I stayed on Fosamax post-Prolia and am still on it but only half a dose. Expect to stop entirely this May after 2 years, when I will get a Dexa scan also after 2 years of flying almost blind. I have had no fractures. My blood turnover markers are OK....not as great as I might like but OK.

My situation is considerably different from what I understand about yours. I took only 2 Prolia injections before my bone density improved significantly and stopped Prolia. If I had been on Prolia for 5 years, like you, and based on what I have learned the past few years, I would question whether Fosamax is powerful enough to counter rebound. If I had fractured like you, I would look at taking a bone builder.

The very best Connect thread discussing getting off Prolia is called 'Support for those quitting Prolia.' It contains extensive, well-reasoned discussions with supporting info/studies.

And the very best deep-dive info about OP is a book entitled 'Great Bones' by Keith McCormick.

Finally, I hope you will educate yourself about the use of blood tests (blood turnover markers) that might be helpful with trying to figure out your continued risk of rebound fracture and whether the path you choose is actually working.

Best of luck to you and I hope you can prevent any further fractures.