Tendon/Ligaments: Structure and Composition.
Authors: S. Durgam
Journal: The Veterinary clinics of North America. Equine practice
Summary
# Editorial Summary Soft tissue injuries of the equine metacarpal region—specifically the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT) and suspensory ligament—represent some of the most persistent challenges in equine practice, and understanding their distinct structural architectures is fundamental to improving diagnostic and therapeutic approaches. Durgam's review examines the hierarchical organisation and composition of these three tissues, highlighting that the mid-metacarpal SDFT operates under repetitive strain at its functional limits, whilst the intrasynovial DDFT's fibrocartilage and embedded chondrocyte-like cells within a proteoglycan-rich extracellular matrix enable low-friction gliding—a specialisation often overlooked when assessing injury patterns. Particularly significant is the discussion of enthesis injuries in the suspensory ligament, where the collagen and non-collagen matrix specialisations at the bone-ligament interface remain poorly characterised despite their clinical prevalence. The structural and compositional differences between these tissues demand that farriers, veterinarians and physiotherapists tailor their diagnostic imaging protocols, rehabilitation timelines and regenerative medicine applications rather than applying generic soft tissue injury frameworks. Practitioners should consider these tissue-specific mechanical and biochemical properties when selecting imaging modalities, interpreting findings, and designing individualised treatment plans to optimise healing and functional restoration.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding the specialized structural differences between SDFT, DDFT, and suspensory ligament is critical for selecting appropriate diagnostic imaging and treatment protocols
- •The fibrocartilage component of the DDFT's intrasynovial portion has specific functional requirements that standard tendon healing may not address—consider tissue-specific rehabilitation strategies
- •Current knowledge gaps regarding enthesis structure mean newer therapies targeting the bone-ligament interface should be approached carefully and monitored closely for efficacy
Key Findings
- •Mid-metacarpal SDFT exhibits hierarchical structure and functions at the limit of repetitive strain tolerance
- •Intrasynovial DDFT contains fibrocartilage with chondrocyte-like cells embedded in proteoglycan-rich extracellular matrix for resistance-free gliding
- •Suspensory ligament enthesis injuries are common but the collagen and non-collagen ECM structure-function specializations at the bone-ligament interface remain understudied
- •Differential micro- and macro-structure of equine tendons and ligaments should inform development and refinement of diagnostic and therapeutic approaches