Knee joint is affected by vitiation of vata and obesity. If u r overweight, then try to reduce weight. There are some do's and don'ts u have to follow: Avoid cold - no cold drinks, no cold water intake. No cold bath. Avoid taking legumes, except moong. Avoid sleeping late night.
U can take Gandh tail oil internally and can apply appropriate oil for local application after consulting ur doctor, followed by hot fomentation. Panchakarma treatment like Janubasti will be very useful.