The Bones Beneath

Janet is seventy-one and broke her wrist catching herself on a kitchen counter. The fracture healed in six weeks. The DEXA scan that followed changed the rest of her life. Her T-score came back at negative 3.2, well past the threshold for severe osteoporosis. The bones beneath had been failing for years, quietly, without symptoms, without anyone checking. Her doctor had never ordered a bone density test. The calcium supplement she took every morning, on her own initiative, was never going to be enough.

Janet’s story is common enough to be almost ordinary. Roughly 69 percent of Americans with osteoporosis do not know they have it. The disease produces no pain, no visible signs, no warnings until something breaks. By the time a fracture announces its presence, the structural damage may already be extensive.

The Quiet Arithmetic of Bone Loss

Bone is not the static scaffold most people imagine. It is living tissue, constantly being broken down and rebuilt through a process called remodeling. In younger adults, the two halves of this cycle stay roughly in balance: old bone is removed, new bone takes its place. After about age thirty-five, the balance shifts. Removal begins to outpace replacement by a small margin each year.

For women, menopause accelerates the process dramatically. The decline in estrogen, which plays a central role in maintaining bone density, triggers a period of rapid loss that can strip 2 to 3 percent of bone mass per year in the first five to seven years after menstruation stops. Men lose bone too, but more gradually, typically about 0.5 to 1 percent per year starting in their fifties.

The numbers add up. By the time a woman reaches seventy, she may have lost 30 to 40 percent of her peak bone density. At eighty, more than three-quarters of women have either osteoporosis or its precursor, osteopenia (low bone mass that has not yet crossed the diagnostic threshold). Among all adults over fifty, 12.6 percent have osteoporosis and another 43 percent have low bone mass. That means more than half the population over fifty is walking on a weakened foundation.

What makes the picture especially troubling is who gets screened and who does not. The U.S. Preventive Services Task Force recommends bone density testing for all women at sixty-five and for younger postmenopausal women with elevated risk. But fewer than 25 percent of patients for whom screening is recommended actually receive it. Among men, the screening gap is wider still: nearly 87 percent of men with osteoporosis go undiagnosed.

The Muscle Problem

Bone does not erode in isolation. It deteriorates alongside muscle in a parallel decline that shares many of the same biological drivers: reduced growth hormone, chronic low-grade inflammation, disuse. The medical term for age-related muscle loss is sarcopenia, and it affects 10 to 16 percent of older adults worldwide, with prevalence climbing steeply after eighty, when it reaches as high as 50 percent.

After age fifty, muscle mass decreases at a rate of 1 to 2 percent per year. Muscle strength drops faster, about 1.5 percent annually in the fifties and 3 percent per year after sixty. These are averages; sedentary adults lose more, active adults less. But the trajectory is universal. Every person who lives long enough will contend with it.

The connection between bone and muscle is not merely parallel. It is mechanical. Muscle contraction stimulates bone formation through the stress it places on the skeleton. When muscles weaken, they pull less forcefully on bone, and bone responds by weakening in turn. This is why prolonged immobility, whether from illness, surgery, or the fear of falling described in installment 3E, accelerates both conditions simultaneously. A person who stops moving because their joints hurt or because a fall frightened them is losing bone and muscle at the same time, each loss compounding the other.

Arthritis: The Condition Everyone Has and No One Understands

Osteoarthritis is the most common joint disease in older adults and the leading reason for joint replacement surgery. About 37 percent of Americans over sixty show radiographic evidence of knee osteoarthritis. By 2040, an estimated 78 million adults will have some form of arthritis. These numbers are large enough that many people treat the condition as simply part of growing old. It is not.

The conventional shorthand for osteoarthritis, “wear and tear,” is both misleading and damaging. It suggests inevitability and passivity: the joints wore out, nothing to be done. The reality is more complex. Osteoarthritis involves inflammation, metabolic disruption, and biomechanical stress acting together on the joint cartilage, bone, and surrounding tissues. Obesity increases the risk not only through additional mechanical load on the joints but through inflammatory chemicals produced by fat tissue that accelerate cartilage breakdown. The prevalence of knee osteoarthritis has roughly doubled since the mid-twentieth century, a rate of increase that aging and obesity alone cannot explain.

What matters to the person living with it is that osteoarthritis reshapes daily life in ways that cascade through every other system. Knee pain makes walking difficult. Difficulty walking leads to inactivity. Inactivity accelerates bone loss, muscle wasting, cardiovascular decline, and weight gain, which further stresses the joints. One-third of adults with arthritis over the age of forty-five meet criteria for depression or anxiety, driven in large part by the progressive constriction of their world: unable to walk to the mailbox, unable to open a jar, unable to stand from a chair without bracing.

Joint Replacement: A Success With Caveats

Hip and knee replacement remain among the most successful procedures in modern medicine. Roughly 90 percent of patients report satisfaction with surgery, and for many, the procedure represents the difference between independence and institutional care. About a million knee and hip replacements are performed in the United States each year, and demand is expected to rise sharply as the population ages.

The caveats are real. Racial disparities in joint replacement referral and outcomes have been documented for decades and show little sign of narrowing. Black patients are referred for joint replacement at lower rates than white patients with comparable disease severity. When they do receive surgery, they experience higher rates of postoperative emergency department visits and readmission. Asian and Hispanic patients receive joint replacements at lower rates as well. The reasons are multiple: differences in physician-patient communication, patient preference shaped by historical mistrust, geographic access to orthopedic care, and insurance coverage that varies by population.

Cost is the other constraint. A total knee replacement carries an average price tag of $30,000 to $50,000 depending on location and insurance, and recovery requires weeks of rehabilitation, time off work for those still employed, and often a caregiver at home during the early postoperative period. For many older adults, especially those without strong insurance or family support, the economic calculus makes the procedure prohibitive regardless of clinical need.

The Treatment Gap

The most alarming pattern in bone health is not the disease itself. It is the failure to treat it. Fewer than 25 percent of patients who suffer an osteoporotic fracture receive appropriate medication afterward. Treatment rates for osteoporosis have actually declined over the past fifteen years, dropping from about 40 percent in 2002 to roughly 20 percent by 2011 among patients discharged from hospital after a hip fracture.

The reasons for this decline are instructive and infuriating in equal measure. Media coverage of rare side effects of bisphosphonates (the most commonly prescribed class of osteoporosis drugs) created disproportionate fear relative to the actual risk. Atypical femoral fractures and jawbone complications from bisphosphonate therapy occur at rates between 1 in 10,000 and 1 in 100,000 per year. For every atypical fracture caused by three years of bisphosphonate treatment, roughly 1,200 standard fractures are prevented, including 130 hip fractures and 850 vertebral fractures. The math is not close. Yet the fear persists, among patients and physicians alike, and the result is that millions of people who could be protected are not.

For osteoarthritis, the treatment gap is different in kind but similar in consequence. Physical therapy has strong evidence for reducing pain and improving function in osteoarthritis. Uptake remains poor, limited by insurance coverage for sessions, geographic access to therapists, and the persistence of a medical culture that reaches for a pill before a referral.

At the Kitchen Table

The skeleton is infrastructure. When it fails, everything built on top of it is at risk: mobility, independence, confidence, social connection, the ability to recover from the falls described in 3E or manage the conditions discussed throughout this series. Bones and muscles respond to demand. They get stronger when loaded and weaker when rested. This is not a metaphor. It is physiology.

If you are a woman over sixty-five, or a man over seventy, or anyone over fifty with risk factors (family history of fracture, long-term steroid use, smoking, low body weight, early menopause), ask specifically about a DEXA scan. Not a general wellness question. A specific request for a specific test. If your doctor has not raised it, raise it yourself.

If you have been diagnosed with osteoarthritis and told to take an anti-inflammatory as needed, ask about physical therapy. Ask about weight-bearing exercise. Ask whether the pain you are avoiding is the kind that signals damage or the kind that accompanies rebuilding. There is a difference, and a good physical therapist can help you learn it.

If you have been prescribed a bisphosphonate and are worried about side effects, have that conversation with your doctor, but have it with the full picture: the fracture you are trying to prevent carries a one-in-five chance of killing you within a year. The medication carries risks measured in single-digit occurrences per hundred thousand. Both numbers matter. One of them is much larger than the other.

The bones beneath do not announce their decline. That silence is not a kindness. It is a reason to look.