Understanding the pathophysiology of nonunion is a prerequisite for success
ful treatment of this disorder. Fracture healing may be impeded by mechanic
al or biological factors as well as a combination of these. A thorough eval
uation of each individual case before surgery is necessary to prevent eithe
r undertreatment or overtreatment. The whole spectrum of methods of interna
l fixation may be utilized for stabilization. To optimize the biological co
mponent, classic methods such as decortication and cancellous autograft may
be employed. It is too early yet to determine if alternative techniques (e
.g, ultrasound) will successfully replace these long-standing options. In a
ny case, these newer modalities cannot supplant the need for skeletal stabi
lization. For infected pseudarthroses the first step is eradication of infe
ction, after which meaures can be taken to unite the fracture. Callus distr
action has opened new and safe ways to treat large bone defects.