Structure, composition and fibril-reinforced poroviscoelastic properties of bovine knee ligaments and patellar tendon

Abstract

Tissue-level stress-relaxation of ligaments and tendons in the toe region is characterized by fast and long-term relaxations and an increase in relaxation magnitude with strain. Characterizing the compositional and structural origins of these phenomena helps in the understanding of mechanisms of ligament and tendon function and adaptation in health and disease. A three-step tensile stress-relaxation test was conducted on dumbbell-shaped pieces of bovine knee ligaments and patellar tendon (PT) ( n = 10 knees). Their mechanical behaviour was characterized by a fibril-reinforced poroviscoelastic material model, able to describe characteristic times and magnitudes of fast and long-term relaxations. The crimp angle and length of tissues were measured with polarized light microscopy, while biochemical contents were determined by colorimetric biochemical methods. The long-term relaxation time was longer in the anterior cruciate ligament (ACL) and PT compared with collateral ligaments ( p < 0.05). High hydroxyproline content predicted greater magnitude and shorter time of both fast and long-term relaxation. High uronic acid content predicted longer time of long-term relaxation, whereas high crimp angle predicted higher magnitude of long-term relaxation. ACL and PT are better long-term stabilizers than collateral ligaments. The long-term relaxation behaviour is affected or implied by proteoglycans and crimp angle, possibly relating to slow structural reorganization of the tissue.

A musculoskeletal finite element model of rat knee joint for evaluating cartilage biomechanics during gait

“…Characterization of rat meniscus material properties and implementation of these properties into FE models are part of our upcoming plan. Sixth, although experimental tests on rat ligaments and tendons are challenging to conduct due to the small size of the samples, it is worth characterizing both the nonlinear toe and linear regions of the ligaments for better understanding of the function of ligaments and tendons in healthy, injured, and diseased knees [ 83 ]. Numerically, knee cruciate and collateral ligaments were modeled as springs since previously they suggested to produce acceptable results [ 17 , 45 ].…”

Near infrared spectroscopic evaluation of biochemical and crimp properties of knee joint ligaments and patellar tendon

“…Even though the biochemical composition [ 8 ] and collagen crimp parameters [ 40 ] differ between primary ligaments and PT, ligament type was not included as a predictor in the PLSR models. Rather, each sample was treated as independent ligamentous tissue.…”

A musculoskeletal finite element model of rat knee joint for evaluating cartilage biomechanics during gait

“…Characterization of rat meniscus material properties and implementation of these properties into FE models are part of our upcoming plan. Although experimental tests on rat ligaments and tendons are challenging to conduct due to the small size of the samples, it is worth characterizing both the nonlinear toe and linear regions of the ligaments for a better understanding of the function of ligaments and tendons in healthy, injured, and diseased knees [73]. Sixth, volumetric information of the healthy tibiofemoral joint of the rat was obtained using the presented MRI acquisition scheme with a high isotropic resolution of 37 µm (using an 11.74T µMRI scanner).…”