HI and welcome to the disABILTIES Board.
If you are short, like KErmit, you may find that most of the rides are not a problem.
Otherwise,
here's a link that should help you out. It's the FAQ page from the official Disney website. One of the questions is about riding on attractions with a full leg cast. It gives a long list of the rides that have extra leg room so you'd be able to ride without bending your leg.
A lot of the rides though, like the pirates of the caribbean, small world, jungle cruise, kilimanjaro safari, Ellen's Univ. of Energy, Living with the land have special cars for those in wheelchairs, and there is lots of extra room that probably will allow you to keep your leg extended. I even think that Peter Pan and Winnie the Pooh may
each have a car specially made for wheelchairs
Wheelchair cars would be a good suggestion, except for one thing; they have nowhere for you to sit because they are made to fit a wheelchair in the space where a seat would normally be. In some rides, there is more leg room in a particular row. Ask the CM who greets you at the ride if there is more leg room depending on where you sit and then ask again when you get closer to boarding.
There are no special wheelchair cars for Pirates of Caribbean, Jungle Cruise and Peter Pan.
You haven't mentioned whether or not you have a wheelchair or
ecv. If you don't have one of your own, you may want to rent one for your trip. They can be rented from the parks on a daily basis, but they are first come, first served, so they may be out of
ecvs or not have a wheelchair that suits you when you ge to the parks.
Here's a list of off site places that DIS posters have reported renting ecvs and wheelchairs from:
Care Medical:
http://www.caremedicalequipment.com/
Walker Mobility: 1-888-726-6837
www.walkermobility.com
RANDY'S Mobility in Kissimmee: 407-892-4777
http://randysmobility.com/
Colonial Medical:
http://www.colonialmed.com/about_cms.html