Bone fractures do not always heal completely. If healing does not occur, a mobile or unstable area arises at the location of the fracture and is called pseudarthrosis (nonunion). Causes can be insufficient stabilization of a fracture or infection of the bone. The latter often occurs with more severe and open fractures.
Other causes include impaired bone quality, insufficient nutrition, and reduced blood flow to the bone. With some underlying diseases, such as long-term diabetes, several factors can render it difficult to cure fractures, especially in the foot and ankle.
When fractures do not heal, additional malalignment is often caused by deviation and malposition of bone fragments. Nonunions and infected nonunions can be cured by refreshing or resecting the affected bone, correcting the alignment and position, and providing good stabilization of the segments. Sometimes in the presence of severe deformity or infection and soft tissue problems, an external fixation frame provides the safest and most successful treatment. If a substantial amount of bone substance needs to be removed, simultaneous bone lengthening to fill in for the excised bone can be performed.