It would be a good idea to consult your veterinarian about the amount and type of feed you're giving your horse during recuperation and early work. During recovery from an injury, a horse's feed should be cut back; and there are alternative feeds that don't make the horse as excitable as its normal feed would. You'll need the help of your vet to determine what is best for your particular horse during this time.
As far as training goes, you can start by taking long walks outside the arena, provided the footing is good. If, however, your horse is very excitable outside, then don't take it out at this crucial point in its recovery. In this case, stay in the ring working on very large bending movements--such as the circle, half-turn, serpentine, etc.--to supple the animal, keep its attention, and help slow its gait. (All bending movements tend to slow a horse.)
You can also take the horse out to graze using a lead rope and halter to contain its energy, rather than turning it out and letting it run. If the horse is too excitable for any of the activities mentioned, speak to your vet about using a mild sedative in the horse's feed for awhile, so that you can continue to deal with the animal during this recovery period without risking injury to the horse or yourself.