<prompt> Earliest X-Ray finding in Osteomyelitis:InvolucrumSequestrumCloacaePeriosteal reaction  <response>: Ans. d Periosteal reactionRef. Maheshwari 8th ed. 169; Harrisons 18th cd. Ch 126 Earliest X-Ray change: Loss of soft tissue plane which is seen after 24 hours. In case of osteomyelitis X-Ray is normal during first 24 hours. 2nd X-Ray change seen in periosteal reaction, which is usually seen 7-10 days after infection. Periosteal reaction can be of 3 types: No reaction: seen in case of TB Narrow zone of activity: Benign condition Ex: in infection like osteomyelitis Wide zone of activity: Malignant condition Ex: Codmans triangle in osteosarcoma 