Osteomyelitis (5) Flashcards
What are the common organisms causing osteomyelitis?
- S. aureus,
- Enterobacter species
- and group A and B Streptococcus species
- H. influenzae (above the age of 4)
- Sickle Cell Anemia Patients: S. aureus is typically most common, but Salmonella species is pathognomonic
What is osteomyelitis?
Osteomyelitis is an infection in the bone and bone marrow.
How can osteomyelitis be classified?
- Osteomyelitis can be classified based on patient age, causative organism, pathogenesis, anatomic location, or duration of symptoms.
- The most commonly used classification system for adult osteomyelitis is the Cierny–Mader staging system.
What are the causes of osteomyelitis?
Risk factors?
- Hematogenous
- Bloodborne organisms of sepsis (often positive blood cultures before antibiotics given)
- Direct inoculation of microorganisms into the bone
- Acute osteomyelitis from open fracture or bone exposed at surgery
- Direct spread from nearby 8nfection
- osteomyelitis from neglected wounds: diabetic feet, decubitus ulcers
Risk factors are immunocompromise:
- Pediatric—immature immune system
- diabetes
- Dialysis patient—rib and spine osteomyelitis
- IV drug abuser—medial or lateral clavicle osteomyelitis
- Long term steroid use
What is the pathogenesis of osteomyelitis?
- Invasions and Inflammation
- Suppuration
- Necrosis (sequestration)
- New bone formation
- Resolution
What is subacute osteomyelitis?
Uncommon osseous infection with bone pain and radiographer changes without systemic symptoms. Usually over 2 week duration.
Residual of acute osteomyelitis versus hematogenous seeding of growth plate trauma
What are the stages of the Cierny-Mader staging system?
- Anatomic Location
- Stage I Medullary osteomyelitis
- Stage 2 Superficial osteomyelitis
- Stage 3 Localized osteomyelitis
- Stage 4 Diffuse osteomyelitis
- Host Type
- Type A Normal host (healthy)
- Type B Compromised locally (e.g chronic lymphoedema, vessel disease etc.) Or systematically (e.g malnutrition, immune disease etc)
- Type C Treatment is worse to patient than infection. Not surgical candidate
What is an abscess?
It is a localized painful collection of pus in tissues, organs, or confined spaces usually because of an infection by a pyogenic organism. It is surrounded by granulation tissue called pyogenic membrane, however it is not a true membrane and is not itself pyogenic.
What is pus?
It is a thick, yellowish liquid that is formed as part of an inflammatory response typically associated with an infection and is composed of exudate chiefly containing dead white blood cells (as neutrophils), tissue debris, and pathogenic microorganisms (as bacteria).
What is the pathogenesis of pus formation?
It involves microbial invasions, acute inflammation with vascular congestion and exudation of fluids with infiltration of PMN cells.
What is the fate of an abscess?
It can resolve, rupture, spread (sepsis), or form into a chronic abscess.
What is a sequestrum?
It is a dead bone that has become separated during the process of necrosis from normal or sound bone. It is a complication (sequela) of osteomyelitis.
What is involucrum?
It is a reactive woven or lamellar bone deposition forming a shell of living tissue around a sequestrum. It can also be a thick sheath of periosteal new bone surrounding a sequestrum.
Why may pus burst through the bone?
It may burst through the bone due to increased intraosseous pressure caused by increased osmolarity which occurs due to tissue breakdown or due to the formation of a large rounded cloacal opening in the involucrum. So, pus will escape through the involucrum and the surrounding soft tissue to the skin surface within a sinus tract.
Why should the fixing plate be removed?
- Septic focus
- Formation of biofilm that is less sensitive to antibiotics
- Implant might become loose.
Compare the crystals in Gout and pseudogout?
