CoolSculpting has FDA approval for fat reduction since 2010. CoolSculpting freezes the fat cells. Fat cells are more susceptible to damage by freezing than the other cells, (nerve, vessel, bone, etc.), around them. The fat cells die via a process called apoptosis, (programmed cell death). The number of fat cells are therefore reduced. This happens over a period of time, so the body is not overwhelmed with dead fat cells. The body will take these cells up, process them and excrete them, just as any other cell. The remnants are filtered through the liver, and then excreted eventually via stool. Knees can be a challenge with any modality. CoolSculpting had been used in this area with good results. See an experienced CoolSculpting practice, they will determine if you are a candidate. Cost will depend on the number of cycles needed.