Structural Analysis of Articular Cartilage Using Multiphoton Microscopy: Input for Biomechanical Modeling

• Published in: IEEE transactions on medical imaging Vol. 30; no. 9; pp. 1635 - 1648
• Main Authors: Lilledahl, Magnus B., Pierce, David M., Ricken, Tim, Holzapfel, Gerhard A., de Lange Davies, Catharina
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.09.2011; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Animals; Cartilage; Cartilage, Articular - cytology; Chickens; Collagen; Collagen - chemistry; Collagen - ultrastructure; Compressive Strength; Computer Simulation; constitutive modeling; Dispersion; Elasticity; Extracellular Matrix; Fabrics; Finite Element Analysis; finite element simulation; Imaging, Three-Dimensional; Microscopy; Microscopy, Fluorescence, Multiphoton - methods; Models, Biological; multiphoton microscopy; poroelasticity; second harmonic generation; Solids; Studies; Three dimensional displays
• ISSN: 0278-0062; 1558-254X; 1558-254X
• DOI: 10.1109/TMI.2011.2139222

The 3-D morphology of chicken articular cartilage was quantified using multiphoton microscopy (MPM) for use in continuum-mechanical modeling. To motivate this morphological study we propose aspects of a new, 3-D finite strain constitutive model for articular cartilage focusing on the essential load-bearing morphology: an inhomogeneous, poro-(visco)elastic solid matrix reinforced by an anisotropic, (visco)elastic dispersed fiber fabric which is saturated by an incompressible fluid residing in strain-dependent pores. Samples of fresh chicken cartilage were sectioned in three orthogonal planes and imaged using MPM, specifically imaging the collagen fibers using second harmonic generation. Employing image analysis techniques based on Fourier analysis, we derived the principal directionality and dispersion of the collagen fiber fabric in the superficial layer. In the middle layer, objective thresholding techniques were used to extract the volume fraction occupied by extracellular collagen matrix. In conjunction with information available in the literature, or additional experimental testing, we show how this data can be used to derive a 3-D map of the initial solid volume fraction and Darcy permeability.