Add squatting to the picture.
Medical anthropologists have determined in broad cross-cultural surveys that people in cultures where squatting is common, versus sitting in chairs, have virtually no knee problems in old age. This is because squatting (sitting with your knees flexed to 180 degrees while the soles of your feet are on the ground) pumps sinovial fluid constantly in and out of the reservoirs into the kneecap, but sitting in a chair for hours causes the sinovial fluid to calcify through inaction.