Metabolic Bone Disease – Radiology

Question 1

What are the two main radiographic signs?

Answer 1

Osteopenia

Osteosclerosis

Question 2

What is the lucency of the following scans proportional to:

a. X rays
b. Densitmetry
c. CT scans
d. MRI scans
e. Radionucline bone scans

Answer 2

a. X rays
Density

b. Densitometry
Density and attenuation

c. CT scans
Density and attenuation

d. MRI scans
Chemical and water content

e. Radionuclide bone scans
Bone turnover

Question 3

What is the main difference between osteoporosis and osteomalacia?

Answer 3

Osteoporosis – decreased bone mass

Osteomalacia – decreased bone mineralisation

Question 4

Describe the microstructure in osteoporosis.

Answer 4

Normal

Though there is an overall decreased quantity of bone

Question 5

What are the features of osteomalacia?

Answer 5

Too little mineral:
osteopenic and soft bone bends and deforms

Too much un-mineralised osteoid:
Looser’s zones

If calcium remains low –> secondary hyperparathyroidism

Question 6

What are Looser’s zones? Where are they found?

Answer 6

Narrow lucency, perpendicular to the bone cortex

Found in the pubic rami, proximal femur, scapular and lower ribs

Question 7

What is a distinctive feature of osteomalacia that can be seen in an X-ray of the vertebrae?

Answer 7

Codfish vertebrae – biconcave loss of height

Question 8

What radiographic feature is common to both osteomalacia and osteoporosis?

Answer 8

Osteopenia

Question 9

What is the key difference between osteomalacia and rickets?

Answer 9

Rickets occurs before the growth plates have fused

As the metaphysis grows most rapidly, it shows the most obvious changes

Question 10

What are the radiographic features of rickets that are linked to the metaphysis?

Answer 10

Indistinct frayed metaphyseal margin

Widened growth plate (no calcification taking place)

Bowing of weight bearing bones

Question 11

What is Rickety Rosary?

Answer 11

Enlargement of the anterior ribs

Question 12

Describe how PTH, calcium and phosphate change in:

a. Primary HPT
b. Secondary HPT
c. Tertiary HPT

Answer 12

a. Primary HPT
PTH – high
Calcium – high
Phosphate – low

b. Secondary HPT
PTH – high
Calcium – low
Phosphate – normal or low

c. Tertiary HPT
PTH – high
Calcium –high
Phosphate – low

Question 13

What are the main consequences of secondary HPT to bone?

Answer 13

Resorption and increased density

Question 14

List 4 types of bone resorption.

Answer 14

Subperiosteal
Subchondral
Intracortical
Brown tumours

Question 15

What are the differences between slow and fast bone loss?

Answer 15

Slow – Involutional Osteoporosis
 Bone has time to remodel
 Bone loss occurs according to mechanical needs

Fast – hyperparathyroidism/disuse osteoporosis
 Bone loss is too rapid
 Loss does not cater to mechanical needs

Question 16

Describe the radiological features of renal osteodystrophy.

Answer 16

1. Osteomalacia and osteoporosis
2. Secondary hyperparathyroidism:
    Subperiosteal bone erosions
    Brown tumours
    Sclerosis – vertebral endplates (rugby jersey spine)
    Soft tissue calcification (vessels, cartilage)

Question 17

What are the features of vit D deficiency?

Answer 17

Biochemistry:
vit d low,
calc normal/low
PTH high

 Inadequate or delayed mineralisation