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Musculoskeletal > LA MS 14: Septic OA > Flashcards

LA MS 14: Septic OA Flashcards

1
Q

Septic OA

A

EMERGENCY
Painful - support limb laminitis
IFX –> IFM
–bacteria: hyaluronidase, cytolytic toxins
–Synovial cells: IL-1B, prostaglandins
Eliminating IFX early = key
Irreversible cartilage degeneration - tx goal is to minimize OA

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2
Q

Classification of Septic Arthritis - hematogenous

A 
SEPTic 
S type = synovium 
E type = epiphysis 
P type = physis 
T type = tarsal bone
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3
Q

Classification of Septic Arthritis - Non hematogenous

A

Puncture wound

Contiguous soft tissue

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4
Q

Septic Arthritis in Foals - Neonatal blood supply

A

In the growth plate, have transphyseal vessels that communicate btw primary and epiphysis artery. Predisposes IFX at growth plate (physis) in foals

  • -over time, lose these connections
  • -Bacteria more likely to lodge in small capillaries
  • -as being vessels, being degraded, bacteria more likely to get stuck so more challenging to dx and treat
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5
Q

Type S

A

Synovial
Septic arthritis resulting from inoculation of the synovial membrane
Often see gas-producing bacteria or open communication to outside world

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6
Q

Type E

A

Subchondral bone IFX present

epiphysis

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7
Q

Type P

A

Physis
Physeal IFX on the metaphyseal side of the growth plate
Often appears lytic
–remember RAD changes always lag behind

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8
Q

Type T

A

Tarsal bones (or carpal bones)
IFX of small tarsal or carpal bones esp in premature foals
Sequela
–collapse and angular limb deformity

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9
Q

Foal vs Adult

A

Prog usually worse in foals

  • -hematogenous
  • -complications from the septicemia
  • -multiple jts = decreased racing prognosis
  • -also osteitis, osteomyelitis, physitis
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10
Q

Other complications assoc w/ foals

A

May have
–septic arthritis only
–septic physitis only
–septic arthritis and physitis
–septic osteomyelitis, physitis
–septic arthritis, physitis and osteomyelitis
BEWARE - premature closing and angular limb deformities

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11
Q

Dx - hx (foals)

A 
FOALS ARE OFTEN FEBRILE 
Hematogenous >>> penetrating 
Prematurity 
FPT 
Usually <1mo
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12
Q

Etiologic Agents

A 
Aerobic/facultative anaerobes in 91% of cases 
Anaerobic - Clostridium 
Mycoplasma 
Rhodococcus 
Fungal agents 
--Scendosporium prolificans 
--Candida
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13
Q

Etiologic Agents: Aerobic/Facultative Anaerobes

A 
Salmonella 
Strep zoo 
E. Coli
Actinobacillus equili
Staph aureus 
Borrelia
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14
Q

Dx Considerations

A 
Hx, PE
--assess entire P
--Articular swelling, lameness, cellulitis +/- predisposing hx 
Synovial fluid analysis 
--cytology, gram stain 
--culture and sensitivity 
RADS
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15
Q

Dx Hx - Adults

A 
ADULTS ALMOST NEVER FEBRILE 
Iatrogenic 
--Staph or Strep either post-op or post jt INJ
Trauma 
Nearby IFX 
--foot abscess 
--cellulitis 
Idiopathic
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16
Q

Dx Sample Collection

A

Minimize blood contamination
Sample away from open wounds
Avoid cellulitis

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17
Q

Sample Types

A 
Cytology/Gram Stain 
--EDTA, heparin 
Culture 
--Blood culture vials 
--Anaerobic/aerobic 
--NO ANTICOAG 
--fluid, fibrin, or synovium can be cultured 
Have dose of ABX ready to infuse
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18
Q

Synovial fluid analysis

A

Translucent yellow
Normal viscosity - mucin, HA –> string btw fingers
Cloudy fluid suggests >30,000 cells/uL

19
Q

Normal Synovial Fluid

A

TP <2.0 to <2.5 g/dL
WBC <450 to <5000
Cell type <10% neutrophils

20
Q

Synovial fluid - IFM

A

TP 2.5 to 4 g/dL
WBC 500 to 20,000
Cell type 10-50% neutrophils

21
Q

Synovial fluid IFX

A

TP >4.0 g/dL
WBC >30,000/uL
Cell type >80% neutrophils

22
Q

Serum Amyloid A

A

Not specific to sepsis

23
Q

Synovial Fluid Cytology

A 
Gram stain 
--ID bacteria in 25% 
--Rapid guidance for ABX selection 
Neutrophils 
--normally <10% synovial fluid 
--usually non-degenerate in early IFX 
-->80% usually always IFX'd 
--degenerate neutrophils ALWAYS bad
24
Q

Dx: culture and sensitivity

A

No growth does not mean not infected
Single organism indicative of IFX
Pos culture correlates w/ decreased prof
Blood culture media increases likelihood of a positive culture

25
Q

Dx - RADS

A

Radiographic lytic changes can occur in <1 week
–lag time
–most changes seen at 7-10d post IFX
Eval RADS for fx, gas opacity, lytic changes, FB

26
Q

Systemic Eval

A 
CBC, fibrinogen, SAA
Fever
Blood culture - foals 
Palpate - umbilicus, other jts 
US - umbilicus, lungs
27
Q

Management Principles

A
  1. Eliminate IFX
  2. Establish drainage
  3. Restore normal synovial jt viscosity and fluid properties - jt milieu
28
Q
  1. Eliminate IFX
A

Local ABX

Systemic ABX

29
Q

Local ABX

A

IA
IV regional limb perfusion
Intraosseus perfusion
ABX-impregnated beads

30
Q

Systemic ABXs

A

Penicillin + amikacin (foals) or gentamicin (adults)

31
Q

Intraosseuous perfusion

A

More invasive than regional limb

Hole drilled into long bone and indwelling cannula is used to deliver ABX infusion - high ABX levels obtained

32
Q

IA Anx

A

High levels directly into jt
Following high vol lavage
IA drains may be used to deliver abx +/- HA - CRI, clotting

33
Q

IV Regional Limb Perfusion - Advantages

A

Mainstay of tx
Far greater ABX [ ] than systemic
Concentration remains higher than after systemic IV
Low dose may be effective - fewer SE
Effective tourniquet essential - heavy sedation or short IV ax

34
Q

IV Regional Limb Perfusion - Disadvantages

A

Req functional tourniquet
Catheter site morbidity
–thrombosis, cellulitis

35
Q

ABX Beads - non-absorbable

A

PMMA

Longest ABX elution (mo)

36
Q

ABX beads - absorbable

A

Collagen
Plaster of Paris (PoP)
Bone cement - calcium phosphate

37
Q

2) establish drainage - basics

A

Lavage-based physiological sln
Arthrotomy
Arthroscopy
Removal of necrotic tissues

38
Q

2) establish drainage - more complicated

A

If significant amt of fibrin or thick synovial fluid or bony lesion, more aggressive drainage selected
–arthrotomy
–arthroscopy
Arthrotomies indicated in horses that do not respond rapidly to jt lavage

39
Q

Arthroscopy vs arthrotomy

A

Experimentally both eliminate the IFX
–arthrotomy faster
Arthrotomy has increased risk of ascending IFX
–sterile bandaging critical

40
Q

3) restoration of joint mileu

A 
Anti-IFM - NSAIDS, HA
Additional analgesia 
--epidural catheter 
--perineural anesthetic 
--IA anesthetics 
--bandaging 
--support CL limb -prevent laminitis
41
Q

Sodium Hyaluronate (HA)

A

Anti IFM

Anti-adhesive

42
Q

Bandaging

A

Reduces swelling, edema, and pain (jt pressure)

Protects arthrotomies

43
Q

PT

A

During and after sepsis

Important to maintain ROM

44
Q

Summary

A 
Potential jt IFX = emergencies 
Early, aggressive tx best 
Foals have 50% prognosis vs 80% in adults 
Combo tx 
--eliminate IFX 
--establish drainage 
--restore jt mileu 
--Analgesia

Musculoskeletal (10 decks)

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