Osteoarthritis (OA) of the knee is the most common form of arthritis and a major cause of disability and pain. Yet not all sore knees indicate that you’re developing arthritis. How can you tell the difference?Researchers sought to answer this question by following a group of 5,000 men and women who had or were at high risk of developing knee OA for seven years, on average. The researchers determined that the very earliest sign of knee osteoarthritis showed up as knee pain while going up and down stairs. This symptom showed up even before x-rays showed any evidence of arthritis. Osteoarthritis is a progressive disease, so without intervention, it progressed from pain on the stairs, to pain while walking, then in standing, and finally in sitting and lying in bed. No one wants to wind up being kept awake by pain when they’re trying to sleep, so what can you do if you find your knees hurting each time you walk up and down a flight of stairs?The good news is that there is a lot you can do…