Abstract
Background: Over several decades, investigators have been trying to identify the painful degenerate disc. Their work included two main methods. The first was to set criteria on the radiological investigations, mainly the MRI scan, to describe the severity of the degenerative disc disease (DDD); and the second was to perform discographies. Neither of these two methods precluded the need for the other.
Purpose: Using Pfirrmann’s classification, we correlated static MRI images, for the severity of segmental disc degeneration, with dynamic lumbar discography, with the aim to improve the identification of painful ‘disco-genic’ intervertebral segments.
Study design: Prospective cohort study. Inclusion criteria included patients with mechanical low back pain who exhausted the conservative measures and required surgical treatment.
Patient Sample and Methods: We investigated 69 patients (45 females, 24 males). The average age was 38.9 years (range 20–56). All patients had degenerative disc disease (DDD) on lumbar MRI scans. Provocative discographies were performed in all cases as a routine investigation to identify painful levels prior to fusion or disc replacement surgery. The severity of DDD was graded using Pfirrmann’s classification. A total of 162 discographies were performed using the ‘miss the facet joint, double needle technique’.
Outcome measures: During discography typical or concordant pain only was regarded as positive. Among each of the five Pfirrmann grades, the percentage of positive discographies was calculated. Significance and correlation then were investigated using the Chi-squared and Spearman’s correlation tests.
Results: 24 discs were classified as Pfirrmann grade I, 33 grade II, 63 grade III, 27 grade IV and 15 grade V. The percentages of positive provocative discography for concordant pain among these groups were 0%, 9.1%, 71.4%, 100% and 100% respectively. Statistical analysis showed a high correlation between the severity of DDD on MRI scan and the result of the provocative discography (Chi2 = 32.96, P < 0.001 and correlation coefficient = 0.756).
Conclusion: The higher the grade of segmental DDD, the more likely it will be painful on discography. All discs showing Pfirmann grade IV and V disease were painful on discography. We strongly recommend the Pfirrmann classification for use in grading the severity of lumbar DDD especially when assessing for its association with discogenic pain as determined by provocative discography.
Correspondence should be addressed to: EFORT Central Office, Technoparkstrasse 1, CH – 8005 Zürich, Switzerland. Email: office@efort.org
