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Ortho > chapter 17 - acute pyogenic bone and joint infections in children > Flashcards

chapter 17 - acute pyogenic bone and joint infections in children Flashcards

1
Q

what is the current theory of osteomyelitis?

A
  • the glycocalyx capsule of the staph aureus has chrondotropism or a selective tendency of adherence to the cartilage growth plate of the growing child
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2
Q

pathophysiology of acute osteomyelitis

A
  • bacteria deposited during a bacteraemic episode into a metaphyseal vessel
  • bacteria escape through endothelial gaps and adhere to the growth plate in the metaphyseal bone
  • proliferating bacteria cause retrograde thrombosis of the nutrient artery
  • abscesses form in the medulla and decompression of pus takes place via volkamnns and haversion canals to the subperiosteal space
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3
Q

which type of osteomyelitis exists in the neonate and infants (<1)?

A

presents with septic arthritis but primary pathology is osteomyelitis

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4
Q

name the type of vessel that exists in neonates and infants and connects the metaphysis with the epiphysis

A

transphyseal vessels

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5
Q

2 complications of osteomyelitis in the neonate and infant

A
  1. destruction of the epiphysis - eg: tom smith arthritis of the hip
  2. growth plate damage eg: coxa vara
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6
Q

in the child older than one - why does subperiosteal decompression take place?

A

the physis acts as a vascular barrier

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7
Q

in ostemyelitis in a child why would the inner half of the cortex die?

A

nutrient artery thrombosis

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8
Q

what is a sequestrum?

A

dead bone

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9
Q

what is the most common cause of septic arthritis?

A

haematogenous spread to synovium

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10
Q

what are two other causes of septic arthritis?

A
  1. intra articular metaphysis decompresses into a joint

2. transphyseal spread in neonate and infant

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11
Q

pathophysiology of septic arthritis

A
  • bacteria and pus destroy cartilage = chondrolysis

- staphylokinase is a proteolytic enzyme and neutrophils release proteolytic enzymes that are chondrolytic

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12
Q

why should you wash out a joint with septic arthritis?

A

to wash out the chondrolytic and proteolytic enzymes

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13
Q

in septic arthritis - what is the complication of having pus in the hip joint?

A
  • pus is chondrolytic

- avascular necrosis: pus stretches the retinacular vessels to the femoral head

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14
Q

how does a neonate or infant with ostemyelitis present clinically?

A

70% not ill, can drink well, apyrexial

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15
Q

what is the most common finding in an neonate or infant with osteomyelitis?

A

pseudoparalysis

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16
Q

how does the clinical presentation of osteomyelitis differ in an infant and child

A

child: frozen joint
infant: reasonable range of passive movement

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17
Q

which sites are commonly affected in a neonate or infant with osteomyelitis

A

proximal hip/femur 50%
proximal shoulder/humerus
distal knee/femur

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18
Q

what are the radiographic features found in a neonate or infant with acute osteomyelitis?

A

metaphyseal rarefaction

subluxation of the hip and shoulder

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19
Q

what are the commonest sites of osteomyelitis in a child(7 yo)?

A

distal femur

proximal and distal tibia

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20
Q

how does a child with osteomyeltiis typically present clinically?

A

bone pain and tenderness in metaphyseal area
ill, pyrexial
refuses to bear weight on leg
± swelling

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21
Q

what determines whether there is swelling present in a child with osteomyeltiis?

A

whether the pus has decompressed sub periosteally

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22
Q

how does septic arthirtis present in a child?

A

warm, painful swelling of the joint
palpable effusion
decreased range of movement

23
Q

what do the radiographs look like in the acute phase of ostemyelitis in a child?

A

normal radiographs in the acute phase

24
Q

in a child when does osteomyelitis become visible on radiograph?

A

after 2 weeks

25
Q

what are the radiographic changes found in a child with osteomyelitis?

A

metaphyseal rarefaction

periosteal reaction

26
Q

which laboratory test may be raised in a child with osteomyeltiis and what would the value be?

A

ESR > 50

27
Q

what is the best investigation to differentiate between osteomyelitis, diffuse cellulitis and mysosits?

A

isotope bone scan with technetium methylene disphosphonate ( 99mm Tc - MDP)

28
Q

how do patients with severe disseminated staphylococcal disease present clinically?

A 
critically ill
septicaemia
metastatic staphylococcal pneumonia
myocardial effusion
bone or joint infection
29
Q

which investigation is mandatory in patients with severe disseminated staphylococcal disease?

A

isotope bone scan

30
Q

what is the usual causative organism of osteomyelitis in child hood?

A

staph aureus

31
Q

what is the commonest causative organism of osteomyelitis in neonates ? and the 2nd and 3rd ?

A
  1. staphylococcus 72%
  2. streptococcus
  3. gram negative - E coli
32
Q

30% of neonates with osteomyeltiis are resistant to X antibiotic? which neonates are more likely to be resistant?

A

cloxacillin

premature neonates - who have spent time in hosptial

33
Q

what is the commonest organism in septic arthritis?

A

staph aureus 30%

34
Q

True or false: In 50% of patients with clinical septic arthritis no organism can be identified

A

true

35
Q

how is the diagnosis of osteomyelitis made? and which investigations are needed?

A
  • a high index of suspicion and clinical diagnosis
  • radiographs in neonates to rule out fracture or tumour
  • FBC, ESR, blood culture
36
Q

when do you admit a patient with osteomyeltiis?

A

if the diagnosis is obvious or if there is doubt

37
Q

how do you manage a patient initially if you suspect osteomyelitis?

A

observation in the ward for 24 hours

±isotope bone scan to confirm diagnosis

38
Q

first line treatment of acute bone and joint infection

A

antibiotics IV for 24 hours

39
Q

antibiotic for all patients with osteomyeltiis and route ?

A

cloxacillin 200mg/kg/day IV

40
Q

if a neonate has been hospitalised previously which additional drug to the antibiotics do you prescribe to treat osteomyelitis? and why?

A

fusidic acid 30mg/kg/day

for staph aureus

41
Q

antibiotic to treat pt with septic arthritis aged 6m to 2 years and route? also what does this cover?

A

ampicillin 150mg/kg/day IV

haemophilus influenzae

42
Q

oral treatment of osteomyelitis caused by staph aureus? and duration of treatment

A

flucloxacillin 100mg/kg/day for 6 weeks

43
Q

oral treatment of septic arthritis and duration of treatment and which 2 drugs to use if there is no growth in the age group 6m to 2 yrs

A
  1. amoxil 75mg/kg/day for 3 weeks

2. cloxacillin + ampicillin

44
Q

which surgery should always be performed in septic arthritis? and what role does it play? what does it do in the hip joint?

A

open arthrotomy and lavage of joint

  • removes chondolytic effects of organisms and pus
  • hip joint: capsular distension is decompressed and prevents avascular necrosis
45
Q

if osteomyelitis presents early can it be treated without surgery?>

A

yes

46
Q

which surgery is useful in patients with osteomyeltiis?

A

draining the subperiosteal pus

47
Q

which 3 conditions are prevented if the pus is drained in a patient with osteomyelitis

A

patient improves clinically

  1. metastatic spread
  2. further periosteal stripping
  3. devascularisation of the cortical bone
48
Q

what can be done to treat a patient with osteomyeltiis if no pus is found outside the bone?

A

3mm drill hole made without stripping periosteum

49
Q

complication of osteomyeltiis

A

chronic osteomyeltiis

50
Q

what is the cause of chronic osteomyelitis

A

presence of sequestrum

51
Q

describe the two types of sequestrum found in a patient with chronic osteomyelitis

A

small: sinus that discharges pus intermittently
large: structural sequestrum with potential to fracture

52
Q

3 complications of septic arthritis explained:

A

chondrolysis - destruction of articular cartilage
stiffness: decreased ROM due to peri and intra articular fibrosis
avascular necrosis

53
Q

which joint is affected by avascular necrosis

A

hip joint

54
Q

when is a patient with septic arthritis at increased risk of avascular necrosis?

A

if treatment is delayed by > 5 days incidence increases by > 50%

Ortho (41 decks)

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