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

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, warmth, 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
• 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 and symptoms

Answer 7

• Risk factors: joint disease (RA), chronic renal failure, immunosupression, prosthetic joints
• Symptoms: acutely inflamed, tender, swollen joint, decreased ROM, systemically unwell

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