My dd had the same break - closed fracture, required sedation to set ... twice! Both radius and ulna completely broke, about 4 inches up from the wrist. She had several casts as well - complete up to shoulder, then below elbow, etc.
Her recovery was long. She was probably out 3 months total before beginning back conditioning only. She was 8 at the time of break. She had some nerve damage, and the nerve takes a lot longer to re-grow than the bone. Once out of the cast, she first did maybe a month of 2-3X weekly OT for fine motor skills. Then at least 2 months of PT before starting back conditioning. She continued PT for another month along with 1 hour conditioning sessions, before going back full hours into the gym.
As far as strength, that is where she excels, so while she obviously lost strength in that arm, she recovered strength pretty quickly. It was the fine motor skills that concerned us. Plus, when her muscles fatigued, her fingers would start to curl, and we were afraid she might slip off the bar, or worse yet, connect with the fingers bent under. They went very carefully with bars work, and kept her out of her
grips for several months until her hand strength was good again.