Sacral pedicle agenesis.

Sacral pedicle agenesis is a very rare anomaly, and only one case has been reported previously in the radiological literature, besides two cases found in a study of osteological anatomy collection. This paper reports a 34-year-old woman with agenesis of the right pedicle of the first sacral vertebra. There was an anomalous facet between L5 and S1. The L5 and S1 nerve roots were conjoined. Developmental stenosis of the lumbar spinal canal was associated with the condition.