Why Do My Knees Hurt?

“Bend the knee,” a triumphant Queen Cersei tells Eddard Stark after outfoxing the nettlesome Northerner in “Game of Thrones.”

When the noble Lord Stark declines, at great risk to his health, it is usually chalked up to an excess of probity. But what if he doesn't bend the knee because he can't bend the knee? The guy is no spring chicken. Maybe, faced with the choice of forcing his achy knee to bend one more time or losing his head swiftly and cleanly, he figures, “Enough already.”

Some of us baby boomers would understand.

As people age, it is often the knee that puts them on notice that their body is not always going to cooperate with whatever they have in mind. It may be stiffness. It may be weakness. It may be pain. But whether you’re just getting out of bed or walking onto the court, you know something has changed.

To a generation used to coming into the office on Mondays and swapping war stories about youthful-sounding injuries like shin splints and rotator cuff tears, the diagnosis may be unwelcome: arthritis. Osteoarthritis, to be exact, which is the most common form of arthritis in the knee.

The condition occurs as the cartilage that coats the bones at the joints and eases their passage, known as articular cartilage, wears away with use. Part of the problem is that with age, the chemistry of the cartilage changes so that it retains less water, making it more susceptible to stress, doctors say. Being overweight can make it worse.

But in the end, genetics, and the kind of cartilage you got from your parents, may play the biggest role. It is a little like buying tires, said Dr. Frederick M. Azar, chief of staff of the Campbell Clinic in Memphis and an official with the American Academy of Orthopaedic Surgeons. “You can get nice treads or you can get retreads,” he said.