bluebonnet, most patients are taking bisphosphonates after Forteo or Tymlos. Even before the black box was lifted, my prescribing endocrinologist knew about the Wister rat and the flaw in the studies. Now, some patients are extending Forteo use without a bisphosphonate in between.
My suspicion is that the idea of "sealing the gains" is a hang-over from the days where there were no anabolics. Now, the understanding is that sealing the gains prevents the important process of remodeling. Look at this though from 2005
The amino-bisphosphonates strongly inhibit osteoclastic bone resorption. During normal bone remodeling, osteoblastic bone formation follows resorption and occurs within the eroded cavities, so inhibition of bone resorption also results in inhibition of bone formation. Bone biopsy studies using double tetracycline labels show that the bone-forming surface is suppressed by 60–90% with usual doses of the bisphosphonates (4, 5). These drugs are certainly not anabolic! The volume of bone does not increase. The bone density as measured by dual-energy x-ray absorptiometry, however, does increase. This is because the bone is no longer remodeling, and so there is not much new bone. The older bone is denser than the newer bone; there is less water and more mineral in the bone, and the radiographic techniques thus measure the higher density.
https://academic.oup.com/jcem/article/90/3/1897/2837115
The article clarifies that there is no known way to remove bisphosphonates from bone and it can persist in preventing remodeling for ten years. Which is why the effect of Forteo is blunted when taken after a bisphosphonate.