Module 2: articular structure and pathology Flashcards by Marialaina Tomolonis

What as the synovial joint comprised of?

Joint capsule
Joint space
Synovial fluid
articular cartilage

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What are the 2 parts of the joint capsule?

Fibrous joint capsule

2. Synovial membrane (inner layer)

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What is the outer layer of the joint capsule called?

Fibrous capsule (stratum fibrosum)

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Fibrous capsule is ____ in blood supply and ____ in joint receptors.

Poor in blood supply but rich in joint receptors

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What is the inner layer of the joint capsule called?

synovium

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What 2 types of cells exist in the synovium?

Type B and Type A

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What is the function of the Type B cells of the synovium?

Synovial fluid production

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What is the function of the Type A cells of the synovium?

Immune function

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What do Type B cells in the synovium secrete?

HA (hyaluronate/hyaluronic acid): Gel to improve viscosity of fluid-attracts H2O

Lubricin: Reduce friction of the joint

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What do Type A Cells in the synovium secrete?

Immunoglobulins
lysosomal enzymes
lyse debris

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What does the term Thixotropic properties refer to?

viscosity varies inversely with velocity of movement

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at rest the synovial fluid _____ movement of the joint?

resists

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At movement synovial fluid _______ ____ ____ to movement

provides less resistance

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What is the function of the hyaline cartilage that covers the ends of most bones?

reduce friction
absorb/disperse
compressive forces

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What is the cellular component of the articular cartilage?

Chondroblasts (chondrocytes)

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What is the function of the chondrocytes?

produce and maintain extra-cellular matrix
Secrete enzymes that assist in matrix
Forms 2% of cartilage

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What are the components of the extra-cellular matrix of the articular cartilage?

non-fibrous

Fibrous

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What is the non-fibrous component of the articular cartilage extra cellular matrix, made up of?

Primarily water (60-80%)
Protein, proteoglycans (5-10%)
regulates fluid flow in/out of cartilage

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What is the fibrous component of the articular cartilage extra cellular matrix made up of?

Collagen fiber (10-30%) TYPE 2 COLLAGEN
arranged to abosorb mechanical stress

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The fibrous component of the matrix is made up of collagen that is arranged to absorb mechanical stress. Describe Zone 1 of the cartilage bone interface:

Smooth surface

Reduce friction of joint surface

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The fibrous component of the matrix is made up of collagen that is arranged to absorb mechanical stress. Describe Zone 2&3 of the cartilage bone interface:

transitional zones, absorb compressive forces

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The fibrous component of the matrix is made up of collagen that is arranged to absorb mechanical stress. Describe Tidemark of the cartilage bone interface:

Interface between uncalcified and calcified layers

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The fibrous component of the matrix is made up of collagen that is arranged to absorb mechanical stress. Describe Zone 4 of the cartilage bone interface:

Calcified cartilage, anchors cartilage to bone

What mediators all play a role in maintaining matrix turnover?

Enzymes
Hormones
Mechanical stimuli

Where are enzymes secreted from and what role do they play in matrix turnover?

Chondrocytes | assist in breakdown and rebuilding matrix

What hormones stimulate chondrocytes in the matrix?

GH and IGF

What occurs to fluid in the synovial space during weight bearing?

Fluid is pushed out of cartilage | when flow becomes slower cartilage is compressed as the resistance becomes exponentially harder.

What is responsible for the regulation of fluid flow in/out of cartilage?

Proteoglycans

What occurs to fluid in the synovial space when non-wt bearing?

Fluid is allowed to re-enter back into cartilage

What is the purpose of the synovial fluid cycle of wt bearing vs. non wt bearing?

allows fluid to enter and exit the space and carry nutrients

Does articular cartilage have nerve supply?

Does articular cartilage have blood supply?

Where does the pain in an articular cartilage injury come from?

inflammation/swelling/irritation of surrounding tissue.

How well does articular cartilage regenerate?

very poorly. | Not a lot of blood supply

Osteoarthritis is considered what type of disease? Inflammatory/non-inflammatory?

non-inflammatory but does have an inflammatory component to it.

what is the MC joint disease?

Osteoarthritis

What is the primary defect of OA?

loss/disruption of articular cartilage | disruption of matrix

What gross articular cartilage changes can be seen in OA?

Smooth glossy surface becomes dull yellow/brown gray color with surface flaking fissures and fibrillations

What do the cellular changes that occur during OA lead to?

Enzymatic changes Hormones insensitivity Cytokines excess Nitric Oxide apoptosis

what enzymatic changes occur during OA?

Excess enzyme secreted from chondrocytes leading to matrix breakdown

What is responsible for the movement of synovial fluid?

proteoglycans

What is broken down by lytic enzymes in OA resulting in loss of fluid regulation?

Proteoglycans, collagen and glycoaminoglycans

What is normally found but is found in excess in the synovial fluid during OA?

PTGs

What hormonal changes occur during OA?

decreased chondrocyte sensitivity to IGF and GH

what agent is not normally found in the synovial fluid but is found in the synovium of pt's with OA?

Nitric oxide

What does NO in the synovium facilitate?

Chondrocyte death (apoptosis)

What is the primary disruption of the articular cartilage matrix in OA?

fluid flows in/out easier due to disruption

What occurs to fluid during rest in OA?

Increased volume of water in the cartilage

During wt bearing activity with OA what occurs to the fluid?

fluid is pushed out too rapidly, cartilage is compressed without much resistance

What is the net result of OA on the articular cartilage?

Limits the ability to absorb forces and provide adequate nutrients to chondrocytes

What effect might OA have on surrounding structures of the articular cartilage?

Subchondral bone sclerosis and cuts Osteophyte formation Synovial thickening

What are the primary risk factors for OA

trauma | genetics

What is the typical pain that a pt with OA will complain of?

Morning pain/following prolonged postural positions relief with easy activity increased with extreme Referred pain in spine for entrapment

Tx of OA: conservative care:

appropriate exercise joint mobility lifestyle changes

Tx of OA: Pharmaceutical

targeted symptomatic relief (OTC-narcotics)

Tx of OA: Surgical:

Viscosupplementation (Hyaluronic injection-joint fluid therapy) Only approved for the the knee

TX of OA: Cartilage "repair" strategies

Arthroscopic lavage Marrow stimulating technique (microfractures) Osteochondral autographs and allographs (OATS) Cell-based repair