Regional and disease-related differences in properties of the equine temporomandibular joint disc.

The research paper presents an in-depth analysis of the differences in properties of horse temporomandibular joint (TMJ) discs due to age, region of the disc, and the presence of TMJ osteoarthritis. The study finds that the TMJ disc of horses, which serves a crucial role in TMJ disorders, exhibits varying levels of glycosaminoglycan content and compressive stiffness across different regions, increases with age, and has region-specific changes related to joint disease.

Sample Collection and Evaluation

• The study involved dissecting discs from both TMJs of 16 horses that were euthanized due to reasons not related to the study. Each joint was thoroughly evaluated and scored as normal, mild osteoarthritis (OA), or severe OA.
• Samples were taken from various regions of the disc: rostral, caudal, lateral, central, and medial. These samples underwent compressive testing, quantitative biochemistry, and histology. The lateral, central, and medial region samples underwent additional tensile property testing in the rostrocaudal and mediolateral directions.

Findings

• The study found that the TMJ disc in horses is highly anisotropic, with varying glycosaminoglycan (GAG) content and compressive stiffness across the disc regions.
• The research revealed an increase in GAG content and compressive stiffness with age.
• The findings also suggest a difference in the mechanical demands on the TMJ disc between horses and other species. This is due to the horse’s TMJ disc exhibiting greater compressive stiffness throughout the disc and more GAG content in its rostral region compared to other herbivores.
• Noteworthy is a region-specific decrease in compressive stiffness associated with joint disease. This decrease in stiffness appears to be related to cartilage erosions in the underlying condylar surface.

Implications

• The results of this research unearth vital information about the TMJ disc properties in horses and its role in TMJ disorders in animals.
• The findings can foster a better understanding of TMJ pathology in animals, leading to more effective treatments for TMJ disorders both in humans and animals.
• The insights have potential applications in veterinary practice, particularly in diagnosing and managing osteoarthritis in horses.