Review Question - QID 5746

Advanced glycation end-products (AGEs) are found in aging and osteoarthritis (OA) and result in increased articular cartilage stiffness and increased brittleness.

AGEs are produced from spontaneous nonenzymatic glycation of proteins when sugars (glucose, fructose, ribose) react with lysine or arginine residues. Because of the low turnover, cartilage is susceptible to AGEs accumulation. The accumulation of AGEs has been thought to play a role in the development of OA of the knee and ankle.

Li et al. reviewed age-related changes in cartilage. They state that with aging, there is excessive collagen cross-linking increases cartilage stiffness, while shortening/degradation of aggrecan leads to loss of sugar side chains and water-binding ability, while increased levels of AGEs are associated with a decline in anabolic activity. There is also increased chondrocyte death and/or apoptosis.

Anderson et al. reviewed the relationship between osteoarthritis and aging. They state that knee cartilage thins with aging (especially on the femoral and patellar sides, suggesting a gradual loss of cartilage matrix. AGEs formation leads to modification of type II collagen by cross-linking of collagen molecules, increasing stiffness and brittleness and increasing susceptibility to fatigue failure.

Incorrect Answers:
Answer 1: While AGEs are found in aging cartilage and predispose to OA formation, increased cartilage stiffness (rather than softening) results.
Answer 3: Unresurfaced patellar cartilage will show similar changes to the other compartments prior to resurfacing. Thinning is a result of loss of cartilage matrix, rather than accumulation of AGEs.
Answer 4: AGEs are characteristic of OA (rather than RA). It is found in articular cartilage (rather than synovium).
Answer 5: AGES are not characterstic of hemarthrosis and do not result in cartilage staining.