OK, I forgot to mention that I also use a unit that's called Smart Relief Tens Unit.. PT also used it on my ankle. It's wonderful on almost any part of your body.. Think about investing in the above brand..the unit has a lithium rechargeable battery whereas the other units use D batteries.. they sell for about $28 - $39..I got mine from Amazon.. it will help when your knee gets tired or achy...The stimulation takes away the pain & achiness...and it reduces the swelling because it has pulsating action Try it..what do you have to lose besides the pain..it may only be a temporary relief.. and I would take that anytime..you know what I mean because I really do feel your pain..been there - done that!. H.