Abstract
We reviewed radiographs and magnetic resonance im ages of 77 young athletes with spondylolysis and spon dylolisthesis (more than 5% vertebral slip) (slip group). The results were compared with similar studies in 88 patients with spondylolysis only (nonslip group). End- plate lesions were found in all patients in the slip group and in 60 (68%) of those in the nonslip group. Slippage between the osseous and cartilaginous endplates was identified in the T1-weighted sagittal magnetic reso nance images and categorized according to the type of slippage: total slip of L-5 or S-1, partial slip of L-5 or S-1, or a combination of these (mixed type). In a study of 31 patients whose slippages progressed, no slip page was associated with the early stage of a pars interarticularis defect. Most vertebral slippages devel oped or progressed in the cartilaginous or apophyseal stage of the lumbar skeletal age. Wedging of the L-5 vertebral body and rounding of the sacrum progressed as the slippage developed; these did not occur in the nonslip group. These results indicate that the ad vanced 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.
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