This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ohopaedics Q Bank, Subject name: Orthopaedics
[{'content': "Chronic osteomyelitis is diagnosed mainly by: \nSelect and explain. \nA. Sequestrum, B. Bone fracture, C. Deformity, D. Brodie's abscess", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sequestrum is the dead bone separated out from the living bone by the granulation tissue. The factors responsible for bone death in chronic osteomyelitis are: raised intravascular pressure Vascular stasis and small vessel thrombosis periosteal stripping bacterial toxins Sequestrum is the hall mark of chronic osteomyelitis Involucrum--periosteal new bone forming later', 'role': 'assistant'}]