Septic Arthritis Flashcards
What are some causes of septic arthritis?
Naturally Occurring - hematogenous (seen in foals), traumatic
Iatrogenic - arthroscopy, arthocentesis, fracture repair, etc
Usually bacterial but can viral/ mycobacterial/ fungal
** Can prevent with lavages, antibiotics, effective drainage
What processes occur that damage cartilage in septic arthritis?
- Fibrin is deposited
- Degradative enzymes ( colagenase, stromelysin, MMP) and cytokines (IL-1, 6, TNF) enter capsule
-Result is a loss of PG, decreased HA synthesis, joint effusion, pain, decreased synovial blood flow
What are the different types of septic arthritis in foals?
S (synovial), E (epiphysis), P
Must ID all joints when diagnosing
What is S-type foal septic arthritis?
Affects synovial fluid and synovial membrane
Occurs in foals < 1 week old
Affects larger/ multiple joints (stifle, tibiotarsal)
CS: acute severe lameness and effusion
What is E-type foal septic arthritis?
Affects bones next to articular cartilage –> appears as subchondral lysis on rads)
Age: weeks old
Hx: FPT, other dz (pneumonia, diarrhea)
Joints:
Multiple
Distal femur, talus, tibia, radius
CS: mild intermittent lameness +-fever…THEN acute exacerbation of lameness/effusion
What is P-type foal septic arthritis?
Occurs on physis of long bone, may include joint
Will appear healthy without disease history
Affects distal physis of MC/T III, radius, tibia –> only one site though
CS: Premonitory lameness THEN acute severe
lameness/swelling, and periarticular swelling without effusion
How do you diagnose P-type septic arthritis?
Radiographs
Physis aspirate
Bone biopsy
DON’T DEBRIDE –> DAMAGES AND CLOSES PHYSIS
What values would you see on a blood work in foal septic arthritis?
Synovial fluid
>50,000 cell count, >90% neuts
Color –normal to cloudy, red, orange, pink
Bloodwork:
Increased fibrinogen +-leukocytosis
Fibrinogen usu. >900 mg/dL with bone involvement
US –> hypercellular fluid detail (hyperechoic)
What is the prognosis for septic arthritis in foals?
77% –> pretty good
What can predispose foals to septic arthritis?
Failure of passive transfer leads to bacteremia, resulting in septic arthritis
What is the difference between swelling and joint effusion?
Effusion is the accumulation of fluid within the joint
Swelling is an accumulation of fluid outside the joint
What risk factors can predispose adult horses to septic arthritis?
Iatrogenic –> Staph usually infects joint
Trauma –> many different possibilities, Enterobacteriaceae most commonly infects (Staph, pseudomonas, sometimes fungi)
** an open joint is an infected joint
What are the clinical signs of septic arthritis in adults?
Similar to foals
Acute severe onset of lameness (important)
Synovial effusion
Peri-articular heat and swelling
May or may not have fever
How do you diagnose septic arthritis?
Joint tap and microbiology –> GOLD STANDARD
Gross exam
TP, cell count, smear stains
C/ S –> Enrichment culture and blood culture *better yield
**In foals, aspirate physis for physitis potential
T/F
When tapping a septic joint, you should tap TOWARDS the wound
FALSE
Tap AWAY from the wound to get a false reading
What Imaging modalities do you want to run to diagnose septic arthritis?
Radiograph –> effusion, soft tissue swelling, osseous involvement
US –> guide for aspirate, hypercellular fluid, umbilicus check in foals
Nuclear scintigraphy
Why do you not want to add chlorhexidine/ povidone iodine in septic arthritis lavages?
Kills healthy cells and doesn’t do anything to fix the disease
What are consequences of septic arthritis?
- Acute synovitis w/ suppurative effusion
- Cartilage destruction
- Capsular fibrosis/ ankylosis
- Degenerative joint disease
- Contralateral limb laminitis
- Possible euthanasia
How do you want to treat septic arthritis?
- Start off with broad spectrum ABs locally–> pen/gen (give for at least 30 days and continue to give 2 weeks after resolution)
- Lavage early and often in large volumes (5-10 L) –> VERY IMPORTANT!!!!!
- Arthroscopic lavage ideal but can use large needle lavage
- Sedate and give local anesthesia (2% mepivacaine in jiont) for arthoscopy/ -otomy
What type of lavage solutions do you want to use for lavage solutions?
- Balanced electrolyte solutions –> LRS, normosol
- DON’T USE CHLORHEXIDINE, POVIDONE-IODINE
- Maybe DMSO
How often do you want to lavage and when should you stop?
- Perform daily if severe enough
- Stop once lameness, effusion/ swelling, other signs resolve
What antibiotics are septic arthritis susceptible to?
Aminogylcosides –> concentration dependent AB
- Give 50 mg Amikacin
How do you perform regional limb perfusion?
- Give local anesthesia and sedation
- Apply tourniquet above and below joint if possible
- Inject solution slowly with butterfly catheter
- Leave tourniquet for 30 min
- Give 1/3 of systemic dose
What antibiotic do you want to use in a regional limb perfusion in cows?
Florfenicol - effective againts F. necrophorum and A. pyogenes
How do you give intra-osseous antibiotics
- Local anesthesia
- Apply Esmarch tourniquet
- Inject solution slowly and leave tourniquet on for 30 min
What other drugs do you want to give for septic arthritis?
- Morphine/ opiates –> very painful condition
- NSAIDs (give GI protectants too)
- Lidocaine and ketamine CRI
- Epidural for hindlimb –> opiates and detomidine
What is the most important way to measure the effectiveness of treatment?
- Clinical lameness and pain
– NSAIDs can mask pain
