This article in the NYT 'New Old Age' reports on over 14 years of research into the effects of a fall and how well a patient recovers afterwards. In short, the higher the level of function prior to a fall the greater the chance of recovery, conversely a lower level of function invariably means less change of recovery and if the level of function is severe then recovery is very unlikely.
Dr. Gill suggested that with little prospect of recovery for those with severe disability before a fall, perhaps the focus of care should be shifted, pain management might be better than intensive physical therapy.
On the other hand, there’s Mrs. Keyishian. If she’d been disabled before the fall and an honest doctor explained that her chances of regaining independence were slim, “I wouldn’t have listened,” she said. “I would have been sure that if I pushed hard enough, I’d get it all back.”
You can read the full article on the New Old Age website.