I have been putting up with NP for years and now at age 93 my right leg is worse. A doctor gave me 2 shots for water on the knee and pain but only lasted less than a month and too expensive to continue. Sitting in my recliner takes away the pain, also a Tylenol helps when needed, and chair exercises. I blame it on all the hiking I used to do since I've never heard of a cause, or a cure and doctors avoid talking much about it, so I just sit in my recliner and think about the good old days. Martha