Saddle height is important. It should be high enough so that there is still a slight bend in your knee and your butt is not rocking on the saddle. Try to keep your cadence up to at least 80 rpm.
My doctor x-rayed my right knee and said the cartilage behind the kneecap is gone. Told me to take glucosamine condroitin for at least 3 months to see if it helps.
Raising the saddle did the most good so far.