Study Design. A prospective in vivo animal study.

Objectives. To determine whether infection in the juvenile spine influences spinal development.

Summary of Background Data. Discitis is thought to occur in children when blood-borne infection penetrates the highly vascular immature disc. The condition generally resolves without apparent complication, but little is known about the long-term effects on the growing spine.

Methods. Twenty-nine 6-week-old lambs underwent discography at multiple lumbar levels using radiographic contrast deliberately inoculated with Staphylococcus epidermidis. No antibiotics were given. Plain radiographs were taken at intervals up to 52 weeks after inoculation for morphometric analysis of the vertebral bodies and discs, and the lumbar spines were prepared for histology.

Results. Sixteen of 44 inoculated discs showed radiological evidence of discitis between 2 and 6 weeks after inoculation. Disc height and disc area were significantly reduced from 2 weeks, and did not recover during the study period. Vertebral body dimensions and overall lumbar spine length were not significantly affected.

Conclusion. Infection of juvenile ovine discs impedes disc development but has no significant effect on vertebral body growth.