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Flashcards in Joint Disease Deck (51)
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1

What are the two layers of a joint?

Fibrous joint capsule
Inner synovial fluid layer

2

What is subchondral bone?

Cortical bone beneath the cartilage of a joint
- provides support for articular cartilage
- Has Haversian system running parallel to the joint surface

3

Describe the synovial membrane...

Vascular connective tissue
- No basement membrane
- Functional continuation of vascular space

4

What are the different types of cells that can be found in a synovial membrane?

- Type A: macrophagic
- Type B: secretory and fibroblastic, possible functional adaptation
- Type C?: Transitional between A and Bs

5

What is synovial fluid composed of?

- Hyaluronic acid
- Collagen
- Lubricin
- pro- MMP
- Interleukins
- Eicosanoids (PGE2)

6

What are periarticular ligaments and joint capsules composed of?

Type I collagen
Elastin fibres

7

Describe the insertion points of periarticular ligaments...

Parallel bundles of collagen course through the fibrocartilage and calcified cartilage before inserting on bone
- reduces that chance of avulsion
- responds to physical stimuli by hyper/ atrophy

8

What are the three words that describe articular cartilage best?

- Aneural
- Avascular
- Alymphatic

9

Describe Articular Cartilage...

- Aneural
- Avascular
- Alymphatic
-- nutrition and metabolic waste removal through diffusion

1-12% chondrocytes
70-80% ECM

10

What is important about synovial joint pressure?

They have a sub-atmospheric pressure when they are in neutral position
- This contributes to the stability of the joint

11

What are the layers of cartilage histologically?

- Superficial
- Intermediate
- Deep
- Tide mark
- Calcified cartilage
- Subchondral bone

12

What are the components of cartilage ECM?

- Collagen
- Aggrecan
- Tissue fluid

13

What are the mechanical properties of cartilage ECM?

- Tensile strength: type II collagen

- Compressive stiffness: the negatively charged glycosaminoglycans attract several times their weight in water
-- responsible for the compressive stiffness of the cartilage

14

Describe the lubrication of joints...

Hydrostatic "Weeping" lubrication
-- Lubrication under load
-- Water is squeezed out of the cartilage matrix


"Boundary" lubrication
-- Low load lubrication
-- Hyaluronic acid and other molecules

15

Describe the biomechanical action of joints...

The correspondence of joints increases under load
- Increased stability

Stress is distributed
- to the epiphysis which deforms
-- subsequent bone remodelling

Muscles absorb large proportion of the load

16

What does bone remodelling aim to achieve?

Maximum strength and shock absorption capacity

17

What does maintaining joint integrity require?

- Healthy cartilage
- Healthy subchondral bone
- Congruent articular surface
- Extra-articular support (ligaments and muscles etc)
- Normal motion

18

What is DJD/ osteoarthritis?

A NON-INFLAMMATORY disorder of movable joints characterised by the degeneration and loss of articular cartilage and the development of new bone on joint surfaces and margins

19

What is the pathogenesis of DJD?

- ABNORMAL cartilage with flawed biomechanical properties undergoing NORMAL forces

OR...

- NORMAL healthy cartilage subjected to ABNORMAL micro/ major trauma

20

What are some examples of Normal stress on Abnormal cartilage?

- Aging
- Osteochondrosis
- Inflammation of soft tissue

21

What are some examples of Abnormal stress on Normal cartilage?

- Cyclic trauma
- Athletic trauma
- Loss of stability i.e. fractures
- Joint congruence changes
- Remodelling and necrosis in SC bone

22

What does fibrillation of cartilage look like?

The cartilage surface looks like floating seaweed

23

What are cartilage wear lines usually caused by?

The presence of fragment in a join

24

Describe severe cartilage erosion...

SC bone exposed with no cartilage at all

25

What are the bony changes that occur with DJD?

- SC bone sclerosis
- Periarticular osteophytosis (bony growths)
- SC bone erosion/ lysis
- SC cyst formation

26

How can DJD be diagnosed?

- Clinical signs
- Diagnostic Imaging
- Synovial fluid analysis
- Surgical techniques

27

What are the clinical manifestations of DJD?

- Pain
- Reduced range of motion
- Effusion
- Synovial fluid changes

28

Describe how the pain comes about in DJD...

- Synovium is stimulated (cartilage aneural)
- Periarticular soft tissues are highly innervated
- Effusion stimulates stretch receptors
- Periarticular fibrosis results in reduced compliance
- Periosteal inflammation
- SC bone pain and increased intramedullary pressure

29

Describe how DJD results in a reduced range of motion...

- Synovial proliferation (Acute)
- Articular fibrosis (chronic)
-- body trying to counteract stability

- Effusion causes pain which negatively feedback to muscles which then change their load to the joint

30

Describe DJD synovial effusion...

Increased permeability of the synovial membrane > protein leakage > increased COP > volume increased > pain and destabilisation


Variable depending on the cause of the process