Lecture 30: MSK 3

Question 1

What is a fibrous joint? Provide 3 examples

Answer 1

fibrous tissue connects the joint

sutures
gomphoses
syndesmoses

Question 2

What is a cartilaginous joint? Provide 2 examples

Answer 2

hyaline or fibrocartilage connects the joint

synchondroses
symphysis

Question 3

What are the 3 parts of a synovial joint

Answer 3

articular cartilage

synovial membrane

joint capsule

Question 4

What are the gross features of the articular cartilage? What is it made of?

Answer 4

white-blue shiny and smooth

no blood vessels or nerves
5% chondrocytes
95% ECM: type 2 collagen/proteoglycans/water

Question 5

What are the parts of the synovial membrane? What is its function?

Answer 5

intima layer: synoviocytes
- make synovial fluid

subintima layer: connective tissue

vascular

Question 6

What is synovial fluid for? What does it look like grossly

Answer 6

source of nutrients and lubrication of the joint

it is thick and pale yellow

Question 7

What are the 2 parts of the joint capsule?

Answer 7

subchondral bone - support

articular capsule - fibrous (for ligament attachment
- has inner synovial membrane

Question 8

How does articular cartilage react to injury

Answer 8

Erosion: superficial loss (no healing)

Ulceration: deep/full thickness loss
- repair with a fibrocartilagenous scar and it will degenerate over time

Poor/no healing due to avascular

Question 9

What is the subchondral bone’s reaction to injury

Answer 9

Sclerosis: exposure of bone increases the corrosive forces resulting in remodelling (as per wolffs law)

Eburnation: complete chronic, severe elceration of cartilage and exposure resulting in sclerosis and polishing of suchondral bone
- pain

Question 10

What is the articular capsules response to injury

Answer 10

fibrosis

Question 11

What is the synovial membranes response to injury

Answer 11

villous hypertrophy and hyperplasia

osteophyte formation

pannus

Question 12

What are osteophytes

Answer 12

periarticular new bone formation either in or out of the joint capsule

can break off and form joint mice

Question 13

What is pannus

Answer 13

overgrowth of the synovial membrane

scar tissue grows over the synovial membrane = fibrovascular granulation

results in lysis of the cartilage underneath because the pannus cuts off nutrient supply

can result in joint fusion

Question 14

What causes pannus to occur

Answer 14

infection or immune mediated disease

Question 15

What is a synovial fossae? What is its significance?

Answer 15

nonarticulating depressions

bilaterally symmetrical on left and right sides

near joint midline

normal

Question 16

List 5 types of developmental joint pathology

Answer 16

osteochondrosis

hip dysplasia

luxation and subluxation

cervical vertebrae malformation

arthrogryposis

Question 17

What is osteochondrosis

Answer 17

focal failure of endochondral ossification of epiphyseal cartilage

reduced blood supply > ischemic necrosis > mineralization stops > reatined growth cartilage

Question 18

What species are most affected by osteochondrosis? What causes it?

Answer 18

pig
horse
large breed dogs
cow
sheep

causes lameness in young animals

multifactorial: genetics/rapid growth/nutritional problems

Question 19

What are the 3 types of osteochondrosis? What are the features of each?

Answer 19

osteochondrosis latens = histo diagnosis + no clinical signs

__ manifesta = gross depression in cartilage
- dx via radiographs

__ dissicans = cartilage dissects to underlying bone causing cracks/clefts/flaps
- cause lameness/joint mice/progress to DJD

Question 20

What is a common signalment for hip dysplasia

Answer 20

young large breed dog

it is a complex polygenetic trait

Question 21

What is hip dysplasia? What are the clinical consequences?

Answer 21

reduced conformity of the acetabulum and the femoral head

can cause
- ostephytes
- articular cartilage erosion, ulceration and subchondral eburnation
- joint laxity
- can progress to DJD

Question 22

List 2 chronic sequelae of hip dysplasia

Answer 22

synvial membrane hypertrophy

subchondral eburnation

Question 23

What is luxation and subluxation? What are the conesquences?

Answer 23

increased joint mobility

causes increased friction = erosion and ulceration of the cartilage and bone eburnation

predispose to DJD

Question 24

List 2 types of luxation/subluxation

Answer 24

atlantoaxial subluxation: mini/toy breeds
- failed fusion of odontoid process and dens
- can cause tetraplegia

patellar luxation: dog
- medial: small breed
- lateral: lg breed

Question 25

What are the associated lesions of cervical vertebrae malformation? What species are most affected

Answer 25

horse and dog diorganized fibrocartilage osteochondrosis of articular facets malformed vertebral bodies and articular processes +/- osteophytes

Question 26

What is arthrogryposis? What causes it?

Answer 26

bilateral symmetrical congenital joint contracture due to reduced fetal mobility - intrauterine viral infection like BVDV - toxic plant (verratum californicum)

Question 27

What is DJD?

Answer 27

aka degenerative arthropath or osteoarthritis it is a sequelae/syndrome fundemental lesion is the progressive loss of articular cartilage

Question 28

What are the causes of primary and secondary DJD

Answer 28

primary = old secondary = underlying causes (laxity/subluxation)

Question 29

What are the lesions of DJD

Answer 29

subchondral eburnation and sclerosis osteophytes synovial membrane hypertrophy and hyperplasia joint capsule fibrosis and anklyosis

Question 30

What are 3 other names for DJD in horses

Answer 30

navicular syndrome ring bone bone spavin

Question 31

Compare osteochondrosis and osteoarthritis

Answer 31

osteochondrosis is the retential of cartilage from when the animal was young osteoarthritis is DJD = non specific sequelae to injury

Question 32

Explain the parts of an intervertebral disc

Answer 32

nucleus pulposes: the center jelly annular fibrosis: the surrounding fibrocartilage tissue cartilagenous end plates: hyaline cartilage coat

Question 33

What is hansen type 1 IVDD? What animals are predisposed?

Answer 33

herniation of the nucleus pulposes out of the disc - breaks through all layers causes an acute space occupying lesion in the spinal cord predisposed in chondrodystrophic breeds (short legged dogs) in younger animals

Question 34

What is hanson type 2 IVDD? What animals are predisposed?

Answer 34

the nucleus pulposes partially herniated out of the disc - slow progression there is no underlying cartilage defect that predisposes - it is an age related change

Question 35

What is spondylosis? What species is it common in? What is the significance?

Answer 35

cartilagenous joints with osteophyte formation DJD in the vertebral column (usually lumbar or sacral) bull/ram/dog incidental

Question 36

What is ankylosing sponylosis?

Answer 36

fusion of the vertebral bodies

Question 37

What is arthritis

Answer 37

inflam of joint

Question 38

What is synovitis

Answer 38

inflam of synovial membrane

Question 39

What is tenosynovitis

Answer 39

inflam of synovial membrane and tendon sheath

Question 40

What is discospondylitis

Answer 40

inflam of intervertebral disc and vertebrae

Question 41

What is a hygroma

Answer 41

a fase burse SC fluid filled space with no connection to the joint space

Question 42

What are the routes of entry for infection into the joint

Answer 42

hematogenous direct extension for osteomyelitis or soft tissue iatrogenic

Question 43

How do you determine if bacterial joint infection is present?

Answer 43

recognize the appearance of the synovial fluid cloudy/liquidy/fibrin flecks

Question 44

What is septic arthritis

Answer 44

joint infection with degenerate neutrophils

Question 45

How does bacterial arthritis occur?

Answer 45

hematogenous infection

Question 46

What animals does bacterial arthritis affect? What are the sequelae? What is the outcome?

Answer 46

young animals polyarthritis and osteomyelitis mild inflammation = resolve severe/chronic inflammation = articular cartilage injury = DJD

Question 47

What is a primary example of viral arthritis?

Answer 47

caprine arthritis and encephalitis virus - small ruminant lentivirus

Question 48

What are the 4 clinical syndromes of CAE and what are the gross lesions?

Answer 48

1. arhritis 2. encephalitis 3. interstisial pneumonia 4. mastitis fibrinous arthritis and carpal hygroma

Question 49

What are 2 types of mechanisms for non infectious joint inflammation

Answer 49

immune mediated crystal deposition

Question 50

What are 2 types of immune mediated joint inflammation

Answer 50

non erosive - antibody antigen complexes depositing in the joint = idiopathic arthritis - no damage to articular cartilage erosive - antibodies target self antigens in joint = rheumatoid arthritis cause polyarthritis in dogs/cats

Question 51

What is gout? What inflammatory process does it cause?

Answer 51

mineral deposits in articular and periarticular tissue granulomatous inflammation

Question 52

Compare true gout and pseudogout

Answer 52

true gout: urate crystal deposition in birds and reptiles pseudogout: calcium pyrophosphate dihydrate deposition in old dogs and humans

Question 53

List 2 types of neoplasias affecting joints

Answer 53

histiocytis sarcoma synovial myxoma/myxosarcoma

Question 54

What is a histiocytic sarcoma? What species does it affect? What is the prognosis?

Answer 54

dendritic cell tumor dogs aggressive with poor prognosis

Question 55

What is a synovial myxoma/myxosarcoma? What species does it affect? What is the prognosis?

Answer 55

synoviocyte origin (not confirmed) dog locally aggressive + no metastasis = amputation is curative

Question 56

List 2 non-neoplastic joint masses

Answer 56

synovial chondromatosis synovial cysts

Question 57

What is synovial chondromatosis

Answer 57

cartilagenous nodules on the synovial surface idiopathic non neoplastic

Question 58

What is a synovial cyst? What animals is it common in?

Answer 58

multiple cysts that communicate with the joint common on old cat elbows