In an adult with chronic osteomyelitis, the radiograph shows a cavity within sclerotic bone containing a dense bony fragment surrounded by pus. This radiological finding is referred to as:
- A Brodie's abscess
- B Involucrum
- C Sequestrum ✓
- D Cloacae
Explanation
A sequestrum is the avascular dead bone fragment seen in chronic osteomyelitis, separated from the living bone by granulation tissue and pus. Radiologically it appears as a dense sclerotic fragment within a cavity. The new bone formed by the elevated periosteum surrounding the sequestrum is the involucrum (B). Cloacae (D) are holes in the involucrum through which pus and dead bone fragments are discharged to form a sinus tract. Brodie's abscess (A) is a localised form of subacute osteomyelitis presenting as a cystic lucency with sclerotic rim in the metaphysis, typically without a sequestrum.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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