Determination of Articular Cartilage Deformation using 2-Photon Microscopy

Abstract

In-vivo movement of bones comprising synovial joints has been evaluated in various ways and has been calculated theoretically to understand joint biomechanics. In order to assess joint loading and bone movements accurately, the deformation behavior of articular cartilage has been investigated in confined and unconfined compression experiments, but to date there exist no data on dynamic in vivo deformation of articular cartilage in intact joints loaded through controlled muscular contraction. The objective of this study was to measure articular cartilage deformations as a function of load in an intact joint of live animals.We developed a novel in-vivo testing system that allows for controlled loading of mouse knees through muscular contractions and quantification of the associated, cartilage and chondrocyte deformations. Imaging of articular cartilage deformation across the entire medial compartment of the knees was performed using Zeiss 510 coupled with a Coherent Chameleon IR-laser tuned at 780 nm for two-photon excitation (Figure 1a, b).Increases in muscular loading of the knee caused an increase in articular cartilage deformation. Fifty and 80% of the maximal muscular forces produced average peak articular cartilage strains for 8s contraction of 10±1% to 19±2% respectively (Figure 1c).View Large Image | View Hi-Res Image | Download PowerPoint Slide