Acute osteomyelitis commonly affects –
**Core Concept**
Acute osteomyelitis is a bone infection caused by bacterial invasion, leading to inflammation and bone destruction. It commonly affects long bones, particularly in children and adolescents. The infection usually spreads from a contiguous site of infection, such as a skin wound or infected joint.
**Why the Correct Answer is Right**
Acute osteomyelitis most commonly affects the metaphysis, the wide portion of long bones adjacent to the growth plate. The metaphysis is rich in blood vessels, making it an ideal site for bacterial colonization. The infection often spreads from a contiguous site of infection, such as a skin wound or infected joint, through direct extension or hematogenous spread. The bacteria, such as Staphylococcus aureus, colonize the metaphyseal blood vessels and cause an inflammatory response, leading to bone destruction and infection.
**Why Each Wrong Option is Incorrect**
**Option A:** The diaphysis, or the shaft of long bones, is not a common site for acute osteomyelitis. While it can occur, the metaphysis is more prone to infection due to its rich blood supply.
**Option B:** The epiphysis, or the end of long bones, is not typically involved in acute osteomyelitis. The growth plate, which separates the epiphysis from the metaphysis, creates a barrier to infection.
**Option C:** The pelvis is not a common site for acute osteomyelitis. While it can occur, the infection more commonly affects long bones, particularly in children and adolescents.
**Clinical Pearl / High-Yield Fact**
The metaphysis is the most common site for acute osteomyelitis due to its rich blood supply and proximity to the growth plate. This is an important consideration for diagnosis and treatment.
**Correct Answer:** C.