Imaging of Clavicular Fractures and Dislocations: Practice Essentials, Radiography, Computed Tomography (2024)

Midclavicle

Evaluation of the clavicle requires a standard AP view centered on the midshaft of the clavicle. The image should be large enough to permit evaluation of the AC joint and the SC joint, as well as the rest of the shoulder girdle and the upper lung fields.

Oblique views can be used to further gauge the degree and direction of displacement. In practice, an AP view with a 20-60° cephalic tilt provides an adequate second view, because interference with thoracic structures is minimized.

(See the image below.)

Because of the shape of the clavicle, fractures of the midclavicle represent multiplanar deformities, and accurate estimates of shortening are difficult to obtain with plain radiographs. CT scans, especially with 3-dimensional reconstructions, improve the accuracy. However, this level of accuracy is rarely required.

Medial clavicle and SC joint

Standard projections for the evaluation of the SC joint include posteroanterior (PA), lateral, and oblique views. Medial clavicular fractures and SC joint injuries may be difficult to appreciate on standard views because of the overlap of the clavicle with the sternum and the first rib. Special projections include Rockwood, Hobbs, Heinig, and Kattan views. The most popular additional view is the Rockwood, or Serendipity, view (seen in the image below). This projection requires a 40° cephalic tilt of both SC joints centering on the manubrium.

The full extent of these injuries is often unclear despite the use of additional radiographic views. The diagnosis is best confirmed with CT scanning, which has the added benefit of the depiction of rib fractures, pulmonary contusion, and pneumothorax.

Of note, the secondary ossification center at the medial end of the clavicle does not appear before the age of 12 years, and it may not unite until the age of 25 years. Therefore, a physeal fracture can be confused with a dislocation of the SC joint on plain radiographs. This possibility should be carefully considered when studies in children or adolescents are being evaluated.

Lateral clavicle and AC joint

A single AP radiograph of the injured side often suffices, but some prefer to obtain comparison views of the opposite shoulder. AP views of the AC joint are performed at 15° of cephalic inclination, along the scapular spine. Normal alignment of the joint is present on an AP view when the joint space measures less than 5 mm wide and when the undersurfaces of the acromion and the distal clavicle form an uninterrupted arc.

Type 1 AC injuries (not to be confused with type 1 clavicular fractures) consist of a minor tear in the AC ligament, with an intact coracoclavicular ligament. This injury is clinically diagnosed when radiographs appear normal but tenderness is present over the joint.

Type 2 AC injuries represent a complete tear of the AC ligaments, with partial tearing of the coracoclavicular ligament. The clavicle is superiorly displaced by less than half of its own width.

(See the image below.)

Type 3 AC injuries signify complete disruption of the AC and coracoclavicular ligaments. Displacement greater than half of the width of the clavicle is present.

(See the image below.)

Radiographic findings are evident in 75% of type 1 and type 2 AC injuries but in virtually 100% of type 3 injuries.

Three additional categories have been introduced to help distinguish severe injuries for which surgical treatment may be warranted:

• Type 4 injuries are similar to type 3 injuries, except that posterior displacement of the distal clavicle is also present. This can be verified on an axillary view.

• Type 5 injuries are characterized by inferior displacement of the scapula, with an increase of the coracoclavicular interspace of 2-3 times its normal size. Such extreme displacement is usually associated with extensive stripping of the trapezius, pectoralis major, and deltoid muscles.

• Type 6 injuries involve inferior displacement of the clavicle. This is a rare type of injury resulting from a direct downward blow.

In the past, stress radiographs were used to differentiate type 2 and 3 injuries (partial vs complete ligamentous tears). Because most surgeons now treat type 2 and type 3 injuries nonsurgically, this distinction is no longer critical, and the use of stress views has fallen out of favor.

Postoperative radiography

Buenter et al performed a retrospective study of 241 patients who underwent operative repair for clavicular fracture to determine how often there is a change in the postoperative treatment plan because of findings on postoperative radiography, which according to the authors is standard procedure in most hospitals. They found that only one patient had an abnormality on postoperative radiography that necessitated additional CT scanning, and no additional re-interventions or deviations from standard postoperative protocol were required. ^[15]