My dad had surgery scheduled for his elbow when he started using glucosamine. Within a week he could feel improvement. He was able to cancel the surgery. It is nearly 10 yrs later and he still has not had any surgery.
My mother had been on traction for her neck and had problems with other joints too. After a couple of weeks on it her chiropractor could tell a difference without any mention from her. Unfortunately regular use was not enough to keep her from needing knee replacement at around age 70.