Metabolic Bone Disease – Radiology Flashcards
What are the two main radiographic signs?
- Osteopenia - decreased bone mass but normal microstructure
(seen in both ostemalacaia and osteoporosis) - Osteosclerosis - abnormal hardening of bone and increased bone density
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
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
(‘lucency’ is a technical term for an area that lets X-rays through the tissue and as a result appears darker on the picture)
What is the main difference between osteoporosis and osteomalacia?
Osteoporosis – decreased bone mass
Osteomalacia – decreased bone mineralisation
Describe the microstructure in osteoporosis.
Normal
Though there is an overall decreased quantity of bone
What are the features of osteomalacia?
- Too little mineral – osteopenic and soft bone bends and deforms
- Too much osteoid – Looser’s zones (they are pseudofractures)
- If calcium remains low –> secondary hyperparathyroidism
What are Looser’s zones? Where are they found?
Narrow lucency, perpendicular to the bone cortex
Found in the pubic rami, proximal femur, scapular and lower ribs
What is a distinctive feature of osteomalacia that can be seen in an X-ray of the vertebrae?
Codfish vertebrae – biconcave deformity of vertebrae (loss of height )
What radiographic feature is common to both osteomalacia and osteoporosis?
Osteopenia
What is the key difference between osteomalacia and rickets?
Rickets occurs before the growth plates have fused
As the metaphysis grows most rapidly, it shows the most obvious changes
What are the radiographic features of rickets that are linked to the metaphysis?
Indistinct frayed metaphyseal margin
Widened growth plate (no calcification taking place)
Bowing of weight bearing bones
What is Rickety Rosary?
Enlargement of the anterior ribs
Describe how PTH, calcium and phosphate change in:
a. Primary Hyperparathyroidism
b. Secondary Hyperparathyroidism
c. Tertiary Hyperparathyroidism
a. Primary HPT (PTH adenoma)
PTH – high
Calcium – low
Phosphate – low
b. Secondary HPT (Vitamin D deficiency, chronic kidney disease etc)
PTH – high
Calcium – low
Phosphate – normal or low
c. Tertiary HPT (autonomous production of PTH)
PTH – high
Calcium –high
Phosphate – low
What are the main consequences of primary secondary hyperparathyroidism to bone?
primary- bone resorption
secondary -Resorption and increased density
List 4 types of bone resorption.
- Sub-periosteal
- Sub-chondral
- Intra-cortical
- Brown tumours
What are the differences between slow and fast bone loss?
- 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
