Mechanical impact and articular cartilage.

Mechanical impact forces on articular cartilage can cause substantial damage. Car accidents, falls, and sports injuries have a tremendous effect on the U.S. and world populations, both in terms of economic and quality of life costs. While the effects of impact forces are known to be damaging, tolerance levels of cartilage to these forces and the mechanobiologic sequelae are still mostly unknown. Impact studies can be difficult to compare to each other due to the complex array of mechanical factors that are involved in a single impact. Previous work includes mathematical models, acute effects of impact, and in vivo and explant models of impact. These experiments have found that articular cartilage has a threshold above which impact forces are damaging, though this threshold is likely dependent on many factors, both genetic and environmental. This type of damage has been shown to vary according to the severity of the impact, from leaving the articular cartilage surface intact to fracture of the subchondral bone. Some studies have initiated investigations into ways to ameliorate the injurious response to impact, which may allow some patients to avoid the ensuing cartilage degeneration and osteoarthritis. Much work remains to be performed in understanding the genetic and biochemical response to impact. The goal of this research is to eventually decrease the incidence of posttraumatic arthritis and possibly even delay primary osteoarthritis, which can be achieved by using a robust testing design that includes morphological, biomechanical, quantitative biochemical, and genetic characterization of a model system for articular cartilage impact. This model system can then be used to test treatments to prevent degenerative changes in articular cartilage.