Although it is less common than common osteoporosis, there have been some reports of regional migratory osteoporosis that have been described in the medical literature. However, intravenous bisphosphonates are not usually given as the first line of treatment -- they are frequently prescribed after other treatments have either failed or not been tolerated. I haven't heard of them being given to someone with a normal DXA scan (the test which is considered the gold standard for diagnosing osteoporosis.) If you and your family have doubts about this physician's recommendation, perhaps you are interested in seeking another opinion from a different specialist before you embark on such a remedy. In the meantime, do take steps to protect your ankle and how much weight you bear on it. Best of luck to you.