In a study of 31 patients whose slippages progressed, no slippage was associated with the early stage of a pars interarticularis defect. Most vertebral slippages developed or progressed in the cartilaginous or apophyseal stage of the lumbar skeletal age. These results indicate that the advanced stage of a pars interarticularis defect in an immature spine is a risk factor for spondylolisthesis. The deformities of the lumbosacral spine are thought to be the secondary changes caused by vertebral slippage.
Spondylolisthesis is defined as the forward slipping of a vertebral body over the one below it.
The purpose of this study was to clarify the pathogenesis of spondylolisthesis in young athletes with spondylolysis. These changes were characterized by an ill-circumscribed radiolucent defect in the early stage, a hairline defect occasionally accompanied by fragments in the progressive stage, and a wide defect with reactive sclerosis and hypertrophy in the terminal stage. Spondylolysis and spondylolisthesis were studied radiographically by AP, lateral, and oblique views of the lumbosacral area. All pars defects were detected at L-5.