Hello , To answer your question , yes , ankle sprains can cause knee pain. The joints of your lower limbs , upto the spine have a chain reaction , wherein , the healthy joint over compensates for the injuries occurred to another joint , proximally or distally, to keep your body balance as much as possible. You mention about your knee being hot and swells on putting a brace. Are you very sure that there wasn t any knee injury of any sort , when you fel down ( twisting , direct blow etc ) ? Had there been no increase in temperature and knee swelling , I would have just said its excess strain on the knee , due to the ankle sprain however swelling and increased temperature suggests some sort of active process going on inside.- again , this needs to be physically examined and confirmed before we can reach to any conclusion. I wouldn t advice you to put on a brace unless you ve got the knee evaluated by an orthopaedic. Braces are meant to support the knee , but can cause space constriction around the joint too in case of an injured , inflamed joint . You should get physiotherapy for your ankle sprain- ankle sprains recur sooner of later , depending upon what activity you do , if there has not been any sort of rehabilitative exercises done following ankle sprains. Physiotherapy treatment ( in various forms like taping, electrotherapy and exercises ) for ankle sprains can begin right from the acute phase , when there is significant swelling, to the chronic stages , when pain is felt only on loading . Also you should have your knee evaluated once again from an orthopaedic. Tc .