Just wait and see what the doc says. Your rehab will depend on your specific injury. I do know that, as somone noted earlier, water running is about as low impact as it gets. However, you wouln't want to begin until a potential tear is healing and inflamation goes down. Rush it and you'll never get back on the mats.
Originally Posted by 3moose1
Well, my question had more to do with weakened legs due to overall disuse. I've already done a lot of physical therapy and will continue to do so.
Well, talk to your doctor of course, but having had two pretty bad knee dislocations/MCL tears, I'd do a shitload of stationary bike riding. Bodyweight squats were beneficial. My doctors had me do leg extensions, but with very light loads. I took to doing only one leg at a time to avoid overloading the weak leg. I also liked straight leg deadlifts with light loads for hamstring development and overall structural support around the knee.
Your kneecap will probably be a little loose for quite some time. Mine tended to shift around for maybe a year after MCL injuries.
Work on regaining your range of motion if you have lost any. Stationary bikes and stretches, obviously. But avoid super-vigorous stretching right before you are planning to practice. I had the most problems with slippage when I did this. My MCL would be all loose and stretchy, then the kneecap would slip. Stick to very light stretching/warmup/range-of-motion exercises before practice.
It really sucks when your leg is going sideways and your kneecap is on the side of your leg. Be careful and listen to your body.