He probably sustained a minor fracture to one of his lower vertebra. The surgery was probably to stabilize things so it could heal properly.
A broken back? A phrase the media uses to make things sound far more dire than the reality of a situation. In all likelihood.
They were much more descriptive in the past...
"Crushed spinal column"
"(Thoracic region)"
ICD code 187, more specifically, Herbert was caught in the belt of his sawmill on his farm. He was injured in the afternoon and died during the night. Not much they could do for that kind of injury back in 1925.