polio knee

I have got polio in 1953 and my knees were put surgically bent backwards in order to walk better. From then on I walked rather well with a cane. In 2002 I began to suffer from a hard pain in both knees due to over benting- My knees were forced to bent more and more backwards by the continuous effort of walking. What can I do? Is there anyone who got the same problem? I'm writing from Italy. Thanks a lot Mirella Santamato -Ravenna- Italy