Ultrasonographic examination of the proximal scutum in the horse.

Normal and abnormal ultrasonographic images are presented of the proximal scutum (proximal sesamoid bones and palmar ligament) in the horse. Comparison between anatomical sections, MRI (magnetic resonance imaging) and ultrasound scans enabled the authors to establish the normal ultrasonographic anatomy of the palmar fetlock. Nine cases of proximal scutum injuries were identified ultrasonographically, of which 4 are illustrated. On normal limbs, the facies flexoria of the proximal sesamoid bones appeared as a thin and regular hyperechoic line and the palmar ligament was regularly echogenic. Lesions of the proximal scutum, that could be documented ultrasonographically, included rupture of the palmar ligament, avulsion fractures of the proximal sesamoid bones and palmar ligament desmopathy. Thinning or degeneration of the palmar ligament, concurrent with osteolysis of the proximal sesamoid bones, were indicative of palmar ligament enthesopathy. Ultrasonographic examination provided essential information for an accurate diagnosis of proximal scutum damage.