Regional differences in biochemical, biomechanical and histomorphological characteristics of the equine suspensory ligament.
Authors: Souza M V, van Weeren P R, van Schie H T M, van de Lest C H A
Journal: Equine veterinary journal
Summary
# Editorial Summary Suspensory ligament injuries occur with different frequencies across anatomical regions, yet the structural basis for this variation remains poorly understood. Souza and colleagues examined 38 forelimbs using biochemical analysis (measuring glycosaminoglycan, collagen and cross-link content across seven regions), biomechanical testing (tensile loading across five regions) and histomorphological evaluation to characterise regional differences in healthy ligaments. The mid-body demonstrated substantially greater stiffness and elastic modulus compared to all other regions (P<0.01), whilst strain at failure was significantly lower in this region (P<0.0001)—a combination reflecting a stiffer but more brittle structure. The origin showed lower cellularity and matrix content relative to branches and mid-body, whilst pentosidine (a non-enzymatic collagen cross-link associated with age-related stiffening) accumulated preferentially in the origin rather than at the lateral insertion. These findings suggest that the mechanical transition between the relatively compliant proximal origin and the stiffer mid-body, coupled with different patterns of collagen remodelling across regions, may predispose specific anatomical zones to injury under load—information relevant for practitioners assessing injury risk, designing rehabilitation protocols, and counselling clients on expected recovery patterns for lesions in different suspensory locations.
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Practical Takeaways
- •The suspensory ligament has distinct regional properties: the mid-body is stiffer and more prone to rupture under high strain, while origin and branches are more compliant—this explains why injuries cluster in specific anatomical locations
- •Lesion prevalence varies by region due to compositional and mechanical differences rather than being random; understanding these weak points helps target prevention and rehabilitation strategies
- •Regional heterogeneity suggests that one-size-fits-all treatment protocols may be suboptimal; rehabilitation and management should account for the specific mechanical demands and tissue characteristics of each ligament region
Key Findings
- •DNA and GAG content were significantly lower in the ligament origin (OL/OM) compared to all other regions
- •Mid-body region demonstrated substantially higher stiffness and modulus of elasticity (P<0.01) compared to branches and origin
- •Pentosidine cross-link levels were highest at the origin and significantly lower at the lateral insertion branches
- •Strain at failure was lower in mid-body despite comparable rupture force to other regions, suggesting regional mechanical specialization