Congenital hypoplasia or aplasia of the lumbosacral pedicle as an unusual cause of spondylolisthesis in the pediatric age group.

The authors describe rare cases of congenital hypoplasia of the L-5 pedicles and the congenital absence of the left S-1 pedicle in 2 young girls, respectively, including the presentation, diagnosis, and treatment. Moreover, they review the literature on this clinical entity. The patients presented with intractable chronic low-back pain. Plain radiographs and 2D CT scanning revealed the presence of the aforementioned anomalies. Degenerative changes to adjacent level and contralateral facet joints were thought to be the result of overload and instability and seemed to have led to spondylolisthesis, micromotion at L-5 and S-1, and subsequent low-back pain. The pediatric patients were treated with posterior instrumented fusion with good functional outcomes at a minimum 3-month follow-up. To the best of the authors' knowledge, these are the first reports of intractable low-back pain and spondylolisthesis accompanied by hypoplastic-aplastic pedicles at the lumbosacral junction in children.