Morphological and imaging evaluation of the metacarpophalangeal and metatarsophalangeal joints in healthy and lame donkeys.

Abstract The donkey is of socio-economic value yet imaging techniques in both healthy and abnormal limbs are a limiting factor in research and medicine. The objective was to determine anatomical features of both healthy and clinically abnormal donkey metacarpophalangeal and metatarsophalangeal joints (n=13) using anatomical dissection, casting, x-ray and computed tomography. The joint capsule contained two palmar/plantar and two dorsal recesses. The proximal-palmar or plantar recess was larger than the distodorsal recess and potential sites of approaches to the recesses were determined. Soft tissue structures were distinguished using computed tomography at 300mA which was superior to 120mA. This methodology gave better assessments of the synovial tendon sheath, joint recesses and cruciate, collateral and short sesamoidean ligaments. Computed tomography provided outstanding discrimination between the cortex and medulla of the third metacarpal, the proximal sesamoid bones, the proximal phalanx and excellent details of the osseous structures. Although the joints appeared free from exostosis using x-ray; the position and extension of exostosis in pathologically affected donkeys (a novel finding) was revealed using computed tomography with 300mA in comparison to 120mA. The study also provided an anatomical record of the metacarpophalangeal and metatarsophalangeal joints using the latest technology which could impact on clinical situations including anesthesia injection sites.