Robert Downey Jr (Iron Man) injured his ankle on 8-16-12 while filming a stunt for the upcoming film Iron Man 3. Ankle injuries are most commonly caused when a person steps on an uneven surface and their foot is forced inward through the subtalar joint and outward through the ankle joint. When this happens the ligament is severely stretched and some of the fibers might have torn. Luckily the ankle should still have it's stability. As a result of injuring your ankle you will experience, pain, localized tenderness, and some swelling. You will want to have an x-ray done to make sure that this is in fact a simple sprain and not a undisplaced fracture. When treating a ankle sprain we will try to immobilize the ankle by using a medical grade ankle brace or a walking boot for four to six weeks. In the case of Robert Downey Jr, having this injury will most likely stop production of the upcoming movie for around five weeks. If Iron Man wears his walking boot or ankle brace and takes it easy he can expect a full recovery very soon.