Septic Arthritis Flashcards
What are naturally occurring routes of septic arthritis?
Hematogenous or traumatic
What are iatrogenic causes of septic arthritis?
Arthroscopy
Arthrocentesis
Fracture repair
Pathogenesis of septic arthritis?
Synovitis/capsulitis Fibrin deposition Cellular infiltrates —> degradative enzymes, cytokines —> collagenases, stromelysin, MMP release —> IL1, IL6, TNF
Creates cycle of cartilaginous matrix destruction
Decreased HA synthesis Loss of PG Joint effusion Pain Compromise synovial blood flow
What are risk factors in foals for septic arthritis ?
FPT — risk of bacteremia (hematogenous)
What are the types of septic arthritis in foals?
S — synovial membrane and fluid
E — epiphysis, bone adjacent to articular cartilage
P — physis of long bones +/- joint
Foal <1week with acute, severe lameness, and effusion of the stifle and tibiotarsal joints.
What type of septic arthritis is this?
S type
Foal a few weeks old that had a mild lameness and fever. Lameness has acutely worsened in the last day. There is effusion in multiple joints, the distal femur, taus, and radius.
What type of septic arthritis is this?
E type
Can confirm with rads —> subchondral bone lysis
Foal a month old that was seemingly healthy that had developed an premonitory lameness which is now acute and severe.
What type of septic arthritis is this?
P type
How can you confirm a P type septic arthritis?
Radiographs —> lysis
Aspirate of physis
Possible bone biopsy
DO NOT debride -> will damage physis, causing premature closure
How can you confirm diagnosis of S and E type septic arthritis ?
Radiographs
Synovial fluid analysis
>50,000 cell count, >90% PMNs
Colour- normla to cloudy, red, orange, pink
Blood work : increase fibrinogen +/- leukocytosis
Fibrinogen >900mg/dL with bone involvement
US: hypercelluar fuild
What is the prognosis for survival for foals with septic arthritis?
77%
What is the most common agent involved in septic arthritis of adult horses?
Enterbacteriaceae
Staph, pseudomonas, or fungi can be involved
T/F: open joint = infected joint
True
Clinical signs of septic arthritis in adults?
Acute onset of severe lameness
Synovial effusion
Peri-articular heat and swelling
+/- fever
What is the gold standard for diagnosis of septic arthritis ?
Microbiology
C/S in blood culture bottles
Repeat for culture if initial sample is negative
Cytology of a joint.
Color: pale yellow
Clear
WBC 400 cells/dL, <10% neutrophils
TP 2g/dL
Normal or abnormal?
Normal
Cytology of a joint.
Colour: orange, turbid
WBC 2000 cells/dL, > 90% neutrophils
TP 3.5g/dL
Normal or abnormal?
Abnormal
Normal WBC <500cells/dL with <10% neutrophils
Normal TP is < 2g/dL
What is the most common isolate in septic joints?
Staphylococcus
Why do we want to do our tap away from the wound?
Prevent contamination from would surface for culture
What are consequences of septic arthritis ?
Acute synovitis with suppurative effusion
Cartilage destruction due to cellular and bacterial enzymes, and cytokines
Capsular fibrosis/ankylosis
DJD
Contralateral limb laminitis
What is the treatment for septic arthritis?
LAVAGE- early and often
- large volumes
Broad spectrum antibiotics
What are two methods of joint lavage?
Arthroscopic (best)
- rapid and accurate delivery
- removal of fibrin clot
- targeted debridement
Needle (through and through lavage)
- use large guage need (16-18g)
- needles can get clogged easily
Can be done with local anesthesia (2% mepivacaine) and sedation or under general anesthesia
What solution do you use in lavage of a joint?
Balanced electrolyte solution — LRS or Normosol
T/F: chlorhexidine or poisoned-iodine can be added to lavage solutions to help as an anti-inflammatory and free radical scavenger
F
These are cytotoxic. NEVER use
Can use DMSO for these purposes
How often should you lavage a septic joint?
Daily initially
Can stop when there is resolution of lameness or effusion/swelling
How long should you give broad spectrum antibiotics for a septic joint? /
Minimum 30days and 2weeks beyond resolution of CS
Why must you be cautions of administering IA injections of antibiotics into multiple joints??
Local IA antibiotics can provide high concentration with int he joints but you must be careful not to exceed the daily total SYSTEMIC dose
How often can regional limb perfusion be done to treat septic arthritis? And how long do you leave the tourniquet inplace?
Performed QOD
Tourniquet in place (above and below site) for 30mins
What is the dosage for regional limb perfusion ?
1/3rd of systemic dose
Diluted to 30ml for distal limb
Diluted to 60ml if above carpus/tarsus
In cattle you can do a regional limb perfusion with __________ which provides a high tissue concentration of antibiotics against F. Necrophorum and A. Pyogenes
Florfenicol
How do you administer intra-osseous antibiotics?
Sedation or local anesthesia a
Drill 4mm hole
Insert the male end of luer tip extension
Add an esmarch tourniquet
Slow injection and leave tourniquet in place for 30mins
Analgesics that can be used in septic arthritis patients?
NSAIDS
Opiates
CRI —. Lidocaine, ketamine
Epidural catheter— opiate, detomidine
What is the most reliable and important way to measure response to treatment in septic arthritis cases?
Clinical lameness
(NEVER discontinue any antibiotic or lavage until a horse is evaluated for lameness AFTER analgesics have been reduced or discontinued)
