Septic Arthritis/Physitis Flashcards
What are naturally occurring causes of septic arthritis/physitis?
Hematogenous, traumatic
What age is hematogenous septic arthritis/physitis more common?
Foals
What are iatrogenic causes of septic arthritis/physitis?
Arthoscopy/centesis, fracture repair
What infectious cause is most commonly the cause of septic arthritis/physitis?
Bacterial
What is joint effusion a response to?
Pain
What are components of septic arthritis/physitis pathogenesis?
Decreased HA synthesis, loss of PG, compromised synovial blood flow, irregular cartilage
How often should you evaluate a septic foal to make sure its joints are ok?
At least 4x/day
What are types of septic arthritis in foals?
Synovial, epiphyseal, physeal
Foals <1wk exhibit acute severe lameness and effusion of the stifle and tibiotarsal (multiple joints common)
Synovial arthritis
Involves the synovial membrane and synovial fluid and requires a synovial sample for dx
Synovial arthritis
Bone adjacent to articular cartilage
Epiphysis
What will you see on rads of an epiphyseal arthritis?
Subchondral lysis
Foals a few weeks old exhibit mild lameness and fever prior to an acute exacerbation of lameness and effusion in multiple joints
Epiphyseal arthritis
What joints are most commonly affected by synovial arthritis?
Stifle and tibiotarsal
What joints are most commonly affected by epiphyseal arthritis?
Distal femur, talus, tibia, radius
What must you ddx epiphyseal arthritis from?
FPT, pneumonia, diarrhea
Affects the physis of long bones with or without joint involvement
Physeal arthritis
Seemingly healthy foal weeks-months old with premonitory lameness prior to acute severe lameness and swelling at only one site
Physeal arthritis
Periarticular swelling usually occurs w/o effusion
Physeal athritis
What joints are most commonly affected by physeal arthritis?
Distal MC3/MT3, radius, tibia
How do you dx physeal arthrtisis?
Rads, aspirate of physis, bone biopsy
What happens if you try to debride a joint affected by phyesal arthritis?
Damage physis = premature closure
Which types of foal arthritis are similar?
Synovial and epiphyseal
What synovial fluid analysis parameters will indicate septic arthritis?
> 50k cell count, >90% PMNs
What bloodwork parameters will indicate septic arthritis?
> 900 fibrinogen +/- leukocytosis
How will synovial fluid appear on US w/septic arthritis?
Hypercellular
What is the px for survival in a foal with septic arthrits?
77%
What area other than the joints should you US on a foal w/septic arthritis?
Umbilicus
What are iatrogenic risk factors for septic arthritis in an adult horse?
Synovial sx, fx repair, arthrocentesis
What bacteria usually causes septic arthritis after an arthrocentesis in an adult horse?
Staph spp.
How common is arthrocentesis post-op septic arthritis?
1/1279 injections
What bacteria is the most common cause of septic arthritis in an adult horse that has suffered trauma?
Enterobacteriaceae
How common is bacteremia in adult horses?
Rare - no hematogenous spread
An open joint is an _____ joint
Infected
What are clinical signs of septic arthritis in an adult horse?
Acute onset of severe lameness, synovial effusion, peri-articular heat and swelling
What is the gold standard for septic arthritis diagnosis?
Microbiology
What media should you use to culture a septic arthritis sample?
Enrichment/blood culture media
What is the normal TP for a horse joint fluid?
<2 g/dL
What is normal WBC for a horse joint fluid?
<500 cells/dL
What is normal differentiation of WBCs in horse joint fluid?
<10% neutrophils
What is the most common isolate from septic arthritis?
Staphylococcus
Where do you joint tap a wounded joint?
Away from the wound
How do you treat septic arthritis?
Lavage, local abx, effective draining
What are consequences of septic arthritis?
Cartilage destruction, DJD, contralateral limb laminitis
How do we return cartilage to its normal environment??
Get rid of infection and inflammation and minimize matrix loss and damage
What broad spec abx should be administered after getting a synovial fluid sample?
Penicillin/gentamycin
What is the mainstay of septic arthritis treatment?
Lavage (5-10L early and often)
What is the best way to lavage a septic joint?
Arthoscopic
How can you lavage an acutely infected joint?
Needle/through and through lavage
Rapid, accurate lavage delivery, removes fibrin clots, targeted debridement
Arthroscopic lavage
This is the only time to use a needle over 20G
Needle/through and through lavage
How do you sedate a horse for joint lavage?
2% mepivicane into the joint
How do you sedate a hores for athroscopy or arthrotomy?
General anesthesia
What lavage solution should you use to flush a joint?
LRS, nomosol (sterile isotonic solutions)
Why would you NOT add clorhexidine or povidone-iodine to your lavage solution?
Cytotoxic and damages cartilage, low efficacy
How does DMSO help if added to your lavage solution?
Reduces inflammation and edema via free radical scavenging
How much DMSO can you add to your lavage solution and why should you not exceed this amount?
10% - any more can cause hemolysis
How often should you lavage and when should you stop?
EOD until lameness and effusion has resolved or use of NSAIDs has started
_____ administration of abx is VITAL to successful arthritis resolution
Local
What is the first choice abx while waiting for synovial culture and sensitivity results?
Amikacin
When should you stop local abx therapy?
Stop w/resolution of CS and normalization of affected area
How are local ab administered to the joint?
Intra-articular
500mg Amikacin provides _____ concentration >MIC for most common pathogens
72hr
When treating multiple joints with local abx, what must you be cautious of?
Do not exceed total systemic dose
Performed QOD w/esmarch tourniquet and a 25-27G butterfly catheter
Regional limb perfusion
What topical NSAID helps limb and vessel maintain and stay usable for duration of regional limb perfusion treatment?
Surpass
What is the general rule of thumb for dosing a regional limb perfusion?
1/3 systemic dose
How do you dilute your abx for a distal limb regional limb perfusion?
Dilute to 30mL
How do you dilute your abx for regional limb perfusion above the carpus/tarsus?
Dilute to 60mL
What do you need to be cautious of when using florfenicol for regional limb perfusion in cattle?
High tissue concentration
How do you deliver intraosseous abx?
Esmarch tourniquet, 4mm hole in bone, leur tip, inject slowly
How long do you leave an esmarch tourniquet on after regional limb perfusion or intraosseous administration?
30min
Why do septic arthritis patients need analgesia?
Extremely painful condition, contralateral limb laminitis
What GI protectants can you use to counteract NSAID tox?
Omeprazole AND sucralfate
What is the most reliable and important measure to assess response to arthritis treatment?
Clinical lameness
What is Dr. L’s favorite adjunct treatment for septic arthritis?
Hylauronic acid