This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Ring sequestrum is seen in? 
Select and explain. 
A. Typhoid osteomyelitis, B. Chronic osteomyelitis, C. Amputation stump, D. Tuberculosis osteomyelitis
C: Amputation stump
Answer: C: Amputation stump 
Explanation: Excessive periosteal stripping is contraindicated as it may result in formation of ring sequestrum in amputation stump. Type of sequestrum Found In Ring sequestrum Amputation stump Around pin tracts ( external fixator) Tubular sequestrum Hematogenous osteomyelitis Segmental fractures ( middle segment) Rice grain sequestrum Tuberculosis Ref: Campbell's operative Ohopaedics 10/e, page 544.