Transcuneal ultrasonographic findings in the podotrochlear apparatus: Comparison with postmortem in 14 equine digits

The objective was to describe the ultrasonographic features of the lesions of the podotrochlear apparatus identified when the foot is imaged through the frog in equine cadaver digits and to compare the ultrasonographic changes with macroscopic findings. Fourteen cadaver feet with abnormalities of the podotrochlear apparatus detected by transcuneal ultrasonography were used for the study. The palmarodistal portion of the podotrochlear apparatus was studied and imaged using the transcuneal approach. The detectable ultrasonographic findings suggesting pathology of the podotrochlear apparatus were described. Ultrasonographic and gross findings in the podotrochlear apparatus were compared to interpret the transcuneal ultrasonographic changes. An abnormal palmar tendon profile was the most reliably detectable ultrasound finding indicating pathology of the deep digital flexor tendon (DDFT). In 5 feet, the tendon appeared ultrasonographically normal but had gross lesions at necropsy. Ultrasonographic features of the lesions of the distal sesamoid bone were mild thickening and roughening of the hyperechoic bone line, severely irregular bone surface, and large erosions with sharp borders. These corresponded, respectively, to full thickness fibrocartilage loss with irregular subchondral bone surface, subchondral bone abnormality, and full-thickness erosion of the palmar compact bone. Abnormalities of the distal sesamoidean impar ligament, the distal border of the distal sesamoid bone, and the distal phalanx were also identified with transcuneal ultrasound. In conclusion, transcuneal ultrasonography, with the equipment used in this study, allowed the identification of abnormal changes in the podotrochlear apparatus but was unable to detect all the tendon lesions palmar to the distal sesamoid bone. The description of the abnormal images provided and knowledge of the limits of transcuneal ultrasonography should be useful as a basis for interpretation of future studies on clinical cases.