I'm sure you have gotten all the answers you need on this, but just wanted to add my .02 in case it helps...
My (then 14yo) kiddo dislocated the left elbow w/ a ME fracture in Aug 15 - she had surgery to reattach w/a screw one week later (waited a week to be able to book a pediatric sports med surgeon). Was in a splint waiting for surgery and for a week after - doctors opted for surgery as they felt she needed the stability of the ME being attached due to the extremity of her sport.
After the splint was removed, she had 2+ mos of PT including a tension splint. She never "zero'd out" on her extension, probably due to scar tissue - she's about 5degrees short of straight - which doesn't seem like much, but her right elbow hyper-extends so the difference between the two is probably close to 10degrees - maybe slightly more.
She ended up competing in January '16 - had to do JO L6 instead of 7 as she wasn't able to train giants because of the elbow, but had a very successful season. She had to re-learn several skills, especially tumbling skills on beam as she had to learn to adjust for one arm being longer than the other (probably 1" difference). She still has pain in the elbow in spurts and has become very good friends with her bottle of Advil but chooses to tough it out because she loves gym.