Maugust789 Looks like a Baker's or Ganglian Cyst. Had one in the back of my knee that popped out while I was running in a 10K race in my stupid younger days as a road runner. Ended up as major surgery - removal of cyst from the joint from the back through to the knee cap, repair of torn calf muscle tendon, and repair anterior crucial and medial collateral ligaments, etc....Not a fun thing. These days when I go golfing I have a knee brace on left knee - where surgery took place in 1981 - 93 - 06; elbow sleeve on both arms for tendon problems; compression hand and wrist mittens, the Sabona kind; and Zero Friction compression golf gloves just like Tommy Two-Gloves for the arthritis in knuckles, tendonitis in joint and thumbs and ligament tears in both wrists. Then, take several 600 milligram Advil's before teeing off.
