Unusual bone fractures put bone quality in the spotlight

good for bone quality (photo: Hades2k via Flickr)

After yet another study came out linking use of osteoporosis drugs to strange and spontaneous bone fractures, I had to learn more.  After all, these drugs are intended to prevent fractures.  The unexpected breaks are in the femur, and the problem is linked to long-term use of bisphosphonate drugs like Fosamax or Actonel.  I interviewed a local expert on osteoporosis, Dr. Michael McDermott, and you can find a transcript of that interview here.  I thought he gave a very clear and understandable explanation of why this might be happening.

In short: the class of bone drugs associated with what are called atypical fractures of the femur (thigh bone) are drugs that work by pumping extra calcium into the bone structure.  That may make bone density look better but unfortunately those drugs also inhibit a process called bone remodeling: the constant turnover of bone tissue every day, for your whole life.  Bone remodeling involves removal of old bone cells and replacement with new cells.  This process is about the quality and strength of bone, not just the amount of calcium.  And one of the key players in bone remodeling is protein.  In fact, protein is the major component of bone structure.  If the dead cells just sit there, quality goes down.

There’s more: when bone remodeling is impaired, then it’s harder for bones to repair themselves.  Small, normally inconsequential stress fractures caused by daily life don’t heal so well, and the femur is particularly susceptible to stress.  So as Dr. McDermott notes, a person who has stress fractures and is taking one of these bisphosphonate drugs may not heal those small stress fractures well.  One false step and the stress fracture turns into a major fracture.

Two key points to take away from this news:

  1. The femur fractures seem to happen after long-term use of the drugs, more than 5 years.  Experts are recommending that doctors re-evaluate whether women should stay on these drugs indefinitely.  If you’ve been on such a drug for years, it’s time to have a discussion with your doctor.
  2. Bone strength is not just about calcium.  Consequently it’s not just about buying some calcium pills and thinking you’re OK.  Bone is about protein, calcium, phosphorus, vitamin D, magnesium, potassium and other minerals and vitamins (vitamin K is now of interest to bone health researchers).  Dairy products like milk an yogurt have protein, calcium, phosphorus and vitamin D.  Few other foods have all of those Top 4 together in significant quantities.  Dark colored vegetables and fruit will fill in the potassium, magnesium and vitamin K.

Meanwhile yet another study links calcium supplements to increased risk for heart attacks.  In large group of subjects surveyed about diet and supplement use, people who took calcium supplements had an 86% increased risk for heart attack.  Again, it’s not clear from this study whether the actual calcium supplements caused anything, or whether they were just a marker for a heart-disease promoting lifestyle.  That’s not hard to picture: people who can’t be bothered to eat right think they can compensate for poor diet by taking pills.  You can’t.

Nevertheless, since bone strength is not just about calcium, relying on calcium supplements isn’t the best strategy for increasing bone quality.

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