I use the slingshots. Cartlidge repair followed by ACL reconstruct about 13 years ago followed by a another blowout that was not treated at current I have arthritis with fluid that gives me issues. I tried splits and though they are good for flutter kicking I had a difficult time with the other kicks (fell free to bash me for that statement). I thought the slingshots where gimicky but I recieved a pair as a christmas gift and figured whats the harm in trying them out. They are great fins. the main thing that helped keep the pain down though has been modifing my kicking. I always did like the breast stroke and frog kicking (kick and glade) does not agrivate them as bad. (I"m also not usually in a rush when I'm under water)