Posterior widening of the S1-S2 interspace in children: a normal variant of sacral development

A lucency in the posterior S1-S2 area of the sacrum was seen in two pediatric patients. Bone scans in both and a myelogram in one case were normal. Follow-up has failed to show any clinical evidence of pathology. The lucencies are felt to represent normal variations in the development of the sacrum. A series of radiographs at different ages is presented to illustrate how normal developmental progresses in this area.