Painless Swelling in the back of the knee

Patient: Hi I’m 20 years old. I played Basketball a lot when i was younger, around 15 – 18. For some reason about 2 years ago I noticed minor swelling at the back of my left knee (jumping knee in basketball), absolutely no pain. And my knee Clicks when it’s extended. There’s no pain but I’m hesitant to participate in sports because I’m afraid If I play I could aggravate an injury I don’t know about. I thought if I played no sports the swelling fluid or whatever it is would go down but there’s no change. I feel as if the clicking could do something weird. So what I’m wondering is if it’s okay to play sports and the swelling is just fluid? And if the clicking is normal

Doctor: The most common mass in the popliteal fossa (the region behind the knee) is the Baker cyst, also called popliteal cyst, , it results from build up or fluid distention of the calf muscles bursa. It usually communicates with the knee joint by way of a slit like opening at the posterior and inner aspect of the knee capsule just superior to the joint line. A Baker cyst may serve as a protective mechanism for the knee, when certain disorders cause joint effusion; this liquid is displaced into the Baker cyst, thus reducing potentially destructive pressure in the joint space. Arthritis is the most common condition associated with Baker cysts, with osteoarthritis probably being the most frequent cause. The treatment of Baker cysts is conservative and includes the use of no steroidal anti-inflammatory medications, ice, and assisted weight bearing, in addition to the correction of underlying intra-articular disorders. If there is poor or no response to conservative treatment, the surgical option might be considered in order to correct internal derangements of the knee with  arthroscopy.