Nonunion

The recognition and treatment of delayed union or nonunion of a fracture is an orthopedic salvage procedure that all veterinary surgeons eventually experience. The major factor in determining whether a fracture becomes a nonunion or goes on to unite is the degree of stabilization of the fracture site. Infection (osteomyelitis) also contributes significantly to the formation of a nonunion. Nonunions can usually be classified clinically and radiographically as either vascular (capable of biologic activity) or avascular (incapable of biologic activity). Once this determination has been made, treatment regimens include application of rigid internal fixation (vascular nonunions) and installation of autogenous cancellous bone grafts after decortication (avascular nonunions). With the complication of osteomyelitis, microbiologic evaluation and antibiotic therapy should be considered even though a fracture will heal in the presence of infection if it is stable.