Study design: This re-analysis was based on 833 computed tomography/discograms collected from 306 candidates for back surgery.
Objectives: The goal was to test the hypothesis that outer anular ruptures are the main determinant of the pain of discography.
Summary of background data: Previous analyses indicated univariate associations of pain with disc degeneration and anular ruptures.
Methods: If present, pain was classified as "exact", "similar", or "dissimilar" reproduction of the previously experienced pain. For each disc, ruptures and degeneration were separately evaluated by a four-point scale. Multiple logistic regression with random effects was used in the analysis.
Results: Outer anular ruptures were the only predictor of the responses "similar" and "exact". General disc degeneration was the only predictor of the response "dissimilar". There was no effect modification due to gender, age, and spinal level.
Conclusions: During discography, the outer anulus appears to be the origin of pain reproduction.