Bone features reinforce differential diagnosis between tuberculous spondylitis and brucellosis spondylitis

Tuberculous spondylitis (TS) and brucellar spondylitis (BS) both cause major long-term morbidity and disability. Though Spondylodiscitis is sensitive to magnetic resonance images, some are difficult to differentiate. This study aims to identify specific bone changes on computed tomography (CT) images, further to differentiate TS from BS.

We retrospectively analyzed and enrolled 70 patients with TS and 65 with BS at our hospital from December 2012 to January 2024. Information of bone destruction and formation, vertebral wall integrity, osteosclerosis, and sequestrum on CT images was collected and compared using the chi-square test or t-test. P < 0.01 was considered statistically significant.

Bone destruction was greater in the TS group compared to the BS group (519.55 mm² vs. 316.00 mm², t = 6.01, P < 0.001), preferentially involving each third of the vertebral body horizontally (41.22% vs. 16.67%, χ² = 77.76, P < 0.001; positive predictive value [PPV] = 80.6%) and the area under the endplate and equatorial portion of the vertebra longitudinally (80.53% vs. 28.20%, χ² = 134.19, P < 0.001, PPV = 82.75%). Patients with BS more frequently exhibited fan-shaped osteosclerosis (12.82% vs. 1.15%, χ² = 71.30, P < 0.001; PPV = 86.96%), longer bone formation surrounding the vertebra (18.06 mm vs. 1.97 mm, t = 14.28, P < 0.001), and longer anterior bone formation (3.86 mm vs. 0.92 mm, t = 6.51, P < 0.001). Anterior and closed bone formation was more common in the BS group than in the TS group (44.87% vs. 7.63%, χ² = 152.53, P < 0.001; PPV = 77.78%). Fragmented and blocked sequestrum was more common in the TS group than in the BS group and tended to spread in and out of the erosions (22.14% vs. 0.64%, PPV = 98.31% and 22.14% vs. 0.00%, PPV = 100%, χ² = 102.43, P < 0.001).

TS and BS exhibit specific features of bone formation, bone destruction, and sequestrum on CT imaging. Our findings indicate that bone features on CT can help clinicians distinguish between two spinal infections.