A note on this column: This article is general medical information, not a description of a service offered at this practice. Dr. Ishiguro's surgical practice is focused on hip and knee joint conditions, including fractures around joint replacements; he does not provide the ongoing medical diagnosis or medication management of osteoporosis itself, which is typically handled by a primary care physician, endocrinologist, or bone metabolism specialist. This column is written to help readers understand a common, often-silent condition and know when and how to seek the right specialist.
What osteoporosis is
Osteoporosis is a disease of the skeleton in which bone density and the internal microstructure of bone both deteriorate, leaving bones weaker and more prone to fracture from forces that wouldn't normally cause a break — a fall from standing height, a stumble, or even a strong cough or sneeze in advanced cases. The name literally means "porous bone": under a microscope, osteoporotic bone shows thinned, more widely spaced internal struts, similar in principle to a honeycomb that has lost much of its scaffolding.
Bone is living tissue that is constantly being broken down and rebuilt throughout life, a process called remodeling. Bone density typically peaks in the late twenties to early thirties, then gradually declines with age. Osteoporosis develops when the balance tips too far toward breakdown — either because peak bone mass was lower to begin with, bone loss accelerates, or both. A related, less severe stage — reduced bone density that hasn't yet reached the osteoporosis threshold — is called osteopenia, and is itself a marker of increased future risk.
How common it is
Osteoporosis is far more common than its lack of symptoms would suggest. In the United States, the estimated prevalence among adults 50 and older is 12.6% overall, rising sharply with age to 27.1% of women and 5.7% of men 65 and older. In Japan, population-based epidemiological studies estimate roughly 15 million people live with osteoporosis, yet only around 20% are receiving treatment for it — a gap attributable in large part to the disease's silent course before a fracture occurs.
The downstream consequence — fragility fracture — is a major driver of the numbers that matter clinically. Japan's most recent nationwide hip fracture survey estimated approximately 193,400 hip fractures occurred in 2017 alone, the large majority in women, with age-adjusted incidence rates that have not meaningfully improved over a 25-year survey period despite advances in treatment. Hip fracture is not a minor event: it is associated with roughly a 10–20% increase in mortality risk in the year following the fracture, and around 60% of patients do not fully regain their prior level of function.
Established risk factors
- Age — bone density declines progressively after peak bone mass is reached in early adulthood
- Female sex and menopause — the drop in estrogen at menopause accelerates bone loss, making postmenopausal women the group at highest risk
- Family history — a parent with osteoporosis or a hip fracture raises individual risk
- Low body weight — a lower BMI is consistently associated with lower bone density
- Prior fragility fracture — having broken a bone from a low-energy fall is one of the strongest predictors of future fracture
- Long-term corticosteroid use — oral steroid medication is among the most common causes of secondary, medication-related bone loss
- Smoking and heavy alcohol use — both are independently associated with reduced bone density
- Certain medical conditions — rheumatoid arthritis and some endocrine disorders are recognized secondary contributors
Symptoms — or the lack of them
Osteoporosis is sometimes called a "silent disease" because it typically causes no pain or outward signs while bone is being lost. Many people first learn they have it only after a fracture, or when a routine bone density scan is performed for another reason. When symptoms do appear, they are usually the result of fractures that have already happened: gradual loss of height, an increasingly stooped posture (sometimes called a "dowager's hump"), or back pain from a vertebral compression fracture — a fracture of a spinal bone that can occur with minimal or no trauma and is sometimes only noticed on an X-ray taken for another reason.
How the diagnosis is made
The standard test for diagnosing osteoporosis is a dual-energy X-ray absorptiometry (DEXA) scan, a low-radiation imaging study that measures bone mineral density, most often at the hip and lumbar spine. The result is expressed as a T-score — a comparison of a patient's bone density to that of a healthy young adult of the same sex.
| T-score | Classification | What it means |
|---|---|---|
| −1.0 or higher | Normal | Bone density within the expected range for a healthy young adult |
| −1.0 to −2.5 | Osteopenia | Lower than normal bone density; increased risk, not yet osteoporosis |
| −2.5 or lower | Osteoporosis | Bone density low enough to meet the diagnostic threshold for osteoporosis |
Because bone density is only part of the fracture-risk picture, many clinicians also use a validated calculator such as FRAX (Fracture Risk Assessment Tool), which combines T-score with clinical risk factors — age, prior fracture, family history, smoking, steroid use, and others — to estimate an individual's 10-year probability of a major fracture. This combined approach helps identify patients who may benefit from treatment even before their T-score alone reaches the osteoporosis threshold.
What the evidence shows: The U.S. Preventive Services Task Force's 2025 recommendation statement, based on a systematic review of the evidence, recommends DEXA screening for all women aged 65 and older, and for postmenopausal women younger than 65 who have one or more risk factors for osteoporosis. The task force found insufficient evidence to issue a screening recommendation for men, reflecting a genuine gap in the research base for that group rather than an assumption that men are not at risk (Nicholson WK, Silverstein M, Wong JB, et al., for the US Preventive Services Task Force, JAMA, 2025).
What the evidence says about prevention and treatment
Management of osteoporosis generally combines lifestyle measures that apply to nearly everyone with medication that is reserved for those at meaningfully elevated fracture risk, based on T-score, FRAX estimate, and fracture history.
Commonly used approaches
- Adequate calcium and vitamin D — through diet and, when needed, supplementation, to support the mineral building blocks of bone
- Weight-bearing and resistance exercise — activities like walking, stair climbing, and strength training stimulate bone formation and help maintain muscle mass and balance
- Fall-prevention measures — addressing home hazards, vision problems, and balance issues, since most fragility fractures result from a fall
- Smoking cessation and moderating alcohol intake — both measurably affect bone turnover
- Bisphosphonates — the most widely used first-line medication class, which slow the cells that break down bone (osteoclasts)
- Denosumab — an injectable antibody-based medication used for patients at high fracture risk or unable to tolerate bisphosphonates
- Anabolic (bone-building) agents — parathyroid hormone analogs, reserved for patients at very high fracture risk, which stimulate new bone formation rather than only slowing loss
What the evidence shows: A Bayesian network meta-analysis of 13 randomized controlled trials involving 11,822 patients found bisphosphonates significantly reduced the risk of new vertebral, hip, and non-vertebral-non-hip fractures in patients with a prior osteoporotic fracture, with alendronate performing most favorably among the bisphosphonates studied for secondary prevention of vertebral and hip fractures (Shi L, Min N, Wang F, Xue QY, BioMed Research International, 2019).
What the evidence shows: The landmark FREEDOM trial, a randomized, placebo-controlled study of denosumab in postmenopausal women with osteoporosis, found significant reductions in vertebral, hip, and non-vertebral fracture risk compared with placebo over 36 months, along with sustained increases in bone mineral density at the spine and hip (Cummings SR, San Martin J, McClung MR, et al., New England Journal of Medicine, 2009). A subsequent 10-year extension of the same trial cohort found continued increases in bone density without a plateau and low ongoing fracture rates among patients who remained on treatment.
Treatment decisions — which medication, at what dose, and for how long — depend on individual fracture risk, kidney function, other medications, and patient preference, and are best made with a physician who manages bone health directly rather than through self-directed supplementation alone. Duration of bisphosphonate therapy is itself an area of ongoing clinical judgment: benefits for vertebral fracture risk appear to persist with longer use, but the evidence for continued benefit against non-vertebral fractures beyond 3–5 years is less consistent, which is why many treatment plans include a scheduled reassessment rather than indefinite, unmonitored use.
Why this matters even outside a fracture clinic
Bone health is relevant well beyond the moment a fracture occurs. Poor bone quality affects how well a fracture heals, how a fixation device or joint replacement implant fixes to bone, and the risk of further fractures after a first one — which is why a fragility fracture, once it happens, is often treated as a signal to formally evaluate and address bone density going forward, not just to treat the break itself.
When to see a specialist
A DEXA scan is reasonable to discuss with a physician for any postmenopausal woman, any adult 65 or older, or anyone with risk factors such as a family history of osteoporosis, long-term steroid use, or a previous low-energy fracture. Anyone who has already fractured a bone from a fall that wouldn't be expected to cause a break — a wrist fracture from a fall onto an outstretched hand, for example — warrants a bone density evaluation even if it hasn't been raised by a treating doctor, since a first fragility fracture substantially raises the risk of a second one without intervention.
References (PubMed / Journal)
Nicholson WK, Silverstein M, Wong JB, et al; US Preventive Services Task Force. Screening for Osteoporosis to Prevent Fractures: US Preventive Services Task Force Recommendation Statement. JAMA. 2025;333(6):498-508. DOI: 10.1001/jama.2024.27154
Cummings SR, San Martin J, McClung MR, et al. Denosumab for Prevention of Fractures in Postmenopausal Women with Osteoporosis. N Engl J Med. 2009;361(8):756-765. DOI: 10.1056/NEJMoa0809493
Shi L, Min N, Wang F, Xue QY. Bisphosphonates for Secondary Prevention of Osteoporotic Fractures: A Bayesian Network Meta-Analysis of Randomized Controlled Trials. Biomed Res Int. 2019;2019:2594149. DOI: 10.1155/2019/2594149
Takusari E, Sakata K, Hashimoto T, Fukushima Y, Nakamura T, Orimo H. Trends in Hip Fracture Incidence in Japan: Estimates Based on Nationwide Hip Fracture Surveys From 1992 to 2017. JBMR Plus. 2021;5(2):e10428. DOI: 10.1002/jbm4.10428