Assuming your doc gave you the ok to start exercising, a stationary bike my work. . Particularly in your situation, a recumbent stationary bike may be better than the traditional stationary bike. Also water exercise or swimming is low impact and is good for conditioning. Lot of local rec programs have low water exercise classes or swim classes. .

Otherwise, your doc may be able to recommend something specific for you. I know when I had a knee injury in high school about a 150 years ago, I had a lot of PT and one of the simple exercises I did at first to strengthen my knee was sitting on edge of my bed and I filled a sock with pennies, tied the end of it, laid it across the top of my ankle and did leg lift reps. I'd increase the weight, using ankle weights every week or so.

And I'd say if you can walk, even with a cane, walk. Even if it's for short distances. But again, I'd ask your doc about this.

At very minimum you could do I think they call them "ankle lifts" where you just move your foot around at the ankle so that you are working your calm muscles similar to if you were walking. If circles are too boring, you could "write" the alphabet in the air or be really creative and draw imaginary artwork. I personally find swimming to be wonderful on my legs, so if that's an option at all, I'd do that.

I have a knee injury and have several exercises (including the ones RMB mentioned) and stretches I'm *supposed* to do daily. I've added several to my workout from the ACE Fitness website. You can search by the body area or by difficulty.

I have lax patellas, and my doc has instructed me to do sitting (chair) leg lifts to strengthen the muscles around my knee. You just lift, and hold. I have ankle weights, but I would just start without. You can also do legs lifts while sitting at a 90 degree angle on the bed or floor. Again, just lift and hold.