Lecture 30: MSK 3 Flashcards
What is a fibrous joint? Provide 3 examples
fibrous tissue connects the joint
sutures
gomphoses
syndesmoses
What is a cartilaginous joint? Provide 2 examples
hyaline or fibrocartilage connects the joint
synchondroses
symphysis
What are the 3 parts of a synovial joint
articular cartilage
synovial membrane
joint capsule
What are the gross features of the articular cartilage? What is it made of?
white-blue shiny and smooth
no blood vessels or nerves
5% chondrocytes
95% ECM: type 2 collagen/proteoglycans/water
What are the parts of the synovial membrane? What is its function?
intima layer: synoviocytes
- make synovial fluid
subintima layer: connective tissue
vascular
What is synovial fluid for? What does it look like grossly
source of nutrients and lubrication of the joint
it is thick and pale yellow
What are the 2 parts of the joint capsule?
subchondral bone - support
articular capsule - fibrous (for ligament attachment
- has inner synovial membrane
How does articular cartilage react to injury
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
What is the subchondral bone’s reaction to injury
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
What is the articular capsules response to injury
fibrosis
What is the synovial membranes response to injury
villous hypertrophy and hyperplasia
osteophyte formation
pannus
What are osteophytes
periarticular new bone formation either in or out of the joint capsule
can break off and form joint mice
What is pannus
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
What causes pannus to occur
infection or immune mediated disease
What is a synovial fossae? What is its significance?
nonarticulating depressions
bilaterally symmetrical on left and right sides
near joint midline
normal
List 5 types of developmental joint pathology
osteochondrosis
hip dysplasia
luxation and subluxation
cervical vertebrae malformation
arthrogryposis
What is osteochondrosis
focal failure of endochondral ossification of epiphyseal cartilage
reduced blood supply > ischemic necrosis > mineralization stops > reatined growth cartilage
What species are most affected by osteochondrosis? What causes it?
pig
horse
large breed dogs
cow
sheep
causes lameness in young animals
multifactorial: genetics/rapid growth/nutritional problems
What are the 3 types of osteochondrosis? What are the features of each?
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
What is a common signalment for hip dysplasia
young large breed dog
it is a complex polygenetic trait
What is hip dysplasia? What are the clinical consequences?
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
List 2 chronic sequelae of hip dysplasia
synvial membrane hypertrophy
subchondral eburnation
What is luxation and subluxation? What are the conesquences?
increased joint mobility
causes increased friction = erosion and ulceration of the cartilage and bone eburnation
predispose to DJD
List 2 types of luxation/subluxation
atlantoaxial subluxation: mini/toy breeds
- failed fusion of odontoid process and dens
- can cause tetraplegia
patellar luxation: dog
- medial: small breed
- lateral: lg breed
What are the associated lesions of cervical vertebrae malformation? What species are most affected
horse and dog
diorganized fibrocartilage
osteochondrosis of articular facets
malformed vertebral bodies and articular processes
+/- osteophytes
What is arthrogryposis? What causes it?
bilateral symmetrical congenital joint contracture
due to reduced fetal mobility
- intrauterine viral infection like BVDV
- toxic plant (verratum californicum)
What is DJD?
aka degenerative arthropath or osteoarthritis
it is a sequelae/syndrome
fundemental lesion is the progressive loss of articular cartilage
What are the causes of primary and secondary DJD
primary = old
secondary = underlying causes (laxity/subluxation)
What are the lesions of DJD
subchondral eburnation and sclerosis
osteophytes
synovial membrane hypertrophy and hyperplasia
joint capsule fibrosis and anklyosis
What are 3 other names for DJD in horses
navicular syndrome
ring bone
bone spavin
Compare osteochondrosis and osteoarthritis
osteochondrosis is the retential of cartilage from when the animal was young
osteoarthritis is DJD = non specific sequelae to injury
Explain the parts of an intervertebral disc
nucleus pulposes: the center jelly
annular fibrosis: the surrounding fibrocartilage tissue
cartilagenous end plates: hyaline cartilage coat
What is hansen type 1 IVDD? What animals are predisposed?
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
What is hanson type 2 IVDD? What animals are predisposed?
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
What is spondylosis? What species is it common in? What is the significance?
cartilagenous joints with osteophyte formation
DJD in the vertebral column (usually lumbar or sacral)
bull/ram/dog
incidental
What is ankylosing sponylosis?
fusion of the vertebral bodies
What is arthritis
inflam of joint
What is synovitis
inflam of synovial membrane
What is tenosynovitis
inflam of synovial membrane and tendon sheath
What is discospondylitis
inflam of intervertebral disc and vertebrae
What is a hygroma
a fase burse
SC fluid filled space with no connection to the joint space
What are the routes of entry for infection into the joint
hematogenous
direct
extension for osteomyelitis or soft tissue
iatrogenic
How do you determine if bacterial joint infection is present?
recognize the appearance of the synovial fluid
cloudy/liquidy/fibrin flecks
What is septic arthritis
joint infection with degenerate neutrophils
How does bacterial arthritis occur?
hematogenous infection
What animals does bacterial arthritis affect? What are the sequelae? What is the outcome?
young animals
polyarthritis and osteomyelitis
mild inflammation = resolve
severe/chronic inflammation = articular cartilage injury = DJD
What is a primary example of viral arthritis?
caprine arthritis and encephalitis virus
- small ruminant lentivirus
What are the 4 clinical syndromes of CAE and what are the gross lesions?
- arhritis
- encephalitis
- interstisial pneumonia
- mastitis
fibrinous arthritis and carpal hygroma
What are 2 types of mechanisms for non infectious joint inflammation
immune mediated
crystal deposition
What are 2 types of immune mediated joint inflammation
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
What is gout? What inflammatory process does it cause?
mineral deposits in articular and periarticular tissue
granulomatous inflammation
Compare true gout and pseudogout
true gout: urate crystal deposition in birds and reptiles
pseudogout: calcium pyrophosphate dihydrate deposition in old dogs and humans
List 2 types of neoplasias affecting joints
histiocytis sarcoma
synovial myxoma/myxosarcoma
What is a histiocytic sarcoma? What species does it affect? What is the prognosis?
dendritic cell tumor
dogs
aggressive with poor prognosis
What is a synovial myxoma/myxosarcoma? What species does it affect? What is the prognosis?
synoviocyte origin (not confirmed)
dog
locally aggressive + no metastasis = amputation is curative
List 2 non-neoplastic joint masses
synovial chondromatosis
synovial cysts
What is synovial chondromatosis
cartilagenous nodules on the synovial surface
idiopathic
non neoplastic
What is a synovial cyst? What animals is it common in?
multiple cysts that communicate with the joint
common on old cat elbows
