The European product withdrawn was Strontium Ranelate - I can't find the report right now.

There are still unanswered questions in the studies -
To date they have been conducted on mice or rats with induced osteoporosis, with durations of only a few weeks to months. Is there a difference between induced and natural osteoporosis?What would be the long-term effects in humans?

As @windyshores mentioned, nobody has yet answered the questions as to whether strontium-reinforced bones are less prone to fracture.