"Theres fresh evidence pointing to a troubling link between commonly used osteoporosis drugs and a rare type of thighbone fracture. When a hip bone breaks because of osteoporosis http the fracture usually involves either the ball at the top of the femur or the narrow neck just below the ball. The unusual fractures that may be associated with certain osteoporosis drugs called bisphosphonates http occur lower on the bone. Ironically thats where the femur the longest bone in the body is usually strongest. These unusual fractures can occur suddenly without any trauma such as a fall. And they can be complex breaks that are difficult to fix and slow to heal. In the study httpjama.amaassn.orgcontent.abstract published in current issue of JAMA researchers looked at  of these fractures in more than  Ontario women who had taken bisphosphonates. Women who had taken the drugs for five years or longer had nearly a three times higher risk of suffering atypical fractures compared with women who had only transient exposure to such drugs. Thats called the relative risk http and it seems alarming. But the absolute risk of these unusual fractures is still pretty low   fractures per year for every  people taking bisphosphonates for five years or longer. That is longterm users have a risk of about a tenth of  percent. Moreover the study verified that longterm use of bisphosphonate drugs reduces the risk of typical osteoporosis fractures by  percent. Thats obviously a lot more benefit than risk. The big message really is the number of typical hip fractures is much much larger than the number of unusual thigh fractures says Dr. Gillian Hawker http of St. Michaels Hospital in Ontario an osteoporosis specialist and study author. So although we believe there is an increased risk of these unusual fractures it doesnt outweigh the benefit of taking osteoporosis drugs. Merck which makes Fosamax http the original and leading bisphosphonate drug criticizes the new study. The company said in a statement to Shots that women who had atypical fractures were different from those who didnt. For instance they started out with a history of more fractures so the comparison isnt valid. Merck believes that the results must be interpreted with caution and should not be overstated says the companys statement. Still the accumulating evidence that there is a risk of these serious unusual fractures associated with bisphosphonates is getting a lot of attention http in the medical community. Last fall the Food and Drug Administration issued http a safety update urging doctors and patients to be on the lookout for the problem. Often the FDA says an atypical fracture is preceded by pain in the thigh apparently from a small stress fracture that signals bone weakness. Although it is not clear if bisphosphonates are the cause these unusual femur fractures have been predominantly reported in patients taking bisphosphonates the FDA says. The concern is heightened by another even rarer possible side effect  osteonecrosis http of the jaw. Basically it means that part of the jawbone dies. Some reports  including one published http earlier this month in the Journal of Dental Research  have found a higher risk of the jaw problem in dental patients taking bisphosphonates. Again Merck disputes the connection. Earlier this month it convinced http_.html a New Jersey jury that Fosamax did not cause one womans jaw problems. Amid all the debate many specialists are wondering if women on bisphosphonates should take a holiday from the drug from time to time. The idea is that perhaps theyd get the osteoporosis benefit without the risks of osteonecrosis and unusual fractures. You could do five years on five years off Dr. Clifford Rosen http a bone specialist at Maine Medical Center tells Shots. Some people are doing three on and three off. But at some point should these patients start taking the drug again I dont think anybody knows Rosen says. The thought is you would have to put them back on at some time."