I have had plenty of knee trouble at my ripe old age of 25. I have had a total of five orthoscopic knee surgeries to take out parts of bone and cartilage that die and break off. Pretty painful to have a piece of bone decided to wedge itself in your joint. It was a cool trick though to show people the chunk I could move around in my knee. Anyway though, the surgeries always were very quick and I was back to normal within a month usually. I probably would have healed quicker, but I'm pretty active and like to push things along. Not smart, but oh well. I guess I'll pay for it later in life when they just want to replace the whole thing.