He's been in need of a hip replacement for years. I can only imagine he never had it done because of the requirement of receiving a blood transfusion intra and post procedurally if necessary-- something Jehovahs Witness do don't. I can only assume he was on high doses of pain meds to midigate the bone on bone pain associated with his hip. High doses of pain meds can yield unpredictable outcomes... The only thing the hospital could have done is change his meds, but I'd imagine he's been thru that process a number of times in the course of managing his pain

These are a lot of assumptions obviously, but certainly not a simple solution