Bone and Joint Infections Flashcards
Define osteomyelitis
Infection of the bone and marrow
What generally causes osteomyelitis (generally speaking)?
An infection
List three ways an infection my seed the bone
Hematogenous spread- (less common- seen in children with growing bones)
Contiguous spread
Direct inoculation
Describe the pathophysiology of hematogenous osteomyelitis
Bacteremia –> deposition within sinusoidal veins and inflammatory response –> necrosis, abscess formation and sequestration of infarcted bone –> spread under pressure into subperiosteal space
What causes sinus formation in bone?
Pressure of dead bone forcing “tracts” through bone for it to escape
What is involucrum?
Formation of new bone following infection/death in osteomyelitis
What is the most common way bacteria is introduced into bone?
Contiguous infection
DM, ischemic ulcers, decubitus ulcers, trauma/surgery
Differentiate spread of infection in newborns/very young vs. older
In younger bones, infection tends to spread directly to the skin (and joint space, in newborns)
In older children, the infection is more contained
In what type of osteomyelitis might you not see an elevated white count?
Chronic infection
What serum markers may be indicative of a chronic infection?
Elevated ESR, CRP
Do gram positive or gram negative organisms most commonly cause osteomyelitis?
Gram positive
Which is the most common organisms that causes osteomyelitis?
Staphylococcus aureus
Which are the organisms most commonly associated with open fractures/surgery related osteomyelitis?
polymicrobial
Which organism causes sickle cell osteomyelitis?
Salmonella
Which are the organisms that cause osteomyelitis in neonates?
Hemophilus influenza B, Group B strep
Which are the organisms most often responsible for cause osteomyelitis following a shoe/puncture wound?
Pseudomonas
WHere does the ideal best culture come from when diagnosing osteomyelitis?
Directly from the bone
What is it called when TB infects the vertebral bones?
Pott’s disease
Do kids usually have acute or chronic osteomyelitis? Adults?
Acute- kids
Chronic- adults
Difficult to tell them apart clinically
What pathogens can cause septic arthritis? Which is an emergency?
Bacteria
Viral
Fungus
Bacterial septic arthritis is an emergency (can lead to joint destruction and loss of joint function)
Name a few risk factors for septic arthritis
Old age (>80) Joint surgery/replacement IVDU Endocarditis Immunosuppression Joint disease (RA, OA, Gout) Skin infection/ulcer
Is it easy for bacteria and inflammatory cells to enter a joint space?
Yes- the synovial fluid is leaky
What causes cartilage/bone necrosis in septic arthritis?
Pressure builds up in joint space/ inflammatory cytokines and proteases
How does septic arthritis present?
Acute painful presentation- within hours to day. Decreased ROM, swelling/warmth, elevated white count, accompanied by fever
Extremely painful
