MSK L10 Bone and Joint Infections

Question 1

Endodontic and periapical dental abscessess:

Answer 1

1. Oral anaerobic bacteria usually predominate, multiple species the norm.
2. Streptococus intermedies [milleri] often present.
3. Bacteria usually antibiotic sensitive, but drain abscess if possible

Question 2

Causes of chronic monoarticular arthritis:

Answer 2

1. Mycobacterium tuberculosis
2. Other mycobacteria (M. Kansasii, M. marinum, M. intracellulare, M. fortuitum, M. leprae)
3. Brucella species
4. Nocardia asteroids
5. Fungi (Sporothrix schencki, coccidioides immitis, Blastomyces dermatitidis, Candida albicans, Pseudoallesscheria boydii).

Question 3

Spinal tuberculosis → Pott disease/tuberculous spondylitis

Answer 3

1. Advanced case → Gibbus deformity
2. Paravertebral swelling and destruction of intervertebral disc
3. Fusion of vertebrae

Question 4

Arthritic symptoms after infection at distant site

Answer 4

1. Gastroenteritis (salmonella, shigella, Yersinia and Campylobacter)
2. Sexually acquired infections (Chlamydia, Ureoplasma, Gonorrhoea)
3. Sore throat (streptococcus pyogenes)
4. Viral infections (influenza, parovirus, hepatitis B and C)

Question 5

Reactive arthritis (reiter’s disease) Often associated with

Answer 5

Conjunctivitis and/or urethritis

Question 6

Reactive arthritis (reiter’s disease) Associated with

Answer 6

HLA-B27

Question 7

Osteomyelitis (OM): definition →

Answer 7

An inflammatory process accompanied by bone destruction caused by an infecting micro-organism.

Question 8

Osteomyelitis (OM): definition → Can involve

Answer 8

Can involve one or several of cortex, marrow, periosteum and adjacent soft tissue.

Question 9

Osteomyelitis (OM): definition → Spread to

Answer 9

Soft tissue and joints, generalized infection or sepsis

Question 10

Waldvogel osteomyelitis classification:

Answer 10

Acute and chronic osteomyelitis resulting from:

1. Contiguous spread from contaminated source following trauma, surgery, joint replacement, wound infection.
2. Vascular insufficiency with infected soft tissue wounds (esp. diabetic feet).

Question 11

Factors increasing susceptibility: (and response to treatment) Systemic

Answer 11

1. Malnutrition
2. Renal or liver failure
3. Diabetes melitis
4. Immune defiency
5. Chronic hypoxia
6. Malignancy
7. Extremes of age

Question 12

Factors increasing susceptibility: (and response to treatment) Local

Answer 12

1. Chronic lymphedaema
2. Venous stasis
3. Blood vessel compromise
4. Arthritis
5. Extensive scarring
6. Radiation fibrosis
7. Loss of local sensation
8. Tobacco abuse

Question 13

Haematogenous osteomyelitis (Childhood)

Haematogenous osteomyelitis (Adults):

Sickle cell disease
Intravenous drug abusers
Vascular insuffiency
Post traumatic osteomyelitis
Chronic Osteomyelitis

Answer 13

1. Acute haematogenous OM mainly a disease of childhood.
2. Growing pains of long bones esp. femur and tibia particularly susceptible.
3. Children

Question 14

Haematogenous osteomyelitis (Adults):

Answer 14

1. Unusual in adults
2. Vertebrae most common site once long bones stop growing
3. Aetiology:
   a. Staph aureus
   b. Strept spp.
   c. Gram Neg bacilli
   d. Mycobacterium tuberculosis

Question 15

Sickle cell disease

Answer 15

Gram negative rods, esp. salmonella enterica and Proteus mirabilis
Staphylococcus aureus
Staph pneumoniae

Question 16

Intravenous drug abusers

Answer 16

Gram negative bacilli inc. Pseudo auruginosa
Staph aureus
Coagulase –ve staphylococci
Staph aureus
Candida

Question 17

Vascular insuffiency

Answer 17

Aetiology reflects soft tissue origins:

1. Staph aureus
2. Streptococcis spp.
3. Enterococcus spp.
4. Gram negative bacilli
5. Anaerobes

Question 18

Post traumatic osteomyelitis

Answer 18

Aetiology consistent with wound infections:

1. Staphylococcus aureus
2. Polymicrobial (mixed)
3. Gram negative bacilli
4. Anaerobes

Question 19

Chronic Osteomyelitis

Answer 19

Usually untreated acute osteomyelitis:

1. Sinus tracts and extension to adjacent soft tissue may develop
2. Fragmentation of dead bone → sequestra (devitalised segments)
3. Fibroblast proliferation and new bone development may envelope affected area → involucrum
4. Dense fibrous capsule surrounding localised infection (pus) = brodie’s abscess

Question 20

Diagnosis of bone and joint infection: Symptomatic

Answer 20

1. Systemic toxaemia (fever)
2. Local inflammation
3. Loss of function (load bearing)

Question 21

Diagnosis of bone and joint infection: Investigations

Answer 21

1. Blood cultures
2. Culture of aspirated joint fluid/pus or bone biopsy (sinus cultures dubious)
3. Radiological examiantionL x-rays, isotopic bone and MRI scanning

Question 22

Diagnosis of bone and joint infection: Other laboratory tests

Answer 22

• Septic arthritis → ESR, CRP and white cell count are elevated, but may be elevated in non-septic arthritis also
• Acute OM → ESR, CRP and white cell count are elevated but WCC rarely >15,000/mm3
• Chronic Om → ESR, CRP modestly elevated

Question 23

Antibiotics with anti-staphylococcal properties and good penetrative properties e.g.

Answer 23

1. flucloxacillin and other beta-lactams
2. Clindamycin/erythromycin
3. Fluoroquinolones e.g. ciprofloxacin
4. Rifampicin may be added for anti-biofilm activity

Question 24

2009 UHB policy (empirical iv therapy)

Answer 24

1. Benzylpenicillin = Flucloxacillin + gentamicin
   Or
2. teicoplanin + Gentamicin (if pen allergic or MRSA suscepted)

Question 25

Treatment of Bone and Joint infection:

Answer 25

Antibiotics with anti-staphylococcal properties and good penetrative properties e.g.
2009 UHB policy (empirical iv therapy)
Effective drainage of purulent synovial fluid
Surgery necessary to remove necrotic bone in OM if not treated early or response to antibiotics is poor (chronic OM)
Immobilization