Q: Septic Arthritis most commonly occurs via? (select one)
A) hematogenous seeding
B) direct inoculation
C) extension of infection
The cause of hematogenous seeding for septic arthritis is most common particularly if bacteremia occurs with Staphylococcus aureus which has a high propensity to adhere to the synovial tissues. The synovial membrane does not carry any limiting basement membrane and thus has a very high risk to acquire infection. This piece of knowledge becomes extremely important in patients with blood cultures positive for Staphylococcus aureus, though other organisms can also cause septic arthritis. Clinical exam in such instances is essential.
Direct inoculation via bites, trauma, post-surgery, procedures like arthroscopy, and unsterile intra-articular injection is also common.
Extension of infections from osteomyelitis or diverticulitis may occur due to the dissection of infection into the adjacent joints. In ICU, line infections may extend into joints, particularly after subclavian and femoral line insertions.
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