Infection Flashcards
transient synovitis septic arthritis acute/subacute/chronic osteomyelits puncture wound infections (48 cards)
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
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
3
Q
What is the pathoanatomy of transient synovitis of the hip?
A
- Non specific inflammation and hypertrophy of the synovial lining/membrane
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
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
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
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
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
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
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
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
12
Q
What are the most important factors to rule out Septic arthritis?
A
- Pt WB on limb
- CRP <20mg/L
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
14
Q
What are the complications of transient synovitis of the hip?
A
- Legg- Calve - Perthes (1-3%)
- Coxa Magna
- Hip dysplasia
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
16
Q
What are the risk factors of hip septic arthritis?
A
- Prematurity
- Cesarian section
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
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
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
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
-
Streptococcus Sp
- _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
What perameters distinguish hip Septic arthritis from Transient synovitis?
* 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
What criteria are the best predictors of SA?
* **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
What will an aspirate from a Septic arthritis show?
* **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
What is the tx of hip Septic arthritis?
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
Can you describe the surgical tx of I&D of hip Septic arthritis?
* 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
What are the complications of hip Septic arthritis?
* **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
What is epidemiology of osteomyelitis in children?
* **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
What are the risk factors for osteomyelitis?
* Diabetes mellitus
* haemoglobinopathy
* Rheumatoid arthritis
* Chronic renal disease
* Immune compromise
* Varicella infection
33
What is the pathophysiology of osteomyelitis?
* Local trauma & bacteremia -\> increased susceptibility to bacterial seeding
34
What are the common organisms involved in osteomyelitis?
* **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
What is the pathoanatomy of acute osteomyelitis?
* **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
What is the pathoanatomy of chronic osteomyelitis?
* 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
What is an involucrum?
* A layer of new bone growth outside exisiting bone seen in osteomeylitis
38
Define a sequestrum?
* Necrotic bone which has become walled off from its blood supply & can present as a nidus for chronic osteomyelitis
39
What is the classifcaiton of osteomyelitis?
* **Acute**
* **Subacute**
* uncommon infection w bone pain and radiographic changes without systemic symptoms
* **Chronic**
40
What are the signs and symptoms of osteomyelitis?
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
What is seen on radiographs with osteomyelitis?
* 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
What other imaging is helpful in osteomyelitis?
_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
What lab results will you see in osteomyelitis?
* _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
Describe the tx of osteomyelitis?
## Footnote
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
What are the complications of osteomyelitis?
* **DVT**
* infrequent complication
* risk factors
* crp \>6
* surgical tx
* age \> 8 years
* MRSA
* **Meningitis**
* **Chronic Osteomyelitis**
* **Septic Arthritis**
* **Growth disturbance & LLD**
* **Pathological fx**
46
What is the most common organism in this injury?
* 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
What is the epidemiology of puncture wound infections?
* following nail puncture thru shoe
* soft tissue infection occurs in 10-15% cases
* **osteomyelitis develops in 1-2%** of cases
48
What is the tx of puncture wound infections?
_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
