Harvard Medical School Commentaries: Medical Myths

Dec132009

Breaking Down Bone Myths

by Robert H. Shmerling, M.D.
Beth Israel Deaconess Medical Center

A patient once told me that he'd never broken a bone but that he'd once had a rib fracture.

Another said he'd rather break his ankle than sprain it because, "as everyone knows," a fracture heals even stronger than before the break.

Still another patient told me he'd heard you could break a bone without even realizing it.

Are these observations accurate or a product of myth and misunderstanding?

In fact, there's some truth and some myth to these statements. Read on to learn more about bone health, bone injuries and common misconceptions about them.

Myth No. 1: A fracture is a milder form of bone injury than a broken bone.

In fact, a broken bone and a fracture are the same thing. While there are many types of fractures, most people are talking about one that follows a significant injury. With enough force, a bone cracks so that the smooth surface of the bone is interrupted.

A severe fracture goes all the way through the bone, leaving it in two or more pieces. This is called a transverse fracture. A less severe type is called a greenstick fracture, named for the way a green stick breaks if it is bent too far. And a hairline fracture describes a tiny break that does not alter the overall position or shape of the bone and may be quite difficult to see on an X-ray. There are many other types of fractures; what they all have in common is that the bone has broken.

Myth No. 2: Once bones are fully developed, they stop changing.

Most people think of bones as they appeared in that skeleton in grade school science class. But in living people, the human skeleton is very much alive and undergoes constant remodeling.

Bone cells, called osteoblasts, continuously create new bone and respond to stress by making even more bone than usual. For example, increased weight-bearing exercise (such as walking or jogging) will stimulate osteoblasts to make more bone. That's one reason that weight-bearing exercise is recommended as a prevention and a treatment for osteoporosis.

Other bone cells, called osteoclasts, nibble away (resorb) bone, a process that is closely linked to bone formation. In fact, osteoblasts and osteoclasts are often found near one another, much as home renovators might be knocking down a wall adjacent to where a new one is going up.

The remarkable thing is that with all this "bone renovation" going on, healthy bone maintains a tight balance between bone formation and resorption, so that the amount of bone at any one time is usually "just right."

Myth No. 3: Osteoporosis is a painful bone condition.

This is a common misconception. Unless a fracture has occurred, osteoporosis causes no pain.

Osteoporosis makes bones weaker than normal because the bone is not dense enough. The name osteoporosis comes from Greek words meaning bone (ostoun) and passage (poros), indicating the increased amount of empty spaces or passageways through the bone.

Osteoporosis is defined by measures of bone mineral density, and most people with osteoporosis have never had a fracture; therefore, they have no symptoms related to their weakened bones. In fact, they would not even know about their condition until a bone mineral density test is performed. That's why testing is so important for people at risk of osteoporosis.

Myth No. 4: Vitamin D deficiency causes rickets, a disease of malnourished children.

This one is partly true: Too little vitamin D does cause rickets, a condition in which developing bones grow abnormally because they are too soft. But vitamin D deficiency can cause problems for adults as well. It's called osteomalacia (literally, soft bones) and is a relatively common problem even among otherwise healthy and well-nourished adults.

We get vitamin D from the diet and from sunlight, which converts an inactive form of vitamin D in the skin to its active form. The body needs this vitamin to promote the deposit of minerals (calcium and phosphate) into bones. Getting these minerals into the bone is a key part of making bones strong. People whose diets are low in vitamin D, who do not absorb nutrients adequately (for example, because of colitis), or who live where sun exposure is limited (such as New England states during the winter) are at risk for osteomalacia.

A study published in 1998 found that nearly 60% of patients admitted to a Boston hospital had low levels of vitamin D. Symptoms include bone and muscle pain and a tendency to fracture easily. In fact, tiny bone fractures may develop even without injury and without the person's being aware the bone is broken (see below).

Myth No. 5: If you have broken a bone, you'll know it right away.

Actually, some fractures cause mild or even no symptoms at the time the fracture occurs. Sooner or later, though, there is usually pain or aching or a change in bone alignment that brings it to the attention of patients and doctors.

Examples include:

  • Stress fracture — Most common in people who engage in repetitive and strenuous activities, a stress fracture develops because small injuries add up and overwhelm the ability of bone to repair them. Marching soldiers and long-distance runners are prone to this type of fracture.
  • Compression fracture — When the rectangular bones of the spine are weakened (most often by osteoporosis), they may collapse or compress, looking more like a triangle than a rectangle. While this may cause sudden pain, many people with these fractures recall no specific onset of symptoms. These fractures often cause the spine to curve forward, making the person appear hunched over.
  • Osteomalacia — As described above, osteomalacia is a condition related to osteoporosis, but osteomalacia is an abnormality of "mineralization." Too little of the minerals calcium and phosphate is deposited in bones, so they are weaker than normal. Tiny fractures develop, and while widespread bone pain is common in people with osteomalacia, the sudden onset of pain related to a specific fracture is less common.
  • Spondylolysis — The bones of the spine (vertebrae) have a complicated shape that helps them protect the spinal cord while maintaining proper alignment, one on top of the other. A fracture can develop as a result of age-related "wear-and tear" or, less commonly, because of an injury. With spondylolysis, the fracture is located in a bone called the pars interarticularis, which connects the front of the vertebra to its protective, cage-like back portion. Back pain is common, but there is often no sudden onset of pain at the time of fracture.

Myth No. 6: A broken bone heals stronger than it was before the break.

When all goes well, bone fractures heal quickly and full bone strength is achieved in a period of months. But there is no evidence that a previously fractured bone is actually stronger than before the break. On the other hand, it's true that a severe sprain (caused by an injured or even torn ligament) may be reinjured rather easily, while a fracture in the same area (for example, the ankle) might heal more quickly and completely.

The Bottom Line

The more I learn about bone development, growth and repair, the more amazed I am at how well this complex organ functions. In fact, most people are completely unaware of the ability of bone to repair injury and respond to stress the way it does – and that makes bone health and disease prime candidates for misunderstanding and myth.

Fortunately, doing your part is not difficult: Learn more, get the recommended daily allowance of calcium and vitamin D, exercise regularly, get some sun (but not too much!), and talk to your doctor about bone mineral density testing.

There's more to bones than most people realize. Sorting out myth from fact can help you keep yours healthy.

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