The Radiology of Metabolic Bone Disease

Question 1

What can imaging of bones be useful for

Answer 1

Reveals structural failures such as fractures and ligamentous injuries
Also serves as proxy to metabolic dysfunction

Question 2

What are the types of imaging that can be done for bone and what are the used for

Answer 2

X-rays - density 
CT - density 
Bone densitometry - density 
MRI - biochemical composition
Radionucleotide Bone scans - bone turnover

Question 3

How can osteoporosis be diagnosed

Answer 3

Bone densitometry, dual-energy absortiometry DEXA
T-score -1.5 to -2.5 = osteopenia
< -2.5 = osteoporosis

Question 4

Describe the DEXA scan

Answer 4

A measure of bone mineral density (BMD)
Compares BMD to normal reference databases
and gives
T-score (ref database white adult premenopausal females)
Z-score (ref database age and sex matched)

Question 5

What are the effects of osteoporosis on bone that you may see in radiology

Answer 5

Loss of cortical bone/thinning of cortex
Loss of trabeculae
Insufficiency fractures

Difficult to separate from osteomalacia

Question 6

What are the causes of osteomalacia and describe the biochemistry of it

Answer 6

Vit D deficiency
Inadequate or delayed mineralisation

Vit D low
Calcium low/none
PTH up

Question 7

What are the effects of osteomalacia on bone that you may see in radiology

Answer 7

Mature skeleton 
Osteopenia
Looser's zones
Codfish vertebrae
Bending deformaties

Question 8

What are the effects of rickets on bone that you may see in radiology

Answer 8

Before growth plate closure
Radiological signs centred mainly to growth plates
Changes of osteomalacia

Question 9

What are looser zones and where are they commonly found

Answer 9

Too much un-mineralised bone seen in osteomalacia

Pseudo/insufficiency fractures at high tensile stress areas 
Medial proximal femur
Lateral scapula 
Public rami
Posterior proximal ulna 
Ribs

Question 10

What are codfish vertebrae and what are they seen in

Answer 10

Biconcave deformity of vertebrae

Seen in osteoporosis and osteomalacia

Question 11

What are the radiological features of rickets

Answer 11

Indistinct/frayed metaphysical margin
Widened growth plate without calcification
Cupping/splaying metaphases due to weight bearing
Enlargement of anterior ribs
Osteopenia

Question 12

What are the effects of primary hyperparathyroidism on bone

Answer 12

Bone resorption

Question 13

What are the effects of secondary hyperparathyroidism on bone

Answer 13

Bone resorption and increased density

Question 14

What are the types of bone resorption

Answer 14

Superiosteal
Subchondral
Intracrotical
Brown tumours

Question 15

What can renal osteodystrophy cause

Answer 15

Osteomalacia
Osteoporosis
Secondary hyperparathyroidism

Question 16

What can secondary hyperparathyroidism lead to

Answer 16

Subperiosteal erosions, brown tumours
Sclerosis - vertebral endplates giving a rugger jersey spine
Soft tissue calcification (vessels, cartilages)

Question 17

What are the effects of Paget’s disease on bone that you may see in radiology

Answer 17

Cortical thickening
bone expansion 
Coarsening of trabecular 
Osteolytic, osteosclerotic and mixed lesions
Osteoporosis circumscripta

Question 18

What are insufficiency fractures

Answer 18

Stress fractures due to normal stress on abnormal bones

Question 19

What may result if calcium remains low in a patient with osteomalacia

Answer 19

Secondary hyperparathyroidism

Question 20

What are the types of bone found in osteomalacia

Answer 20

Decreased bone mineralisation
Osteopenic bone
Soft bone

too much un-mineralised osteoid
Looser’s zones