Assessing the micromechanical architecture of joint tissues with speckle rheological microscopy

Joint tissues rely on a finely tuned interplay between solid (elastic) and fluid (viscous) constituents to support their mechanical function. Degradation of these constituents due to disease or trauma disrupts the elastic and viscous susceptibility of joint tissues, directly impairing joint function. We present Speckle rHEologicAl micRoscopy (SHEAR) to investigate the viscoelastic behavior of intact joint tissues without making contact or otherwise manipulating the sample, offering a promising non-destructive imaging tool for assessing mechanical function in degenerative joint disease. SHEAR demonstrated strong correlation to conventional rheometer in healthy swine knee joint tissues. In swine cartilage with focal lesions and surgically excised cartilage specimens from human patients undergoing knee replacement, SHEAR revealed transformation in both the elastic and viscous landscape of the tissue. SHEAR has the potential to provide a powerful tool for biomechanical analysis of joint structures and pave new paths for improved diagnosis and therapy of degenerative joint disease. SHEAR provides a contact-free, non-destructive imaging tool for assessing mechanical function of joint tissues in degenerative joint disease and repair via high-resolution mapping of frequency-dependent tissue viscoelastic properties.