Not all two handed backhands are hit with an open stance - here's an example with Murray using a closed stance: http://www.tennisone.com/club/lesson....php?print=yes
You're still going to put a good amount of stress on that right leg digging out a wide ball and hitting an open stance forehand. You'll still used a closed stance with a two handed backhand when you hit slice. Plus tennis requires a lot of stop and start and cutting anyway.
Probably the smartest thing to do is be smart about rehab and get fit enough to play with minimal risk of injury.
Who knows, you may be better with a two hander, but it's probably not going to make much of a difference unless your one handed technique caused or contributed to the injury.