Regional differences in biochemical, biomechanical and histomorphological characteristics of the equine suspensory ligament.

The research investigates the variation in characteristics of different portions of horse suspensory ligaments (SLs) such as structure, composition, and function. It explores whether regional diversities within this ligament could explain why varying frequencies of ligament-related illnesses occur in different parts of it.

Methodology

• The researchers collected suspensory ligaments from 38 horse limbs for this study.
• The collected ligaments underwent biochemical (20 ligaments), biomechanical (14 ligaments), and histomorphological (4 ligaments) assessments.
• The assessments observed seven specific regions of the SL: the lateral and medial part of the origin, mid-body, axial and abaxial parts of the lateral and medial branches.
• The team analysed sulphated glycosaminoglycan (S-GAG), DNA and collagen content, degree of lysyl hydroxylation, and counts of enzymatic and nonenzymatic cross-links in these regions.
• The passive resistance to tensile loading was measured in five regions within the ligament, excluding the lateral and medial part of the origin.

Results

• The findings suggest that the DNA content in the lateral and medial part of the ligament’s origin is lower compared to the other areas.
• Glycosaminoglycan content was also seen to be lower in the lateral and medial part of the origin and highest in abaxial parts of the lateral and medial branches.
• Collagen content was least in the origin and greatest in the axial part of the lateral and medial branches.
• Regarding pentosidine levels, the highest were found in the origin and significantly lower in the lateral insertion.
• There were no noted differences regarding hydroxylysylpyridinoline (HP) cross-links or lysyl hydroxylation across the sections.
• The middle section showed considerably higher measures of stiffness and modulus of elasticity compared to all other regions, excluding the medial part of the abaxial branch.
• The strain at failure was observed to be lowest in the middle section, yet it produced a comparable force at rupture similar to other regions.

Conclusions

• The research concludes that while the matrix composition shows some variation across different regions of the SL, these differences are relatively minor.
• The middle portion of the ligament demonstrates greater stiffness than the branches, signifying distinctive properties and relevance.
• These mechanical differences between the mid-body, branches, and origin of the ligament may be the explanatory factors behind use-related differences in the prevalence of lesions occurring.