Comparison of Culture Results from Bone Biopsy versus Disc Aspiration in Infectious Diskitis

Purpose: Infectious spondylodiscitis requires long-term appropriate antibiotic treatment, frequently based on disc aspiration or bone biopsy cultures. Previous studies have compared biopsy and aspiration, however, a direct comparison between bone biopsy and disc aspiration when both procedures are performed together in the same patient is notably absent in the literature {1}. Our hypothesis posits that disc aspiration surpasses bone biopsy in yielding positive culture results, potentially serving as a stand-alone diagnostic tool for infectious spondylodiscitis.

Materials and Methods: This retrospective study reviewed results from 96 patients with suspected infectious spondylodiscitis who underwent disc aspiration and vertebral biopsies between 2018 and 2023. Positive culture rates between disc aspiration and vertebral biopsy were compared.

Results: 44/96 (46%) patients had positive cultures. 9 (20%) of these 44 patients were positive only from disc aspiration and 9 (20%) were positive only from bone biopsy. Therefore, had only aspiration or biopsy been performed, 20% of positive cultures would have been missed. 47% of disc aspiration and bone biopsy-negative patients had a pathology report positive for osteomyelitis. 25% of disc aspiration and bone biopsy-positive patients had a pathology report negative for osteomyelitis.

Conclusion: Both disc aspiration and bone biopsy should be performed when diagnosing infectious diskitis. Our data contradicts previous studies which found that disc aspiration was significantly more sensitive than bone biopsy {2}. However, these previous publications examined patients who had received disc aspiration or bone biopsy, not both, and were therefore subject to selection bias. The discrepancy between culture and pathology report results suggests that the former should continue to be used to diagnose infectious diskitis.