Flashcards in Bone and Joint Infections Deck (40)
Infection of the bone
3 mechanisms of how bone infection may be brought about
Haematogenous- bacteria in the blood seed bone
Contiguous focus-spread from adjacent area of infection
Direct incoculation-trauma or surgery
Stage 1 of osteomyelitis and likely cause
Medullary-necrosis of medullary contents- haematogenous
Stage 2 of osteomyelitis
Superficial-necrosis limited to exposed surfaces
Cause of stage 2 superficial osteomyelitis
Contiguous- Diabetic foot ulcer, pressure sores
Complications of stage 3
Necrosis- no blood supply- can't treat with antibiotics. Surgery required to cure
Stage 3 osteomyelitis
Localised- full thickness cortical sequestation, stable before and after debridement
Stage 4 osteomyelitis
Diffuse- extensive, unstable bone
describe the pain with osteomyelitis
localised pain, not relieved with resting and progressive
Clinical presentation of osteomyelitis
Soft tissue swelling
Reduced movement of affected limb
Systemic upset uncommon (fever, chills, night sweats)
Most common causative organism of osteomyelitis (60%)
6 main causative organisms of osteomyelitis
Gram -ve bacilli
Gold standard diagnostic procedure for osteomyelitis
Cultures and histology of bone biopsy/needle aspirate
Name 4 diagnostic tests for osteomyelitis
When would you give empirical antimicrobial therapy in osteomyelitis?
When signs of sepsis
Which 5 antibiotics have acceptable penetrance in bone?
What is the treatment of choice for Staph A. osteomyelitis
How are antibiotics usually administered in osteomyelitis?
Inflammatory reaction in joint space (arthritis) caused by infection, resulting from direct invasion of the joint
2 classifications of septic arthritis
Native (natural) joint infection
Prosthetic (artificial) joint infection
2 ways in which organisms enter the joint in native joint infection
Haematogenous or trauma
How does synovial tissue facilitate 'seeding'?
Highly vascular and lacks a basement membrane
Predisposing factors for native joint infection
Prognosis for native joint infection
Not fatal but severe lack of function if not treated
How do organisms enter the joint in prosthetic joint infections?
During surgery or following wound infection after surgery
Why are prosthetic joints susceptible to infection?
Cement provides a surface for bacterial attachment
How does infection affect the joint in prosthetic infection?
Polymorph infiltration results in tissue damage instability of the prosthesis
How does infection affect the joint in native infection?
Cartilage erosion causes joint space narrowing/impaired function
Predisposing factors to prosthetic joint infection
Prior surgery at site
Poor nutritional status