Type:
Educational Exhibit
Keywords:
Musculoskeletal bone, Bones, Conventional radiography, Education, Education and training
Authors:
A. Chellathurai; Chennai/IN
DOI:
10.26044/ecr2019/C-2998
Findings and procedure details
Savoca [42] described stress fractures as compression or distraction fractures.
Compression fractures generally occur in cancellous bone such as the neck of the femur,
the proximal shaft of the tibia,
and the calcaneus.
Distraction fractures occur more commonly in compact bone.
The exact radiologic appearance,
however,
depends on the amount of time between the onset of injury and the imaging examination and on whether the patient continued participation in the activity despite pain.
In the early phase,
on radiographs,
a fracture in the shaft of a long bone may appear as a lucency through the cortex without any periosteal reaction or callus .
In cancellous bone,
the first manifestation may be a focal linear area of sclerosis perpendicular to the trabeculae .As the bone heals,
solid or thick lamellar periosteal reaction occurs .
Often,
this occurs on the endosteal surface as well as on the periosteal surface .
The degree of reactive bone is generally confined to a small area of cortex and usually involves only one of the cortical surfaces.
Ultimately,
the area of periosteal reaction thickens,
and the fracture line,
if actually seen previously,
disappears.
Devas [14] described an unusual variety of stress fracture that was longitudinal and involved up to half the length of the tibia or femur.
MR imaging in patients with stress fractures has been
described in figure.
MR findings parallel those found on scintigrams.
If the patient is imaged within days after he or she becomes symptomatic,
MR images will show low signal in the marrow areas on Ti weighted sequence.
The signal is increased on T2 weighted sequence and with short tau inversion recovery (STIR) sequences.The findings are nonspecific and represent the edema in the marrow or in the soft tissues surrounding the fracture.
The findings can easily be confused with those seen in transient osteoporosis,
neoplasm,
or infection.
If the patient is imaged much later,
linear areas of low signal may be seen on Ti -weighted images .
These linear abnormalities have low signal on T2-weighted images and represent the callus and new bone formation at the fracture site and are suggestive of the diagnosis.
Usually at this point,
however,
the radiographs or CT scans show the true nature of the lesion.
The MR appearance parallels the scintigraphic appearance in that it is nonspecific early in the evolution of the stress fracture and more suggestive later .