Humeral head-split fracture in two dogs

Introduction / Purpose:
The humerus is the least commonly fractured long bone in the dog, and proximal humeral fractures are the rarest form of injury. This is most likely due to the enclosed location of the humeral head within the glenoid fossa of the scapula as well as its close location to the trunk. We report two cases of humeral head-split fracture in skeletally immature dogs, following a low energy trauma.
Methods:
Institutional archives were searched for radiographic and computed tomography (CT) examinations of incomplete humeral head fractures.
Results:
Only two cases were available for review through a 24-year period. Case 1 had radiographs and a CT examination, and case 2 only underwent radiographic examination.
Both cases shared a fissured appearance of the caudal humeral head, secondary to an
incomplete Salter Harris type IV fracture. The cartilage covered caudal humeral head
fragment remained attached to the metaphyseal bone and was displaced beyond the caudal margin of the glenoid fossa of the scapula, resulting in neoarthrosis. These atypical fractures shared a distinct Enoki-mushroom-like appearance, where to fruiting bodies arise from a common stem. Both cases were conservatively managed.
Discussion / Conclusion:
Humeral head-split fractures can be recognized in the dog with characteristic radiographic and CT features of a fissured appearance of the humeral head with a distinct Enoki-mushroom-like appearance. Recognition of this condition is relevant in raising awareness of the radiographic appearance and better understanding the outcomes and treatment options available.