Acquired spondylolysis and spondylolisthesis in the young child.

The cause of spondylolysis and spondylolisthesis remains unknown. There is increasing evidence that the defect in the pars interarticularis is due to fatigue fracture rather than being of congenital origin. We describe the youngest patient on record with spondylolysis and spondylolisthesis in whom roentgenograms that showed no abnormality had previously been taken. This case supports the hypothesis that spondylolysis and spondylolisthesis are acquired and not congenital, even when discovered in a very young child.