Hounsfield unit is associated with vertebral body re-collapse 3 months after surgery in working-age patients with a thoracolumbar burst fracture: A retrospective register-based cohort study

Purpose Factors associated with early re-collapse after posterior fixation of thoracolumbar burst fractures have been sparsely examined in previous studies. We investigated the factors associated with re-collapse within the first 3 months after posterior fixation of thoracolumbar burst fractures. Methods This retrospective study used data from the Swedish Fracture Register (2015–2019), encompassing patients aged 18 to 66 who sustained a single-level thoracolumbar burst fracture between T11 and L3 and underwent posterior fixation. The fractures were classified by a modified AO classification and the load sharing classification (LSC). Hounsfield unit (HU) values were used to evaluate bone quality. Vertebral collapse assessment included measurements of the kyphosis angle, wedge angle, and anterior/posterior height. Moreover, pull-out of pedicle screws was assessed. Multiple logistic regression analysis assessed the factors associated with re-collapse within 3 months after surgery Results This study comprised 100 participants, of whom 58 were male and 42 were female. Some 16 patients had radiographic vertebral re-collapse and 15 had pedicle screw pull-out. A statistically significant association was observed between HU values and re-collapse (odds ratio [OR]: 0.97, 95% confidence interval [CI]: 0.94–0.99). Preoperative LSC also tended to be associated with re-collapse (OR: 2.35, 95% CI: 1.07–6.82). However, no association with screw insertion depth or the number of fixated vertebrae was seen in this study. Conclusion Three months post-surgery, a statistically significant association was noted between HU values and early re-collapse after posterior spinal fixation in patients with thoracolumbar burst fractures.