Osteomyelitis

Question 1

What is osteomyelitis?

Answer 1

Infection of the bone.

Typically acute bacterial, but can become chronic if the infection does not fully resolve.

Question 2

What are the common causative organisms of osteomyelitis?

Answer 2

• S. aureus (most common)
• Streptococci
• Enterobacter spp
• H. Influenzae

Question 3

What are the three ways that infection can spread in osteomyelitis?

Answer 3

• Hematogenous spread (blood) - norm to metaphysis of bone
• Direct inoculation of micro-organism into the bone (following an open fracture)
• Direct spread from a nearby infection (adjacent septic arthritis)

Question 4

What bones are most commonly affected in osteomyelitis?

Answer 4

• Adults = vertebrae and great hallux
• Children = long bones such as the tibia and femur

Question 5

What is the basic process happening in osteomyelitis?

Answer 5

Infection of the bone often by hematogenous spread to metaphysics , leukocytes migrate to the area, engulf infectious organisms, release enzymes that lyse the bone, and pus spreads into the bone’s blood vessels impairing blood supply, infection more difficult to treat

Areas of devitalized infected bone known as sequestra form the basis of a chronic infection.

Question 6

What organism is most commonly seen in IVDU in osteomyelitis?

Answer 6

Staphylococcus aureus

Question 7

Who is most at risk of developing osteomyelitis?

Answer 7

• IVDU
• Diabetics (neuropathy and small vessel disease)
• Peripheral arterial disease
• Recent trauma - open bone fracture
  In dwelling devices such as Cather etc inc risk of heamatogenic spread
• Orthopaedic operations
• Immunosuppression
• Sickle cell disease

Question 8

What are some clinical features of acute osteomyelitis?

Answer 8

• Pain
• Warmth, erythema, and swelling of soft tissue surrounding the affected bone
• Tenderness in the area
• Systemic symptoms such as fever and malaise

Question 9

What are the features of chronic osteomyelitis?

Answer 9

• Local symptoms such as swelling, erythema, and pain
• Draining sinus tract may be seen
• Present as non-healing fractures

Question 10

What is the antibiotic choice for osteomyelitis?

Answer 10

• 1st line is flucloxacillin 6w - IV for first 2w
• May add rifampicin + fusidic acid
• If penicillin allergy -> consider clindamycin
• If MRSA -> consider teicoplanin or vancomycin
• If chronic - prolonged duration of 3m or more.

Question 11

How would you investigate osteomyelitis?

Answer 11

• Bedside: Obs, examination, wound swab
• Bloods: CRP, WCC, FBC, ESR, LFT, U&Es, bone profile, blood cultures
• Imaging: Bone density scan, X-ray
• Other: Biopsy

Question 12

What is the gold standard investigation for osteomyelitis?

Answer 12

Bone biopsy with histopathological examination and tissue culture.

Question 13

What is the typical management for osteomyelitis?

Answer 13

• Medical = long term IV antibiotics (4-6w) tailored to culture results
• Surgical = if clinically deteriorates, remove necrotic bone and debridement of infected surrounding tissue.

Question 14

What might osteomyelitis look like on an x-ray?

Answer 14

• May be negative - typically normal for the first 2 weeks of infection
• Periosteal reaction
• Localized osteopenia
• Destruction to some areas of the bone.

Question 15

What is the relevant epidemiology of osteomyelitis?

Answer 15

Less common than bone mets and cellulitis; peak incidence 60-70 years; 20 cases per 100,000 person years.