When infection becomes architecture: structural predictors of surgical management in spondylodiscitis.

BACKGROUND: Spondylodiscitis is an increasingly recognised spinal infection, but surgical decision-making is often difficult because microbiological, inflammatory, neurological, and structural features may not align. This study evaluated factors associated with surgical management and vertebral collapse in a tertiary spinal cohort. METHODS: A retrospective cohort study was performed of consecutive patients referred to a tertiary spinal centre in England with radiological evidence of spondylodiscitis between 2016 and 2023. Demographic, clinical, microbiological, radiological, treatment, and outcome variables were collected. Logistic regression was used to assess factors associated with surgical management and vertebral collapse. RESULTS: A total of 101 patients were included. Median age was 67.0 years, and 66 patients were male (65.3%). A microbiological diagnosis was achieved in 70 patients (69.3%), with Staphylococcus aureus the most common organism (45.5%). CT-guided biopsy was positive in 18 of 28 patients (64.3%) and in five of 10 blood-culture-negative patients who underwent biopsy. Thirty patients (29.7%) underwent surgery. CRP and WBC did not differ between surgical and medically managed patients. Surgery was associated with younger age, thoracic-only disease, and vertebral collapse. In multivariable analysis, vertebral collapse remained independently associated with surgery (adjusted OR 4.41; 95% CI 1.46-13.31; p = 0.0085). Vertebral collapse was present in 45 patients (44.6%) and was strongly associated with endplate damage (adjusted OR 24.12; 95% CI 2.72-213.91; p = 0.0043). CONCLUSIONS: In this tertiary spinal cohort, surgical management of spondylodiscitis was associated more with structural and anatomical disease features than with systemic inflammatory markers. CT-guided biopsy provided additional diagnostic value in blood-culture-negative cases, but microbiological diagnosis alone did not define surgical relevance. Assessment of spondylodiscitis should include microbiological diagnosis, neurological severity, and structural features such as endplate damage, vertebral collapse, and thoracic involvement.