Association between Type 1 Modic Changes and Propionibacterium Acnes Infection in the Cervical Spine: An Observational Study.

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Research on the association between Propionibacterium acnes in the disc space and type 1 Modic changes in adjacent vertebrae is limited and has produced mixed results. The prevalence of bacteria in intervertebral discs contradicts the prior understanding that skeletal areas in the human anatomy are sterile; yet it opens new treatment possibilities. We investigated the relationship of P acnes and type 1 Modic changes in the cervical spine. Over a 36-month period, we collected intraoperative biopsies of patients undergoing a routine cervical spine operation for degenerative disc diseases. The disc material was cultured aerobically and anaerobically for 7 days. All preoperative MR images were evaluated for Modic changes by a board-certified neuroradiologist. Medical records were reviewed for other spine interventions before the operation. The study population consisted of 48 patients. Of these, 14 patients tested positive for P acnes (29%) at ≥1 level. Additionally, 13 patients had type 1 Modic changes (27%) at ≥1 level; 54% (95% CI, 27%-84%) of patients who had type 1 Modic changes were also positive for P acnes compared with 20% (95% CI, 7%-33%) of patients without type 1 Modic changes. The difference between these proportions was 34% (95% CI, 4%-64%). The Fisher exact test produced a P value of .03 for the association between P acnes and MC1, and .53 for the association between P acnes and prior procedures. We conclude that P acnes was prevalent in the degenerated cervical spine and that type 1 Modic changes were predictive of a culture positive for P acnes. We also found that the prevalence of P acnes was not associated with previous interventions. If these results are validated by future studies, they could have a major impact on the standard of care for back and neck pain.