Lecture 11 & 12 - Joint Physiology & common diseases Flashcards
what are the three types of synovium?
Type A = phagocytic
Type B = synthetic activity –> produce hylauronan and lubricin
Type C = intermediary
synovium is vascular rich
what is the primary determinant of joint health?
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.
what is the framework for the organization of the extracellular matrix within articular cartilage?
type II collagen
what type of forces does the collagen within articular cartilage counteract?
tensiel (pulling) stresses due to its arcade arrangement
what forces do aggrecan proteoglycans resist within articular cartilage?
osmotic properties generated by the negative charge of GAGs keep aggregan molecules separated and traps water providing resistance to compression.
what two structures within articular cartilage resist two opposing forces?
collagen resists tensile forces (pulling forces)
aggrecan resists compressive forces
what two proteins make up the GAG core protein within articular cartilage?
chondroitin sulphate and karatan sulfate
what 3 steps do you take in every case when diagnosing OA?
- PE
- local anesthesia - nerve blocks vs joint blocks (perineural, intra articular)
- radiographs
should you take a cytology of Synovial fluid?
no! its not helpful
what does decreased viscosity in synovial fluid indicate?
abnormal! its a sign of joint disease
what is the viscosity of synovial fluid in a swollen joint?
viscosity of synovial fluid will be decreased
what are the effects of NSAIDs on OA?
inhibits cyclo-oxygenase –> reduces prostaglandin production –> reduces matrix catabolism
what are the role of corticosteroids as a therapy for OA? what type is most common?
they are potent inhibitors of joint inflammation
intra-articular is the most common
what type of corticosteroid is used for low motion joints?
methylprednisolone acetate
which joints are considered high motion?
shoulder, carpus, fetlock, hip, stifle
which joints are considered low motion?
lower joints in the hock
which corticosteroid is used for high motion joints?
triamcinolone acetonide
what type of drug therapies are used for the treatment of OA?
- NSAIDs
- corticosteroids
- slow acting disease modifying drugs
- DMSO
what is hyaluonan (hyaluronic acid) and what is its function?
hyaluonan is a slow acting disease modifier.
its function is lubrication and anti-inflammatory
what is polysulphated glycosaminoglycan and what is unique about it?
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.
types of hematogenous septic arthritis in foals:
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)
clinical signs of septic arthritis
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
how do you diagnose septic arthritis?
radiographs
chronic changes - joint space narrowing, subchondral bone lysis, periosteal proliferation
what is the clin path of the synovial fluid associated with septic arthritis?
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
what is the synovial lactate in a case of septic arthritis
> 4.9 mmol/L
what is the blood serum- synovial fluid glucose difference in a case of septic arthritis?
it will be lower - which is commonly associated with degenerative disease especially sepsis.
in humans the difference is 15 or greater
when culturing a joint that has septic arthritis from a foal, what common pathogens are found?
- enterobacteriaceae: E.coli, enterobacter, klebsiella, proteus, providencia, salmonella
- actinobacillus equuli
- streps
- rhodococcus equi
- NOT PASTEURELLA!
what results in the highest antimicrobial concentration in synovium during tx of septic arthritis?
intra-articular antibiotic delivery
what are the 3 criteria by which immune mediated polyarthritis is diagnosed?
- inflammatory process affecting synovium of two or more joints
- no identifiable infectious component
- responsive to immunosuppressive therapy
what is immune mediated polyarthritis?
what are the clinical signs?
what is seen on culture in the synovial fluid
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
which joint does not have collateral ligaments?
the shoulder
