Radial Head Fractures
Radial head fractures frequently result from a fall on an outstretched arm and may be difficult to see on x-rays.
The radial head is palpated on the lateral elbow as a structure that rotates during pronation and supination and that articulates with the lateral epicondyle. The lateral epicondyle and radial head typically form an isosceles triangle with the olecranon. Joint effusions (common with radial head fractures) may be palpable over this triangle.
Radial head fractures are more common among adults than children.
Anteroposterior, lateral, and oblique views are taken. But because x-rays may show only indirect evidence of fracture, diagnosis relies heavily on physical examination.
Routine anteroposterior and lateral x-rays often do not show the fracture but usually show a joint effusion, which is indicated by the presence of abnormal fat pads on x-rays. Displacement of the anterior fat pad may indicate joint effusion but is not specific; visibility of the posterior fat pad on a true lateral view is specific for joint effusion but not highly sensitive. Patients with localized radial head tenderness and effusion require oblique views (which are more sensitive for fracture) or presumptive treatment of a fracture.
The radiocapitellar line is a line through the midshaft of the radius on a lateral x-ray of the elbow. Normally, this line transects the middle of the capitellum (see Figure: Anterior humeral line and radiocapitellar line.). Sometimes in children, the only sign of fracture on x-rays is displacement of this line.
Anterior humeral line and radiocapitellar line.
Arthrocentesis may be done to remove blood from the joint to help differentiate mechanical blockage of passive joint motion from restriction due to pain and muscle spasm. Then, a local anesthetic is injected to relieve pain.
Stability is tested by applying stress to the elbow medially and laterally and checking for laxity or increased motion. If the joint does not move when stress is applied, the fracture is stable and associated ligaments are probably uninjured.
Fractures with minimal displacement and no restriction of passive elbow motion or instability can be treated with a sling, which can be applied for comfort with the elbow flexed 90°. Elbow range-of-motion exercises should be started as soon as patients can tolerate them.
If the elbow is unstable or motion is mechanically blocked, fractures are treated surgically.
The radial head is tender, and pain is worse during supination.
Take anteroposterior, lateral, and oblique x-rays, but because x-rays may show only indirect evidence of fracture, physical examination is very important in diagnosis.
If the radial head is tender and clinical or radiographic evidence suggests an elbow effusion, treat presumptively for radial head fracture even if the x-ray shows no fracture.