Lecture 11 & 12 - Joint Physiology & common diseases

Question 1

what are the three types of synovium?

Answer 1

Type A = phagocytic
Type B = synthetic activity –> produce hylauronan and lubricin
Type C = intermediary

synovium is vascular rich

Question 2

what is the primary determinant of joint health?

Answer 2

articular cartilage bc it has very limited ability to self repair, once its damaged there is no going back.

there is no other substance on earth that can replace hyaline (articular) cartilage bc it is the lowest source of friction.

Question 3

what is the framework for the organization of the extracellular matrix within articular cartilage?

Answer 3

type II collagen

Question 4

what type of forces does the collagen within articular cartilage counteract?

Answer 4

tensiel (pulling) stresses due to its arcade arrangement

Question 5

what forces do aggrecan proteoglycans resist within articular cartilage?

Answer 5

osmotic properties generated by the negative charge of GAGs keep aggregan molecules separated and traps water providing resistance to compression.

Question 6

what two structures within articular cartilage resist two opposing forces?

Answer 6

collagen resists tensile forces (pulling forces)

aggrecan resists compressive forces

Question 7

what two proteins make up the GAG core protein within articular cartilage?

Answer 7

chondroitin sulphate and karatan sulfate

Question 8

what 3 steps do you take in every case when diagnosing OA?

Answer 8

1. PE
2. local anesthesia - nerve blocks vs joint blocks (perineural, intra articular)
3. radiographs

Question 9

should you take a cytology of Synovial fluid?

Answer 9

no! its not helpful

Question 10

what does decreased viscosity in synovial fluid indicate?

Answer 10

abnormal! its a sign of joint disease

Question 11

what is the viscosity of synovial fluid in a swollen joint?

Answer 11

viscosity of synovial fluid will be decreased

Question 12

what are the effects of NSAIDs on OA?

Answer 12

inhibits cyclo-oxygenase –> reduces prostaglandin production –> reduces matrix catabolism

Question 13

what are the role of corticosteroids as a therapy for OA? what type is most common?

Answer 13

they are potent inhibitors of joint inflammation

intra-articular is the most common

Question 14

what type of corticosteroid is used for low motion joints?

Answer 14

methylprednisolone acetate

Question 15

which joints are considered high motion?

Answer 15

shoulder, carpus, fetlock, hip, stifle

Question 16

which joints are considered low motion?

Answer 16

lower joints in the hock

Question 17

which corticosteroid is used for high motion joints?

Answer 17

triamcinolone acetonide

Question 18

what type of drug therapies are used for the treatment of OA?

Answer 18

1. NSAIDs
2. corticosteroids
3. slow acting disease modifying drugs
4. DMSO

Question 19

what is hyaluonan (hyaluronic acid) and what is its function?

Answer 19

hyaluonan is a slow acting disease modifier.

its function is lubrication and anti-inflammatory

Question 20

what is polysulphated glycosaminoglycan and what is unique about it?

Answer 20

its a slow acting disease modifier and reduces the amount of bacteria needed to cause a septic joint so if you are infusing IA you must always infuse with abx.

for this reason it is most often given IM.

Question 21

types of hematogenous septic arthritis in foals:

Answer 21

S type - synovial membrane and fluid (no osteomyelitis)
E type - subchondral bone of the epiphysis (osteomyelitis of epiphysis)
P type - physis - may extend into joint (osteomyelitis adjacent to growth plate)

Question 22

clinical signs of septic arthritis

Answer 22

non-weightbearing lameness, heat and swelling (swelling due to edema), synovial effusion, may be depressed, inappetant

foals will be systemically ill - febrile, primary septicemia, physeal infection painful on palpation

Question 23

how do you diagnose septic arthritis?

Answer 23

radiographs

chronic changes - joint space narrowing, subchondral bone lysis, periosteal proliferation

Question 24

what is the clin path of the synovial fluid associated with septic arthritis?

Answer 24

fluid will not be clear - may be yellow or pink
viscosity will be decreased - more liquidity
WBC > 30,000/uL with 90% neutrophils that will be degenerate
TP elevated at >2 g/dL
rarely see bacteria
lactate > 4.9 mmol/L
synovial glucose will be lower than blood serum

Question 25

what is the synovial lactate in a case of septic arthritis

Answer 25

> 4.9 mmol/L

Question 26

what is the blood serum- synovial fluid glucose difference in a case of septic arthritis?

Answer 26

it will be lower - which is commonly associated with degenerative disease especially sepsis.

in humans the difference is 15 or greater

Question 27

when culturing a joint that has septic arthritis from a foal, what common pathogens are found?

Answer 27

• enterobacteriaceae: E.coli, enterobacter, klebsiella, proteus, providencia, salmonella
• actinobacillus equuli
• streps
• rhodococcus equi
• NOT PASTEURELLA!

Question 28

what results in the highest antimicrobial concentration in synovium during tx of septic arthritis?

Answer 28

intra-articular antibiotic delivery

Question 29

what are the 3 criteria by which immune mediated polyarthritis is diagnosed?

Answer 29

1. inflammatory process affecting synovium of two or more joints
2. no identifiable infectious component
3. responsive to immunosuppressive therapy

Question 30

what is immune mediated polyarthritis?
what are the clinical signs?
what is seen on culture in the synovial fluid

Answer 30

its usually an idiopathic, inflammatory process affecting the synovium of two or more jionts.

• seen primarily in small animals
• CS: effusion of multiple joints, pain, lameness
• synovial fluid contains: protein >2.5, NCC > 3000 cells/ul

Question 31

which joint does not have collateral ligaments?

Answer 31

the shoulder