New Insights into Degeneration of Knee Joints

Duke University Medical Center and Durham VA Medical Center researchers have shown that while the mechanical stresses of normal exercise are important for the health of the meniscus, a layer of buffering tissue in the knee joint, these stresses coupled with a potent immune system response can lead to the ultimate degeneration of the knee joint as seen in osteoarthritis.

Furthermore, the researchers report, the chemical nitric oxide is a critical "signal" in controlling how the immune system responds to the stress. This insight could lead to new therapies for osteoarthritis that would target this interaction between nitric oxide and the inflammatory response, the researchers added.

The primary function of the meniscus, which is located within the knee joint between the thigh bone (femur) and the lower leg bone (tibia), is to act as a shock absorber and a distributor of weight within the joint. It is a type of cartilage made up of a matrix of fibers, primarily collagen, which provide toughness and durability.

"Contrary to common perception, the meniscus is a living tissue that is slowly and continually breaking down old collagen and building new collagen," said Farshid Guilak, Ph.D., director of orthopedic research at Duke. The findings of the Duke and VA team were published today (July 1, 2003) in the Journal of Applied Physiology.

"We have found that mechanical stresses on the meniscus