MSK Flashcards
What does osteomyelitis denote?
inflammation of bone and marrow, virtually always secondary to infection.
How does osteomyelitis typically manifest?
a primary solitary focus of disease but can also be a complication of any systemic infection.
What types of organisms can cause osteomyelitis?
Osteomyelitis can be caused by viruses, parasites, fungi, and bacteria, but certain pyogenic bacteria and mycobacteria are the most common culprits.
What is the most common cause of pyogenic osteomyelitis?
yogenic osteomyelitis is almost always caused by bacterial infection.
How can organisms reach the bone in pyogenic osteomyelitis?
Organisms can reach the bone through hematogenous spread, extension from a contiguous site, or direct implantation (e.g., in traumatic injury).
In healthy children, how does osteomyelitis most commonly occur?
In otherwise healthy children, osteomyelitis is most often due to hematogenous spread and involves long bones.
What are common sources of the initiating bacteremia in children with osteomyelitis?
The initiating bacteremia in children may stem from trivial mucosal injuries, such as during defecation or vigorous chewing of hard foods, or from minor skin infections.
In adults, how does osteomyelitis typically occur?
In adults, osteomyelitis more often occurs as a complication of open fractures, surgical procedures, or infections of the feet in the setting of diabetes.
Why is osteomyelitis particularly worrisome in infants?
Osteomyelitis is worrisome in infants because epiphyseal infection can spread to a joint, causing septic arthritis, articular cartilage destruction, and permanent disability.
What is the most common organism responsible for pyogenic osteomyelitis?
Staphylococcus aureus is responsible for 80% to 90% of culture-positive pyogenic osteomyelitis.
How does Staphylococcus aureus contribute to osteomyelitis?
Staphylococcus aureus’ bacterial cell wall proteins bind to bone matrix components, such as collagen, which facilitates adherence to bone.
Which organisms are common causes of osteomyelitis in individuals with genitourinary infections or intravenous drug users?
Escherichia coli is common in individuals with genitourinary tract infections or intravenous drug users.
What organisms are commonly found in neonates with osteomyelitis?
Haemophilus influenzae and group B streptococci are common in neonates with osteomyelitis.
What disease predisposes to Salmonella infection, a cause of osteomyelitis?
Sickle cell disease predisposes to Salmonella infection, which can lead to osteomyelitis.
How often is no specific organism identified in osteomyelitis cases?
No specific organism is identified in nearly 50% of osteomyelitis cases.
: How does the location of bone infections vary with age?
In neonates, infections often involve the metaphysis, epiphysis, or both; in older children, the metaphysis is typically involved; in adults, the epiphyses and subchondral regions are more commonly affected.
: Why are metaphyseal vessels significant in osteomyelitis?
In neonates, metaphyseal vessels penetrate the growth plate, making the metaphysis, epiphysis, or both more vulnerable to infection.
How does the vascular circulation of bones influence osteomyelitis?
After growth plate closure in older children and adults, the merger of metaphyseal and epiphyseal vessels provides a route for bacterial spread, influencing the location of bone infections.
What is a common cause of mixed bacterial infections in osteomyelitis?
Mixed bacterial infections typically result from direct spread or inoculation during surgery or open fractures.
What role does bone matrix play in osteomyelitis caused by Staphylococcus aureus?
Bacterial cell wall proteins of Staphylococcus aureus bind to bone matrix components, such as collagen, facilitating adherence to the bone.
How does the vascular circulation in bones differ by age in relation to osteomyelitis?
The osseous vascular circulation varies with age, influencing the location of bone infections. In neonates, the infection often involves the metaphysis and epiphysis, while in older children and adults, different regions are typically involved.
What are the potential outcomes of osteomyelitis in infants if the infection spreads to joints?
If osteomyelitis spreads to joints in infants, it can lead to septic or suppurative arthritis, articular cartilage destruction, and permanent disability.
Which group of individuals is most at risk for osteomyelitis caused by Escherichia coli?
Individuals with genitourinary tract infections or intravenous drug users are at higher risk for osteomyelitis caused by Escherichia coli.
How do the growth plates in neonates contribute to osteomyelitis?
In neonates, metaphyseal vessels penetrate the growth plate, making the metaphysis, epiphysis, or both more susceptible to infection.
