Ultrasonographic examination of the palmar aspect of the pastern of the horse: Sesamoidean ligaments

The suspensory apparatus is composed of the third interosseous muscle (TIOM) or suspensory ligament, the proximal sesamoid bones, palmar ligament and distal sesamoidean ligaments (DSL). Of these structures, the suspensory ligament is the most frequently implicated in conditions seen in race and sport horses; nevertheless, DSL lesions are not rare and often associated with other injuries that can modify patient prognosis and management. Ultrasonography has been shown to be valuable in the assessment of DSL desmitis. In contrast to the metacarpal area, the pastern region has been considered technically more difficult to scan because of the small and irregular contact surface and frequent artefacts. Advances in imaging techniques with adapted ultrasound probes and the use of magnetic resonance imaging (MRI) for equine lameness evaluation have revealed that distal sesamoidean ligament injuries are more frequently implicated in lameness than previously suspected.