Knee - Drained Weekly!

I've had two meniscus repairs in the last 6months (one 5 weeks ago). Doc said my femur is damaged and could need a cartilage transplant but, it the damage is in the back. Now for the last 2 weeks he has drained 50cc's of yellow/bloody fluid. After the last time it was drained (last friday) it was completely filled again by monday and slowly getting worse. Cortizone and other injections were tried this time but, to no avail. The pain at night is horrendous and MRI's/X-ray show no damaged to the top of the knee where the fluid builds up. I go back to the doc tomorrow - I think a surgery is in need but, what is the problem? The doctor, and trainers have never seen the fluid build so rapidly. Any insight? Thanks

PS - I'm 21 male college athlete.

a couple things come to mind but more guesses than anything else

synovitis? The knee is lined by a thin membrane call the synovium and produces the fluid(synovial fluid) that lubricates the knee (yellow fluid). If the synovium gets inflammed it could produce an excess of fluid. The blood in the synovial fluid indicates something within the knee is actively bleeding so maybe something with the last surgery has caused this.

The swelling in the "top" of the knee you describe probably has nothing to do with where the actual problem is. Once the joint is full of fluid it will just kind of collect in the superior pouch of the joint capsule, which extends above the patella.

For now this is the only thing I can think of that might cause this. Good luck with this. Update this as you find out more. I'm very intrigued by this.

Just got back. The doc tried to drain the fluid this time but, nothing came out. He tried 4-5 different times/areas. Sometimes the needle hits a fat pad? and just basically gets sucked dry, was his explaination. He thinks it is one of 3 things. The synovium lining is very inflamed and producing this fluid. The ding (missing cartilage on the back of the femur) is trying to be protected. Or something is floating around from the meniscus surgery. He suggested a second opinion (which I will get monday) and possibly just going in and cleaning it out/looking at everything first hand.