Intervertebral Disc Changes in Adolescents with Isthmic Spondylolisthesis

The lower lumbar discs in adolescent patients with isthmic L5 spondylolisthesis requiring operative treatment were evaluated by means of plain radiography, discography, and magnetic resonance imaging (MRI). There were 14 girls and 13 boys, mean age on admission 14.4 (range, 11-18) years. The mean slip in girls was 45 +/- 23% and in boys 27 +/- 17% (p less than 0.05). Discography was performed in 23 patients (42 discs) and MRI in 16. In 12 patients, both examinations were made. In plain radiographs, normal presacral disc height was seen in 11 patients with mean 14.5% slip, narrowing of the disc height less than 50% in four patients with mean 24% slip, and greater than 50% in 12 patients with mean 52.6% slip. In discograms and MRIs, the presacral disc was pathologic in all patients. Pathologic changes of the fourth lumbar disc were frequent. Concerning disc degeneration, there was poor correlation between findings in plain radiography compared with those seen in MRI or discography. MRI findings correlated with those of discography in most cases. However, MRI was normal in two discs with a pathologic discogram.