diminish artifact and are capable of submillimeter
slice thickness. CT is often utilized as a surrogate for
MRI, in cases where MRI is contraindicated. A disad-
vantage of CT is limited soft tissue contrast. With
exception of anatomic areas where various position-
ing is possible, (e.g., ankles, feet, and hands) direct
imaging is limited to the axial or near axial plane.
Reconstruction artifact is commonly encountered
with older generation scanners.- The strength of ultrasonographylies in its ability to
acquire dynamic images. It depicts soft tissue
pathology of structures while in motion. A normal
control is readily available by acquiring images from
the contralateral side. There is direct patient contact
of the sonographer, facilitating immediate cus-
tomization of the exam to patient’s symptoms.
Ultrasound is strongly operator dependant, requiring
intense training with extensive hands-on experience
for competency. The need to compare to the con-
tralateral side may prolong examination time, and
thus decrease patient compliance. Ultrasound does
not provide adequate resolution of intra-articular
structures. - Radionuclide bone scanningis extremely sensitive for
detecting areas of increased bone turnover. It is, how-
ever, nonspecific, and traumatic lesions cannot be dif-
ferentiated from inflammation or neoplasia. Correlation
with plain films is usually needed. There is also poor
spatial resolution, which may be improved by obtaining
oblique projections and single photon emission com-
puted tomography(SPECT).
SPECIFIC USES
- Radiographyshould usually be used for the initial
assessment of an acute traumatic event to assess for
fracture and/or alignment abnormality. In the case of
chronic disorders, radiographs can eliminate alternate
diagnoses, such as arthritis or neoplasia. Radiography
is also the standard method for following fracture
healing and alignment corrections (subluxation or dis-
location). - Stress radiographyfinds its niche in cases of chronic
trauma with instability and suspected soft tissue
injury. It has, however, been widely replaced by MRI. - Arthrography is utilized when joint distention is
required for lesion detection. This may include cases of
ligamentous injuries, capsular tears, and intra-articular
loose bodies. - MRIis used for suspected bone or soft tissue injury,
especially when plain radiographs are normal. There
are indications for MRA, including chronic glenoid or
acetabular labral tears, low grade superior labrum
anterior-posterior (SLAP) lesions, evaluating for
retear of a repaired knee meniscus, and detection of
noncalcified intra-articular loose bodies.- CT is indicated for demonstrating the extent and
anatomy of fractures. It is especially useful with com-
plex pelvic trauma, where plain radiography is limited
and the pelvic three-dimensional architecture is com-
plex. It is also useful for evaluation complex elbow
trauma, another joint that is difficult to depict three-
dimensionally with plain film. CT with multiplanar
reformations provides an excellent road map for the
surgeon in planning the appropriate operation. CT is
also used for intra- versus extra-articular localization
of peri-articular mineralization seen on plain film, and
is well suited for demonstrating calcifications associ-
ated with ligaments and tendons. This latter finding is
often associated with chronic injury. - Ultrasoundis used when dynamic imaging is desired,
as in cases with snapping ankle and hip tendons, and
rotator cuff impingement. It is sensitive in demon-
strating minute calcium deposits and tiny abnormal
fluid collections in and around tendons and ligaments.
Mobile field side units are now frequently utilized
outside the United States of America., and are gaining
popularity here. This allows immediate field-side
evaluation of injured athletes for tendon tears, muscle
strains, and hematomas. - Radionuclide bone scansare useful for localizing the
site of bone pathology in cases where symptoms are
diffuse. In lesions such as pars defect, a bone scan
done with SPECT will show if the lesion is associated
with abnormal activity, implying an active and likely
symptomatic lesion. It also provides information
about the chronicity of an abnormality, as acute
lesions show intense tracer accumulation, and more
chronic quiescent conditions appear more normal.
CONSIDERATIONS- Considering that different modalities have differing
sensitivity to demonstrate certain pathology, it
becomes evident that clinical information is para-
mount in not only deciding which method to use, but
also to tailor the imaging study to the patient’s spe-
cific needs. - Clinical information also helps to choose the correct
modality for acute versus overuse injury. In both
cases, one should usually begin with plain radiogra-
phy. In cases of normal radiographs and suspected
acute bone injury, one may choose to obtain an MRI
to evaluate edema and a possible nondisplaced frac-
ture. MRI is also useful for more chronic injuries
where a soft tissue abnormality is suspected.
108 SECTION 2 • EVALUATION OF THE INJURED ATHLETE