A once-a-year injection could replace osteoporosis drugs, the results from a new study indicate.

Treatment with injections of zoledronic acid, part of a class of drugs called bisphosphonates, reduced the risk of vertebral fractures by 70% and hip fracture by 41%, according to researchers. In the three-year study, annual injections of zoledronic acid replaced monthly pills to treat the bone-thinning disease. Bisphosphonates, the most commonly used treatment for osteoporosis, work by slowing the body’s natural reabsorption of bone.

Many patients have trouble remembering to take the monthly pills, researchers note. The study report is in the New England Journal of Medicine.