Nonunion fracture refers to the permanent failure of healing following a broken bone, even after treatment, which can become a serious health threat requiring medical attention, perhaps including orthopedic surgery. Individuals with nonunion fractures in their legs, ankles or feet may need crutches, wheelchairs or other assistive devices to retain mobility.
In some cases, nonunion fractures eventually heal on their own—this is called delayed union—and every person’s bones heal differently. In general, though, if the fracture hasn’t healed within six months, a nonunion has developed.
There are two major types of nonunion fractures: hypertropic non-union and atrophic non-union. A hypertropic non-union refers to the nonunions that result from a mechanical issue at the fracture site; this can lead to what is often called “elephant foot,” or a bulge at the fracture site that is caused by a large amount of callus formation. Surgery for this condition seeks to stabilize the fracture by compressing the two fragments. An atrophic non-union, meanwhile, is caused by poor healing due to a lack of blood supply. Treatments for atrophic non-union fractures are more complex; the fracture must be held in place while the tissue around the bone ends is removed and the avascular bone ends are hollowed out. After that, a bone graft is packed around the fracture area.
While nonunions can occur in any bone, they are most commonly found in the tibia, humerus, talus and fifth metatarsal bone.