Sudden bone breaks reported in patients taking Fosamax

You might have heard of the drug Fosamax.

Nearly 40 million prescriptions have been written for the popular osteoporosis medication.

It's part of a group of drugs called bisphosphonates that are supposed to make bones stronger.

But now some doctors say there's mounting evidence that these medications could cause spontaneous breaks and fractures.

"I was on my way to work, walking up the hill to catch the bus and I heard a snap. And I didn't realize that it was my leg until I fell."

Sheridan Powell says she didn't trip on anything. She hadn't have an accident. Her leg just broke. It snapped like a twig.

"You don't just break your leg. You usually fall and break it. I said I felt I must have tripped over something, but there was nothing there."

Powell was taken to the hospital, where doctors found she had a rare type of femur fracture. X-rays showed there was a clean break in the middle of her thigh bone. Doctors were left wondering -- what could have caused the largest bone in her body to suddenly snap in two?

"We think of the middle of the thigh bone as being a very strong bone. It's not a bone that typically an osteoporatic patient would fracture and in these patients they fracture with almost no trauma."

National Rehabilitation Hospital rheumatologist Dr. Robert Bunning says he's seen this before. And once he learned Powell had been taking the popular drug, Fosamax, for about eight years to treat osteoporosis, he says he had a pretty good idea what could have caused the break.

"The drugs are supposed to work by shutting down the cells that re-absorb the bone, the osteoclasts. The ones that make the bone, the osteoblasts, are supposed to keep working. However in biopsies of patients who have had the fracture, it shows that both are shut down."

Bunning calls it "frozen bone," which is brittle and more susceptible to these types of clean fractures. He says in the U.S. There have been 50 to 60 reported cases of this.

"Even thought it's rare, I think we're going to be seeing quite a few more cases."

Dr. Bunning says that in all of the reported cases, most patients had been taking Fosamax or another type of bisphosphonate for more than 5 years.

"The drugs clearly were designed to make the bones stronger and I think they do for the first few years. They make them denser."

The manufacturer of Fosamax, Merck, says there has been no "causal link" demonstrated between long-term use of fosamax and fractures. Clinical studies have not shown any increased risk of fracture in any part of the body.

A spokeswoman for the Food and Drug Administration says they are "aware of this issue and are actively investigating it."

Dr. Bunning agrees that Fosamax is safe to take for up to 5 years, and it's been shown to benefit many patients with osteoporosis.

But for patients like Sheridan Powell -- who had to undergo surgery plus weeks of rehabilitation just to be able to walk again -- she says she wishes she had known about the risks.

"It's kind of hard to believe that something that saves your bones can break the largest bone in your body."

A big question is whether the osteoporosis itself can cause these fractures.

Dr. Bunning says typically, patients with that condition will suffer breaks in the hip area -- and that usually occurs after a fall.

With all of these patients, the breaks are occurring in the thigh and without any sort of trauma.

Dr. Bunning says that in many of these patients they had experienced vague thigh pain before their femur broke.

So Dr. Bunning says if you or someone you know is taking one of these drugs, make sure to see your doctor right away if something doesn't feel right.