Collagen fibre arrangement and functional crimping pattern of the medial collateral ligament in the rat knee

Abstract

Ligaments have been described as multifascicular structures with collagen fibres cross-connecting to each other or running straight and parallel also showing a waviness or crimping pattern playing as a shock absorber/recoiling system during joint motions. A particular collagen array and crimping pattern in different ligaments may reflect different biomechanical roles and properties. The aim of the study was to relate the 3D collagen arrangement in the crimping pattern of the medial collateral ligament (MCL) to its functional role. The MCL is one of the most injured ligaments during sports activities and an experimental model to understand the rate, quality and composition of ligaments healing. A deep knowledge of structure-function relationship of collagen fibres array will improve the development of rehabilitation protocols and more appropriate exercises for recovery of functional activity. The rat MCL was analysed by polarized light microscopy, confocal laser microscopy and scanning electron microscopy (SEM). Histomorphometric analysis demonstrated that MCL crimps have a smaller base length versus other tendons. SEM observations demonstrated that collagen fibres showing few crimps were composed of fibrils intertwining and crossing one another in the outer region. Confocal laser analyses excluded a helical array of collagen fibres. By contrast, in the core portion, densely packed straight collagen fibres ran parallel to the main axis of the ligament being interrupted both by planar crimps, similar to tendon crimps, and by newly described right-handed twisted crimps. It is concluded that planar crimps could oppose or respond exclusively to tensional forces parallel to the main ligament axis, whereas the right-handed twisted crimps could better resist/respond to a complex of tensional/rotational forces within the ligament thus opposing to an external rotation of tibia.

Tissue Strain Reorganizes Collagen With a Switchlike Response That Regulates Neuronal Extracellular Signal-Regulated Kinase Phosphorylation In Vitro: Implications for Ligamentous Injury and Mechanotransduction

“…In addition, although fibers have been reported to uncrimp during tensile loading of ligaments in animal and computational studies [72,82], that additional mechanism of fiber deformation was The distribution of fiber angle indicates more realignment toward the loading direction (690 deg) at 16% strain, which is different from the uniform distributions that are observed at 0% and 7% strain. Plotting the Chi-squared statistic against the applied bulk strain shows that the fiber angle distribution becomes less uniform with increasing strain above 10%.…”

“…When the bulk tissue strain remains within the physiologic limit ($8-12%), collagen fibers undergo almost no realignment but may bend and/or uncrimp to accommodate macroscopic deformation [72,[81][82][83]; during that regime, the fibers experience small strains that are even lower than the bulk strain (Figs. 5 and 6).…”

Anatomia microscópica e ultraestrutura do joelho da paca (Cuniculus paca Linnaeus, 1766)

“…A organização paralela, a orientação longitudinal ao eixo do ligamento e o agrupamento em feixes das fibras de colágeno contribuem para resistência dos ligamentos à carga de tração aplicada de um osso a outro durante o movimento (Provenzano & Vanderby Jr 2006, Franchi et al 2010b.…”

“…As ondulações das fibras de colágeno possibilitam resistência ao ligamento durante o estiramento (Franchi et al 2010a, Franchi et al 2010b. Estas ondas evitam o rompi- mento do ligamento, desde que o estiramento ocorra dentro dos limites normais (Viidik & Ekholm 1968, Frank et al 1985, Benjamin & Ralphs 1997.…”

Application of quantitative second-harmonic generation microscopy to posterior cruciate ligament for crimp analysis studies

“…[34][35][36] This helical fashion is also called "fibrillar crimp." 37,38 Furthermore, the regional difference between the periphery (anterior, posterior) and core portions within ligaments has been analyzed using metrics such as the number of crimps, fibril diameter, and fiber arrangement. 38,39 However, these approaches have low-axial resolution and require relatively invasive sample preparation stages including fixation, dehydration, and coating with gold.…”