Over time, wear and tear on the knee can erode the protective cartilage that cushions the surfaces of the knee joint. When the cartilage erodes, the result is often a painful condition known as osteoarthritis.
"Classic symptoms of osteoarthritis in the knee include stiffness after prolonged sitting. In the early stages, after you stand up and move around, you loosen up and feel better," says Dr. Matthew T. DesJardins. "Eventually, as the osteoarthritis progresses, the patient experiences pain with activity that doesn't resolve, as well as decreased mobility."
Osteoarthritis is one of the most common ailments of the knee and is quite often associated with aging. However, even young athletes can experience the condition. "Take a high school soccer player who experiences a major knee injury that requires surgical repair," Dr. DesJardins says. "If there is an injury to the cartilage, this can progress over the years into degenerative arthritis."
Further, genetics and lifestyle - such as a job that puts a lot of wear and tear on the knee - can predispose someone to osteoarthritis.