@isabelle7 can he get a second opinion from a good endocrinologist? It's concerning that this rheumatologist has never heard of Evenity, and 10 years of Fosamax is not recommended by my docs. Also -3.4 would seem to need a bone builder like Evenity, Tymlos, Forteo before Fosamax. What I am seeing if I look up treatment for steroid induced osteoporosis is that the older articles still online mention bisphosphonates like Fosamax as "first line" but in the context of taking them within the first 3 months of steroid use. Any articles that are more current suggest an anabolic bone builder (Forteo and Tymlos) if risk is already present. Evenity is new (2019) but should be considered too. It sounds like his rheumatologist is, well, old-fashioned and not up to date.

Here is a quote from an article on studies of treatment for osteoporosis from steroids, which mentions that bisphosphhonates like Fosamax could be helpful if prescribed within 90 days of steroid treatment. For your husband, with a -3.4, that ship has already sailed.

For an anabolic, this mentions teriparatide (Forteo) but would apply to Tymlos as well, which is similar. Evenity is a possible too but not mentioned here because the article may predate Evenity's more common use. Here is the quote:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613168/
"GIOP (glucosteroid induced osteoporosis) is a condition where the principal cause of bone loss is reduction in bone formation. This is the rationale for using teriparatide, a parathyroid hormone peptide producing anabolic skeletal effects by stimulation of bone formation. In a 18-month randomised trial conducted in patients with GIOP, teriparatide 20 µg daily was compared to alendronate 10 mg daily; as expected, the increase in BMD was higher with the anabolic agent as compared to the antiresorptive one (7.2% vs 3.4% at the lumbar spine). More importantly, a significantly lower number of vertebral fractures was observed: 0.6% and 6.1% in the teriparatide and alendronate groups, respectively.76 77 Data were confirmed over 36 months."

Here is another one:
https://pubmed.ncbi.nlm.nih.gov/37845798/ (2022 upsdate)

" For adults at medium, high, or very high fracture risk, we strongly recommend pharmacologic treatment. Choice of oral or intravenous bisphosphonates, denosumab, or parathyroid hormone analogs should be made by shared decision-making. Anabolic agents (Forteo, Tymlos, Evenity are anabolics) are conditionally recommended as initial therapy for those with high and very high fracture risk."