From long experience w/casts & stitches (I spent 6 months in a leg cast due to being hit w/a car, I've broken both feet at different times, broken ankles, you name it) - watch for swelling - not of the cast, but your arm inside the cast. Yes, anything that's had surgery can hurt, and inflammation affects not only the immediate area, but all the surrounding areas as well.

Ibuprofen is specific for swelling, and you can ice the outside of the cast to relieve the swelling on the inside. If you're trying to perform a lot of strenuous activities w/the casted arm, you can aggravate any inflammation that's there.

Keep an eye on your fingers - if they are always cold, look fish-belly white or start to get bluish under the nails, immediately go to a doctor or emergency room - it means that your circulation is being affected & no oxygen is getting to your hand.

If you're stuck in the cast & you start to get itchy, since you've had surgery, you don't want to stick anything down inside the cast to physically scratch yourself - if you break the skin this can cause an infection to set in. Instead, try an OTC antihistamine like Sudafed or Benadryl. When you do shower, check the cast over for moisture - you can use a blow drier on its lowest settings to make sure it's completely dry - you can end up w/an athlete's foot-type fungus on your arm if it's constantly moist underneath the cast material.

Hopefully your time in plaster bondage will be short & your healing will be quick and successful!