After a failed attempt to get the hard-brace on, and an MRI... the docs decided that dad needed a spinal fusion. His spinal column wasn't quite straight, so there was a little pressure on the nerves leading to his lower extremities. The MRI showed that his muscles were also strained (from the fall) and lacked the support to allow natural healing. He went into surgery today at 3pm, and its a 5 hour procedure to get the bad vertebrae out... shave it down a bit, and re-insert it within a titanium cage that will connect it to the vertebrae above and below the bad one. This added support will allow his back muscles and bone to heal without requiring him to lay flat without moving for months. He should be out of the O.R. by 8pm, and then he'll be here for another 3 days of recovery, at which time he will be transferred to a nursing home where he can rehabilitate. When he is clearly able to get around and take care of daily living requirements... he can go back to his house in the hills.
EDIT: He's out of the O.R. Everything went well. He'll be sedated overnight but should be awake in the morning.