@jchet,
a friend had foot drop--both feet. Imaging revealed hardware movement subsequent to surgery compressing the perineal nerve. Complete recovery wasn't immediate after revision--removal and replacement of screws, which suggests that the nerve was partially damaged. He recovered during (maybe with the help of) physical therapy.
Though I was with him for each stage of the process, second hand is never as good as the lived expression.
I hope you repose the question directed or not, so that genuine players will respond.
Reimaging is crucial. And in his case hard to get.