rstern447, it's been 4 months since your post. I'm wondering if your son has shown good recovery?
ashley339, my understanding is that the gastro muscles are not so critical and are often removed in calf reduction surgeries (ie cosmetic reasons!).
p/s My son's (14 this year) avm involved all 3 calf muscles: peroneus, soleus and gactrocnemius so surgery is out for now. But curious all the same.