(Table 1).
21
In their study, they were able to reduce the cost to
the emergency department by three million dollars annually
by following their guidelines yet still accurately detecting
ankle fractures.
Ultrasound has been advocated for the evaluation of acute
ankle ligament injuries because it allows for noninvasive and
dynamic assessment of the ankle. However, ultrasound is
highly dependent upon equipment and operator skill level.
Ligament tears are usually seen at insertional sites or in the
central third. Acute tears are visualized as ligament swelling,
discontinuity, hypoechogenicity, and nonvisualization. The
diagnostic accuracy for ATFL tears by ultrasound is 95%
and for CFL tears is 90%.
22,23
CT and MRI scans are not typically indicated for acute
ankle sprains. However, if there are other suspected injuries,
MRI can be useful to elucidate associated conditions. The
differential diagnosis of ankle injuries is varied, ranging from
fractures to other ligamentous injuries (Table 2). Frey and
associates
24
correlated MRI with clinical findings and found
a high percentage of peroneal tendon pathology. Posterior
tibial tendon and deltoid ligament injury was also common.