The last time osteoporosis came up in the gospel according to Doc Gumshoe it was in the context of “not good news.” Starting in the year 2002, there had been a steady decline in the number of hip fractures sustained by women on Medicare over the age of 65, from 931 per 100,000 in 2002 to 730 per 100,000 in 2015. But this decline came to a screeching halt after 2015. If the reduction in the number of these events had continued to the present, it is estimated that about 11,500 fewer women would have broken their hips.
In the great majority of cases, hip fractures occur in persons with osteoporosis. Scrupulous health professionals shrink from calling osteoporosis the “cause” of hip fractures, or of vertebral fractures, which are also very much associated with osteoporosis. Usually, the immediate cause is a fall, but in a person whose bones had not become porous, such falls do not necessarily result in a fracture. The fall is the precipitating event, but the underlying cause is the fragility of the bones.
Almost certainly, the decline in hip fractures was due to the introduction of the drug Fosamax (alendronate), which was approved by the FDA in 1995 and fairly quickly came into wide use. Admittedly, this drug was initially overprescribed, not only to patients (mostly women) with frank osteoporosis, but to many, many women in the early stages of bone loss, termed osteopenia. Fosamax and other kindred drugs including Actonel (risedronate), Reclast (zoledronate) are in the bisphosphonate class, and while in persons with osteoporosis they reduce the risk of fracture by as much as 50%, they are not recommended for persons whose degree of bone loss has not progressed to osteoporosis.
About ten years after the introduction of Fosamax and other bisphosphonates, the news of genuinely scary side effects began to trickle out. One was osteonecrosis of the jawbone, leading to fractures. The other was a fracture of the femur – the long bone of the upper leg – called atypical femoral fracture. As the news of these adverse events spread, the use of bisphosphonates plummeted, falling by about 50% between 2008 and 2012. This reduction in the use of bisphosphonates likely accounted for the end of the decline in hip fractures.
It didn’t seem to make much difference when the health-care authorities tried to assure potential candidates for this therapy that the incidence of these side effects was extremely rare – somewhere between one case in 10,000 patients to one case in 100,000 patients. The reaction in many people seems to have been that they preferred to accept the risks associated with osteoporosis than the risk of these truly terrifying incidents.
… but what are the risks associated with osteoporosis?
The quick answer is, a good deal more substantial than most people think. Osteoporosis is thought by many, especially women, to be an almost inevitable consequence of aging. If asked what they fear more, osteoporosis or breast cancer, most women would surely respond that breast cancer is much more scary than osteoporosis. And yet, if we consider the statistics, it’s by no means so open and shut. For one thing, the incidence of osteoporosis is higher than that of breast cancer – about 15.4% across all age brackets for osteoporosis in women, versus 12.4% for breast cancer. And breast cancer mortality has declined since 1990, by 39% through 2015. That decline has resulted in 322,000 deaths averted. Currently, the 5-year mortality rate for women diagnosed with breast cancer is about 10%.
In contrast, about half of women with osteoporosis will experience some kind of fracture, and these fractures can have dire consequences. Studies of mortality in women following hip fractures report significantly higher mortality rates than in women with breast cancer. A study in elderly patients with hip fractures reported a one-year mortality rate of 21.2%, which is, as you will note, almost double the five-year mortality with breast cancer. Another study found a five-year mortality of 32.3% in individuals following hip fracture.
About a third of all patients who experience hip fractures are discharged to a nursing home, and most of these do not recover the level of activity they enjoyed before their fracture. Moreover, individuals who have osteoporotic fractures, whether of the hip or the vertebrae, are at three times the risk of another fracture due to the frailty of their bones.
All in all, it would not be an exaggeration to say that osteoporotic fractures present far more of a risk to life and to quality of life than breast cancer.
What happens in osteoporosis?
One might think of osteoporosis as a natural process gone off the tracks. Contrary to what most people might assume, even fully mature bones are in a constant state of change, called “remodeling,” in which older bone tissue is being replaced with new, stronger bone tissue. Our bones consist mostly (about 70%) of crystalline calcium salts deposited in a framework which is 90% to 95% collagen fibers. Collagen is a protein consisting of amino acids twisted together to form long, strong fibers. It is these fibers that provide tensile strength to our muscles, tendons, ligaments, and skin. Collagen also provides tensile strength and a degree of elasticity to our bones.
Bone remodeling is a continuation of the process through which our bones grew in the first place, from the tiny bones of an infant to the much larger, heavier bones of a mature adult. Bone growth is also responsive to the stress placed on the bones. A weight lifter will develop much thicker and heavier bones than a sedentary person.
The agents that do the bone remodeling are osteoclasts and osteoblasts. The osteoclasts are fairly large cells of the phagocyte type, meaning that they devour all manner of substances, including foreign particles, bacteria, dead cells, and waste. Osteoclasts are able to absorb both the solid part of the bone – the crystalline calcium part – and the collagen. They usually eat away at the bone for a few weeks, making tunnels up to one millimeter in diameter. Then, their job done, they retreat, and the osteoblasts move in. These are much smaller cells, and they keep at their job of depositing new bone tissue for up to several months. First, the organic tissue is deposited, including coll