Bone and soft tissue infections Flashcards Preview

Yr 3 MSK > Bone and soft tissue infections > Flashcards

Flashcards in Bone and soft tissue infections Deck (46):
1

What is osteomyelitis?

Bone infection. Can be acute or chronic. Either specific (eg TB) or non-specific (most common)

2

In acute osteomyelitis when is it more common?

-Mostly in children
-Boys>girls
-Trauma history
-Other disease (DM, rheum arthritis, immunocompromised, steroid treatment, sickle cell)

3

What are the different sources of infection? What typically causes infection in infants, children and adults?

-Haematogenous spread - children and elderly
-Local spread from contiguous infection site: trauma (open #), bone surgery (ORIF), joint replacement
-Secondary to vascular insufficiency

In infants: infected umbilical cord
In children: boils, tonsilitis, skin abrasions
In adults: UTI, arterial line

4

In infants <1y what are the causative organisms of acute osteomyelitis?

-Staph aureus
-Group B Streptococci
-E. coli

5

In older children what are the causative organisms of acute osteomyelitis?

-Staph aureus
-Strep pyogenes
-Haemophilus influenzae

6

In adults what are the causatuve organisms of acute osteomyelitis?

-Staph aureus
-Coagulase -ve staph (prostheses)
-Mycobacterium tuberculosis
-Pseudomonas aeroginosa (esp secondary to penetrating foot injuries, IVDA)

7

Likely causative organism of acute osteomyelitis in

-Diabetic foot/pressure sores
-Sickle cell disease
-Fishermen
-HIV/AIDS patients

-Diabetic foot: mixed
-Sickle cell: salmonella spp
-Fishermen: Mycobacterium marinum
-HIV/AIDS: Candida

8

What long bones (metaphysis) are acute osteomyelitis likely to start?

-Distal femur
-Proximal tibia
-Proximal humerus

9

What joints with intra-articular metaphysis are acute osteomyelitis likely to start?

-Hip
-Elbow (radial head)

10

What is the pathology of acute osteomyelitis?

-Starts at metaphysis
-Vascular stasis (venous congestion+arterial thrombosis)
-Acute inflammation, suppuration, release of pressure
-Necrosis of bone (sequestrum)
-New bone formation (involcrum)
-Resolution (or not - chronic osteomyelitis)

11

Clinical features of acute osteomyelitis in infants?

-May be minimal/very ill
-Fail to thrive
-Drowsy or irritable
-Metaphyseal tenderness and swelling
-Dec. ROM
-Position change
-Commonest around knee

12

Clinical features of acute osteomyelitis in children?

-Severe pain
-Reluctant to move (neighbouring joints flexed), no weight bearing
-Tender fever (swinging pyrexia) and tachycardia
-Malaise (fatigue, nausea, vomiting)
-Toxaemia

13

Clinical features of acute osteomyelitis in adult?

-More common in thoracolumbar spine (primary OM)
-Backache
-UTI/urological procedure history
-Elderly, DM, immunocompromised
-Secondary OM more common (open #, surgery etc)

14

Diagnosing acute osteomyelitis?

-History and exam (pulse+temp)
-FBC and WBC
-ESR and CRP
-Blood culture
-U and Es

15

Diff diagnosis of acute OM?

-Acute septic arthritis
-Acute inflammatory arthritis
-Trauma
-Transient synovitis
-Rare (sickle cell, Gauchers, rheumatic fever, haemophilia)

16

What soft tissue infections are differential diagnoses of acute OM?

-Cellulitis (Gp A strep)
-Erysipelas (Gp A strep)
-Necrotising fasciitis (gp A strep, clostridia)
-Gas gangrene (clostridium perfringens)
-TSS (staph aureus)

17

Investigations for acute OM?

-X-ray
-USS
-Aspirate
Isotope bone scan
-Labelled white cell scan
-MRI

18

Look on slide 21 for radiograph changes

:p

19

How do you use microbiology to diagnose acute OM?

-Blood cultures
-Bone biopsy
-Tissue or swabs at debridement if any
-Sinus tract, superficial swabs (may be misleading)

20

Treatment for acute OM?

-Supportive (analgesia, rest, splintage)
-Antibiotics (IV/oral, 4-6wks, Fluclox/benzylpen while waiting)

21

Why do antibiotics fail in acute OM?

-Drug resistance
-Bacterial resistance (dormancy)
-Poor host defences
-Poor drug absorption
-Drug inactivation by host flora
-Poor tissue penetration

22

Indications for surgery on acute OM?

-Aspiration of pus
-Abscess drainage
-Debridement of dead/infected/contaminated tissue
-Refractory to non-operative Rx

23

Complications of acute OM?

-Septicaemia, death
-Metastatic infection
-Pathological #
-Septic arthritis
-Altered bone growth
-Chronic osteomyelitis

24

When may chronic OM occur?

-May follow acute OM
-De novo (following op/open #, immunosuppressed, DM, elderly, IVDA etc)
-Repeated breakdown of healed wounds

25

Organism in chronic OM?

-Usually same organisms each flare up
-Usually staph aureus, e. coli, strep pyogenes, Proteus

26

Pathology in chronic OM?

-Cavities, poss. sinuses
-Dead bone
-Involucrum
-Chronic inflammation on histology

27

Complications of chronic OM?

-Chronically discharging sinus and flare ups
-Ongoing metastatic infection
-Pathological #
-growth disturbance and deformities
-SCC

28

Treatment of chronic OM?

-Local/systemic antib (gentamicin cement, orally, IV)
-Surgically remove bone infection
-Soft tissue problems
-Correct deformities
-Amputation

29

Route of infection in acute septic arthritis?

-Haematogenous
-Erupting bone abscess
-Penetrating wound/intra-articular injury/arthroscopy (direct invasion)

30

Common organisms in acute septic arthritis?

-Staph aureus
-Haemo. influenzae
-Strep pyogenes
-E. coli

31

Pathology in acute septic arthritis?

-Acute synovitis with purulent joint effusion
-Articular cartilage attacked by bacterial toxin and cellular enzyme
-Destruction of articular cartilage

32

Sequelae of acute septic arthritis?

-Recovery or
-Partial loss of articular cartilage and subsequent OA or
-Fibrous or bony ankylosis

33

Picture of acute septic arthritis in infant?

Septicaemia picture
-Irritable
-Won't move
-Ill

34

Picture of acute septic arthritis in child/adult?

-Reluctant to move joint
-Inc temp, tenderness and pulse

35

Investigations of acute septic arthritis?

-FBC, WBC, ESR, CRP, blood culture
-X ray
-USS
-Aspirate

36

Commonest cause of acute septic arthritis?

Infected joint replacement (Staph aurerus most common)

37

Differential diagnosis of acute septic arthritis?

-Acute OM
-Trauma
-Irritable joint
-Haemophilia
-Rheumatic fever
-Gout
-Gauchers disease

38

Treatment of acute septic arthritis?

-Supportive measures
-Antibiotics 3-4w
-Surgical drainage and lavage

39

Classification of areas affected by TB?

-Extra-articular
-Intra-articular
-Vertebral body

40

Clinical features of TB in bone/joint?

-Malaise
-TB contact
-Pain (esp night), swelling, weight loss
-Low grade pyrexia
-Dec. ROM
-Ankylosis
-Deformity

41

TB pathology?

-Primary complex (lung or gut)
-Secondary spread
-Tuberculous granuloma
-Role of nutrition/other disease (eg HIV/AIDS)

42

Spinal symptoms of TB?

-Little pain
-Present with abscess or kyphosis

43

Diagnosing TB?

-History
-Involving single joint
-Thickening of synovium
-Muscle wasting
-Periarticular osteoporosis

44

Investigating TB?

-FBC, ESR
Mantoux test
-Sputum/urine culture
-Xray
-Aspirate and biopsy joint

45

Diff diagnosis of TB?

-Transient synovitis
-Monoarticular RA
-Haemorrhagic arthritis
-Pyogenic arthritis
-Tumour

46

Treatment of TB?

Chemo
-RIPE (remember from 2nd year)
-Rest
-Operative drainage if needed