Podium 2: Osteoarthritis, Treatments & Mechanisms

Shu-Jin Kust, Dana Voinier, Kyle D. Meadows, Dawn M. Elliott, Daniel K. White, and Axel C. Moore

University of Delaware

Articular cartilage lines the ends of long bones in synovial joints and functions to provide load-bearing and low-friction articulation. These biomechanical functions are largely driven by the poroelastic mechanics (fluid pressurization) of the articular cartilage. Unfortunately, the same poroelastic pressure that leads to load-bearing and lubrication also drives fluid exudation and concurrent tissue strain. In vivo static loading (e.g., standing) produces as much as -30% strain in 60 min. Interestingly, in vivo active loading (e.g., walking, knee bends, cycling, running) produces an initial period of fluid exudation and strain (~ -5%); after which, active loading arrests further fluid loss and tissue strain. While static and active loading drive fluid exudation and cartilage strain, static unloading (e.g., lying down) provides recovery, and to date, is the only in vivo mechanism that has been shown to restore hydration and strain. We hypothesize that active loading is actually a recovery mechanism that has yet to be observed.

In this study, we use magnetic resonance imaging to evaluate the in vivo strain of articular cartilage in human knees following: (1) standing, (2) lying down, and (3) walking. The results demonstrate that active loading (walking) is indeed an in vivo recovery mechanism for articular cartilage.

Research Area: Cartilage