Technetium-99m-diphosphonate, gallium-67 and labeled leukocyte scanning techniques in tibial nonunion.

On the technetium-99m bone scan the vast majority of nonunion cases show an intense tracer uptake at the fracture site, as do fractures undergoing normal healing. Therefore static bone scintigraphy usually does not contribute to the diagnosis of nonunion. One of the main causes of delayed fracture healing is infection. Increased blood flow and blood pool as demonstrated during the first and second phases of a 3-phase bone scan are consistent with an inflammatory reaction but are not pathognomonic for infection. A gallium-67 scan is indicative of infection if Ga-67 uptake exceeds Tc-99m uptake on the bone scan. The most specific tracers for infection however are leukocytes labeled with indium-111 or technetium-99m.