Risk factors for insufficient reduction after short-segment posterior fixation for thoracolumbar burst fractures: Does the interval from injury onset to surgery affect reduction of fractured vertebrae?

BACKGROUND: Many surgeons have encountered patients who could not immediately undergo surgery to treat spinal fractures because they had associated injuries and/or because a complete diagnosis was delayed. For such patients, practitioners might assume that delays could mean that the eventual reduction would be insufficient. However, no report covered risk factors for insufficient reduction of fractured vertebra including duration from injury onset to surgery. The purpose of this study is to investigate the risk factors for insufficient reduction after short-segment fixation of thoracolumbar burst fractures. METHODS: Our multicenter study included 253 patients who sustained a single thoracolumbar burst fracture and underwent short-segment fixation. We measured the local vertebral body angle (VBA) on roentgenograms, before and after surgery, and then calculated the reduction angle and reduction rate of the fractured vertebra by using the following formula: [Formula: see text] A multiple logistical regression analysis was performed to identify risk factors for insufficient reduction. The factors that we evaluated were age, gender, affected spine level, time elapsed from injury to surgery, inclusion of vertebroplasty with surgery, load-sharing score (LSS), AO classification (type A or B), preoperative VBA, and the ratio of canal compromise before surgery. RESULTS: There were 140 male and 113 female patients, with an average age of 43 years, and the mean time elapsed between injury and surgery was 3.8 days. The mean reduction angle was 12°, and the mean reduction rate was 76%. The mean LSS was 6.4 points. Multiple linear regression analysis revealed that a higher LSS, a larger preoperative VBA, a younger age, and being female disposed patients to having a larger reduction angle and reduction rate. The time elapsed from injury to surgery had no relation to the quality of fracture reduction in the acute period. CONCLUSIONS: Our findings indicate that if there is no neurologic deficit, we might not need to hurry surgical reduction of fractured vertebrae in the acute phase.