Alpaka 5 months of age Male intact Presented with a history of lameness front right of 2 weeks duration On the clinical examination a focal moderate soft tissue swelling at the level of the mid metacarpal bone was noted and the lameness was scored 2/5 Radiographs of the right metacarpal region were taken Radiographic examination (right) view oLateromedial (left) and dorsopalmar f the right metacarpus Radiographic findings
- There is a focal, moderate soft tissue swelling accentuated dorsal and lateral at the level of the diaphysis of the metacarpal bone (big arrows).
- An oval, app 2 X 1 cm in size mineral opacity is visible, separated from the metacarpal bone by a mildly irregular radiolucent halo (arrowheads). There is complete interruption of the cortical bone and this bone fragment has a increased radiopacity compared to the surrounding cortical bone.
- There is ill defined, continous and solid, palisading new bone formation around the lesion (small arrows).
Radiographic diagnosis Close up of the lateromedial and dorsopalmar view of the right metacarpus The radiographic diagnosis is sequester formation on the middiaphysis of the right metacarpal bone with associated moderate soft tissue swelling. Comments
- A bone sequestrum is a fragment of bone that has lost ist blood supply and is no longer viable.
- Sequestra are classified in parosteal, cortical, intramedullary or fracture fragment.
- Additionaly, they are divided in sterile or infectious.
- A classic sequestrum is recognized as a sharply marginated sclerotic bone fragment (sequestrum) surrounded or separated from the parent bone by a radiolucent zone that is surrounded by sclerotic bone (involucrum). In some instances a draining tract (cloaca) arises from the radiolucent necrotic area surrounding the sequestrum and extends to the skin surface.
- Generally less reaction occurs surrounding a sterile sequestrum: However, determining wheter the sequestrum is infected or sterile is not always possible radiographically.
- In this case no skin lesion or sign of puncture wound were noted. The patient was managed with a surgical approach.
