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MSK > Bone Infection (Acute, Subacute and Chronic Osteomyelitis, Tuberculous Osteomyelitis) > Flashcards

Bone Infection (Acute, Subacute and Chronic Osteomyelitis, Tuberculous Osteomyelitis) Flashcards

1
Q

How can bone infections spread?

A

Can occur from metastatic haematogenous spread (carried in the blood), or from local infeciton. They can also occur 2o to vascular insufficiency.

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2
Q

What organisms most commonly affect infants (<1yr)?

A
  • Staph aureus
  • Group B streptococci
  • E. coli
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3
Q

What organisms commonly affect older children up to age of 4?

A
  • Staph aureus
  • Strep pyogenes
  • Haemophilus influenzae
  • Kingella kingae
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4
Q

What organisms commonly affect Adults?

A
  • Staph aureus
  • Coag negative staphylococci - prostheses
  • Propionibacterium spp - prostheses
  • Streptococcus pyogenes - infectious arthritis
  • Mycobacterium tuberculosis
  • Pseudomonas aeroginosa - esp. secondary to penetrating foot injuries, IVDAs
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5
Q

What is the pathogenesis of osteomyelitis?

A

The classical sequence of changes in osteomyelitis is as follows:

  1. Transient bacteraemia - e.g. Staphylococcus aureus
  2. Focus to metaphysis of long bone
  3. Acute inflammation - increased pressure within haversian canals in cortical bone and under periosteum ⇒ periosteum lifts off and interrupts blood supply to underlying bone
  4. SEQUESTRUM - Caused by necrosis of bone fragments
  5. INVOLCURM - New reactive bone formation created by the elevated periostium
  6. Outcome ⇒ resolution or chronic osteomyelitis
    • If untreated, sinuses form, draining pus to the skin surface via cloacae ⇒ Chronic Osteomyelitis
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6
Q

How do bone Abscesses form?

A
  • Acute inflammatory response ⇒ granulation tissue ‘walls off’ sequestrum
  • Bacterial proliferation in dead tissue ⇒ ­pressure & toxins
  • Adjacent healthy bone devascularised, further destruction
  • Fibrous membrane forms around abscess
  • Reactive bone forms ⇒ involucrum ⇒ Bacteria isolated from host defences!
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7
Q

What is the pathophysiology of Chronic osteomyelitis?

A
  • Cavities, poss. sinus(es)
  • Cloacae
  • Sequestrum + involcrum + sinus
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8
Q

What is the pathophysiology of Tuberculous Arthritis?

A
  • 2 phases
  1. Early short lived vascular
  2. Chronic avascular
  • Obliterative endarteritis - poor entry of antibiotics
  • Less plasminogen activation - less joint destruction
  • Primary complex (in the lung or the gut)
  • Secondary spread
  • Tuberculous granuloma
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9
Q

What are the clinical features of Acute Osteomyelitis in infants?

A

May be minimal signs, or may be very ill

  • FTT
  • Possibly drowsy or irritable
  • Metaphyseal tenderness + swelling
  • Decreased ROM

*Commonest around the knee

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10
Q

What are the clinical feautrues of Acute Osteomyelitis in children?

A

Vascular bone most affected - long bone metaphyses, esp. distal femur, upper tibia

  • Severe pain - May be tender and inlamed
  • Reluctant to move - neighbouring joints held flexed
  • Not weight bearing
  • Fever (swinging pyrexia) + tachycardia
  • Systemic features - Malaise fatigue, nausea, vomiting
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11
Q

What are the clinical features of Acute osteomyelitis in an adult?

A

Usually gradual/several days

  • Localized bone pain - gradual onset over the course of a few days
  • Localised findings
    • Overlying tenderness
    • Warmth
    • Erythema
    • Swelling
  • Systemic features - fever, malaise, chills
  • Slight effusion in neighbouring joints
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12
Q

What is the presentation of subacute osteomyelitis?

A
  • Long history
  • Variable symptoms - pain, limp
  • Local swelling/warmth, with Tenderness
  • Brodie’s abscess - well defined cavity in cancellous bone
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13
Q

What are the clinical features of Chronic Osteomyelitis?

A

usually following a prior episode of osteomyelitis; may last for months:

  • Recurrent Pain
  • Fever
  • Sequestra - small peice of dead bone separated from live bone
  • Sinus suppuration (pathognomic)
  • Swelling/redness
  • Risk factors - Diabetic ulcer, Vascular insufficiency
    • If bone can be felt on probing ulcer ⇒ CHRONIC OSTEOMYELITIS
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14
Q

What are the clincial featues of Tuberculous Osteomyelitis?

A
  • Insidious onset & general ill health
  • Pain - esp. at night
  • Swelling
  • Weight loss
  • Low grade pyrexia
  • Decreased ROM
  • Ankylosis
  • Deformity
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15
Q

What investigations would you do in the context of suspected osteomyelitis?

A

Clinical Diagnosis, plus

  • Bloods - FBC,ESR, CRP, Blood cultures
  • Imaging - X-Ray, USS, Isotope Bone Scan, Labelled white cell scan, ​MRI
  • Specific - Biopsy, Tissue swabs, Aspiration
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16
Q

What investigations would you perform if you suspected Tuberculous Osteomyelitis?

A

Clinical diagnosis

Bloods

  • FBC
  • ESR

Imaging

  • X-ray - Soft tissue swelling, periarticular osteopaenia, articular space narrowing

Other

  • Mantoux test
  • Sputum/urine culture
  • Joint aspiration and biopsy
17
Q

How would you treat someone with Acute osteomyelitis?

A

Supportive treatment – general care, analgesia

Rest & splintage

Antibiotics

  • Flucloxacillin +/- Rifampicin while waiting for cultures
  • IV Vancomycin if MRSA

Surgery

  • Aspiration of pus for diagnosis & culture
  • Abscess drainage
  • Debridement
18
Q

What are the complications of acute osteomyelitis?

A
  • Septicemia
  • Pathological fracture
  • Septic arthritis
  • Altered bone growth
  • Chronic osteomyelitis
19
Q

How would you manage someone with chronic osteomyelitis?

A
  • Long-term antibiotics
    • Local (gentamicin cement/beads, collatamp)
    • Systemic (orally/ IV/ home AB)
  • Surgery
    • Soft tissue injury
    • Deformity correction
    • Massive reconstruction
    • Amputation
20
Q

What are the complications of Chronic osteomyelitis?

A
  • Chronically discharging sinus + flare-ups
  • Ongoing (metastatic) infection (abscesses)
  • Pathological fracture
  • Epithelioma
  • Growth disturbance + deformities
  • Amyloidosis
  • Squamous cell carcinoma (0.07%)
21
Q

What is the treatment for Tuberculous Bone Infection?

A
  • 6 months
    • Rifampicin
    • Isoniazid
  • First 2 months
    • Ethambutol
    • Pyrazinamide
22
Q

What is the following?

A

Sinus caused by chronic osteomyelitis

23
Q

What are the characteristics of an infected joint on examination?

A

Hot, swollen, tender, erythematous joint with decreased ROM. MAy or may not have a fever

24
Q

How would you distinguish haemtogenously spread osteomyelitis from exogenous osteomyelitis in terms of number of pathogens?

A

Haematogenous - often one organism

Exogenous - often multiple organisms

25
Q

What is the differential diagnosis for someone who is presenting with symptoms of acute osteomyelitis?

A
  • Soft tissue infection - Cellulitis, Erysipelas, Necrotising fasciitis, Gas gangrene, Toxic shock syndrome
  • Acute septic arthritis
  • Trauma
  • Acute inflammatory arthritis
  • Transient synovitis (“irritable hip”)
  • Rare - sickle cell crisis, Gaucher’s disease, rheumatic fever, haemophilia
26
Q

What are examples of routes of infection which lead to exogenous osteomyelitis?

A
  • Post-traumatic
  • Spread from adjacent issues
27
Q

What are examples of local risk factors which increase the risk of developing osteomyelitis?

A
  • Poor tissue perfusion
  • Open fractures
  • Severe soft tissue injury
28
Q

What are examples of systemic risk factors which increase the risk of developing osteomyelitis?

A
  • Impaired immunocompetence (e.g., immunosuppression, HIV infection, neoplastic diseases)
  • Systemic diseases (e.g., diabetes mellitus, atherosclerosis)
  • IV drug use
29
Q

What initial work up would you want to do for someone with suspected osteomyelitis?

A
  • Bloods - FBC, ESR/CRP, BCs
  • Imaging - X-rays
30
Q

Why would you consider MRI for imaging if someone presented with features of osteomyelitis for < 2 weeks?

A

Early stages (< 2 weeks of symptoms onset): x-rays typically show no pathological findings

31
Q

What is involved in biopsy for confimation of osteomyelitis?

A

Bone biopsy: MRI/CT-guided needle or open biopsy + gram staining, culture, and histology

32
Q

What are indications for surgery in osteomyelitis?

A
  • Refractory to treatment
  • Abscess
  • Post-traumatic
  • Prosthetic involvement
  • Revascularisation

MSK (27 decks)

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