Review of spondylolisthesis and spondylolysis in paediatric practice.

Presenting radiographs of 30 children with spondylolisthesis and spondylolysis were reviewed. A 67% incidence of spina bifida occulta was noted, a 13-fold increase of the incidence in the normal population, and a mechanism whereby this may precipitate a spondylolysis is given. The value of the spinous process rotation sign on AP radiographs and facet joint mal-alignment on oblique radiographs in paediatric practice was assessed, and the incidence was 39% and 56% respectively, compared with 92% and 91% in adult practice. Reasons for the reduced incidence are suggested. Oblique radiographs provided further diagnostic information only in the absence of a spondylolisthesis. Follow-up radiographs showed further slip in only five patients. The one constant factor in these five patients was the presence of a spina bifida occulta, indicating the necessity for close observation of such patients with a spondylolisthesis during the adolescent growth spurt. 99Tcm MDP bone scans were performed in three patients, in whom 4 of 5 spondylolyses were shown to have a high uptake. One lesion subsequently became of low uptake as symptoms subsided. Bone scanning in spondylolisthesis needs further evaluation but the finding of increased bone activity suggests a healing process. Spondylolysis is a differential diagnosis to be considered in a positive scan for evaluation of back pain.