Degenerate-disc infection study with contaminant control (DISC): Application of a proposed histological scoring system.

Recent evidence into an infectious etiology of discogenic back pain/leg pain are ongoing with contradictory data in literature. We sought to validate the clinical relevance of histopathological evidence of inflammation through a previously proposed histological grading system. In this prospective cohort study, 124 consecutive patients undergoing an elective spinal decompression and/or fusion procedure involving discectomy were selected with intraoperative tissue sampling of intervertebral disc and paraspinal tissue at a single institution. The histological domains were correlated with positive disc cultures to assist in identifying relevant positive infections. Inter-observer analysis of the scoring system was also performed. There were 124 samples (36 cervical and 88 lumbar) obtained. 29 (23.4%) disc specimens and 37 (29.8%) of ligament samples demonstrated growth of C. acnes. In total, 38/124 (30.6%) of disc specimens were positive for growth of any species. There was poor association between positive disc culture and the presence of neutrophilia (p = 0.123) or chronic inflammatory changes (p = 0.092) on histopathological assessment. There was no statistical significance noted across all histological domains examined within the finalised scoring system and positive culture across disc specimens. There was moderate agreement in between observers (kappa range: 0.41-0.60) in the assessment of inflammatory changes using the proposed scoring system. The current study suggests poor correlation between histopathological evidence of chronic or acute inflammation and positive disc cultures questioning the idea that disc infection is the root cause of acute or chronic back pain/leg pain.