What is fracture risk and why does it matter more than your T-score?

Fracture risk is a probability. It is an estimate of the likelihood that you will experience a bone fracture within a given timeframe, typically the next ten years. It is expressed as a percentage. A fracture risk of 15 percent means that out of 100 women with your profile, approximately 15 would be expected to experience a fracture within ten years. It is not a certainty. It is a way of quantifying risk so that treatment decisions can be made on evidence rather than guesswork.

Why bone density is only part of the story

Bone density is the most important single factor in fracture risk. But it is far from the only one. Research has consistently shown that a significant proportion of fractures occur in women whose T-scores fall in the osteopenia range, not the osteoporosis range. This is partly because there are simply more women with osteopenia than osteoporosis, and partly because fracture risk is shaped by factors that a DEXA scan cannot measure.

A 75-year-old woman with a T-score of -2.5 faces a substantially higher fracture risk than a 50-year-old woman with the same score. This is because age affects bone quality, balance, muscle strength, and the likelihood of falling. The scan looks the same. The risk is very different.

The factors that contribute to fracture risk

Beyond bone density, the following are recognised independent risk factors - meaning each one raises fracture risk regardless of T-score:

• Age - risk increases significantly with each decade after 50

• Previous fragility fracture - having already broken a bone from a minor fall or movement is one of the strongest predictors of future fracture

• Parental history of hip fracture - particularly a mother who broke a hip, which carries an independent genetic and structural risk

• Current smoking - directly impairs bone formation and increases bone loss

• Alcohol - consuming three or more units per day is an independent risk factor

• Glucocorticoid use - long-term use of corticosteroids such as prednisolone significantly accelerates bone loss and increases fracture risk independently of bone density

• Rheumatoid arthritis - carries an elevated fracture risk beyond what is explained by bone density alone

• Secondary osteoporosis - bone loss driven by another medical condition, such as coeliac disease, inflammatory bowel disease, or hyperthyroidism

• Low body weight - a BMI below 19 is associated with higher fracture risk

How fracture risk is calculated

The most widely used tool for calculating fracture risk is the Fracture Risk Assessment Tool (FRAX) developed by the World Health Organization and the University of Sheffield. FRAX takes your T-score and combines it with the clinical risk factors above to produce two estimates: your ten-year probability of a major osteoporotic fracture (spine, hip, forearm, or shoulder), and your ten-year probability of a hip fracture specifically.

What happens with that number

FRAX scores are used alongside clinical guidelines to determine whether treatment is recommended. In most countries, the threshold for recommending medication is not simply a T-score cutoff. Rather, it is a combination of T-score and fracture risk. A woman with a T-score of -2.0 and multiple additional risk factors may have a higher calculated fracture risk than a woman with a T-score of -2.8 and no other risk factors, and may therefore be more likely to be recommended treatment.

This is why understanding your fracture risk (not just your T-score) gives you a much more complete picture of where you stand and why your doctor is recommending what they are.

What you can do with this information

Some fracture risk factors cannot be changed: your age, your family history, previous fractures you have already had. But several can be modified: smoking cessation, reducing alcohol, managing secondary conditions, and starting appropriate treatment all have a meaningful impact on fracture risk. Understanding which factors apply to you helps you have a more informed conversation with your doctor about which levers are worth pulling.