Dual-energy X-ray absorptiometry

Dual-energy X-ray absorptiometry, or DXA, measures bone mineral density using low-dose X-rays. Usually performed at the hip and lumbar spine, it contributes to osteoporosis assessment and fracture-risk evaluation alongside clinical history and other risk factors, rather than diagnosing pain itself.

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Meaning on imaging

DXA estimates the amount of bone mineral projected over an area. It does not show discs and nerves in the way MRI does. The examination is usually brief and painless. Its main purpose is to assess bone health rather than directly identify the source of low back pain.

Indications and assessment

Indications depend on factors including age, a fragility fracture, medicines such as glucocorticoids and other risks. Results include density measurements and comparison scores. In postmenopausal women and men aged at least 50, the T-score is used for densitometric classification. The relevant population must be considered before applying a threshold.

Limitations and interpretation

A T-score of −2.5 or lower at a valid measurement site can indicate osteoporosis in these populations. Z-scores are preferred in younger adults. Arthritis, fractures or hardware may interfere with lumbar measurements. Fracture risk also depends on clinical history, and cannot be reduced to a score or used to predict an individual fracture with certainty.

Role of TAGMED care

At TAGMED, known bone fragility should influence precautions and any proposed mechanical loading. DXA examinations and osteoporosis medication belong within appropriate medical services. Symptom-focused care does not replace fracture prevention or management of a recent fracture. New focal pain following a minor injury may require medical assessment before physical treatment.

Frequently asked questions

Is DXA an MRI examination?

No. It uses low-dose X-rays to measure bone mineral density.

Does a normal score exclude every fracture?

No. Fractures can occur when density does not meet the osteoporosis threshold.

Does the same threshold apply to younger adults?

No. Z-score interpretation and the clinical context are particularly important.

Should small differences between scans be compared?

Only with attention to precision, positioning and comparability of the equipment.

When should DXA be repeated?

The clinician individualises the interval according to risk and whether results would change management.

Educational information from The Spine Page. This entry does not replace an individual assessment. Documentary version: October 12, 2026. Sylvain Desforges, B.Sc., D.O., N.D., osteopath and naturopath.