Effects of osteoarthritis and pathological walking on contact stresses in femoral cartilage.

Osteoarthritis is a widespread abnormality in synovial joints leading to increasing pain and potential work disability in middle-aged and older populations. A primary cause of osteoarthritis is related to damages from high local stresses combined with insufficient self-healing of cartilage. In this framework, it is the goal of the present contribution to offer a thermodynamically consistent simulation of a highly anisotropic, heterogeneous, osmotic swelling and poroviscoelastic model of healthy and osteoarthritic articular cartilage based on the Theory of Porous Media. Physiological and pathological loading patterns are included by means of multi-body system calculations on patients. The contact stresses at the cartilage surface are represented by means of three-dimensional and simplified stereographic views of the femoral head. For normal walking, the stress peaks are higher in the degenerated case than in the healthy case. Interestingly, pathological walking combined with degenerated cartilage tissue minimises the occurrence of high local stresses.