The elbow is made up of three separate bones. The top part is actually formed by the bottom of your humerus or upper arm bone. It meets the top part of the two bones in your forearm (the radius and the ulna).
There are lots of ways the bones in the elbow can be fractured. We call these fracture patterns. When you say that both sides of the elbow are affected, we’re not sure if that means top and bottom (all three bones or at least the humerus and one of the two forearm bones) or if both sides of just one bone (the humerus) are broken.
In either case, you know there is going to be surgery. So that tells us the broken pieces of bone will be put back together like the pieces of a puzzle. When the surgeon gets everything back as close to normal as possible, then the pieces are held together with bits of wire, or screws, or sometimes metal plates screwed into the bone. This is called fixation with hardware.
When everything is stable and in one place with the fixation, then the surgeon puts the arm in a cast, splint, or sometimes a sling to keep it immobile (not moving). Your grandpa will have to take it easy for a few weeks. But then a physical therapist will work with him to keep his shoulder and wrist moving. When the immobilizer is taken off, the therapist will show him how to move the elbow and keep it from getting it stiff.
Your love and concern are the best therapy your grandpa can get. Keep up those prayers and maybe even send him a card you made yourself. That usually cheers up any grandparent who has had a bad injury!