Ultrasonographic appearance of bony abnormalities at the dorsal aspect of the fetlock joint in geriatric cadaver horses.

The research article explores the use of ultrasonography in identifying bony abnormalities in the dorsal aspect (the top side) of the third metacarpal/metatarsal bone in the horse’s fetlock. The study uses horse cadavers with radiographic signs of osteoarthrosis, a joint condition which involves degradation of joints including cartilage and subchondral bone.

Methodology

• The researchers utilized ultrasonographic (US) imaging, which utilizes sound waves to create images of internal body structures, to explore bony abnormalities of the fetlock joint, a key joint in horses located between the hoof and the shank.
• Utilizing twelve fetlock joints, the study determined each joint had more than one bone abnormality visible on US.
• Additional computed tomography (CT) scans were also undertaken to better characterise and accurately draw the identified lesions.

Normal and Abnormal Bone Features

• On ultrasonographic imaging, normal subchondral bone appeared as a well-defined, regular hyperechoic line with distal acoustic shadowing.
• The study catalogs seven different types of bone abnormalities which included:
• Gaps in the upper subchondral bone, filled with material of different brightness levels on the US.
• Bone fragments were represented as small, straight, smoothly delineated bright lines with distal shadowing, and were located superficially to the surface of the adjacent bone.
• Proximal new bone formation could be seen as ranging from mild to severe bone protrusions.
• Appearance of marginal osteophytoses, bone spurs at the edges of the joint surfaces, were observed as an elevation of the bright surface of the subchondral bone.
• Indentations in the subchondral bone, seen as a concave deviation of the bright line, but without any interruption in it.
• Focal or spread irregularities of the subchondral bone were marked by disruptions in the normal smooth contours of the bone.
• Focal bright spikes originating from the subchondral plate and moving towards the articular cartilage were noted.

Conclusion

• This information is important for equine veterinarians and researchers, aiding in the understanding, detection and potential treatment of joint degradation in horses.