I am 49 years old, 53 - 130 lbs.  have a hard lump on the outside of my left knee.  This knee has given me pain over the last couple of years, but the lump has really become larger over the last 6 months.  Now it is hard for me to straighten and the pain is almost constant.  Pain in also now going behind the knee on the left side.  The lump does not hurt and is not moveable like fluid.
Hi, Dear,thanks for the query to Chat Doctor. After going through the query in details, In my opinion--Your lump on the knee left-is Synovitis with Effusion with knee arthritis?early-OA.-Cause- is the aging OA due to overuse of the joint and disuse atrophy of the qua Chat Doctor. Synovitis of the knee joint with overgrowth of the synovial granular tissue erodes the knee joint surfaces and OA occurs with reactionary fluid in the knee joint as in your case.-Your symptoms suggest progression to the back of the left knee from the front knee area.-Treatment- I would advise you to see Orho-Surgeon / Physician who would treat it after proper investigation. Hope this would help you to plan treats with your doctor. Wishing you fast recovery and Healthy life. Wellcome to Chat Doctor for further query to My Chat Doctor clinic. Have a Gd day.