Epiphyseal cartilage canal blood supply to the metatarsophalangeal joint of foals.

The research investigates the patterns of blood supply and its role in the development of the metatarsophalangeal joint in young horses. It particularly monitors the number and direction of vessels in the epiphyseal growth cartilage.

Methods

• Eight Standardbred foals were used in the study, ranging from newborns to 7-weeks-old.
• They underwent a barium perfusion procedure to map out the blood vessels within growth cartilage canals of a hindlimb.
• The joints were cleared using methyl salicylate and observed in their intact form.
• The bones were then cut into 5 mm thick sections, decalcified, and radiographed.
• Selected sections were cleared again using methyl salicylate and examined under low magnification.
• Finally, sections from specific areas of the bones (the sagittal ridge of the distal third metatarsal bone and the plantar half of the proximal phalanx) were examined histologically.

Findings

• Areas with thicker cartilage had a higher number of perfused vessels compared to thinner counterparts.
• The blood vessels within the cartilage canals were oriented either parallel or perpendicular to the ossification front – the area where bone formation occurs.
• As growth continues, these vessels are integrated into the ossification front and switch to relying on a source of blood from arteries beneath the cartilage.
• No significant lesions were observed in the foals macroscopically.
• However, microscopic examination revealed pathological changes in one of the foals – a 7-week-old specimen displayed an area of cell death in the cartilage surrounded by tissue growth.

Conclusions

• The study identified a particular anatomical feature that introduces vulnerability in blood vessels, with implications for disease onset. This feature – the route of vessels through the ossification front to enter cartilage canals – is also reported in the tarsus, another part of the hock often affected by bone and cartilage disease.
• Due to their shared anatomical feature, the researchers suggest osteochondrosis (a group of disorders affecting bone growth) in the metatarsophalangeal joint may occur through the same pathogenetic mechanism as observed in the tarsus.

This research improves understanding of how blood supply to growing cartilage can impact joint health in young horses, opening avenues for further studies in preventative measures and treatments for related disorders.