Other Bone Problems

Question 0

What is the risk of osteoporosis based on

Answer 0

Peak bone mass
+
Rate of bone loss

Question 1

What is osteoporosis

Answer 1

Lots of trabecula spongy bone mass – >

form POROUS (porosis..) bone – >

increased risk of fracture

Despite
normal bone mineralisation +
lab values of calcium + phosphate

Question 2

What age is the peak bone mass occurring

Answer 2

30

Question 3

What three things determine how high the peak bone mass will be?

Answer 3

Diet
Exercise
Inherited vitamin D receptor

Question 4

What are the determinants of bone loss rate?

Answer 4

Diet
Exercise
For women – oestrogen:
@menopause – >lose oestrogen – >lose bone mass rapid I.e. increased bone resorbtion

Question 5

What test is used to check for osteoporosis?

And what is the T score to determine osteoporosis?

Answer 5

Bone mineral density test = DEXA

T score < -2.5

Question 6

Two types of osteoporosis?

Answer 6

Type 1 = postmenopausal

Type to senile > 70 years

Question 7

Where do you fractures usually occur in osteoporosis?

Answer 7

Weight-bearing areas:

Vertebrae –> decreased height + kyphosis
Hip - femoral neck
Distal radius - COLLES fracture

Question 8

In osteoporosis what are the lab works like?

Answer 8

Normal – calcium/phosphate/ALP = HALLMARK

Question 9

What is the prophylaxis treatment for osteoporosis

Answer 9

Weight-bearing exercise

Decent calcium/vitamin D in adulthood/childhood

Question 10

Treatments for osteoporosis

Answer 10

Bisphosphonate is:
attach to bone – >osteoclast eat bisphosphonate – > osteoclast apoptosis – > decreased bone resorption

Oestrogen replacement therapy – could cause breast cancer

Denosumsb - monoclonal antibody against RANKL

Question 11

What drug is contra indicated for osteoporosis

Answer 11

Glucocorticoids

Question 12

What happens in pagets disease of bone

Answer 12

Osteoclast + osteoblast function in balance

Question 13

Four stages of pagets disease of bone

Answer 13

1.osteoclastic lytic stage:
Osteoclast goes crazy – resorb bone without permission of osteoblast

2. Mixed osteoclast osteoblast stage:
   Bone very weak – osteoblast recognises need to lay down bone ASAP to protect
3. Osteoblastic sclerotic stage:
   Osteoclast burns out –> osteoblasts only lays bone in rush -> sclerotic thick bone
4. Quiescent stage decreased osteoblast osteoclast activity

Question 14

What age does Padgett’s affect?
Aetiology?
Localisation?

Answer 14

60 years
Unknown – possibly viral – infect osteoblast
Localised = 1+ bones BUT not @ entire skeleton

Question 15

What do you see on histology for pageants disease of bone

Answer 15

Cement lines @bone = not sealed
-> Thick bone BUT fragile – >

Mosaic pattern of lamellar bone

Question 16

Clinical features of pagets

Answer 16

Pain
ALP⬆️
Grrrrrr lion face
Ear - hearing loss
Thicken calvarium @school – > ⬆️Hat size

Question 17

Treatment for Paget bone disease

Answer 17

Calcitonin – inhibit osteoclast

BISPHOSPHONATES

Question 18

2 complications are Padgett disease of bone

Answer 18

Remodelling of bone – > form arteriovenous shunts
-> hard pushed to aviation – >
high output cardiac failure

Osteoplast produces loads of bone – >
osteoblasts mutate – >osteosarcoma

Question 19

In Rickets + osteomalacia what is the problem

Answer 19

Defective mineralisation of osteoid due to vitamin D deficiency

Question 20

What are the risk factors for rickets/osteomalacia

Answer 20

Decreased sun exposure
Shit diet
Malabsorption – vitamin D = fat soluble vitamin
Liver + renal failure – need it to activate vitamin D

Question 21

How does a child with rickets presents?

Answer 21

Frontal bossing – enlarged forehead = Osteoid deposition

Pigeon breast deformity:
inward bending of ribs +
anterior protrusion of sternum

Rachitic rosary(beads THASBY!!!):
Osteoid deposition @costochondral junction

Bowlegged – >1 years start walking

Question 22

Who get osteomalacia

Answer 22

Vitamin D deficiency in adults

Question 23

Lab work for osteomalacia/Ricketts

Answer 23

Decreased vitamin D – >decreased serum calcium- >

Increased PTH secretion – >

• decreased phosphate serum
• osteoblast hyperactivity – >increased ALP

Question 24

What happens in achondroplasia

Answer 24

Disorder of cartilage proliferation @ growth plate

Question 25

Explain the pathogenesis of achondroplasia

Answer 25

85% – Sporadic mutation 15% – autosomal dominant + full penetrance – lethal -> Activating mutation @ fibroblast growth factor 3 (FGF – 3) – > Inhibit chondrocyte proliferation – >impaired cartilage proliferation @growth plate – > Short extremities only

Question 26

At embryology what are the two ways to form bone

Answer 26

1.intramembranous: Connective-tissue matrix –> form woven bone of skull + chest + flat bones of wrist 2. Endochondral bone formation: Establish cartilage matrix -> cartilage dies -> calcifies + mineralised -> form woven BONE - long -> lamellar bone

Question 27

Explain how the chondrocyte make cartilage at the growth plate

Answer 27

Chondrocytes make cartilage – > growth plate expands – > Chondrocytes die @ edge of plate – > dead chondrocytes replaced with bone = longer In achondroplasia there's a problem with the chondrocyte proliferation hence why the short extremities

Question 28

Explain osteogenesis imperfecta

Answer 28

Autosomal dominant defect in collagen type one synthesis – > Congenital defect in formation – >weak bone

Question 29

Clinical features of osteogenesis imperfecta

Answer 29

Blue sclera – thinning of squirrel collagen – > reveal choroidal veins = blue Hearing loss – break malleus incus stapes Multiple fractures because of shit collagen

Question 30

Explain osteoPETROSIS pathogenesis

Answer 30

Inherited defect of bone result shown due to defective osteoclast – > thick dense bones prone to fracture

Question 31

Where is the mutation in osteopetrosis

Answer 31

Carbonic anhydrase 2 mutation – | Need acid environment to resorb bone i.e. remove calcium

Question 32

What does x-ray reveal osteopetrosis

Answer 32

Bone in bone appearance – can't see dark space outside of medulla

Question 33

Explainwhy we get pancytopenia in osteopetrosis

Answer 33

CA deficiency – >bone thickens – > Fills medullary/marrow space = MYELOPHTHISIC process – > pancytopenia

Question 34

Explain why there is vision and hearing loss in osteopetrosis

Answer 34

CA deficiency – >bone thickens – > | compress cranial nerves = vision and hearing decrease

Question 35

Explain why we get hydrocephalus in osteopetrosis

Answer 35

CA deficiency – > bone thickens @Foramen Magnum = narrow – > Hydrocephalus

Question 36

Explain rather get renal tubular acidosis and osteopetrosis

Answer 36

Decreased CA – >Decreased H+ – > can't excrete enough H+ & No net gain of HCO3 -> Acidotic

Question 37

Treatment for osteopetrosis and why?

Answer 37

Bone marrow transplant Haematopoiesis well –> make normal monocytes – > make normal macrophages e.g. osteoclasts

Question 38

Most common reason for dwarfism

Answer 38

Achondroplasia

Question 39

Explain the relationship between oestrogen and osteoporosis

Answer 39

Oestrogen inhibits apoptosis in osteoblasts Oestrogen induces apoptosis in osteoclasts At menopause get XS remodelling cycles and XS bone resorption