I am 67 yrs old and have a problem with my left knee joint. Whenever I straighten my left leg from a sitting position, the knee joint makes a sound like "tak. The right knee when touched by hand while straightening, I can feel some friction sound. In fact I had visited an Ortho a couple of months back and was under treatment for around 2 months. I find it a bit difficult while getting down the staircase. When I stand on left leg, at times I fail to balance properly. When I get down from the Bus in which I travel to my work place, I get a slight jerk on landing on my left leg. Please advise.