The function of the knee is particularly important for weight bearing activities, such as walking, running and going up/down stairs. The load distributed over the kneecap can be up to five times the body weight, particularly on going down stairs. Knee pain is a common problem with many causes, from acute injuries to medical conditions. Common causes of knee pain include sprains and strains, anterior knee pain (pain around the kneecap), cartilage damage, osteoarthritis, tendonitis and many more.