BAKERSFIELD, Calif. -- Patients take osteoporosis drugs such as Fosamax, Actonel, Boniva and Zometa to reduce their odds of a bone break. However new research has suggested that these medications may raise the risk of stress fractures if taken longer than 4 to 5 years.

The drugs are called bisphosphonates, and studies show that they successfully cut the odds of spine and hip fractures resulting from osteoporosis. They suppress the rate of bone molecule turnover thus reducing bone loss over time.

But two new studies presented at the American Academy of Orthopedic Surgeons meeting in New Orleans have found that long-term suppression of bone turnover can lead to microscopic damage.

Researchers analyzed the bones of women who had these stress fractures and found that the osteoporosis drugs were linked to changes in the mineral content that weakened the bones.

Experts emphasized these fractures are rare -- but patients need to be aware of the risks. If a person is taking an osteoporosis drug, they are encouraged to talk to their doctor about how long to use it -- and if they have sudden thigh pain, they should consult a physician right away.