ORTHO 119 Shoulder Trauma Flashcards

1
Q

What is bone?

A

A specialised form of connective tissue

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2
Q

What are the two types of bone?

A

Trabecullar (cancellous) and cortical (compact) bone

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3
Q

Describe trabecular bone

A

Spongy bone with high turnover axially. Site of bone remodelling and mineral homeostasis

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4
Q

Describe cortical bone

A

Compact bone with low turnover, found peripherally. Has trabecullar shell and has mainly mechanical and protective functions. Contain lacunae, haversian canals, osteons and canniliculi

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5
Q

Describe lacunae and where are they found?

A

Concentric layers of dense connective tissue in cortical bone

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6
Q

What type of collage comprises most of organic bone?

A

Type 1 from osteoblasts

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7
Q

What is inorganic bone?

A

Bone with high mineral content of calcium hydroxyapetitie crystals

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8
Q

What is an osteoid?

A

It is an area of newly formed unmineralised bone

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9
Q

What are the 4 types of bone cells?

A

Osteoprojenitor, Osteoblasts, osteocytes and osteoclasts

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10
Q

What are osteoprojenitor cells?

A

Self replicating precursor cells that differentiate into bone forming cells

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11
Q

What are osteoblasts?

A

Bone forming cells that deposit osteoid and control mineralisation

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12
Q

What are osteocytes?

A

Modified osteoblasts which have become surrounded by newly formed bone

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13
Q

What are osteoclasts?

A

Macrophage like cells that resorb bone

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14
Q

What is the role of canniliculi?

A

They permeate through the new bone and link lacunae between adjacent osteocyte processes
Act as mechanotransducting cells

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15
Q

What controls bone resorption and remodelling?

A

The RANK/OPG system

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16
Q

What causes increased OPG and therefore decreased bone resorption?

A

Oestrogen, IL1 and TNF alpha

17
Q

What causes increased RANK and therefore increased resorption?

A

PTH, Vit D3 and PgE2

18
Q

How does cartilage work as a shock absorber?

A

Collagen forms a meshwork holding in the proteoglycans. Proteoglycans have a high osmotic potential drawing water into the joint

19
Q

What is the dry weight of cartilage?

A

3/4 collagen and 1/4 proteoglycans

20
Q

What is the wet weight of cartilage?

A

70% water, 20% collagen, 7% PG’s, 2% cells and 1% of other proteins

21
Q

What is the major proteoglycan in cartilage?

A

Aggrecan

22
Q

What is the structure of aggrecan?

A

Protein core surrounded by covalently attached glycosaminoglycans. Contains hydroxyl and sulfate groups as well as chondroitin, keratin sulfate and hyaluronan groups

23
Q

What enables the strong binding of water to aggrecan?

A

Its negatively charged hydroxyl and sulfate groups

24
Q

What is the difference between adult and young cartilage?

A

Adult: hypocellular, aneural, avascular, extensive matrix, zonal morphology and tidemark
Young: hypercellular, little organisational matrix, no zonal morphology or tidemark

25
Q

What is the function of the tidemark?

A

Prevents cartilage from utilitsing blood supply and therefore nutrients from subchondral bone

26
Q

What are the two main classes of proteolytic enxymes involved in the degradation of cartilage?

A

ADAMTS and MMP’s

27
Q

Name the 3 matrix metalloproteinases and what they degrade

A

Collagenases- triple helix collagens, gelatinases - denatured collagens and stromelysins - non-collagenous matrix proteins (not aggrecan though)

28
Q

Where is the specific activity of ADAMTs

A

Between the glutamate and alanine in aggrecans interglobular domain

29
Q

What occurs to cartilage in ageing?

A
Slowed cell metabolism
Increased collagen and matrix protein cross linking
Decreased collagen IX synthesis
Changes in aggrecan
Accumulation of degradation products
30
Q

What is arthritis?

A

Joint space narrowing can cause pain, swelling, loss of function

31
Q

What is RA due to?

A

Deposition of immune complexes in joint space, therefore influx of inflammatory cells and secretion of cytokine which degrade cartilage

32
Q

What is OA usually as a result of?

A

Increased mechanical stresses on the joint, often after injury or trauma

33
Q

What is the commonest cause of shoulder pain?

A

Rotator cuff tendonosis - often following trauma worse on arm abduction and elevation
= painful arc

34
Q

What is dupytrens contracture?

A

Painless palpable fibrosis of the palmar aponeurosis with fibroblasts invading the dermis.