Ans: B i.e. 10 days The earliest sign to appear on the X-ray is a periosteal new bone deposition (periosteal reaction) at the metaphysis. It takes about 7-10 days to appear Osteomyelitis Earliest site of involvement: Metaphysis Diagnosis of acute OM: Blood culture (positive in 65% cases) Periosteal reaction seen in acute OM appears after: 10 days MC organism in acute OM: Staph. aureus Brodies abscess: - Equilibrium between host & organism; - Abscess cavity remains without fuher enlargement