Dear patient Polio virus affects anterior horn cells of spinal cord and leads to permanent damage to them and as a result there is atrophy of lower limb muscles. This wasting and atrophy is permanent. As patient grows he learns to walk with hand to knee gait and can walk without support. This damage to lower limb muscles is permanent and cannot be reversed. Although strength of muscles can be increased with excersise. If you want to make your leg straight it can be done but then you have to use calliper and support may be required. You should visit expert orthopaedic surgeon nearby you and get yourself examined and opined. All the best.