Bisphosphonate drugs are a go-to treatment for osteoporosis, but they come with a significant risk of triggering an atypical femoral fracture, especially if you use them for more than five years. Their use is controversial, particularly because bone mineral density isn’t an accurate measure of bone strength and fracture risk. And yet, bisphosphonate drugs are the first-line therapy for the prevention and treatment of osteoporosis, with 14.7 million prescriptions written annually in the U.S.[i] The drugs, which include alendronate (Binosto, Fosamax), ibandronate (Boniva), risedronate (Actonel, Atelvia), and zoledronic acid (Reclast, Zometa),[ii] work to inhibit bone resorption by blocking the action of osteoclasts, which are cells that degrade bone. Osteoclasts, however, have many functions beyond bone resorption, including affecting immune responses, and their role of bone degradation serves to initiate the normal bone remodeling process. Drugs that inhibit osteoclast activity, therefore, may have “unexpected negative … effects on bone homeostasis.”[iii] One risk that’s been …