COMMENTARY

Bone Fragility in Childhood: How Many Fractures Are Too Many?

Laura K. Bachrach, MD

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March 24, 2021

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This transcript has been edited for clarity.

Hi. I'm Dr Laura Bachrach, a professor of pediatrics in the area of endocrinology. For the past 25 years or more, I've been really interested in the problem of pediatric bone health. In my own practice as an endocrinologist, I'm seeing an increasing number of children coming to me with the question of whether their bones are developing normally or whether their bone fragility risks are increased. I'm even seeing children who actually have what we call "pediatric osteoporosis." So, what I'd really like to talk about for a few minutes are some of the controversies, the key areas where we have made progress, and the areas where we need to do more research.

First of all, what do I mean by pediatric osteoporosis? In older people, one can diagnose osteoporosis on the basis of a bone density test or a DEXA scan. If the bone density is low enough on the DEXA, you earn yourself the diagnosis of osteoporosis if you're a postmenopausal woman. But in childhood, even though we have normative data, there isn't a cut point, a fracture threshold to allow us to make that diagnosis. So we are increasingly focusing on fractures in children as the gold standard for deciding when somebody does or doesn't have osteoporosis. If you've had a low-trauma fracture of the femur or the spine, that's enough to buy you the diagnosis. Having recurrent low-trauma fractures may also give you that diagnosis, especially in combination with a low bone density.

How Many Fractures Are Too Many Fractures?

Some of the cases that I presented at the Endocrine Society meeting this year relate to special areas of children at high risk. One case involved a ballet dancer who has been exercising intensively and has a stress fracture. Is that osteoporosis? How should we treat that? Another case is a child with Duchenne muscular dystrophy who has difficulty with mobilization, is not doing much weight-bearing physical activity, and therefore doesn't stimulate the bone to grow stronger, and then to compound things, has inflammation from the Duchenne muscular dystrophy and is on high-dose glucocorticoids. Is that a child who warrants investigation and treatment? These are typical cases that might come to an endocrinologist or even to a general practitioner, with the question of how many fractures are too many fractures?

My general advice for evaluating a child like this is to do a comprehensive screening: Go over nutrition; vitamin intake; physical activity; and family history of recurrent or frequent fractures, low-trauma fractures, and history of hip fractures in the elderly. In terms of the laboratory investigation, we always look at things like vitamin D level and often look for celiac disease, which can cause bone fragility. We're concerned about the possibility of sex steroid deficiency, and we definitely go into genetic studies if there are concerns for osteogenesis imperfecta or other genetic defects associated with bone fragility.

Is a DEXA Scan Necessary?

A controversial area is whether and when to do a DEXA scan. Many families come in knowing about bone density testing. And this is a really challenging area because we can do a DEXA scan, but the results don't necessarily drive treatment. Because, as they say, the diagnosis of osteoporosis is really based on fracture history rather than bone density alone. So we can do a bone density test and see a low bone density for age but not necessarily decide that it's time to pull out a drug.

Part of the evaluation process, in addition to potentially doing a bone density test, is to do a lateral spine x-ray. The lateral spine x-ray looks everywhere from the upper to the lower spine. If you see vertebral compression fractures in a child, that by itself is enough to give a child a diagnosis of osteoporosis, even if there is no DEXA done. So the lateral spine x-ray is definitely a reasonable evaluation tool to add to the tool kit.

Treatment

There is no FDA-approved drug for the treatment of osteoporosis [in children]. On a compassionate use basis, we are using bisphosphonates. We rely on the intravenous forms of these drugs rather than the oral forms because of studies that suggest that the IV form is more efficacious to prevent vertebral fractures, which is often what we're trying to treat.

There are two drugs out there: pamidronate and zoledronic acid. They're not FDA approved, but we use them as the only drug in our toolkit that we have the most experience with in treating children with fragility fractures. Because they are not FDA approved, we want to be very judicious about when we pull these drugs out. Generally, we treat or offer treatment to a child who has had a fragility fracture. By that, I mean a fracture of the long bones — let's say, the femur — from standing height or less. So if you walk across the living room and trip on the shag carpet and have a femur fracture, that would be a very concerning, abnormal bone fragility fracture. That's as opposed to a child who falls off the jungle gym and has a distal forearm fracture. Those are common childhood fractures.

The other fractures to really pay attention to are vertebral compression fractures. Pretty much the only drugs we have in our toolkit are the bisphosphonates. And there are different protocols; people have different arguments about exactly what dose to use and for how long to treat, but it is an option for children who have a diagnosis of osteoporosis based on those fractures.

Sometimes patients and providers are so worried about a child who is high risk that they want to use this as primary prevention before first fracture occurs. If you have a child with Duchenne muscular dystrophy and they're on high-dose glucocorticoids, you might feel like, Wow, I think there's a 20%-40% chance that they're going to have a fracture in their life. Can't we get started now?

We aren't ready yet to do primary prevention — that is, start this prophylactically before the first fracture occurs. But this is a rich area for investigation where we should do some studies and decide if we can identify well enough children at high risk to start a randomized controlled trial of using bisphosphonates for primary prevention.

Final Words

This is a very important area for endocrinologists and general providers to know about, to think about bone fragility in childhood. If you hear a history of low-trauma or recurrent fractures, think about the fact that a child actually could have enough in the way of risk factors early on in life to warrant drug therapy. And really understand the pitfalls of just doing a DEXA scan. If you have a low bone density for age but no history of fractures, do we do more harm than good by raising parental anxiety or anxiety on the part of the patient when we're not necessarily going to treat on that basis? These are all important areas for discussion. There are a lot of questions and a lot of opinions, but with attention to bone health, I think things can be looking up. Thank you so much.

Laura K. Bachrach, MD, is a pediatric endocrinologist.

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