Practice Essentials
Elbow fractures are the most common type of fractures in children, primarily occurring from a fall on an outstretched hand. Elbow fractures include supracondylar, lateral condyle, medial condyle, radial head and neck, and olecranon.
The evaluation of pediatric elbow radiographs in the setting of acute trauma may be challenging for many emergency department physicians, orthopedic surgeons, and radiologists. Diagnostic difficulties stem both from the complex developmental anatomy of the elbow and from significant differences between children and adults in the patterns of injury after elbow trauma.
Standard radiographic evaluation of the elbow includes imaging in the anteroposterior (AP) and lateral views. Other views may also be helpful, such as the internal oblique view for lateral condyle fractures.
Because supracondylar fractures may be oriented obliquely on the lateral view, coursing proximally from anterior to posterior, an AP view with cephalad angulation of the x-ray beam may help to better demonstrate such a fracture. The capitellum and radiocapitellar joint are best seen on the radiocapitellar view.
Knowledge of the mechanisms of injury, the range of skeletal and soft tissue findings in the different patterns of injury, and the proper indications for additional views all aid in the recognition of subtle fractures.
A review of medical records of 462 children (median age, 6 yr) with elbow fractures identified the most common fractures as supracondylar (N=258, 56%), radial neck (N=80, 17%), and lateral condylar (N=69, 15%). On follow-up, additional fractures were seen in 32 of the children, and of these, 25 had a different type of fracture than that identified on the initial radiographs. The most common follow-up fractures were olecranon (N=23, 72%), coronoid process (N=4, 13%), and supracondylar (N=3, 9%). The frequency of olecranon fractures on follow-up may suggest the occult nature of these fractures.
A study of 62 elementary school baseball players (grades 4-6; ages 9-12 yr) for elbow injuries using MRI found positive findings in 26 (41.9%), all confined to the MCL. Screening was performed using low-magnetic-field (0.2-T) MRI.
In a study of 900 young baseball players (aged 7-11 yr), 35.2% reported episodes of elbow pain.
The American College of Radiology Appropriateness Criteria for chronic elbow pain includes the following
:
Initial evaluation of chronic elbow pain should begin with radiography.
Chondral and osteochondral abnormalities can be further evaluated with MRI or CT. The addition of arthrography is helpful, especially for detecting intra-articular bodies.
Radiographically occult bone abnormalities can be detected with MRI, CT, or bone scintigraphy.
Soft-tissue abnormalities (tendon, ligament, nerve, joint recess, and masses) are well-demonstrated with MRI or US.
Dynamic assessment with US is effective for diagnosing nerve or muscle subluxation.
According to Rabiner et al, ultrasonography is highly sensitive for elbow fractures, and a negative ultrasound may reduce the need for radiographs in children with elbow injuries. Of 130 patients (mean age, 7.5 yr), 43 (33%) had a radiograph result positive for fracture. A positive elbow ultrasound had a sensitivity of 98% and a specificity of 70%.
Tokarski et al found that use of conventional radiography may be reduced in patients with a low clinical concern for fracture and normal elbow ultrasound. In the study, after clinical examination and before radiography, pediatric emergency physicians performed elbow US of the posterior fat pad and determined whether radiography was required. The overall sensitivity of elbow US was 88%. Elbow US combined with clinical suspicion for fracture had a sensitivity of 100%. In addition, elbow US took a median of 3 minutes, while elbow radiography took a median of 60 minutes.
Anatomy
Understanding the developmental anatomy of the pediatric elbow helps ensure that normal ossification centers are not misinterpreted as fracture fragments. It also aids recognition of an injury when the pattern is altered. For example, the medial epicondyle usually ossifies prior to the trochlea. Therefore, if the medial epicondyle is not seen in its expected location and a single ossicle is seen beneath the medial aspect of the distal humeral metaphysis, the ossicle should be interpreted as an avulsed medial epicondyle that is entrapped in the joint rather than a normal trochlea.
The chronologic order of appearance of elbow ossification centers is as follows: capitellum, radial head, medial epicondyle, trochlea, olecranon, and lateral epicondyle at 1, 5, 7, 10, 10, and 11 years, respectively.
The elbow is composed of 3 articulations. The ulna articulates with the humerus at the trochlea, which is the grooved and rounded medial articular portion of the distal humerus. The articular portion of the ulna is formed by the olecranon process proximally and by the coronoid process more distally. This humeroulnar or trochleoulnar joint is a hinged articulation that essentially permits motion in a single plane, allowing flexion and extension. The concave head of the radius articulates with the capitellum, which is the convex lateral articular surface of the distal humerus. This humeroradial or radiocapitellar joint permits the radius to flex and extend relative to the humerus and to rotate throughout elbow flexion and extension. This rotation allows for supination and pronation of the forearm and depends on proper motion of the proximal radioulnar joint (the third articulation of the elbow) and on the normal mobility of the forearm and wrist.
The distal humeral articular surface has several grooves and ridges that are important in determining anatomic stability after a fracture. Medially, the trochlear notch articulates with a corresponding ridge along the ulna. More laterally, the capitellotrochlear sulcus separates the humeral articular surface of the radius from that of the ulna. Between these grooves is the lateral crista of the trochlea, which provides lateral stability to the trochleoulnar joint.
See the Medscape Reference article Salter-Harris Fracture Imaging for more information. For patient information resources, see eMedicineHealth’s First Aid and Injuries Center, as well as Broken Elbow and Elbow Dislocation.