Leahdragonfly,

I had to wear a body cast for 3 months after my uninstrumented fusion surgery in 1984, and although I felt fine physically, I refused to go to high school in it. My mom had to get a home teacher through the school district.
I think your mom was very smart and I wouldn't hesitate to do the same with any child that was having problems adjusting at school with a temporary body cast. I suspect the school districts would certainly understand.