Bone Disease

Question 1

arthritis

Answer 1

inflammation of joints

Question 2

arthrosis

Answer 2

non inflammatory joint disease

Question 3

arthralgia

Answer 3

joint pain

Question 4

3 main features of bone

Answer 4

1. load bearing
2. dynamic - constantly changing so adaptive
3. self repairing

Question 5

describe bone turnover cycle

Answer 5

bone removed by osteoclasts and deposited by osteoblasts
osteoclasts eat away at bone matrix and are replaced by osteoblasts which deposit osteoid matrix that is mineralised to leave resting bone
cycle takes place over 3-6mths

Question 6

bone cycling requires what nutrients

Answer 6

calcium
phosphate
Vit D

Question 7

bone + calcium

Answer 7

bone provides store for Ca, some of which is exchangeable and some which isn’t
Ca moves from bone to ECF and is absorbed from here into the gut
Ca can be lost from gut and urine
involved in nerve & muscle function so must maintain Ca levels at all times
bone & ECF work together with parathyroid hormone to maintain calcium homeostasis

Question 8

what happens if low dietary Ca detected

Answer 8

reduction in plasma Ca -> increased PTH secretion causes:
- increased active Vit D so intestinal Ca absorption increased
- decreased urinary Ca so conservation of dietary Ca
- increased bone loss so increased bone Ca release
leads to restoration of normal plasma Ca

Question 9

parathyroid hormone and Ca

Answer 9

maintains serum Ca level; raised if Ca levels fall
increases Ca release from bone
reduces renal Ca excretion

Question 10

hypoparathyroidism

Answer 10

low serum Ca

Question 11

hyperparathyroidism

Answer 11

primary - gland dysfunction; potential tumour, high serum Ca results due to inappropriate activation of osteoclasts
secondary - low serum Ca causes activation of osteoclasts
both result in increased bone reabsorption

Question 12

what causes reduced Vit D synthesis

Answer 12

low sunlight exposure
poor GI absorption i.e. poor nutrition, small intestinal disease - malabsorption
drug interactions - some antiepileptic drugs e.g. carbamazepine, phenytoin

Question 13

osteoporosis

Answer 13

bone adequately mineralised but not enough bone mass
an age related change that is inevitable

Question 14

osteomalacia

Answer 14

poorly mineralised osteoid matrix & poorly mineralised cartilage growth plate
during bone formation = rickets
after bone formation = osteomalacia
serum calcium preserved at expense of bone

Question 15

bone effects of osteomalacia

Answer 15

bones bend under pressure - bow legs in kids / vertebral compression in adults
bones ache to touch

Question 16

hypocalcaemia effects of osteomalacia

Answer 16

muscle weakness
trousseau & chvostek signs positive - carpal muscle spasm & facial twitching from VII tapping

Question 17

osteomalacia management

Answer 17

correct cause i.e. malnutrition & control GI disease
sunlight exposure
dietary Vit D

Question 18

risk factors of osteoporosis

Answer 18

age
female
endocrine - oestrogen & testosterone deficiency, Cushing’s (increased corticosteroid levels in blood)
genetic - family history, race (caucasian/asian), early menopause
patient factors - inactivity, smoking, excess alcohol use, poor dietary calcium
drugs - steroids, antiepileptics

Question 19

osteoporosis & gender

Answer 19

males have higher peak bone mass
oestrogen lost during menopause so protection it offers is lost

Question 20

effects of osteoporosis

Answer 20

increased bone fracture risk
height loss
kyphosis - stooping forwards
scoliosis
nerve root compression - back pain
lifetime risk of hip fracture >50yrs

Question 21

prevention of osteoporosis

Answer 21

1. build max peak bone mass - exercise / high dietary Ca intake
2. reduce rate of bone mass loss - exercise & Ca intake, reduce hormone related effects i.e. HRT in early menopause
3. reduce drug related effects i.e. osteoporosis prevention via bisphosphonates

Question 22

hormone replacement therapy

Answer 22

oestrogen only - reduces osteoporosis risk but increased breast cancer risk, increased endometrial cancer risk - ptx who have not had a hysterectomy so combine with progestogen to reduce risk, increases DVT risk, may reduce ovarian cancer risk
benefit lost after HRT stops

Question 23

3 main bisphosphonates prescribed

Answer 23

alendronate
zoledronate
ibandronate

Question 24

effect of bisphosphonates

Answer 24

act by prevention of osteoclast action by poisoning them & reducing their numbers
reduce vertebral fracture risk by 50%
benefit lost if drug discontinued
can be combined with HRT

Question 25

risks of bisphosphonates in dentistry

Answer 25

as they interfere with bone resorption by osteoclasts they can inhibit tooth movement, impair bone healing and induce osteonecrosis of the jaw