Fracture margin sequestration in mandibular fractures in three horses: Radiographic, computed tomographic and histological appearance

Abstract

Three horses with mandibular fractures (two chronic and one acute) were referred for fixation. Clinical signs, radiographical findings, computed tomography (CT) appearance of fractures and complicating fracture margin sequestra were documented and histology performed. The chronic fractures were treated with an external skeletal fixator type I (Horse 1) and an internally applied locking compression plates (LCP) (Horse 3). Horse 2 (acute fracture) was treated with an LCP applied as external fixator type I. All horses developed fracture margin sequestration visible radiographically and on CT, representing three parallel zigzagging radiolucent/hypoattenuating lines, consistent of a central fracture line, paralleled by two elongated sequestra and additional parallel demineralised lines separating the sequestra from the parent bone. Horses 1 and 2 were euthanised. Histology showed sequestra of the fracture margins, osteoclasts and inflammatory cells. In Horse 3, the fracture healed and the implants were removed. Drainage persisted for 3 years post-operatively due to the non-accessible fracture margin sequestra. Possible aetiology of fracture margin sequestration included motion in the region of the fracture, infection and disruption of the mandibular blood supply.