Podium 2: Osteoarthritis, Treatments & Mechanisms

Meghan E. Kupratis, Uriel Gonzalez, Atia Rahman, Elise A. Corbin, David L. Burris, Christopher Price

University of Delaware

During osteoarthritis (OA), decreased stiffness is thought to expose cartilage to elevated compressive and shear strains. Increasing cartilage stiffness via collagen crosslinking (CXL) has seen interest as a means to stabilize cartilage and prevent degeneration. However, recent studies from our group reveal that mechanical properties are poor predictors of healthy cartilage tribomechanics during biofidelic sliding. We can replicate in vivo friction behaviors in the convergent stationary contact area (cSCA) via a novel mechanism known as tribological rehydration. To determine whether CXL alters cartilage lubricity, bovine osteochondral explants underwent sequential microindentation and cSCA characterization in their naïve state and after CXL via glutaraldehyde or genipin exposure. As expected, CXL significantly increased cartilage tensile and compressive moduli. During cSCA tests, strain during ramp loading to 7N decreased following CXL, resulting in decreased in situ contact areas. Consequently, CXL cartilage experienced 66% higher contact stresses. Naïve cartilage sustained near-physiological friction in PBS-lubricated contacts (µ=0.010?0.003) and in vivo-like friction (µ=0.003?0.001) in synovial fluid (SF). CXL led to elevated friction in both PBS- and SF-lubricated contacts (µ=0.16?0.007 and µ=0.038?0.017, respectively). Collectively, this work demonstrates that increased cartilage stiffness does not necessarily equate to improved, or even adequate, tribomechanical function under biofidelic sliding conditions.

Research Area: Cartilage