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small animal final year > Orthopaedic infections > Flashcards

Orthopaedic infections Flashcards

1
Q

There are 3 main underlying causes of orthopaedic infection in animals?

A
  • Haematogenous spread
  • Direct contamination from trauma / puncture wound
  • Post-operative infection, usually associated with an implant
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2
Q

If only bone is infected, it is classified as?

A

osteitis

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3
Q

if bone marrow is infected, it is correctly termed?

A

osteomyelitis

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4
Q

Most common cause of orthopaedic infection of Neonates of all species?

A
  • Navel haematogenous – joint ill.
  • Acute haematogenous osteomyelitis.
  • Management.
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5
Q

Most common infectious agents causing osteomyelitis in Neonates of all species?

A

Enterobacteriacae (poop)

E.coli

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6
Q

Most common cause of orthopaedic infection of dogs?

A
  • Iatrogenic – orthopaedic sx
  • Contaminated wounds –> extension of soft tissue wounds to bone
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7
Q

Most common infectious agents causing osteomyelitis in dogs?

A

Staphylococcus, strep, E.coli, proteus

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8
Q

Most common cause of orthopaedic infection in cats?

A

Contaminated wounds – CBA à extension of soft tissue wounds to bone

Iatrogenic – orthopeaedic sx

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9
Q

Most common infectious agents causing osteomyelitis in cats?

A

Anaerobes – CBA: Pasteurella multocida and bacteroides sp.

Staph and streps from skin

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10
Q

Most common cause of orthopaedic infection in Farm animals (sheep and cows)?

A

Haematogenous

Direct spread from neighbouring tissue

Trauma

Deep digital sepsis

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11
Q

Most common infectious agents causing osteomyelitis in Farm animals (sheep and cows)?

A

Epiphyseal osteomyelitis – salmonella

Physeal osteomyelitis – Corynebacterium pyogenes and salmonella

Actinomyces

Deep digital sepsis: Treuperella pyogenes

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12
Q

Most common cause of orthopaedic infection in Horses?

A

Septic arthirits 2° to surgery or injections

Osteomyelitis – wound, implant infection, fracture repair

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13
Q

Most common infectious agents causing osteomyelitis Horses?

A

Staph aureus and staph coagulase -ve

Enterobacteriacae - pseudomonas

Strep

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14
Q

Most common cause of orthopaedic infection in birds?

A

Haematogenous

Extension from soft tissie (tendontits à bone)

Bumblefoot

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15
Q

Most common infectious agents causing osteomyelitis in birds?

A

Poultry: Mycoplasma synoviae, Staph (can be vertically transmitted), E.coli (less common)

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16
Q

Why do post-operative / implant associated infections need to be treated differently?

A
  • Greatest treatment challenge – multiple bacteria à broad spectrum antibiotics
  • Biofilm formation on implant – antibiotics can’t penetrate
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17
Q

If you have a fracture which has been fixed with implants, and it develops a post-operative infection, should you remove the implants, and if so, when?

A

Indications for removal

  • If the fracture is healed – doesn’t need implant
  • If the implant isn’t providing any stability

Indications for leaving in

  • If the fracture is unstable and not healed and the implants are providing stability.
  • Bone CAN heal with infection provided its kept stable.
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18
Q

In Early disease (< 2 weeks) (NB bony changes usually take at least 14 days to develop) what radiographic changes may be seen?

A
  • Soft tissue swelling, can have bone lysis in later stages of acute disease.
  • Rarely gas shadows – IF the causative bacteria is gas producing (eg:clostridia)
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19
Q

In Late / advanced disease what radiographic changes may be seen?

A
  • Bone lysis
  • Periosteal new bone
  • Sclerosis
  • Cortical thinning
  • Involucrum (area of sclerotic bone surrounding sequestrum)
  • Delayed fracture healing/non union
  • Sequestrum
20
Q

What other differential diagnoses can cause similar radiographic changes which can appear like the early stages of osteomyelitis?

A

Soft tissue swelling: Muscle bruising, neoplasia, seroma, joint instability

21
Q

What other differential diagnoses can cause similar radiographic changes which can appear like Late / advanced osteomyelitis?

A

Malignant neoplasia, bone cyst, disuse osteopenia, vascular infarctions

22
Q

In early disease (< 2 weeks) (NB bony changes usually take at least 14 days to develop) what diagnostic tests to confirm diagnosis of infection vs other disease can be done?

A

Bloods – haematology for infection, bacteriology of blood.

Joint tap (if soft tissue swelling near joint) – Rule out septic arthiritis

Bone scintigraphy à Facilitates early diagnosis (rule in)

FNA of anything lumpy

23
Q

In late/advanced disease what diagnostic tests to confirm diagnosis of infection vs other disease can be done?

A

Bone biopsy – Jamshidi

Swabs from discharging sinuses

Tissue samples for culture and sensitivity

FNA

24
Q

Other problems / complicating factors that may be present in cases with osteomyelitis in early disease (< 2 weeks) (NB bony changes usually take at least 14 days to develop)?

A
  • Sepsis (cause).
  • Look for failure of passive transfer of colostrum in neonates as a cause.
25
Q

Other problems / complicating factors that may be present in cases with osteomyelitis in late / advanced disease?

A

Sepsis – because of infection spread

Anaerobes hard to culture

Pathological fracture – makes infection management for complicated.

Involvement of surrounding structures: muscle, soft tissue, nerves (neuro defecits), joint involvement.

26
Q

What can be seen here?

A

Mediolateral radiograph of a humerus showing chronic osteomyelitis.

Although the # has healed, a large sequestrum is present (arrow) surrounded by an involucrum.

27
Q

Treatment should be considered in three stages:

A

1) Identify and treat underlying causes
2) Use of antimicrobials
3) Medical vs surgical treatment

28
Q

Identify three underlying problems that could cause recurrent / resistant infection?

A

Antibiotic resistance

Immune compromise (failure of passive transfer)

Implants – persistent FB, sequestrum –> BIOFILM

29
Q

What is a sequestrum and how would you treat it?

A
  • Area of necrotic bone surrounded by sclerosis. Formed within a diseased bone. Common in chronic osteomyelitis.
  • Treatment: Remove sequestrum, debride affected area and sinus tracts, remove necrotic bone, alow for drainage and obliterate dead space –> don’t close skin and just pack to allow drainage –> primary closure when discharge stops, antibiotcs to treat and prevent infection.
  • In severe cases with joint and soft tissue complications –> amputate
30
Q

How would you identify fungal osteomyelitis, and where does it usually occur (http://cal.vet.upenn.edu/projects/saortho/chapter_37/37mast.htm is a helpful resource)?

A
  • Common in hot, wet regions
  • Young/immunosuppressed animals most at risk
  • Abnormalitis on haem and biochecm
  • ALWAYS thoracic rads – resp signs common
  • Plumonary granulomas may be mistaken for lung metastases with bone lesions
  • May present with lameness and limb swelling
  • DIAGNOSIS: Histopathology and isolation of organism
  • TREATMENT: Ketoconazole – 10mg/kg sid for 2 months then 5mg/kg for a further 2 months.
  • Prognosis poor for aspergillus infections – Will need to be on permanent treatment ith ketoconazole or itraconazole.
31
Q

Antimicrobial options to use in osteomyelitis (including route of administration, and duration) of dogs?

A
  • Amoxiclav (can add metronidazole – anaerobes –> broader spectrum)
  • Clindamycin
  • 1st gen cephalosporins – Cephalexin (can add metronidazole – anaerobes –> broader spectrum)
  • Long course: 6-8 weeks
32
Q

Antimicrobial options to use in osteomyelitis (including route of administration, and duration) Farm animals (sheep and cows)?

A
  • Penicillin IM
  • Sodium iodide
33
Q

Antimicrobial options to use in osteomyelitis (including route of administration, and duration) in Horses?

A

Enterobacteriacae and staph –> Amikacin (aminoglycoside)

Strep –> Cephalothin

Enterobacteriacae à Sefotaxmine

Penicillin IM

Gentacicin IV

Metronidazole PO or IV

34
Q

Antimicrobial options to use in osteomyelitis (including route of administration, and duration) in Birds?

A

Amoxyclav

35
Q

Which antibiotics would you avoid in neonates?

A
  • Bacteriostatic or orals
  • Tetracyclines
  • Chloramphenicol
36
Q

What are the screening tests/diagnosis and surgical treatment for Sequestrum?

A
  • Diagnosed by characteristic appearance on radiography – presence of sequestrum +/- involucrum
  • All dead / necrotic bone must be removed or will act as a nidus for infection. Good prognosis once removed.
37
Q

What are the screening tests/diagnosis and surgical treatment for Foreign material present?

A
  • Radiography, Ultrasound
  • Remove it
38
Q

What are the screening tests/diagnosis and surgical treatment for Associated synovial infection?

A
  • Joint tap
  • Could flush?
  • Antibiotics mostly
39
Q

What are the screening tests/diagnosis and surgical treatment for Umbilical infection in neonates?

A
  • Palpation
  • Culture bloods
  • none
40
Q

What are the screening tests/diagnosis and surgical treatment for Unstable fractures?

A
  • Radiographs
  • Stabilise fracture
41
Q

What are the screening tests/diagnosis and surgical treatment for Dead space / soft tissue defects?

A
  • Radiographs
  • Drain and oppose
42
Q

What are the screening tests/diagnosis and surgical treatment for Implants present?

A
  • Radiographs
  • Discussed earlier
43
Q

What are the screening tests/diagnosis and surgical treatment for Antibiotic resistance?

A
  • C & S
  • Appropriate antibiotic
44
Q

What are the screening tests/diagnosis and surgical treatment for Tissue necrosis / vascular impairment?

A
  • Visualisation
  • Radiographs
  • Debride, remove sequestrum
45
Q

What are the basic principles of surgical treatment in these cases – i.e. what is the underlying principle that you are trying to achieve?

A
  • Make it clean
  • Fix it
  • Remove dead stuff or underlying cause
  • Minimise dead space
46
Q

How can you minimise the risk of post-operative infection?

A
  • Good sterile technique
  • Prophylactic antibiotics 1 hr before, 24h after… should be avoided.
  • Longer antibiotics if clean-contaminated surgery

small animal final year (317 decks)

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