Bridget, do you have access to a pool, especially a pool with a deep end? If so, you might invest in an Aqua Jogger or similar float device that buckles around the waist to keep your head above water, and do aqua jogging drills that can target the legs and the upper body. The pool / gym facility might even have these as part of its array of equipment for its aqua group fitness classes or general membership perks. Deep water workouts can be a great way of getting your cardio in as well as total body muscle conditioning (including the lower body muscle groups in some surprising ways) in an entirely zero-impact, non-weight-bearing mode.
If this is of interest to you, please let me know here and I can cough up some drill and overall workout suggestions.
HTH -
A-Jock