RELATIONSHIP BETWEEN COLLAGEN ORGANISATION AND MATERIAL PROPERTIES OF TENDON: IMPLICATIONS FOR RECONSTRUCTIVE SURGERY

Abstract

Introduction: Different tendons and ligaments have a specific elasticity which relates to their role in joint movement and locomotion. To ensure an optimal functional outcome it is essential that this mechanical property is restored following surgical procedures to repair or replace damaged tendons and ligaments. This demands appropriate selection of an autograft or artificial construct aided by an understanding of how molecular composition and morphology determines the stiffness of the material. This study tests the hypothesis that tendons with a higher elastic modulus (stiffer) have larger collagen fibril diameters and lower water and sulphated glycosaminoglycan (GAG) contents.

Methods: The superficial digital flexor tendon (SDFT, 30 pairs), deep digital flexor tendon (DDFT, 6 pairs), suspensory ligament (SL, 6 pairs) and common digital extensor tendon (CDET, 6 pairs) were collected from the forelimbs of horses aged 2–23 years destroyed for reasons other than tendon injuries. Left limb tendons were tested to failure in a hydraulic materials testing machine (Dartec) following measurement of cross sectional area. Collagen fibril diameters, water content and sulphated GAG content were measured in tendon tissue from the right limb. Statistical significance was evaluated using Spearman’s correlation and a general linear model (SPSS software).

Results: The elastic modulus was significantly (p< 0.001) different between the different structures and showed a significant positive correlation with the mass average collagen fibril diameter (MAFD) for the different structures and within the SDFT (FIG. I). The water content showed a significant negative correlation with elastic modulus and significant positive correlation with GAG content.

Discussion and Conclusion: Tendons composed of a stiffer material have larger collagen fibril diameters which are associated with lower water and GAG contents. These characteristics should be considered when choosing suitable replacements in tendon reconstruction procedures. Future work to determine the mechanisms that control collagen fibril diameters and water content will aid in the design of bioengineered constructs.