joint fluid Flashcards
role of synovial fluid
- Lubricate joints
- Shock absorption
- Nutrient absorption + waste removal
- Barrier against cell entry/fluid exit
ddx for increased soft tissue opacity in the joint space
degen, inflam, infectious, traumatic, neoplasia
necessary equipment for arthrocentesis
- 21G needle, 40mm
- 5ml syringe (dogs)/2ml (cats)
- EDTA blood tube
- Blood culture tube
- Slides
technique of carpus arthrocentesis
- Flexed 90degrees
- Depression at radiocarpal jt
- Needle medial to cephalic vein, btwn CDE (lateral) + ECR (medial)
technique of talocrural joint arthrocentesis
- No flexion
- Needle medial to lateral malleolus at dorsomedial aspect of joint
- Direct needle plantar + medial
technique of stifle jt arthrocentesis
- Slight flexion + external rotation
- Needle lateral to patella lig, midway btwn patella + tibial tuberosity
- Direct needle 45degrees to skin + parallel to patella tendon + lateral to patella
normal gross appearance of joint fluid
- Volume: <0.5ml (distal joints)
- Viscosity: strand test - 2.5cm stretch
- Colour: colourless
- Turbidity: clear
gross appearance of infectious OR inflammatory joint fluid
- Volume: increased/normal
- Viscosity: reduces
- Colour: yellow, serosanguinous
- Turbidity: increased
preparation of joint fluid samples
- Slides for cytology - air dry + diff quik
- EDTA tube 0.1ml
- Blood culture tube 0.5ml
- aerobic media = blood
- *anaerobic media = transport
info gained from cytology
bacteria in 50% of septic arthritis cases
RBCs
neuts
normal TP of synovial fluid
<2.5g/dL
cell count characteristics of infectious/inflammatory synovial fluid
neut heavy
percentage of false negatives w/ joint culture
20-50% of cases thus neg. culture is not definitive
pathogens assoc. w/ septic arthritis in a dog
Strep. intermedius, beta-haemolytic strep
Staph. aureus
pathogens assoc. w/ septic arthritis in a cat
Bacteroides (fights)
Pasteurella multocida
Tx of septic arthritis
initial IV ABs, + ongoing PO 1month
ie. amoxiclav
when is sx intervention indicated in septic arthritis
- Gross contamination (FB/implant)
2. No response to medical management
resolution of septic arthritis is confirmed by….
repeat synovial analysis consistent w/ OA fluid
<3% neuts
prognosis of septic arthritis
resolves in 95% of cases
note: ongoing OA management indicated
synovial structures in the distal forelimb of a horse
- Coffin jt + navicular bursa
- Pastern jt
- Fetlock jt
+ assoc. DFT sheath
synovial structures in the carpus of a horse
- Carpometacarpal jt + carpal sheath
- Middle carpal jt + CDE + LDE tendon sheath
- Radiocarpal + ECR tendon sheath
synovial structures in the shoulder of a horse
bicipital bursa + glenohumeral jt
signalment of neonatal synovial sepsis in foals
<30d, failure of passive transfer –> haematogenous spread from other source
ie. pneumonia, umbilical infection, gastroenteritis
organisms commonly involved in foal synovial sepsis
Enterobacteriaceae
Salmonella
Satphylococcus
pathogen assoc. w/ iatrogenic synovial sepsis in adult horse
Staph. aureus
pathogens assoc. w/ synovial sepsis in adult horse
enterobacteriaeceae, clostridium, staph.aureus
ddx for adult horse synovial sepsis
subsolar abscess, fractures, severe cellulitis
method of synoviocentesis for horses
US guided is best
- if diff. to collect inject 5-10ml saline + aspirate –> cytology is still relevant
what test can you use to test communication of joints/wounds?
pressure testing (injecting saline at pressure - watching exit wounds for fluid)
what neut and protein parameters indicate synovial sepsis of a horse?
> 90%
40g/L protein
*must interpret in light of case
aims of treatment of equine synovial sepsis
- Eliminate causative organisms
- Remove inflammatory mediators
- Maintain normal joint function
components of treatment of equine synovial sepsis
- ABs: systemic and local
- Lavage of synovial cavity: arthroscopic or needle
- Analgesia and anti-inflams
- Chondroprotective therapy
- Physiotherapy
routes of local antibiotics to tx equine synovial sepsis
- intra-synovial
- regional perfusion: IV or intraosseous
examples of intra-synovial ABs to tx equine synovial sepsis
- 250mg ceftiofur
- 250-500mg amikacin
- 150mg gentamicin
describe admin of intra-synovial ABs in tx of equine synovial sepsis
direct injection of ABs into synovial cavity q24h 3-5days
describe admin of intravenous regional perfusion ABs in tx of equine synovial sepsis
- Sedate
- Tourniquet proximal to affected synovial structure
- 20G butterfly cath into SF vein; saphenous, cephalic, palmar digital
- Inject 10ml lignocaine or mepivacaine first
- Infuse over 5 min
- Remove tourniquet after 20-30minutes
- Rpt q24-36h after 3-5tx
describe frequency of lavage to tx equine synovial sepsis
- Initial arthroscopic lavage preferred
2. 3-5 subsequent lavages may be required –> rps if lameness increases, synovial fluid cytology deteriorates
appropriate NSAIDs to tx equine synovial sepsis
Bute 2.2mg/kg BID
OR flunixin, meloxicam, firocoxib
prognosis of equine synovial sepsis
- Success can be up to 80% if early aggressive therapy and arthroscopy
- Prognosis reduced if:
- bone involvement
- failure to remove fibrin at lavage that can harbor bacteria
- recrudescence of infection following discontinuation of tx
- resistant organisms
- chronic change in the jt causing persistent lameness - Tx can be expensive and protracted –> unresponsive infection/tx failure can necessitate euthanasia on humane grounds
