“The doctor said Mom has advanced osteoporosis,” said my sister. “How does he know that?”

The short answer is, because her hip broke spontaneously. At least the doctor mentioned why the fracture happened, even if he didn’t explain his reasoning. In the case of two friends who recently told me their mother had broken a hip, no one ever mentioned that the cause was osteoporosis, although that’s undoubtedly what it was.

In working on an article for Nature Outlook on current research into and treatment of osteoporosis, my eyes were opened to the widespread misunderstandings surrounding this common disease.

First, most people are unaware that a bone fracture in someone over 55 is usually due, at least partly, to loss of bone mass and density. In reading about the disease, I found the US guidelines are notably up front about the situation. The authors say:

“… most fractures in older adults are due at least in part to low bone mass, even when they result from considerable trauma. A recent fracture at any major skeletal site in an adult older than 50 years of age should be considered a significant event for the diagnosis of osteoporosis and provides a sense of urgency for further assessment and treatment.”

Yet they point out that in the US “many patients who have osteoporosis-related fractures are not being diagnosed with osteoporosis” and certainly not given lifestyle counselling and drug therapy to prevent the next, inevitable fracture. Anecdotally, I have seen this in Canada as well — many older people with osteoporosis are never diagnosed (or, more precisely, never told they have osteoporosis), even after a fracture.

It would help if people at risk of fractures and their families and friends understood osteoporosis, but most people know little or nothing about it, which becomes clear in the reactions and comments when their mother, father, aunt or uncle breaks a bone.

So let’s clear up some of these misunderstandings right here.

First, the broken bone is the end of a long process that has been going on for years. The bones have become progressively less dense, with larger holes in the sponge-like interior “trabecular” bone. By the time the bone breaks, it was hanging on by a thread. A fracture had become highly probable.

If you think about it, prime-age adults (25 to 60) rarely break a bone. If they do, it’s usually because of a major trauma such as a skiing or car accident. That’s because their bones are healthy. I’ve fallen down a few times during endurance sports such as skating, cross-country skiing or running — the worst thing I got was a bruise.

Second, about falls. If someone has osteoporosis, it’s advisable to prevent falls in a variety of ways. It takes very minor trauma to break a bone affected by advanced osteoporosis. However, as the US guidelines point out, sometimes the bone can break spontaneously if it is fragile enough, with no trauma at all. This is what happened to my mother. Elderly people can fall for a variety of reasons (many aging-related processes affect balance), and osteoporosis should be considered one of them. I have heard about many cases of frail elderly people with diminished cognition who had a fall and broke a bone, but it’s not clear whether the fall broke the bone or the broken bone caused the fall. Friends and families often wring their hands about why the person fell, often from a sense of responsibility for the person’s well-being. But they can let themselves off the hook:  the chances of a fracture were high, fall or no fall, and the fracture may have caused the fall.

Third, many people think that if you eat calcium and get vitamin D, you won’t get osteoporosis. In fact, three things give you your best shot at delaying or decreasing the effects of osteoporosis: calcium (better to eat calcium-rich foods than to take supplements, which can contribute to kidney and gall bladder stones), vitamin D (Canadians need supplementation in the winter), and exercise. Recent research shows that the chemical “crosstalk” between muscles and bones is very important — working your muscles strengthens your bones. As people age, they should get more exercise, not less. But these steps may not fully prevent osteoporosis. In fact, they probably won’t.

Why is this? The new research shows that not only do women lose a lot of their bone mass during menopause, then men and women are hit by a second, age-related bone mass loss after age 65. This one is caused by the bone cells becoming senescent and ceasing to function, as well as the stem cells producing fat cells rather than bone cells. There’s only so much that lifestyle can do to counteract these effects.

If you have a family history, talk to your doctor, and if the densitometry tests show you’re seriously losing bone mass, you may need medication.

Unless you have a strong family history of osteoporosis at a young age, you probably don’t need to worry about testing until you reach your 60s, when the second effect starts to kick in. In the meantime, calcium, vitamin D, exercise.

Yeah, aging sucks. But it’s better than the alternative.