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Paediatrics FCRS > Infection > Flashcards

Infection Flashcards

transient synovitis septic arthritis acute/subacute/chronic osteomyelits puncture wound infections

1
Q

What is transient synovitis of the hip?

A
  • Hip pain due to inflammation of the synovium of the hip
  • most common cause of hip pain in paeds population
  • most common in aged 4-8 years
  • male : female 2:1
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2
Q

Describe the risk factors of transient synovitis of the hip?

A
  • Cause of transient synovitis of the hip is unknown
  • however related to
    • trauma
    • bacterial or viral infection ( poststreptococcal toxic synovitis)
    • higher interferon concentration
    • allergic reaction
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3
Q

What is the pathoanatomy of transient synovitis of the hip?

A
  • Non specific inflammation and hypertrophy of the synovial lining/membrane
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4
Q

What is the prognosis of transient synovitis of the hip?

A
  • Natural hx of disease
    • usually benign
    • marked improvements usually in 24-48hrs
    • complete resolution of symptoms will usually occur in <1 week
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5
Q

What are the key questions to ask in hx?

A
  • Site of pain
    • groin vs hip ( referred)
    • Timing ( intermittent vs constant)
    • Lack of mechanical symptoms ( locking/catchng giving way)
    • Assoc limp
    • constitutional symptoms
    • recent infection/trauma
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6
Q

What are the signs /symptoms of transient synovitis of the hip?

A

Symptoms

  • Mild/ absent fever
  • Acute/ insidiuos onset of groin/thigh pain
    • pain is worse on awaking
    • refusal to wb on affected extremity
    • usually improves during the day ( can walk w a limp later in day)
    • muscle spasms

Signs

  • hip in Flexion, Abduction, and External rotation ( position of least amount of intracapsular pressure)
  • child usually doesn’t have toxic appearance
  • mild to moderate restriction of hip abduction= most senstive rom restriction
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7
Q

What is seen on xray in transient synovitis of the hip?

A
  • AP , Lateral and frog lateral
  • usually normal appearance
  • may show medial joint space widening
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8
Q

What do uss in transient synovitis of the hip show?

A
  • Accurate for detecting intracapsular fluid/effusion
  • may show synovial membrane thickening
  • difficult to distinguish transient synovitis from septic arthritis
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9
Q

Is MRI useful in transient synovitis of the hip?

A
  • Yes it can distinguish transient synovitis of the hip from septic arthritis
  • BUT a GA is required
  • so not first line investigation
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10
Q

What are the labs values seen in transient synovitis of the hip?

A
  • WBC maybe slightly elevated
  • CRP >20mg/l is the dtrongest independent risk factor for Septic arthritis
  • ESR is usually < 20mm/h
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11
Q

What are Kocher’s criteria?

A
  • Criteria for septic arthritis
  • 3 out of 4 =93% chance of SA
    • Fever >38.5oC
    • WBC >12,000mm3
    • NWB on affected limb
    • ESR >40mm/h
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12
Q

What are the most important factors to rule out Septic arthritis?

A
  • Pt WB on limb
  • CRP <20mg/L
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13
Q

What is the tx of transient synovitis of the hip?

A

Non operative

  • for pt afebrile last 24hrs, mild symptoms
  • improve ambulation
  • Kocher’s criteria <2
  • tx with IV/PO NSAIDS and Observe 24hrs
  • early wb with physio
    • if improve w nsaids likely to be TS
    • symtpoms resolve in <1 week

Surgery

  • Joint aspiration USS /II, then initation of IV antibiotics
    • high suspicion of SA
    • worsening hip pain
    • Kocher’s score> 2
  • Irrigation and debridement of hip
    • documented infection
    • kocher criteria 4/4
    • outcomes= tx is time sensitive
    • prolonged infection will affect cartilage survival
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14
Q

What are the complications of transient synovitis of the hip?

A
  • Legg- Calve - Perthes (1-3%)
  • Coxa Magna
  • Hip dysplasia
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15
Q

What is hip septic arthritis?

A
  • A surgical emergency that requires prompt recognition & tx
  • Peaks first few years of life
  • 50% cases occur in children < 2years
  • hip joint involved in 35% of all cases of SA
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16
Q

What are the risk factors of hip septic arthritis?

A
  • Prematurity
  • Cesarian section
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17
Q

What is the pathophysiology of hip septic arthritis?

A
  • Direct inoculation from trauma or surgery
  • Haematogenous seeding
  • Extension from adjacent bone
    • can develop from contiguous spread of osteomyelitis
    • often from metaphysis
      • common in neonates who have transphyseal vessela that allow spread into the joint
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18
Q

What joints in children have intra-articular metaphyses

what is the relevance of this?

A
  • Hip
  • shoulder
  • elbow
  • ankle
  • NOT THE KNEE
  • septic arthritis may occur secondary to direct intra-articualar spread from metaphyseal osteomyleitis
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19
Q

What is the mechanism of destruction in hip septic arthritis?

A
  • Release of proteolytic enzymes ( matrix metalloproteinases) from inflammatory and synovial cells, cartilage, & bacteria which may cause articular surface damage within 8 hours
  • increase joint pressure may cause femoral head osteonecrosis if not relieved promptly
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20
Q

Describe the organisms that affect

Neonates

Infants

Children

Adolescents

Adults

Iv drug abusers

A
  • _Neonates _
    • Streptococcus Sp
      • ​group A beta-haemolytic strep - most common post varicella infection
      • Group - B post community acq infection
    • Gram negative bacteria
  • _Infants _
    • Staphylococcus aureus
    • Haemophilius influenza
  • Children
    • Staphylococcus aureus
    • Salmonella
  • Adolescent
    • Staphylococcus aureus
    • Neissera Gonorrhoea
  • Adults
    • Staphylococcus aureus
    • Streptococcus
    • Gram negative organisma
  • IV drugs
    • Suspect Pseudomonas
    • atypical organisms
21
Q

What organism responsible for SA are isolated from blood culture media?

A

HACEK

  • Haemophilus
  • Actinobacillus
  • Cardiobacterium
  • Eiknella
  • KIngella
22
Q

What is the prognosis of hip Septic arthritis?

A
  • Usually good unless dx is delayed
  • poor prognsotic indicators
    • age < 6months
    • assoc osteomyelitis
    • hip joint ( verus knee)
    • delay > 4 days until presentation
23
Q

What are the signs and symptoms of hip Septic arthritis??

A

Symptoms

  • Presents more acutely than osteomyelitis
  • often assoc with fever
  • toxic shock appearance
  • children refused to walk / move hip

Signs

  • Localised swelling
  • effusion, warmth, tenderness
  • hip rests in ABDUCTION, FLEXION & EXT ROTATION
    • ​hip capsular vol is maximised in this position
  • ROM
    • severe pain with passive motion
    • unwillingness to move joint ( pseudoparalysis)
    • examine adjacent joints- to rule out other invovlement
24
Q

What is seen on imaging in a pt with hip Septic arthritis?

A

Xrays

  • Ap, lateral , frog lateral
    • normal
    • widening of joint space, subluxation/dislocation/ lateral displacement of femoral head

USS

  • Maybe helpful to identify effusion
  • can guide aspiration
25
Q

What perameters distinguish hip Septic arthritis from Transient synovitis?

A
  • Kocher’s criteria - 1st 4 , Caird added CRP
  • 90% chance of SA when 3 out of 4 present
  • WBC >12,000 cells/uL
  • Inability to WB
  • Fever >38.5oC
  • ESR >40mm/h
  • CRP >2.0 mgldl
26
Q

What criteria are the best predictors of SA?

A
  • Fever >38.5oC
  • ​CRP >2.0 mg/dl
  • then ESR/ refusal to WB, & serum WBC
  • from Caird ‘s level 1 evidence paper JBJS am 2006
27
Q

What will an aspirate from a Septic arthritis show?

A
  • WBC >500,000/mm3 with 75% PMN
  • glucose 50mg/dl less than serum levels
  • high lactic acid levels with infections due to gram positive cocci / gram negative rods
28
Q

What is the tx of hip Septic arthritis?

A

Non operative

  • Antibiotics alone
    • adolscent Neisseria gonorrhoea infection
    • large doses of penicllin alone
    • usually doesn’t require surgical debridement

Operative

  • emergency I&D
  • for most septic joints
  • emergency as chrondrolytic effect of pus
29
Q

Can you describe the surgical tx of I&D of hip Septic arthritis?

A
  • Medial approach to hip
  • anterolateral approach
  • Arthrotomy may to remove all pus & irrigate joint
  • Synovial culture and drain placement is recommended
  • follow w iv antibiotics targetting pathogens based on age & medical comorbidities
  • convert to po when clinical picture improves and sensitivities return
  • antibiotic therapy usually 3-4 weeks
  • terminate AB when CRP/ESR normal
30
Q

What are the complications of hip Septic arthritis?

A
  • Femoral head destruction
    • complete destruction of femoral head,neck easily visible on xray- see pic
    • salvage operations including varus/valgus proximal femoral osteotomies
  • Deformity
    • physeal damage -> late angular deformity & LLD
  • Joint destruction
  • Hip dislocation
  • Growth disturbance
  • Gait abnormalities
  • osteonecrosis
31
Q

What is epidemiology of osteomyelitis in children?

A
  • incidence 1 in 5000 children
  • 50% cases in pts < 5years
  • 2.5 x more common in boys
  • more common in 1st decade of life due to rich metaphyseal blood supply and immature immune system
  • not uncommon in healthy children
  • typically Metaphyseal via Haematogenous seeding
32
Q

What are the risk factors for osteomyelitis?

A
  • Diabetes mellitus
  • haemoglobinopathy
  • Rheumatoid arthritis
  • Chronic renal disease
  • Immune compromise
  • Varicella infection
33
Q

What is the pathophysiology of osteomyelitis?

A
  • Local trauma & bacteremia -> increased susceptibility to bacterial seeding
34
Q

What are the common organisms involved in osteomyelitis?

A
  • Staph aureus
    • most common organism in children
    • recent strains co comunity acquired MRSA ahev genes encoded for panton valentine leukocidin
    • PVL positive strains are assoc w more complex infections
    • MRSA assoc with increased risk of DVT/septoc emboli
  • Group B Strep
    • most common organism in Neonates
  • Kingella Kingae
    • More common in younger age group
  • Pseudomonas
    • Assoc w direct puncture wounds to the foot
  • H Influenza
    • less common w advent of haemophilus influenza vaccine
  • Mycobacteria tuberculosis
    • children > chance of extrapulmonary involvement
    • biopsy stains & culture for acid-fast bacilli is dx
  • Salmonella
    • more common in sickle cell pts
35
Q

What is the pathoanatomy of acute osteomyelitis?

A
  • Most Haematogenous
  • inital bacteremia may occur from a skin lesion, infection or even trauma from tooth brushing
  • Microsopically
    • sluggish blood flow in metaphyseal capillaries due to sharp turns=> venous sinusoids which gie bacteria time to lodge in this region
    • the low pH & low O2 tension around the growth plate assist in bacterial growth
    • infection occurs after the local bone defenses have been overwhelmed by bacteria
    • spread thru bone via Haversian & volkmann canal systems
    • purulence develops in conjunction with osteoblast necrosis, osetoclast activation adn release of inflammatory mediators & blood vessel thrombosis
  • Macroscopically
    • Subperiosteal abscess develops when the purulence breaks through the metaphyseal cortex
    • septic arthritis develops when the purulence breaks thru a_n intra-articular metaphyseal cortex_ ( hip,shoulder, elbow, ankle)
  • Infants <1 year can have infection spread across the growth plate via capilaries causing osteomyelitis in the epiphysis
36
Q

What is the pathoanatomy of chronic osteomyelitis?

A
  • Periosteal elevation deprives the underlying cortical bone of blood supply leading to necrotic bone ( sequestrum)
  • An outer layer of new bone is formed by the periosteum - Involucrum
  • chronic abscess may become surrounded by sclerotic bone & fibrous tissue -> Brodie’s abscess
37
Q

What is an involucrum?

A
  • A layer of new bone growth outside exisiting bone seen in osteomeylitis
38
Q

Define a sequestrum?

A
  • Necrotic bone which has become walled off from its blood supply & can present as a nidus for chronic osteomyelitis
39
Q

What is the classifcaiton of osteomyelitis?

A
  • Acute
  • Subacute
    • uncommon infection w bone pain and radiographic changes without systemic symptoms
  • Chronic
40
Q

What are the signs and symptoms of osteomyelitis?

A

Symtpoms

  • LImp or refusal to WB
  • Generally not toxic appearance
  • +/- Fever

Signs

  • Inspection/palpation
    • oedematous, warm, swollen, tender limb
    • evaluate for point tenderness in pelvis, spine or limbs
    • restriction in rom due to pain
41
Q

What is seen on radiographs with osteomyelitis?

A
  • Early films maybe normal or show loss of soft tissue planes & soft tissue oedema
  • new periosteal bone formation (5-7 days)
  • osteolysis (10-14 days)
  • Late fims 1-2 wks - metaphyseal rarefraction (reduction in metaphyseal bone density) or possible abscess
42
Q

What other imaging is helpful in osteomyelitis?

A

MRI

  • T1 signal Decreased
  • T1 with gadolinium signal Increased- see pic
  • T2 signal increased
  • 88%-100% sensitivity

​Bone scan

  • non diagnostic xray
  • localised pathology of infant/toddler with non focal exam
  • tech- 99m can localised the focus of infection & show multifocal infection
  • 92% sensitivity
  • cold bone scan- assoc w more aggressive infections

Bone aspiration

  • for definitive DX
  • 50%-85% affected pts have positive cultures

​

43
Q

What lab results will you see in osteomyelitis?

A
  • WBC
    • elevated in 25% pts
    • correlated poorly w tx response
  • CRP
    • elevated in 98% pts
    • elevated within 6 hours
    • most sensitive to monitor therapeutic repsonse
    • Declines rapidly with successful early tx
  • ESR
    • elevated in 90% pts
    • rises rapidly and peaks 3-5 days but declines too slowly to guide tx
  • Blood Culture
    • only positive in only 30-50% of time
  • Plasma Procalcitonin
    • new serological test rises rapidly with bacterial infections
    • elevated 58% pts with paediatrtic om
44
Q

Describe the tx of osteomyelitis?

A

Non operative

  • Aspiration
  • Antibiotic tx
    • early disease, no pus on aspiration, no abscess
    • surgery not indicated if clinical improvement in 48hrs
    • typicall y tx 4-6 wks iv
    • empiric therapy oxacillin
    • if gram stain gram neg bacteria- add third cephalosporin
    • when tx acute om obtain Biopsy ad culture - rule out tumour

​​Surgery

  • Surgical drainage, debridement and antibiotics
    • ​for deep or subperiosteal abscess
    • failure to respond to antibiotics
    • frank pus on aspiration
    • chronic infection
      • evaculate all purulence, debride devitalised tissue & drill as needed into intraosseous collections
      • remove sequestrum in chronic cases
      • send tissue for culturee and pathology
      • close wound over drains/packs adn redebride in 2-3 days
45
Q

What are the complications of osteomyelitis?

A
  • DVT
    • infrequent complication
      • risk factors
      • crp >6
      • surgical tx
      • age > 8 years
      • MRSA
  • Meningitis
  • Chronic Osteomyelitis
  • Septic Arthritis
  • Growth disturbance & LLD
  • Pathological fx
46
Q

What is the most common organism in this injury?

A
  • Pseudomonas aeruginosa
  • gram negative rod
  • most common organismm from a nail puncture thru a sneaker
  • different organisms more common in diabetic and immunocompromised pts
47
Q

What is the epidemiology of puncture wound infections?

A
  • following nail puncture thru shoe
  • soft tissue infection occurs in 10-15% cases
  • osteomyelitis develops in 1-2% of cases
48
Q

What is the tx of puncture wound infections?

A

Puncture without established infection

  • prophylatic antibiotics for a recent puncture wound with no clear evidence of infection is contraversial

Puncture wound w infection

  • Ceftazidime/ Cefepime antibiotic
    • esatblished infection
    • alternative ab ciprofloxacin in adults, imipenem, cilastin, 3rd gen cephalosporin
  • Surgical debridement
    • deep infection with osteomyelitis and not improving on ora antibiotics

Paediatrics FCRS (27 decks)

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