MSK 3 Flashcards
why is articular cartilage not very good at regernating?
there is limited blood supply
little lines/superficial defects in articular cartilage that look like a vinyl record?
erosions
do injuries to artcular cartilate cause pain?
pain requires injury to the synovium or subchondral bone. if just the articular cartilage is affected there will be no pain
what happens when there is a full thickness defect in the articular cartilage?
ulcerations form and they can become filled with fibrocartilage
when the articular cartilage gets injured, what is the process behind which the cartilage matrix becomes destroyed?
injury stimulates an increase in enzymes, cytokines, prostaglandins and other molecules, which leads to destruction of the cartilage matrix
this is the joint surface. the green line is pointing to _____ and the black line is pointing to ______
green: linear erosions
black: ulceration
what is the role of subcondral bone?
to support the articular cartilage and dissipate the forces born by the joints
what happens to the subcondral bone if there is damage to and/or loss of articular cartilage?
if there is loss of articular cartilage, the subchondral bone experiences more forces and there is a response in accordnce to Wolff’s Law (increased formation and decreased bone resorption), which leads to net bone thickening (sclerosis)–>subchondral bone sclerosis
what is enburnation?
complete ulceration of articular cartilage and exposure of subchondral bone, increase in bone density, appears polished from bone to bone contact
what is the following lesion?
eburnation/ulceration of articular cartilage
inflammation/injury of the synovial membrane leads to:
villous hypertrophy/hyperplasia
describe the lesion(s)
there is eburnation on the bone
there is also villous hypertrophy/hyperplasia
inflammation of the synovial membrane in response to cartilage debris is called:
synovitis
generic term for joint inflammation:
arthritis
generic term for joint disease:
arthropathy
a fluid filled sac that develops in areas of high pressure inclduing adjacent to joint:
hygroma
joint fusion is called
anklyoses
what is an osteophyte?
proliferative new bone along joint margins in responseto inflammation and/or joint instability
what are the arrows pointing to?
osteophytes
what are the two broad classifications of arthritis?
inflammatory (infectious or not infectious)
osteoarthritis
what are the 5 ways infection can get into a joint
- hematogenous
- extension from osteomyelitis
- spread from soft tissue infection
- iatrogenic (surgery, joint injections)
- penetrating injury/trauma
suppurative arthritis is associate with
bacterial infection, purulent exudate in synovial fluid
what are gross lesions of suppurative arthritis?
synovial fluid is turbid (pus) and red (hemorrhage), synovial membrane proliferation, fibrin in the joint
how does the articular cartilage change in suppurative arthritis ?
acute changes: normal to slightly thin articular cartilage
chronic changes: severe erosions/ulcerations
what is a cause of suppurative arthritis in cattle and pigs?
trueperella pyogenes
this is tissue from a steer. diagnosis?
suppurative arthritis (maybe from trueperella pyogenes infection)
what is a common result of embolic suppurative osteomyelitis of the growth plate in neonatal calves, foals, and lambs?
spread of infection into the joint space
what is shown here?
suppurative arthritis. you can see suppurative osteomyelitis near the growth plate with a pathological fracture and suppurative exudate in the joint space
what is fibrinous arthritis and what is it often cuased by?
it is when fibrinous exudate is in the synovial fluid
bacterial infection
what are gross lesions of fibrinous arthritis?
synovial fluid contains fibrin and severe synovial membrane prliferation, maybe some cartilage damage
what happens to the articular cartilage acutely and chronically in fibrinous arthritis?
acute: cartilage can be normal to slightly thin
chronic: may develop erosions/ulcerations but not consistently
what is this disease process? is this likely acute or chronic? what caused this disease (given this is tissue from a steer)?
fibrinous arthritis (you can see the fibrin indicated by the black arrow)
it is likely acute because the articular cartilage appears shiny, white, and relatively thick
cause: bacterial septicemia, histophilus somni
histophilus somni can cause lesions in what other 3 locations besies the joints?
the lungs (fibrous pleuritis)
the brain (meningioencephalitis)
heart (myocarditis)
describe the outcomes of both fibrinous and suppurative arthritis if:
- inflammation is mild
- inflammation is severe
mild: resolution
severe: enzymes, cytokines, prostaglandins and other molecules all cause damage to the cartilage and synovial membrane causing osteoarthritis/degenerative joint disease. joint rigitity, loss of function, ankylosis.
what is the name of the tick borne spirochete bacteria associated with Lyme Disease that causes fibrinosuppurative polyarthritis?
borrelia burgdorferi
mycoplasma bovis in cattle causes what MSK disease?
fibrinous to pyogranulomatous arthritis
this is a stifle joint of a bison. describe the lesion. what is this and what caused it?
the articular cartilage is ulcerated with exposure of sunchondral bone, the joint cavity is filled with fibrin and pus
fibrinosuppurative arthritis caused by mycoplasma bovis
viral arthritis is rare in animals but it does happen in _______ caused by ________
turkeys and chickens
reovirus arthritis/tenosynovitis
what is tenosynovitis?
inflammation of the protective sheath that surrounds your tendons
goats can get a virus called ________ that causes viral arthritis
caprine arthritis and encephalitis virus, a lentivirus
what are clinical signs of caprine arthritis and encephalitis virus in goats?
severe lameness
describe the lesions of caprine arthritis and encephalitis virus
fibrinous arthritis, carpal hygroma, synovial hyperplasia, bursitis
this is tissue from the carpal joint of a goat. describe the lesions. what is your differential?
there is joint capsule thickening, and fibrinous exudate in joint.
this is caprine arthritis and encephalitis virus
what is the name of the autoimmune disease in dogs that causes villus hyperplasia and synovitis but does not affect the articular cartilage?
systemic lupus erythematosus (SLE)
describe what systemic lupus erythematosus (SLE) is, the disease process, and the gross lesions
it is an autoimmune disease in dogs where there is formation of antinuclear autoantibodies.
lesions: villus hyperplasia and synovitis of synovial membrane but articular cartilage is NOT affected, neutrophils in synovial fluid
what are cystal deposits? name two examples
cystalized mineral deposits in articular cartilage and other joint tissues that stimulate inflammation
ex) urates and calcium molecules
what is Gout? what are gross lesions? clinical signs?
urate crystal deposits in and around joints, affects birds and reptiles
gross lesions: white, caseous material within joints
clinical signs: lameness, nonspecific signs of illness
describe the lesions. differential?
digits are swollen, accumulation of white gritty material within and around joints
Gout
this is the joint of a chicken. describe the lesion. differential?
chalky white exudate in the joint space/urate crystals
gout
what is osteoarthritis?
also called degenerative joint disease, a descructive condition of articular cartilage in synovial joint. it is an end stage disease that is caused by a variety of insults that initiate joint/articular cartilage damage
what is the pathogenesis of osteoarthritis?
inciting cartilage damage–> decreased proteoglycans in cartilage–>this leads to retained water and chondomalacia–>leads to abnormal wear –>leading to cartilage erosion and ulceration
what are the main lesions of osteoarthritis? list some accompanying changes?
articular cartilage roughening progressing to fissures/grooves, erosions/ulcerations ans eventually ebernation (exposure of the subchondral bone)
accompanying changes:
- subchondral bone sclerosis (thinning)
- synovitis
- joint capsule fibrosis
- osteophytes
- joint stiffness
- ankylosis
tissue from a horse. describe the lesions. differential?
there is synovial hyperplasia, ulcerated cartilage, and linear erosions in the articular cartilage.
this is osteoarthritis
tissue from a dog. describe the lesions. differential?
the articular cartilage is thin, there are linear grooves of articular erosion
describe a brief pathogenesis from canine hip dysplasia to osteoarthritis, and then describe lesions you might see
congenital joint laxity–>chronic subluxation–>severe osteoarthritis
lesions: articular cartilage erosions and ulceration, bone modeling of the acetabulum and femoral head and neck, in advanced cases eburnation and flattening of femoral head and periarticular osteophytes
_______ is a result of intervertebral disk disease
ankylosing spondylosis
what is the pathogenesis of intervertebral disc disease/ankylosing spondylosis?
the inner core of the vertebral disk dehydrates and increases in collagen content, annulus fibrosus weakens, leads to herniation of nucelus pulposus dorsally, leads to collpase of the disk space, leading to osteoarthritis and periosteal new bone formation (spondylosis) and ankylosis (joint fusion) = ankylosing spondylosis
tissue from a bull. describe the lesion. differential?
there are osteophytes bridging and fusing adjacent vertebrae
ankylosing spondylosis
neoplasia of the joint is _____ and typically arises from _______. two examples are:
rare
synovial membrane
histiocytic sarcoma
synovial cell sarcoma
what is osteochondrosis?
common lesions of the growth cartilage caused by abnormal endochondral ossification = cartilage fails to calcify and is not replaced by bone
where does osteochondrosis usually happen and what are the gross lesions?
location: metaphyseal grwoth plate and junction of artcular cartilage and epiphysis, often bilaterally symmetrical
gross lesions: focal grwoth cartilage retention
describe this lesion. what is wrong with it?
the cartilage is extensing into the epiphysis composed of necrotic epiphyseal cartilage that has failed to undergo endochondral ossification and been retained, whereas the remainder of the cartilage has been converted to bone. the retained cartilage is yellow ish in color compared to the overlying articular cartilage due to degernation and necrosis of the retained cartilage
this is osteochondrosis
tissue from a pig. what disease is this?
osteochondrosis
what is the pathogenesis of osteochondrosis?
it is multifactorial but in general:
some sort of vascular injury in growth cartilage, cartilage undergoes ischemic necrosis, fails to mineralize and is not replaced by bone, articular cartilage damaged because subchondral bone is not there to support it
what is osteochondrosis dissecans (OCD)?
clefting from retained cartilage up through articular cartilage with exposure of subchrondral bone, flaps ay form
what are joint mice?
free floating flaps within joint that can interfere with movement
tissue from a dog. describe the lesion. differential?
a flap of thickened cartilage has detached from the underlyingbone. the synovium is also hyperemic and hyperplastic
osteochondrosis dissecans
what is wobbler’s syndrome?
a specific condition of osteochondrosis, also called cranial cervical stenotic myelopathy, affects horses and dogs, osteochondrosis suspected to be an underlying cause of vertebral abnormalities
animals with wobblers syndrome often have neurological signs. why?
it is a congenital and developmental abnormality, the cervical vertebrae are abnormal, leading to spinal cord injury myelopathy, which then leads to neurological deficiencies
osteochondrosis can progress into
osteoarthritis
what are some ways you can differentiate osteoarthritis and osteochondrosis
- osteoarthritis is often in older animals, osteochondrosis is often in younger animals
- ostearthritis is caused by cartilage desruction, osteochondrosis is caused by vascular injury leading to abnormal ossification of subarticular bone
what is arthrogryosis? what is it caused by? what is the pathogenesis?
it is a congenital contraction of joints
caused by: intrauterine viral infection like blue tongue, hereditary, toxic plants
pathogenesis: inciting cause leads to decreased fetal motion during development, leading to inflexible joints
explain why tendon stretch causes tendon injury
tendon stretch–>ruptured collagen fibers and capillaries –>fibrin exudation –> myofibroblasts stimulated to form scar collagen type III vs type I which is less stretchy)–> tendon is less able to stretch and prone to re injury
what are the clinical signs of acute tendon injury vs chronic tendon injury?
acute: tendon is swollen, warm, painful
chronic: tendon is thicker and possibly longer than normal
what is this?
bowed tendons aka tendonitis in a horse from tendon injury
