Congenital defect of the posterior arch of cervical spine : report of three cases and review of the current literature.

Abnormalities of the posterior arch, including congenitally absent cervical pedicle and cervical spondylolysis, are rare entities that are usually found incidentally on neck radiographs. It is important to recognize these characteristic radiological features because their radiographic appearance may cause them to be confused with more serious entities such as fractures, locked facets, and tumor-induced bony erosions. Also, it is important to distinguish these abnormalities from similar pathologies to prevent the use of inappropriate treatment. We report the relevant clinical and radiological findings seen in three cases of posterior arch defect after trauma with review of pertinent literature.