Revision

Question 1

Compact bone (cortical)

Answer 1

Long bones
80% of skeleton
appendicular skeleton
80-90% calcified
mainly mechanical and protective

Question 2

Trabecular bone (cancellous)

Answer 2

Vertebrae & pelvis
20% of skeleton
axial skeleton
15-25% calcified
mainly metabolic, large surface

Question 3

describe the fibre organisation in woven bone (immature)

Answer 3

Randomly oriented collagen fibres, becomes lamellar after remodelling

Question 4

Lamellar bone (mature)

Answer 4

Collagen fibres in lamellae (sheets), oriented in the same direction in each layer, different directions in different layers ↑ strength

Question 5

cortical bone lamellae structures

Answer 5

circumferential
concentric
interstitial
trabecular

Question 6

what are the types of bone biopsy?

Answer 6

• Closed (needle)
  : core biopsy (with Jamshidi needle)
• Open
  : for sclerotic (hardening) / inaccessible lesions

Question 7

what is metabolic bone disease?

Answer 7

reduced bone mass
reduced bone strength
due to imbalance of vitamins, hormones, minerals

Question 8

what effect does metabolic bone disease have on bones?

Answer 8

• altered bone cell activity
• rate of mineralisation
• changes in bone structure

Question 9

what are the most common metabolic bone disease?

Answer 9

Osteoporosis
Osteomalacia/Rickets
Primary hyperparathyroidism
Renal osteodystrophy
Paget’s disease

Question 10

which enzyme converts vitamin D into 25 dihydroxy Vit D? where is this enzyme produced?

Answer 10

25 hydroxylase

produced in the liver

Question 11

which enzyme converts 25 dihydroxy Vit D to 1,25 dihydroxy Vit D? where is this enzyme produced?

Answer 11

1 alpha hydroxylase

produced in the kidney

Question 12

describe osteoporosis in two phrases

Answer 12

reduced bone mass

normal bone chemistry

Question 13

define rickets/osteomalacia simply

Answer 13

Defective mineralisation of normally synthesized bone matrix

Question 14

what are the causes of rickets/osteomalacia?

Answer 14

• Deficiency of vitamin D, Calcium, Phosphate
• High alkaline phosphatase
• anticonvulsants
• phytic acid chelates Vit D
• lack of sun

Question 15

what is sequelae?

Answer 15

bone pain/tenderness, fracture, proximal weakness, bone deformity

Question 16

what are the causes of osteoporosis?

Answer 16

• hyperthyroidism
• Cushing’s syndrome
• lack of exercise and disuse
• lack of oestrogen

Question 17

describe Paget’s disease simply

Answer 17

Disorder of bone remodelling of unknown cause where there is increased bone resorption followed by increased compensatory bone formation

Question 18

features of primary hyperparathyroidism?

Answer 18

hypercalcaemia:

Stones (Calcium oxalate renal stones)
Bones (osteitis fibrosa cystica, bone resorption)
Abdominal groans (acute pancreatitis)
Psychic Moans (psychosis & depression)

Question 19

radiology of osteoporosis

Answer 19

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

normal bone chemistry
reduce bone mass

Question 20

what are the radiological signs of osteomalacia?

Answer 20

• Looser’s zones (translucencies in X-ray)
• Codfish Vertebrae (biconcave deformity)
• Osteopenia
• Bending deformities

demineralisation of normal bone matrix

Question 21

radiology of rickets

Answer 21

• Indistinct metaphyseal margin
• Widened growth plate without calcification
• Cupping metaphases due to weight bearing
• Enlargement of anterior ribs
• Osteopenia

immature bone in the young with demineralisation

Question 22

radiology of hyperparathyroidism

Answer 22

• Bone resorption (subperiosteal, subchondral, intracortical)
• Brown tumuors

high Calcium due to increased bone resorption

Question 23

what is a brown tumour?

Answer 23

lesion caused by excessive osteoclast activity (bone resorption due to high PTH)

Question 24

radiology of Paget’s

Answer 24

• Cortical thickening
• Bone expansion
• Coarsening of the trabeculae
• Osteolytic, osteosclerotic and mixed lesions
• Osteoporosis circumscripta

bone remodelling disorder
more resorption and more formation

Question 25

radiology of renal osteodystrophy

Answer 25

• Subperiosteal erosions
• Brown tumours (more osteoclast activity)
• Soft tissue calcification (vessels, cartilages)