Congenital pseudarthrosis of the tibia. Factors that affect results.

Congenital pseudarthrosis of the tibia is a rare disease of unknown etiology and variable natural history. Treatment offers a high percentage of poor results. The decision of when the limb will be cosmetically and functionally better than a below-knee prosthesis is a critical one that the orthopedic physician must reach with the patient. The presence or absence of neurofibromatosis apparently does not alter the result. Those cases which show a cystic radiographic appearance have a more favorable prognosis than those which become or present as dysplastic. The more times the patient is bone grafted without success, the worse the result is likely to be. Shortening of the limb is not only important from a functional standpoint but may also serve as a prognostic index for the difficulty of achieving union as well as subsequent problems with ankle stiffness, pain, and deformity. The response to grafting may also be an important factor in determining the result; those patients who rapidly resorb the graft have a poor chance for a successful outcome. It does not appear that the type of bone grafting procedure is of large significance unless the graft has its own blood supply. Although prophylactic grafting cannot be demonstrated to alter the natural history of this disease, it, along with other developmental techniques, may be advisable.