Strontium-89 injections were indeed used as a palliative treatment for bone cancer, though I think they've been discontinued.

The short half life makes it less problematic than its 90 neighbour. It also decays to a stable isotope.

Fwiw supplements containing strontium exist (strontium ranelate mostly), which is supposed to assist with osteoarthritis symptoms and bone growth.

None with Strontium 90

“Taken up” mean it participates in the same sort of biological processes