It’s tough to beat opioids for severe pain.
I don’t know Tom Petty’s particular situation. Sounds like he suffered from emphysema- may mean that he’s been on high dose steroids, (prednisone?), long term, to aid his breathing-which in turn can induce osteoporosis. He always looked pretty slight of build and may not have started with a robust baseline bone density. I’ve heard that he was trying to soldier on and complete his tour with a cracked tibia that progressed to a full fracture. That would be damned painful. Also seems a little “out there” to continue, while I’m wildly speculating, maybe his judgement was impaired by the very meds he was using for pain.