Tendon/Ligaments: Structure and Composition.

This research focuses on the structure and composition of frequently injured soft tissues – the mid-metacarpal SDFT, intrasynovial DDFT, and suspensory ligament – in equine athletes, highlighting their unique characteristics and the importance of considering these factors in the diagnostics and therapies for healing and restoring functionality.

Middle Metacarpal SDFT Structure

• The mid-metacarpal SDFT, or the superficial digital flexor tendon, in horses is a tendon that frequently sustains injuries, particularly in equine athletes.
• This tendon exhibits a hierarchical structure that involves a complicated system of progressively larger fibrils, fibres, fibre bundles, and fascicles, allowing it to withstand repetitive strains at its functional limit.
• This repeated stress constitutes the crux of many tendon injuries in horses.

Intrasynovial DDFT Composition

• The intrasynovial deep digital flexor tendon (DDFT) possesses fibrocartilage, a tough, dense, fibrous material that helps resist tension and compression forces. This structure allows the equine tendon to glide without resistance against opposing bony surfaces, reducing the likelihood of injury.
• The DDFT contains chondrocyte-like cells that are embedded in an extracellular matrix (ECM) rich in proteoglycans, a group of compounds important for joint lubrication and hydration.

Suspensory Ligament Injuries

• The suspensory ligament in horses is also prone to injury, particularly at the enthesis, or point of attachment to the bone.
• This research highlights that the collagen and non-collagen extracellular matrix structure-function specializations at the bone-ligament interface are generally understudied, which could provide significant insights for injury treatments.

Conclusions and Future Work

• The study emphasizes the significant differences in micro- and macro-structures of equine tendons and ligaments when considering diagnostic approaches and therapeutic interventions.
• The researchers suggest that understanding these structural details can help refine current techniques or implement novel ones aimed at enhancing healing and restoring functionality to these crucial tissues.