Vitamin K2-MK7 or K2-MK4 could shuttle that calcium into his bones from his arteries.
One study on animals showed a 50% regression in two months.
Do you know if the shuttling can work in the opposite direction?
My mom has early onset osteoporosis due to a decades long problem with her parathyroid. A recent surgery fixed the parathyroid with amazing results but she is now in the slow process of recalcifying her bones. I wonder if the K vitamins you mentioned could help speed it up.