Fig. 2. A, Normal sonographic appearance of the suspensory branch at three levels. The proximal branch demonstrates a round to oval shape. The mid branch is oval with a more triangular shape axially. The insertional branch is triangular in shape and the abaxial surface of the sesamoid bone is smooth and regular. A mostly linear fiber pattern is seen at each level. B, Common areas of sonographic artifact/misinterpretation. a, Sonographic image of the suspensory branch insertion. The image on the left is using proper on-beam scanning technique. The image on the right is at the same level of the same branch, but there is off-incidence beam angle artifact along the axial portion of the ligament that should not be confused with a hypoechoic lesion. b, Linear hypoechoic artifact (white arrow) due to a normal anatomical fold in the distal suspensory branch.
Careful scanning in both transverse and longitudi- nal sections is helpful in distinguishing between an actual injury and an artifact. Sonographic appearance of SB injuries can be variable in appearance (Fig. 3). A central hy- poechoic to anechoic area accompanied by fiber tear- ing on longitudinal views is indicative of significant injury; however, this cannot always determine the acute or chronic nature of the injury. Perhaps a better indication of disease chronicity is concentric periligamentous fibrosis or, in some instances, dys- trophic mineralization within the ligament. Injury can happen at any level of the branch and can be
either focal or diffuse in nature. In some instances, an increase in cross-sectional area is associated with injury. Injury at the insertion of the SB is com- monly associated with bony changes to the sesamoid bone (including bony irregularity and avulsion-type injuries). Non-weightbearing ultrasound examina- tions can sometimes be helpful in determining the extent of linear hypoechoic-type injuries. It can also sometimes be helpful in cases where the fetlock joint communicates with a tear in the SB. Al- though small, focal hypoechoic lesions may not be clinically significant, it is less predictable if “wear and tear” type injuries (characterized by reduced
