The routine radiographic examination of the long bones must include both frontal and lateral projections. A single projection of a long bone is an inadequate radiographic study (Fig. 23.1) except in the severely injured patient, and then only neurologic or hemodynamic instability or possible acute traumatic aortic injury should take precedence. Prior to definitive evaluation, however, radiographs of the long bones in orthogonal planes must be obtained to provide the necessary data on which management decisions can be made.

It is equally fundamental to include the entire long bone(s) in the examination whenever possible. When not possible, for whatever reason, the joint closest to the site of injury must be included in the examination. The purpose of the “closest joint” tenet is to be able to accurately localize the injury and to identify concomitant injuries that frequently occur close to or involve the joint (Fig. 23.2).

Shortening of one of the bones of the forearm or leg as a result of angulation or overlap of fragments can be accommodated only by either a fracture or dislocation of the other bone. Therefore, when one of the bones of the forearm or leg is shortened as a result of fracture, it is imperative to examine the entire part radiographically to diagnose the fracture or dislocation that must involve the other bone (Figs. 23.3 and 23.4).

The distal fragment of midfemoral or midtibiofibular fractures may be externally rotated as much as 90 degrees. This feature may not be appreciated unless the entire part is included in the radiographic study (Fig. 23.5).

Thus, radiographic reports of diaphyseal fractures should address the fracture pattern, the bone quality, and the presence of bone loss especially if there is comminution, the amount of limb shortening, and the presence of air in the soft tissues.

The most commonly accepted convention for describing the relationship of the fragments of long or short tubular bones is to relate the position of the distal fragment to that of the proximal fragment. Alignment is the relationship of the longitudinal axis of the distal fragment to that of the proximal fragment. If the long axis of each fragment is parallel, alignment is said to be normal. Displacement refers to translation of the distal fragment in any direction with respect to the proximal fragment without angulation. “Angulation” indicates that the long axis of the distal fragment is canted (angled) with respect to the long axis of the proximal fragment. A distal fragment may be displaced, angled, or displaced and angled (Fig. 23.6) with respect to the proximal fragment. Proximal retraction of the distal fragment
with respect to the proximal is referred to as overriding (Fig. 23.6).

A segmental fracture is one in which two fractures occur at disparate locations within the same long bone, resulting in a separate and discrete fragment that is not attached to either the proximal or the distal fragment. The separate fragment is the “segment” of a segmental fracture (Fig. 23.7).

Peripheral Doppler ultrasound and computed tomography angiography (CTA) play an important role in the evaluation of traumatic lesions of the extremities. Although it is the responsibility of the attending physician to specifically evaluate the circulation of an injured extremity, it is equally the responsibility of the radiologist to identify and indicate to the attending physician those injuries that, because of the normal anatomic relationship between the arteries and the bones, have the potential for associated vascular involvement. However, the “proximity of wound” alone is not an indication for emergent CTA in the presence of an otherwise clinically normal extremity. Obviously, clinical signs or symptoms of arterial compromise distal to either a penetrating injury or a displaced long bone fracture

require at least consideration of CTA or peripheral angiography. The priority of the CTA or angiogram and where it is performed (e.g., the emergency center, the angiography suite, the operating room) must be determined jointly by the attending physician and the radiologist based on the patient’s overall condition and the availability of angiographic facilities.