What exercises can I do to help with knee movement after being in leg cast?

Motion & quadstrengt. After immobilization in a cast you will be stiff and have muscular atrophy. The only good part about the cast is that it helps the injured area to heal - it makes the surrounding areas worse due to lack of use. You will need therapy to regain your motion and to gradually increase your quad and hamstring strength to be able to regain your normal activities.