A pitcher in our organization (15 yo) is under the knife at this very moment for her ACL. She's getting a cadaver achilles tendon put in place of her ACL. She was told by the doctor that the fix will be better than it was before the injury and she can be back pitching in 3-4 months. Should be fully healed in 6 months. We will see.
Although every case is unique, a 15yo doesn't need surgery to repair an ACL. The 10yo will be fine, too...could be 100% within 6
months with normal diet and rehab.
Not that this applies to a 10 year old but there's life after a torn ACL.
I tore my ACL and MCL (stepping on an improperly mounted base). As long as you do rehab, which begins right after surgery. It is a lot of swimming, etc.
You have to get full range of motion as soon as the therapist allows. Rehab helps prevents scar tissue. I had this cool thing that ran cold water from an ice bucket to promote healing. Th erapists know the drill. You have to wear a metal brace for awhile when playing.
I kept up with weightlifting, cardio, and strict warm up routines before games for career. I ditched the knee brace the minute I was allowed and have been able to bash into people sliding or whatever no issue. I recommend weightlifting starting around 14 years old.
I had it done awhile ago, so I am not sure but I think it was 4 months recovery (with brace). Brace off after one year.
The recovery and treatment of this CHILD will be determined by her parents and her treating physician(s). Everyone else is guessing. If you want to know anything more precise, ask her parents.