2. Metabolic Bone Disease – Radiology Flashcards
What are the two main radiographic signs?
Osteopenia
Osteosclerosis
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
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
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 loss of height
Osteopaenia (increased lucency)
Pencilled in margin
What radiographic feature is common to both osteomalacia andosteoporosis?
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 HPT
b. Secondary HPT
c. Tertiary HPT
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
What are the main consequences of secondary HPT to bone?
Resorption and increased density
List 4 types of bone resorption.
- Subperiosteal
- Subchondral
- Intracortical
- 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
Describe the radiological features of renal osteodystrophy.
Subperiosteal bone erosions
Brown tumours
Sclerosis – axial skeleton/vertebral end plates (rugby jersey spine)
Soft tissue calcification (arteries/cartilage)
What are the 4 factors that make bones strong?
4Ms
- Mass
- Matrix and Material Properties
- Microarchitecture
- Macroarchitecture
What constitutes material properties of a bone?
Collagen, cross-linking, advanced glycation end products
Woven vs lamellar bone
Mineralization
Microcracks
What constitutes microarchitecture of bone?
Trabecular thickness
Trabecular connectivity
Cortical porosity
What constitutes macroarchitecture of bone?
Hip axis length
Diameter of bone
What are the compounds measured in serum biochemical investigations in bone disease?
Calcium Corrected calcium (albumin) Phosphate Alkaline phosphatase Creatinine PTH 25(OH)D3
What are the compounds measured in urine biochemical investigations in bone disease?
Calcium
Phosphate
NTX
In osteoporosis radiology, what are the main observations?
- Loss of cortical bone/ thinning of cortex
- Loss of trabeculae
- Insufficiency fractures
Where are Looser’s Zones commonly found?
Insufficiency fractures at high tensile stress areas
- Medial proximal femur
- Lateral scapula
- Pubic rami
- Posterior proximal ulna
- Ribs
