Alteration of distal tarsal subchondral bone thickness pattern in horses with tarsal pain.

This research explores the link between altered subchondral bone (beneath the cartilage) thickness in horse’s hocks (distal tarsal joints), and tarsal pain or osteoarthritis, using magnetic resonance imaging. The study found noticeable changes in the thickness patterns of the subchondral bone in horses with joint pain; these could be indicative of different pathological processes.

Methods

• The study utilized sixteen tarsal joints from nine mature horses that had a history of tarsal pain and radiographic evidence of osteoarthritis (OA).
• For comparison, the researchers also examined three tarsal joints from two mature horses with a history of tarsal pain, but no radiographic abnormalities.
• These joints were scanned using high-resolution magnetic resonance imaging (MRI) to generate a detailed view of the subchondral bone (SCB) – the layer of bone just beneath the cartilage.
• The thickness of the SCB was measured in the dorsal (upper) and plantar (lower) locations, on both the proximal (nearer to the center of the body) and distal (further from the center of the body) aspects of the central (CT) and third tarsal (T3) bones, as well as on the proximal aspect of the third metatarsal bone (MT3).

Results

• The measurements revealed that the SCB in horses with radiographically evident OA had different thickness patterns than horses without OA.
• In particular, SCB thickness was greater on the medial (inner) and lateral (outer) sides than the midline, on both the proximal and distal aspects of CT and T3.
• Unlike normal horses, painful tarsi exhibited greater SCB thickness medially (on the inner side of the joint) than laterally (on the outer sides).
• Moreover, there was an increase in SCB thickness at the majority of locations relative to normal horses, suggesting a probable correlation between increased SCB thickness and OA.
• The study, however, lacked a sufficient dataset for horses without radiographic abnormalities, which limited the statistical analysis needed for definitive conclusions.

Conclusions

• The study concludes that horses with tarsal pain show an alteration in the normal SCB thickness patterns.
• These altered patterns could be indicative of different types of pathological processes leading to OA – highlighting the importance of SCB thickness as a potential diagnostic and prognostic tool for equine OA.
• The findings, however, necessitate further research to elucidate the exact pathological processes leading to OA of the distal tarsal joints and to substantiate the usefulness of SCB thickness as an indicator for OA.