This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection of Bones & Joints, Subject name: Orthopaedics
X-ray appearance of sequestrum is - 
Select and explain. 
A. Unnatural radiodense fragments, B. Osteopenic fragment, C. Fragment with honeycomb loculated appearance, D. Radiolucent area with speckled calcification
A: Unnatural radiodense fragments
Answer: A: Unnatural radiodense fragments 
Explanation: Ans. is 'a' i.e., Unnatural radiodense fragments Sequestrum* Sequestrum is a piece of dead bone, surrounded by infected granulation tissue trying to eat the sequestrum away.* The sequestrum is hardl, rough, porus, light in weight and lighter in colour than normal Normal pattern of bone is lost. (Note : Sequestrum in syphilis and TB is heavier than normal bone because sclerosis usually precedes the death of the bone).* On x-ray, sequestra show up as unnatural dense fragments, in contrast to the surrounding osteopenic bone.