T&O - Bone Infections (osteomyelitis, Septic Arthritis And AVN)

Question 1

Acute osteomyelitis: sources and organisms

Answer 1

Can be local (from surgery) or haematogenous

Organisms:

• Staph aureus (main one)
• Strep
• E. coli
• Pseudomonas
• Salmonella - sickle cell

Question 2

Acute osteomyelitis: risk factors

Answer 2

• Vascular disease
• Trauma
• Immunosuppression
• Children (rich blood supply to growth plate)
• Systemic disease

Question 3

Acute osteomyelitis: signs and symptoms

Answer 3

• Pain
• Tenderness
• Erythema
• Wwarmth
• Decreased ROM
• Effusion in neighbouring joints
• Signs of systemic infection/coryzal symptoms

Question 4

Acute osteomyelitis: Ix

Answer 4

• Raised ESR/CRP/WCC
• Positive blood cultures in 60% of pts
• X-ray: haziness + decreased bone density, sub-periosteal reaction
• DIagnositic: MRI ( sensitive and specific)

Question 5

Acute osteomyelitis: Mx

Answer 5

• IV ABX Vanc+cefotaxime (check local trust guidelines!) - may take several weeks
• Drain abscess and remove sequestration
• Analgesia

Question 6

Septic arthritis: source, differential and organisms

Answer 6

Source: local or haematogenous

Differential:

• Crystal arthropathy
• Reactive arthritis

Organisms: staph (60%), streps, gonococcus, gram -ve bacilli

Question 7

Septic arthritis: risk factors

Answer 7

• Joint disease (RA)
• Chronic renal failure
• Immunosupression
• Prosthetic joints

Question 8

Septic Arthritis: Ix

Answer 8

• Joint aspiration for MCS
• Raised ESR/CRP, blood cultures
• X ray

Question 9

Septic arthritis: Mx and complications

Answer 9

• IV ABX
• Consider joint washout under GA
• Splint joint
• Physio after infection resolved

Complications: osteomyelitis, Arthritis, ankylosis (fusion)

Question 10

Avascular necrosis: pathophysiology

Answer 10

Disruption of blood supply either due to interruption of arterial inflow (fracture) or blockage of venous outflow (infiltrative disorders)

Question 11

Avascular necrosis: causes

Answer 11

• Fracture/dislocation
• Sickle cell disease: clumping of RBCs leads to diminished capillary flow - infarcted areas of bone become infected with unusual organisms such as salmonella
• Decompression sickness/Caisson disease/Bends
• Gaucher’s disease: rare familial disorder of lipid metabolism - blocks venous outflow
• Drug induced: esp corticosteroids -Idiopathic

Question 12

Septic arthritis: symptoms

Answer 12

• Acutely inflamed
• Tender
• Swollen joint
• Decreased ROM
• Systemically unwell