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LOCO2 > Bone and Joint Infections > Flashcards

Bone and Joint Infections Flashcards

1
Q

What is septic arthritis?

A
  • most common destructive arthroplasty
  • mostly mono-articular (90%) poly (10%)
  • in extremes of ages (very young and very old)
  • increase intra-articular injections/joint replacements/investigations have greater risk of infection so increased in adults
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2
Q

What is acute septic arthritis?

A
  • pyogenic
  • mild in most cases
  • limitation of joint movement
  • synovial effusion = swelling
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3
Q

What is the difference between acute and chronic septic arthritis?

A
  • acute = pyogenic

- chronic = non-pyogenic

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4
Q

What is the pathogenesis of septic arthritis?

A
  • most common = infection via haematogenous route

- other mechanisms involve adjacent osteomyelitis, penetrating trauma..

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5
Q

What are the common organisms which destroy bones/joints?

A
  • gram positive cocci = s. aureus, streptococci (pyogenes, pneumonia, Group B)
  • gram positive bacilli (clostridium sp.)
  • gram negative cocci (Neisseria gonorrhoea)
  • gram negative bacilli (Escherichia coli, pseudomonas aeruginosa, haemophilus influenzae (before immunisation), eikenella corrodens (human bites))
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6
Q

What is the most common causative organism for septic arthritis?

A
  • staph apart from 16-50 year olds where gonococcus is
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7
Q

What are the predisposing factors of septic arthritis?

A
  • previous joint damage
  • untreated systemic infection
  • condition affecting blood supply to joint
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8
Q

Which joints are most commonly affected by septic arthritis?

A
  • knee
  • also hip/ankle/eblow
  • rarely wrist/shoulder/fingers
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9
Q

How is septic arthritis diagnosed?

A
  • elevated ESR/CRP
  • neutrophilia (inflammation marker)
  • synovial fluid examination (turbid or purulent, leukocyte no., glucose)
  • blood culture
  • culture other sites
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10
Q

What may be seen in radiology for septic arthritis?

A
  • destruction changes seen at least after 2 weeks so not useful in early stages
  • soft tissue swelling, erosion of articular cartilage, associated soft tissue swelling
  • mycobacterial infection = joint space narrowing, effusion, erosions, cyst formation
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11
Q

What is the differential diagnosis of septic arthritis?

A
  • acute rheumatoid arthritis
  • gout
  • chondrocalcinosis
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12
Q

What is the treatment for septic arthritis?

A
  • drainage of joint

- antibiotics (start with broad spectrum if stain not known, IV 3-4 weeks)

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13
Q

What is reactive arthritis?

A
  • reiter’s arthritis
  • reactive to bacteria or post-infections
  • common in presence of HLA-B27
  • proceeded by genitourinary infection (STI - chlamydia trachomatis or enteric infections (enteritis - salmonella)
  • sterile inflammatory process
  • usually extra-articular symptoms (lower back pain and diarrhoea)
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14
Q

How can TB cause joint infection?

A
  • often goes into soft tissues secondarily
  • slow growing but very destructive
  • Pot’s disease = vertebra destruction as TB on spine = spinal compression
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15
Q

How is osteomyelitis spread?

A
  • haematogenous

- contiguous spread from infected focus

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16
Q

What are the types of osteomyelitis? Who are they more common in?

A
  • acute haematogenous = primarily in children
  • contiguous focus = more common in young adults
  • spinal = adults over 45
17
Q

Where do lesions form in osteomyelitis?

A
  • at metaphysis of EGP where there is a rich blood supply as constant remodelling
  • abscess grows and pushes/dislodges periosteum
18
Q

What are the consequences of an osteomyelitis abscess?

A
  • microabscess = bone tries to prevent spread making a bony barrier
  • however bacteria eventually eats through
19
Q

What are the predisposing factors of osteomyelitis?

A
  • impairment of immune surveillance (malnutrition, extremes of age)
  • impairment of local vascular supply (diabetes mellitus, venous stasis, radiation fibrosis, sickle cell disease)
20
Q

What are the clinical features of osteomyelitis?

A
  • haematogenous spread in long bone (abrupt onset of high fever, decreased limb movement, adjacent joint effusion)
  • local and non-specific pain
  • elevated neutrophil count
  • elevated ESR
21
Q

What are the clinical features of chronic osteomyelitis?

A
  • local bone loss

- persistent drainage through sinus

22
Q

What are the rare complications of chronic osteomyelitis?

A
  • squamous cell carcinoma

- amyloidosis

23
Q

What is Broca’s abscess?

A
  • lytic lesion in oval shape

- surrounded by thick dense reactive sclerosis

24
Q

What are the investigations made in diagnosis of osteomyelitis?

A
  • bone biopsy
  • blood cultures
  • neutrophil count/ESR
  • radiography/isotope scan
25
Q

What is the management of osteomyelitis?

A
  • surgical debridement to remove dead bone
  • reconstruct bone (allograft to autograft)
  • antibiotics for 4-6 weeks
26
Q

What antibiotics are used for osteomyelitis?

A
  • vancomycin
  • flucloxacillin (gram positive)
  • clindamycin (oral and foam)
  • piperacillin (broad spectrum IV)
  • ciprofloxacin (broad spectrum)
27
Q

How can a prosthetic bone have a joint infection?

A
  • in osseous tissue adjacent to prosthesis
  • bone contiguous with prostehesis
  • from haematogenous spread
  • from local inoculation at surgery or post-op spreads from wound sepsis
28
Q

What are the risk factors of infection in prosthetic bone and how are they prevented?

A
  • prior surgery at site of prosthesis -> eliminate infected foci before surgery
  • RA -> use peri-operative antibiotics
  • diabetes mellitus -> use laminar flow theatre ventilation
  • obesity -> exhaust ventilated body suits worn by surgical team
  • malnutrition -> prophylaxis
29
Q

What are the clinical features of prosthesis joint infection?

A
  • usually gradual onset with progressive pain

- occasional sinus development

30
Q

What are the investigations for prosthesis joint infection?

A
  • x-rays (lucencies at bone cement interface and change in component composition)
  • cement fractures
  • periosteal reactions
  • gas in joint
31
Q

What is the management for prosthesis joint infection?

A
  • simple debridement and retain prosthesis plus antibiotics (20% success)
  • removal of prosthesis, antibiotics for 6 weeks, re-implantation (90% success)
  • removal of prosthesis, immediate reimplantation, antibiotics (70% success)

LOCO2 (26 decks)

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