What exactly is osteoporosis? The standard World Health organization (WHO) definition is that osteoporosis is “a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture,” which is certainly a mouthful, if not a particularly enlightening one. Osteoporosis is the most common bone disease by far, but it’s a disease many people don’t understand.
Most people think of osteoporosis only in terms of bone fractures or loss of height, but osteoporosis is far more complicated. You’d probably understand osteoporosis most clearly if you could see a bone specimen affected by osteoporosis under the microscope, but you’re not likely to ever be privy to a bone biopsy. Doctors don’t usually perform bone biopsies in their patients to diagnosis osteoporosis, although pathological examination of bone is still the gold standard in diagnosing osteoporosis. Normal bone has a network of strong plates and bands. In osteoporosis the bands become thinner and weakened, and worse yet there are tiny breaks in the plates and bands.
Another way to define osteoporosis is that osteoporosis is present if bone mineral testing value is more than 2.5 standard deviations below the average adult, even if there’s no history of fractures. The word “osteoporosis” actually means porous bones. If something is porous, it has holes in it. Although all bone has cavities filled with cells and blood, in osteoporosis, the normal bony cavities enlarge. When the “holes” become larger, bone becomes more fragile and more susceptible to breaking. Minimal trauma can cause a fracture when you have osteoporosis.
Osteoporosis is a systemic disorder that affects the entire skeleton. Bone is in a constant state of remodeling; old bone is broken down and replaced with new bone. Osteoporosis can occur when you lose more bone than you rebuild, or when more bone than normal is broken down.
Bone mass decreases between 1 and 5 percent per year after age 40 in women, and less than 1 percent in men. Women are more likely to develop osteoporosis because they generally have less bone mass to start with than men do. The sudden loss of estrogen, a sex hormone that is instrumental in building healthy bone, in menopause also contributes to women’s increased risk of osteoporosis.