This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint and Soft tissue infections, Subject name: Orthopaedics
Acute osteomyelitis of long bones commonly affects the: 
Select and explain. 
A. Epiphysis, B. Diaphysis, C. Metaphysis, D. Aicular surface
C: Metaphysis
Answer: C: Metaphysis 
Explanation: Metaphysis of long bone is the earliest and most common site involved in osteomyelitis. It stas in metaphysis because of: Defective phagocytosis in metaphysis (Inherently depleted Reticuloendothelial System Rich blood supply Hair pin bend of metaphyseal vessels (leads to vascular stasis and decreased oxygen tension) Metaphyseal hemorrhage due to repeated trauma (acts as culture media)