What is Pseudoarthrosis?

A pseudoarthrosis is literally a “false joint,” where a fractured bone fails to heal and the ends of the broken bone round with wear and move against each other in ways similar to a joint. Unlike true joints, however, pseudoarthroses do not have capsules filled with joint fluid and do not develop musculature to support the joint. As a result they are very unstable and sometimes painful. Real joints connected to a bone with a pseudoarthrosis will in turn be destabilized because the supporting bone is no longer intact.

When bones fracture, there can be a risk that they will not heal properly. Certain things can be recognizable risk factors, like a bone with a poor blood supply, a severe break, the age of the patient, and the patient's medical history. Sometimes this results in a delayed union, where the bone takes a long time to knit back together. In other cases, there is a nonunion; the ends of the bone do not rejoin, and a pseudoarthrosis can develop.

A congenital pseudoarthrosis can occur if someone experiences a fracture near birth and it results in a nonunion. The rapidly growing child's bones will adapt to the nonunion and start to round off. The bones also typically bow because of the lack of support. Nonunions in children can lead to gait abnormalities and other problems. Adults can also experience nonunions and sometimes develop nonunions after fusion surgery on the spine.

There are a variety of treatment approaches to a pseudoarthrosis. Less invasive techniques, like electrical stimulation of the bones to promote the growth of new bone, will be tried first. If these are not effective, grafting can be used to encourage the bones to grow together. Fixation, where orthopedic devices are fitted onto the bone to hold it in place while it heals, can also be an option. Fixation may keep the ends of the bone stabilized long enough for a new matrix of bone to start forming so that the nonunion can heal.

When a fracture is diagnosed, the possibility of the development of a pseudoarthrosis may be considered. Immobilization with a cast is typically used to treat fractures, so the bones will have an opportunity to heal, and additional measures, such as fixation at the time of the fracture, may be used as well. Follow-up examinations will be used to check on the course of the healing and to identify early signs of a delayed union or pseudoarthrosis.