Evaluation of age-related changes in the structure of the equine tarsometatarsal osteochondral unit.

This research investigates how age affects the thickness and structure of various components of the horse’s tarsometatarsal joint, including the hyaline cartilage, calcified cartilage, total cartilage, and subchondral bone. The study found that age-related changes vary across these tissues and could influence the joint’s overall properties.

Methodology

• The researchers collected 23 tarsal joints from the cadavers of 23 ponies that were aged from 11 days to 25 years. Note that the ponies were limited to pasture exercise and were euthanized due to reasons unrelated to this study.
• The tarsal joints were categorized into different age groups: 11 days old, 6 to 9 months old, 2 to 3 years old, 6 to 8 years old, 11 to 17 years old, and 20 to 25 years old.
• A histological examination and histomorphometric measurements were performed on the hyaline cartilage, calcified cartilage, total cartilage, and subchondral bone at medial and lateral sites.

Results

• A significant decrease in the thickness of the hyaline cartilage and total cartilage was observed with increasing age.
• Conversely, there was a significant increase in the thickness of the calcified cartilage and subchondral bone with increasing age.
• Changes in the arrangement of chondrocytes and collagen fibers, as well as the morphology of the tidemark and osteochondral junction, were noticeable across different age groups.

Conclusions

• The study concluded that the various tissues of the osteochondral unit undergo different changes with age. The way each tissue responds may be related to how they respond to strains caused by pasture exercise.
• This disparity in the response of tissues could influence how the overall properties of the osteochondral unit change with age.
• The results suggest that these age-related changes might be indicative of changes that develop before osteoarthritis symptoms appear.