because of the proximity of the brachial artery and median nerve to the distal spike of the proximal fragment. Neurologic injury or vascular insult and Volkmann ischemic contracture can result from this type of fracture. A direct neurovascular injury may occur from the fracture spike, or neurovascular compromise may occur from severe swelling that accompanies the injury.
Before reduction, the fractured elbow should be splinted in extension so that arterial circulation is not compromised by flexion of the distal fragment. When the injury is evaluated in the emergency department, the neurovascular status of the limb should be carefully determined and monitored. The first focus of management is on reduction of the displaced fracture fragments to alleviate any neurovascular compression if it is present. The supracondylar fracture should be reduced as soon as possible after injury, preferably with the patient under conscious sedation or general anesthesia. Closed reduction is carried out by gentle distraction in the line of the forearm until the humerus is restored to its full length. The medial or lateral angulation is corrected, and in extension-type injuries the elbow is flexed greater than 90 degrees for added stability. With the elbow in extreme flexion, the posterior periosteum and the aponeurosis of the triceps brachii muscle act as a hinge to maintain the reduction of the fragments. In more stable fractures (some type II fractures), this posi- tion may be secure enough with a plaster splint or long-arm cast alone for 4 to 6 weeks to prevent redisplacement of the fracture fragments and allow healing.
In assessing the reduction achieved, displacement in the anteroposterior plane is not nearly as important as the presence of lateral or medial angulation. If the fracture heals with the distal fragment tilted medially or laterally, a significant deformity, either cubitus varus or cubitus valgus, results. Varus or valgus angulation after reduction is best diagnosed on an anteroposterior radiograph or a Jones view of the elbow, which reveals a lack of contact between the two bone fragments on one cortex.
If the adequacy of the reduction or if the vascular supply of the limb is in question, the fracture should be treated either with percutaneous pin fixation performed under image intensification or with open reduction and internal fixation. Type III fractures and many type II fractures require pin fixation for stability. Image intensification allows closed reduction of the fracture and percutaneous insertion of two or three Kirschner wires. Open reduction is usually done through a lateral approach to the distal humerus. Pins can be passed in a crossed (medial and lateral pins) or divergent (all lateral pins) pattern, with care to avoid injury to the ulnar nerve when placing any medial pins. After internal fixation, the elbow can be splinted in any angle of flexion to avoid compromising the function of the brachial artery. Vascular exploration and/or repair is rarely needed but may be indicated if a pulseless, unperfused extremity does not improve after fracture reduction and operative fixation.
The major long-term complication of very severe fractures is a change in the carrying angle of the elbow, primarily cubitus varus, owing to incomplete or loss of reduction at the time of treatment. The normal carrying angle of the elbow (10 to 20 degrees of valgus) is decreased or reversed. Despite the abnormal appearance of the elbow, function is not typically compromised, even with a severe varus deformity. Closed or open reduction and percutaneous pinning of unstable fractures (types II and III) are used to prevent varus deformity. Angular malunions that result in a significant loss of function or cosmetic deformity are best treated with a corrective osteotomy at the site of the original fracture. The alignment of the corrective osteotomy is maintained with a plate and screws or an intramedullary nail. The osteotomy is often supplemented with cancellous bone grafts to ensure healing. Neurologic injury, although not common, does occur and can involve either the median, radial, or ulnar nerve, with median nerve injury the most common. Vascular injury is a devastating complication because it can lead to Volkmann contracture from a resulting missed compartment syndrome. Regardless of the reduction and fixation method, care should be taken once the limb is splinted or placed in a cast to closely monitor it for adequate circulation and a stable neurologic examination. Distal pulses may not always be easily palpable owing to vascular spasm from the injury, but if distal perfusion and capillary refill are normal with no evidence of compartment syndrome then the limb is likely stable. Finally, all elbow fractures can potentially result in decreased motion and stiffness.
|SUBLUXATION OF RADIAL HEAD|
Fractures Of Lateral Condyle
A lateral condyle fracture is the second most common elbow injury in children. Typically, it occurs as an avulsion injury of the attached extensor muscles. If not reduced well and securely fixed, this type of fracture tends to lead to significant long-term problems, includ- ing nonunion, cubitus valgus, and tardy ulnar neuropathy. Growth arrest of the lateral humerus produces a progressive valgus deformity of the joint, which, in turn, may lead to ulnar nerve palsy later in life. Non-displaced fractures of the lateral condyle can be treated with immobilization in a cast. However, because of a significant risk of late displacement of the fracture, the patient must be monitored with frequent radiographic examinations during the first 2 weeks after injury. Displaced fractures require open reduction and pin or screw fixation to maintain a satisfactory reduction and avoid the deformity and neurologic complications asso- ciated with this injury.
Fractures Of Medial Epicondyle
This injury is the third most common elbow fracture in children. It results from a valgus stress applied to the elbow causing an avulsion injury of the medial epicondyle due to contraction of the flexor-pronator muscles. The fracture is frequently associated with a posterior or lateral dislocation of the elbow joint. Dislocation causes the strong ulnar collateral ligament to pull the epicondyle fragment free from the humerus. During reduction of the dislocation, the fragment sometimes becomes trapped in the elbow joint. If not incarcerated in the joint, the fragment may be slightly displaced or rotated more than 1 cm away from the distal humerus. A significantly displaced fragment is sometimes easily palpable and freely movable on the medial aspect of the elbow joint.
Nondisplaced and minimally displaced fractures heal well with splint or cast immobilization. A displaced fragment trapped in the joint as a result of an elbow dislocation requires open reduction to restore joint congruity and stability. Significantly displaced fragments outside the joint may not heal, and some surgeons recommend open reduction and internal fixation. However, even if the fragment fails to unite, long-term complications are few.
Fracture Of Radial Head Or Neck
During a fall on the outstretched hand, the radial head or neck may fracture as it impacts against the capitellum, typically from a valgus stress on an extended elbow. Fractures are usually through the proximal physis and into the radial neck in a Salter II pattern. Significant angulation of the radial head fragment may occur, and if the angulation is greater than 30 degrees the fracture should be reduced with closed manipulation. Reduction is achieved using digital pressure over the angulated head while alternatively supinating and pronating the forearm. Although closed reduction is sufficient for most fractures, severely displaced or angulated fractures of the radial head require percutaneous or open reduction and internal fixation. Even completely displaced fragments should be reduced and fixed in place. In a growing child, the radial head should never be excised, because excision always leads to sig- nificant loss of elbow function.
Dislocation Of Elbow Joint
This childhood injury is less frequent in younger children but commonly seen in boys between 13 and 15 years of age and is frequently associated with athletic injuries. Apparent elbow dislocations in young children or infants should raise concern for a transphyseal fracture of the distal humerus that is the result of child abuse. Radiographs of these fractures may be confused for dislocations because of the lack of ossification of the distal humerus at this age. Most elbow dislocations in children are posterior, as in adults. Associated avulsion fractures of the elbow, particularly avulsion fractures of the medial epicondyle, can occur. With adequate anesthesia, most elbow dislocations can be reduced easily. The elbow is initially placed in a splint after reduction; and for stable, isolated injuries, the management is similar to that for adults.
Subluxation Of Radial Head
This injury, also known as nursemaid elbow, is the most common elbow injury in children younger than 5 years of age and results from longitudinal traction applied to the limb. The annular ligament moves proximally and becomes interposed between the radius and ulna, causing the radial head to subluxate. Clinical findings are characteristic: the injured limb hangs dependent and the child avoids arm use, the forearm is pronated, and any attempt to flex the elbow or supinate the forearm produces significant pain. Radiographs do not show any significant bone abnormality about the elbow. Physical examination almost always reveals localized tenderness over the radial head. In most patients, reduction can be achieved by complete supination of the forearm, pressure on the radial head, and subsequent elbow flexion. Although this causes a moment of fairly severe pain, supination causes the radial head to slide back into its normal position, and frequently a “click” is felt as the annular ligament slides back around the radial neck. Reduction brings almost immediate and complete relief of pain; and within a few moments, the child begins to use the elbow. If the closed reduction is successful, immobilization is not necessary. The physician should explain the cause of the subluxation to the child’s parents and tell them to avoid longitudinal traction on the limb. The risk of recurrent subluxation is minimal.