I think you can request the surgical notes, taken during surgery or right after??
That might be another piece of paperwork that could have clues , or general info that is needed. Not sure if hospital and dr office has those , I'd check hospital first.

Perhaps make a time line of sx pre surgery & post surgery and as best as you can dates of those.
How long after the surgery did the new sx begin?

But perhaps a call to some malpractice attys will give better guidance and what is needed for a possible claim.