you dont need to start a whole new program but just modify the weights., to lighter weight or even machineswith a stack or a smith machine. you should use lighter weight b/c you can't balance yourself on one leg. you this time to shock your mucles. like pre-exhaus, superset and etc or do 100 reps a set.. just dont let the cast get in your wau.. your not doomed at dude. just find a new way to make your muscle work.
without your legs, everyones weak. i had a friend that had to wear a brace of he's knee and could not even do half the weight he normal do b/c he couldn't drive up from the legs