Metabolic bone disease on X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Advanced

Metabolic bone diseases affect the whole skeleton: how much bone there is, how well it is mineralised, and how it is remodelled. On X-ray they show as generalised changes in density and texture, often with characteristic fractures or deformities at particular sites. The plain film is insensitive for some (osteoporosis) and almost diagnostic for others (Paget disease, rickets, hyperparathyroidism). This page covers the conditions you are most likely to meet and the signs that separate them, and makes clear when another test, such as DEXA or MRI, is the right one.

1. An approach: density, texture, distribution

• Density: is the bone too dark (osteopenia) or too white (sclerosis)? Judge cortical thickness rather than overall greyness, which depends on exposure.
• Texture: fine and sparse trabeculae (osteoporosis), blurred and indistinct (osteomalacia), coarse and thickened (Paget disease), or "salt and pepper" (hyperparathyroidism).
• Specific sites: phalanges for hyperparathyroidism, metaphyses for rickets, the femoral neck and pubic rami for Looser zones, the spine for fractures and endplate changes.
• Fractures: are there fragility fractures, insufficiency fractures or pseudofractures?

"Osteopenia" on a radiograph simply means the bone looks less dense. It is a description, not a diagnosis.

2. Osteoporosis

Osteoporosis is a loss of bone mass with normal mineralisation, which weakens bone and causes fractures with little trauma.

• The X-ray is insensitive: roughly 30–50% of bone mineral must be lost before osteopenia is visible.
• Signs: thin cortices, loss of horizontal trabeculae with relatively prominent vertical trabeculae in the vertebral bodies, and fragility fractures.
• Typical fractures: vertebral wedge or compression fractures, hip fractures, distal radius fractures and proximal humerus fractures.
• Insufficiency fractures of the sacrum and pubic rami may be invisible on X-ray; MRI or CT is more sensitive.
• DEXA (dual-energy X-ray absorptiometry) is the diagnostic test. The WHO definition of osteoporosis is a T-score of −2.5 or lower.

Long-term bisphosphonate use is associated with atypical femoral fractures: a transverse fracture of the lateral cortex of the subtrochanteric region or shaft, often with focal cortical thickening ("beaking"). Image the other femur as well.

3. Osteomalacia and rickets

Both are caused by defective mineralisation, most often from vitamin D deficiency. In adults it is called osteomalacia; in children, whose growth plates are open, it is rickets.

Osteomalacia

• Generalised osteopenia with indistinct, blurred trabeculae.
• Looser zones (pseudofractures): transverse lucent bands running perpendicular to the cortex, often bilateral and symmetrical. Typical sites are the medial femoral neck, pubic rami, ribs and the lateral (axillary) border of the scapula.
• Bowing of long bones and protrusio acetabuli can occur.

Rickets

• Widened physes with cupping, fraying and splaying of the metaphyses, best seen at the fastest-growing sites: the wrist (distal radius and ulna) and the knee.
• Generalised osteopenia.
• Rachitic rosary: enlarged costochondral junctions on a chest film.
• Bowing of the legs once the child walks.

Rickets is an important differential when fractures are found in an infant, but the two can coexist; see non-accidental injury. Physeal anatomy is explained in Salter-Harris fractures.

4. Hyperparathyroidism and renal osteodystrophy

Excess parathyroid hormone increases bone resorption. Primary disease is usually caused by a parathyroid adenoma; secondary disease most often accompanies chronic kidney disease.

• Subperiosteal bone resorption on the radial aspect of the middle phalanges of the index and middle fingers: considered pathognomonic.
• Acro-osteolysis (resorption of the terminal tufts) and resorption of the lateral ends of the clavicles.
• A "salt and pepper" (pepperpot) skull from tiny areas of resorption.
• Brown tumours: lytic, expansile lesions that can mimic tumours (see bone tumours).
• In renal osteodystrophy, a mixture of hyperparathyroidism, osteomalacia and sclerosis: the "rugger-jersey spine", with dense bands at the vertebral endplates, plus soft-tissue and vascular calcification.

Chondrocalcinosis can accompany hyperparathyroidism (see crystal arthritis).

5. Paget disease of bone

Paget disease is a disorder of excessive, disorganised bone remodelling in older adults. It affects one or several bones, commonly the pelvis, spine, skull, femur and tibia. It progresses through phases that may coexist in the same patient.

Phase	Signs
Lytic	A sharply demarcated "blade of grass" or flame-shaped lytic front advancing along a long bone; osteoporosis circumscripta (a large lucent area) in the skull.
Mixed and sclerotic	Cortical thickening, coarse trabeculae and bone enlargement. The "picture-frame" vertebra (thick dense edges), the "ivory" vertebra, the "cotton-wool" skull, thickening of the iliopectineal line, bowing (such as an anteriorly bowed "sabre" tibia) and protrusio acetabuli.

New pain, a destructive area or a soft-tissue mass in Pagetic bone should raise concern for sarcoma and needs urgent review.

6. Avascular necrosis and sickle cell disease

Avascular necrosis (osteonecrosis)

• Bone death from loss of blood supply, commonly in the femoral head. Causes include steroids, alcohol, sickle cell disease, trauma, decompression ("Caisson") disease, Gaucher disease and systemic lupus erythematosus.
• The X-ray is normal early. Later signs are patchy sclerosis, a subchondral lucent line (the crescent sign, a subchondral fracture), then flattening and collapse of the head and secondary OA.
• MRI is the most sensitive test and shows disease before X-ray changes. The Ficat system grades severity.
• The childhood equivalent at the hip is Perthes disease (see the paediatric hip).

Sickle cell disease

Recurrent infarction produces bone infarcts, AVN of the femoral and humeral heads, H-shaped vertebrae (central endplate depressions) and, in infants, dactylitis. Osteomyelitis is also more common and can be hard to distinguish from infarction (see osteomyelitis).

7. Pitfalls and mimics

• Calling osteoporosis from film density: exposure and processing change how dark bone looks. Use cortical thickness and fractures, and refer for DEXA.
• A normal X-ray does not exclude osteoporosis, insufficiency fractures or early AVN.
• Looser zone versus stress or atypical fracture: Looser zones are often bilateral and symmetrical on the compression (medial) side of the femoral neck; atypical femoral fractures start on the lateral cortex.
• Paget disease versus sclerotic metastases: look for bone enlargement and trabecular coarsening (Paget) rather than multiple separate foci without expansion (metastases). Lymphoma also causes ivory vertebrae.
• Brown tumours versus tumours: check the phalanges and clavicles for resorption, and the calcium level.
• Myeloma can present as diffuse osteopenia without discrete lesions. Unexplained osteopenia with vertebral fractures in an older adult may need myeloma screening.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Osteoporosis versus osteomalacia, rickets at the wrist, the hyperparathyroid hand and Paget disease features.
Nurse / practitioner	Fragility fractures should trigger bone health assessment; know who to refer to for fracture liaison.
Junior doctor	Report and act on incidental vertebral fractures, request DEXA rather than relying on films, and recognise atypical femoral fractures.
Radiographer	Consistent exposure so that apparent density is meaningful, and appropriate views of both femurs when an atypical fracture is suspected.
Advanced / FRCR	Renal osteodystrophy, Looser zones, Paget phases and complications, and the differential of ivory vertebra and diffuse sclerosis.

Practise on bone and joint X-rays →

References

1. Radiopaedia. Paget disease of bone. radiopaedia.org
2. National Institute for Health and Care Excellence. Osteoporosis: assessing the risk of fragility fracture (CG146). nice.org.uk
3. Shane E, et al. Atypical subtrochanteric and diaphyseal femoral fractures: second report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res 2014;29(1):1–23.
4. World Health Organization Study Group. Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. WHO Technical Report Series 843. Geneva: WHO; 1994.
5. National Institute for Health and Care Excellence. Myeloma: diagnosis and management (NG35). nice.org.uk
6. Radiology Masterclass. Musculoskeletal X-ray tutorials. radiologymasterclass.co.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.