Certain drugs used to treat the bone-thinning disorder osteoporosis may increase the risk of a rare type of break in the hip or thighbone, the Food and Drug Administration said on Wednesday. The drugs, in a class called bisphosphonates, are Fosamax, Fosamax Plus D, Actonel, Actonel with Calcium, Boniva, Atelvia, and Reclast (and their generic products). The types of break account for less than 1 percent of all hip and thigh fractures, and it is not certain that the drugs are to blame, but many people with these injuries have been taking the drugs. Warnings will be added to the drug labels. Patients are advised not to stop the drugs without consulting their doctors, and to tell a doctor if they develops hip or thigh pain while taking the medicines.