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Year 3 - MSK > Bone and Soft Tissue Infection > Flashcards

Bone and Soft Tissue Infection Flashcards

1
Q

what is Osteomyelitis?

A

Infection in bone

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2
Q

what are the different types of Osteomyelitis?

A

acute

chronic

specific (e.g. TB)

non-specific (most common)

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3
Q

who gets Acute Osteomyelitis?

A
  • mostly children (different ages)
  • boys > girls
  • history of trauma (minor)
  • Adults - other disease: diabetes, rheum arthritis, immune compromise, long-term steroid treatment, sickle cell
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4
Q

what is often the source of infection in Acute Osteomyelitis?

A
  • haematogenous spread – children and elderly
  • local spread from contiguous site of infection – trauma (open fracture), bone surgery (ORIF), joint replacement
  • secondary to vascular insufficiency
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5
Q

what is the most common source of infection in Acute Osteomyelitis?

A

haematogenous spread

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6
Q

what are exampels of source of infection in an infant

A

infected umbilical cord

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7
Q

what are exampels of source of infection in children?

A

boils, tonsilitis, skin abrasions

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8
Q

what are exampels of source of infection in adults?

A

UTI, arterial line

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9
Q

what organisms are responsible for Acute Osteomyelitis in infants <1 year

A

Staph aureus, Group B streptococci, E. coli

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10
Q

what organisms are responsible for Acute Osteomyelitis in older children

A

Staph aureus, Strep pyogenes, Haemophilus influenzae (immunisation significantly reduced)

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11
Q

what organisms are responsible for Acute Osteomyelitis in adults?

A

• Staph aureus

−coagulase negative staphylococci (prostheses), Propionibacterium spp (prostheses)

− Mycobacterium tuberculosis

− Pseudomonas aeroginosa (esp. secondary to penetrating foot injuries, IVDAs)

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12
Q

What are examples of organisms responsible for Acute Osteomyelitis in special cases?

A
  • Diabetic foot and Pressure sores - mixed infection including anaerobes
  • Vertebral osteomyelitis – S. aureus, TB
  • Sickle cell disease – Salmonella spp
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13
Q

What are examples of other organisms responsible for Acute Osteomyelitis?

A
  • Brucella (butchers)
  • Mycobacterium marinum (fishermen, filleters)
  • Proteus mirabilis
  • Candida (debilitating illness, HIV AIDS) (long-term antibiotic treatment, extensive GI surgery, malignancy)
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14
Q

pathology - where does Acute Osteomyelitis occur?

A

• long bones – metaphysis:

  • distal femur
  • proximal tibia
  • proximal humerus

•j oints with intra-articular metaphysis:

  • hip
  • elbow (radial head)
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15
Q

what is the pathology of actue oesteomyelitis?

A

starts at metaphysis – role of trauma?

vascular stasis (venous congestion + arterial thrombosis)

acute inflammation – increased pressure

suppuration

release of pressure (medulla, sub-periosteal, into joint)

necrosis of bone (sequestrum)

new bone formation (involucrum)

resolution - or not (chronic osteomyelitis)

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16
Q

what are the clinical features of osteomyelitis in infants?

A

may be minimal signs, or may be very ill

failure to thrive

poss. drowsy or irritable

metaphyseal tenderness + swelling

decrease range of motion

positional change

commonest around the knee

Often multiple sites

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17
Q

what are the clinical features of osteomyelitis in a child?

A

severe pain

reluctant to move (neighbouring joints held flexed); not weight bearing, may be tender

fever (swinging pyrexia) + tachycardia

malaise (fatigue, nausea, vomiting – “nae weel” - fretful

toxaemia

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18
Q

what are the clinical features of osteomyelitis in a adult?

A

Primary OM seen commonly in thoracolumbar spine

backache

history of UTI or urological procedure

elderly, diabetic, immunocompromised

  • Secondary OM much more common
  • often after open fracture, surgery (esp. ORIF)
  • mixture of organisms
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19
Q

how is the diagnosis of acute osteomyelitis made?

A

history and clinical examination (pulse + temp.)

FBC + diff WBC (neutrophil leucocytosis)

ESR, CRP (both should be elevated)

blood cultures x3 (at peak of temperature - 60% +ve)

U&Es - ill, dehydrated

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20
Q

what imaging techniques may be used in the diagnosis of osteomyelitis?

A

X-ray (normal in the first 10-14 days)

ultrasound

aspiration

Isotope Bone Scan (Tc-99, Gallium-67)

labelled white cell scan (Indium-111)

MRI

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21
Q

how may radiographs appear in acute osteomyelitis?

A

early radiographs minimal changes

10-20 days early periosteal changes

medullary changes - lytic areas

late osteonecrosis - sequestrum

late periosteal new bone - involucrum

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22
Q

what scans may be used in Acute Osteomyelitis?

A

Technetium-99m labelled diphosphonate

Gallium 67 citrate delayed imaging

Indium-111 labelled WBC scan

MRI

Technetium scan- early and late phases

Growth plates light up as active but on the left leg it is abnormally active

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23
Q

what are some differential diagnosis for Acute Osteomyelitis?

A

lacute septic arthritis

acute inflammatory arthritis

trauma (fracture, dislocation, etc.)

transient synovitis (“irritable hip”)

rare:

  • sickle cell crisis
  • Gaucher’s disease
  • rheumatic fever
  • haemophilia
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24
Q

what are some soft tissue infections that may be a differential diagnosis for acute ostemoyelitis?

A

cellulitis - (deep) infection of subcutaneous tissues (Gp A Strep)

erysipelas - superficial infection with red, raised plaque (Gp A Strep)

necrotising fasciitis - aggressive fascial infection (Gp A Strep, Clostridia)

gas gangrene - grossly contaminated trauma (Clostridium perfringens)

toxic shock syndrome - secondary wound colonisation (Staph aureus)

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25
Q

How is a Microbiological diagnosis of Acute Osteomyelitis done?

A
  • blood cultures in haematogenous osteomyelitis and septic arthritis
  • bone biopsy
  • tissue or swabs from up to 5 sites around implant at debridement in prosthetic infections
  • sinus tract and superficial swab results may be misleading (skin contaminants)
26
Q

what is the treatment of osteomyelitis?

A

supportive treatment for pain and dehydration – general care, analgesia

rest & splintage

antibiotics:

  • route (IV/oral switch – 7-10 days?)
  • duration (4-6 wks – depends on response, ESR)
  • choice - empirical (Fluclox + BenzylPen) while waiting
27
Q

when giving antibiotics to treat osteomyelitis, what needs to be thought about?

A
  • spectrum of activity
  • penetration to bone
  • safety for long term administration
28
Q

when treating acute osteomyelitis with antibitcs, why may they fail?

A
  • drug resistance – e.g. b lactamases
  • bacterial persistence - ‘dormant’ bacteria in dead bone
  • poor host defences - IDDM, alcoholism…
  • poor drug absorption
  • drug inactivation by host flora
  • poor tissue penetration
  • MRSA, etc.!!
29
Q

how is surgery used to treat acute osetomyelitis and what are indications ofr surgery?

A

indications:

  • aspiration of pus for diagnosis & culture
  • abscess drainage (multiple drill-holes, primary closure to avoid sinus)
  • debridement of dead/infected/contaminated tissue
  • refractory to non-operative Rx >24..48 hrs

timing, drainage, lavage

infected joint replacements - one stage revision/two stage revision/antibiotics only?

30
Q

if pus is present why remove it

A

as antibiotics cant reacha pus filled cavity

31
Q

whata re some complications of Acute Osteomyelitis?

A

septicemia, death

metastatic infection

pathological fracture

septic arthritis

altered bone growth

chronic osteomyelitis

32
Q

how may Chronic Osteomyelitis develop?

A

may follow acute osteomyelitis (now much rarer in children)

may start de novo - following operation, following open # (poss. many years earlier), immunosuppressed, diabetics, elderly, drug abusers, etc.

repeated breakdown of “healed” wounds

33
Q

what organism is usually resopnsible for Chronic Osteomyelitis?

A

often mixed infection

usually same organism(s) each flare-up

mostly Staph. Aureus, E. Coli, Strep. pyogenes, Proteus

34
Q

what is the pathology of Chronic Osteomyelitis?

A

cavities, poss. sinus(es)

dead bone (retained sequestra)

involucrum

histological picture is one of chronic inflammation

35
Q

what is the treatment of chronic osteomyelitis?

A
  • long-term antibiotics? - local (gentamicin cement/beads, collatamp), systemic (orally/ IV/ home AB)
  • eradicate bone infection - surgically (multiple operations)
  • treat soft tissue problems
  • deformity correction?
  • massive reconstruction?
  • amputation? (how many operations/years later?)
36
Q

what are some complications of chronic osteomyelitis?

A
  • chronically discharging sinus + flare-ups
  • ongoing (metastatic) infection (abscesses)
  • pathological fracture (infected bones are weaker)
  • growth disturbance + deformities - Acute and chronic infection near a growth plate can cause growth disturbance and can cause significant deformities
  • squamous cell carcinoma (0.07%)
37
Q

“Chronic osteomyelitis is a time bomb which ticks for the patient’s lifetime.”

A

Once its established it never goes away

You can supress it but tends to reoccur

Discharging sinus

38
Q

Acute Septic Arthritis

A
39
Q

what is the route of infection in Acute Septic Arthritis?

A

haematogenous (most common)

eruption of bone abscess

direct invasion - penetrating wound (iatrogenic? – joint injection), intra-articular injury, arthroscopy (a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the joint through a small incision)

40
Q

metaphyseal septic focus

it can lead to what 2 things?

A

either septic arthritis

or osteomyelitis

41
Q

what organisms are responsible for causing acute septic arthritis?

A

Staphylococus aureus (most common)

Haemophilus influenzae

Streptococcus pyogenes

E. coli

42
Q

what is the pathology of Acute Septic Arthritis?

A

acute synovitis (synovial membrane becomes inflamed) with purulent joint effusion

articular cartilage attacked by bacterial toxin and cellular enzyme

complete destruction of the articular cartilage

43
Q

what may the result of Acute Septic Arthritis be?

A

complete recovery

or

partial loss of the articular cartilage and subsequent OA (osteoarthritis)

or

fibrous or bony ankylosis (abnormal stiffening and immobility of a joint due to fusion of the bones)

44
Q

how would Acute Septic Arthritis present in a Neonate?

A

Picture of septicaemia

irritability

resistant to movement

ill

45
Q

how does Acute Septic Arthritis present in a Child/Adult?

A

Acute pain in single large joint

reluctant to move the joint (any movement – c.f. bursitis where RoM OK)

increase temp. and pulse

increase tenderness

Swelling – seen in superficial joint

NOT erythema – unless superficial and later

46
Q

how does Acute Septic Arthritis present in a Adult?

A

often involves superficial joint (knee, ankle, wrist)

rare in healthy adult

May be delayed diagnosis

Anyone with a temperature and joint that is sore to move

47
Q

what investigations would you do for Acute Septic Arthritis present in a Adult?

A

FBC, WBC, ESR, CRP, blood cultures

X ray

ultrasound

Aspiration - Aspirate joint and culture the aspirate

MRI

48
Q

Acute Septic Arthritis may occur in an Adult during Infected Joint Replacement, how?

A

now most common cause of septic arthritis in adult

rare (1-1.5%) but very significant:

  • Death
  • Amputation
  • removal of arthroplasty
  • Recurrent operation

changing picture of organisms, but Staph epidermidis/aureus still most common

49
Q

what is the differential diagnosis of Acute Septic Arthritis?

A

acute osteomyelitis

trauma

irritable joint

haemophilia

rheumatic fever

gout

Gaucher’s disease

50
Q

what is the treatment of acute septic arthiritis?

A

general supportive measures

antibiotics (3-4 weeks)

surgical drainage & lavage - emergency (“never let the sun set on pus” ); open or arthroscopic lavage;

linfected joint replacements - one stage revision, two stage revision, antibiotics only?

51
Q

Tuberculosis Bone and Joint is often called the great mimic, why?

A

Mimics other conditions, e.g. bone cancer

Rare in UK

52
Q

what are the different classifications of Tuberculosis Bone and Joint?

A

Classification:

  • extra-articular (epiphyseal / bones with haemodynamic marrow)
  • intra-articular (large joints)
  • vertebral body
53
Q

Can multiple lesions be seen in patiants with TB in bones and joints?

A

multiple lesions in 1/3 of patient

54
Q

what are the lcinical features of TB in bones or joints?

A

insidious onset & general ill health

contact with TB

pain (esp. at night) (may confuse it with bone cancer), swelling, loss of weight

low grade pyrexia

joint swelling (may be seen depending on site)

decrease ROM (range of motion)

ankylosis (Join will fail to move and stick together eventually)

deformity

55
Q

what is the pathology of TB?

A

primary complex (in the lung or the gut)

secondary spread

tuberculous granuloma (at the site)

n.b. role of nutrition/other disease (e.g. HIV AIDS) - associated with other conditions

56
Q

how does spinal TB present?

A

little pain

present with abscess or kyphosis

Spinal TB is the commonest

(Collapse of vertebral bodies at the top and bony destruction)

57
Q

what should be done and looked for when making a diagnosis of TB?

A

long history

involvement of single joint

marked thickening of the synovium

marked muscle wasting

periarticular osteoporosis

Bone around the joint is effected and becomes extremely osteoporotic and osteopenic (lose bone mass and your bones get weaker)

58
Q

what investigations can be done for TB?

A

FBC , ESR

Mantoux test

Sputum/urine culture

Xray - soft tissue swelling, periarticular osteopaenia, articular space narrowing

Joint aspiration and biopsy - AAFB identified in 10-20%, culture +ve in 50% of cases

59
Q

what are some differential diagnosis of TB?

A

transient synovitis

monoarticular RA

haemorrhagic arthritis

pyogenic arthritis

Tumour

60
Q

what is the treamtent of TB (it is constantly changing)?

A

chemotherapy

initial - rifampicin, isoniazid 8 weeks, ethambutol

then - rifampicin and isoniazid 6-12 month

rest and splintage

operative drainage/fusion of spine or affected joint rarely necessary

Year 3 - MSK (45 decks)

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