I have had my right knee replaced because the meniscus was worn and torn. It was caused by thirty years of running and tennis. I first developed chondromalacia in the knees after 6-7 years of running. Went to see the orthopedic doctors and they said I should quit running and tennis. Part of my problem was that my patellas are congenitally off track, they are rotated a few degrees towards the outside of the knees.
I used ice, heat and knee braces, including those with metal structures designed to reduce the load on the joint. They helped with tennis, but not with running. I eventually gave up running: it was too painful. Continued playing tennis until that became too painful. The pain kept me awake sometimes and I was taking large daily doses of tylenol, naproxen and ibuprofin. Not good for kidneys and liver.
Went to see the Kaiser docs, and they suggested I quit tennis as well as running, and take supplements, chondroitin and glucosamine. After two years, no improvement. Still played tennis, just not as often, and the pain kept up.
I went back to Kaiser orthopedics, and they recommended synvisc shots to lubricate the joints, every three months for a few years, then steroids/cortisone shots. If that regimen didn't help the pain, then arthroscopic surgery. The last resort would be knee replacement surgery. Then the pain escalated, mostly in the right knee, lesser pain in left. Couldn't walk long distances or play tennis without severe pain.
Decided to see a non-Kaiser ortho/knee specialist. He took MRIs and discovered both meniscuses were worn to less than half the usual thickness and had micro fractures throughout. No cartilage under the patella on the right knee and only a little on the left. He suggested immediate knee replacement for my right knee, and monitor my left knee. He gave me a cortisone shot in the right knee and it did relieve the pain for the two months before surgery.
After knee replacement, major improvement in pain and mobility. I am able to walk 6-7 miles at a time without pain, just fatigue.No tennis, except an occasional light game of doubles. No singles tennis, no running or any athletic activities involving running, jumping, sudden stopping and starting. Doctor suggested I take up golf, biking and swimming. Left knee is still OK, since I quit tennis. I ride a bicycle for 35-40 miles occasionally, without pain.
So the only pain relief for me was the cortisone shot. I was able to walk pain-free for two months of pre-surgery fitness. A friend of mine tried the synvisc (artificial cartilage like lubricant) and it didn't help him.
Good luck, DED.