Imaging

Daniel R. Lewis

Radiographic imaging is essential in diagnosing most traumatic injuries of the musculoskeletal system. Unfortunately, poorly taken radiographs or medically unnecessary advanced imaging can lead to a delayed diagnosis or misdiagnosis. A fundamental knowledge of how to obtain and interpret proper skeletal imaging is paramount to the treating clinician. Even more important is the clinical examination of the patient, which identifies the anatomic location of concern and establishes a differential diagnosis to guide further evaluation.

RADIOGRAPHS^1,2

Standard Views

Finger examinations should include at a minimum a posteroanterior (PA) and a lateral view. The joint spaces on PA views should be visible and symmetric. Lateral views should be taken with minimal to no rotation.
The basic radiographic examination of the hand and wrist includes, at a minimum, orthogonal views in the PA and lateral planes.
For optimal results, the shoulder should be abducted to 90° and the hand placed on the imaging cassette for PA views. This allows for neutral rotation views, which are optimal for anatomic measurements. The PA view is extremely useful for initial survey of the wrist and hand. Fractures of the radius and ulna, carpus, metacarpals, and phalanges can be identified. The type of fracture, presence of comminution, displacement, angulation, and ulnar variance may be measured. This view also aids in the evaluation of carpal alignment in the coronal plane, including scapholunate diastasis and the alignment of the carpal rows (Gilula arcs). Radial height, inclination, and ulnar variance can also be measured (Figure 2.1).
The anteroposterior (AP) plane may be used if range of motion of the extremity is limited.
An optimal lateral radiograph of the wrist will show the pisiform superimposed over the scaphoid tuberosity. The alignment of the distal
radius articular surface, including location and position of fracture fragments and articular tilt, can be demonstrated. The lateral view is also extremely valuable for identifying dislocations of the carpus (eg, perilunate injuries) and carpometacarpal (CMC) joints. Important intercarpal measurements, including scapholunate and radiolunate angles, can also be performed.
An oblique radiograph performed in 45° of pronation can be performed to evaluate fractures of the scaphoid, the scaphotrapezial-trapezoidal joint, dorsal triquetral avulsion fractures, and dorsoulnar corner fractures of the radius.
Supinated 45° oblique films may be taken to evaluate the pisotriquetral joint and fourth and fifth CMC joints.

Specialized Views

The following are common specialized views that aid in the diagnosis of specific anatomic locations often performed by orthopedic clinicians.

The scaphoid view is PA wrist view taken with the wrist in maximal ulnar deviation, which extends the scaphoid and brings it into full profile. The radiograph beam may be angled between 0° and 30° to obtain a series.
Bilateral clenched or pencil grip PA wrist films are the most sensitive radiographs to evaluate scapholunate diastasis secondary to dynamic scapholunate instability.
The first CMC joint views are true AP (or hyperpronated PA) and lateral of the thumb and CMC joint and are often used to determine joint congruity and the presence of arthritis.
The second and third CMC joints will be seen best on a lateral wrist film with the wrist in flexion and slightly supinated.
The hook of hamate view is performed with the wrist in the lateral position with maximal radial deviation and slight supination. The thumb should be abducted palmarly as much as possible to allow adequate viewing of the entire hamate hook (Figure 2.2).