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
[{'content': 'Ring sequestrum causes: \nSelect and explain. \nA. Typhoid osteomyelitis, B. Chronic osteomyelitis, C. Amputation stump, D. Tuberculosis osteomyelitis', 'role': 'user'}, {'content': 'Answer: C \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 Ring sequestrum causes : Ring sequestrum * Amputation stump * Pin tract infection Cylindrical/pencil like Infants Green Pseudomonas osteomyelitis Black Amputation stump due to exposure of bone with air.', 'role': 'assistant'}]