11 - Risk Factors for Insufficient Reduction of Intracanal Fragment After Short-Segment Posterior Fixation for Thoracolumbar Burst Fractures

Introduction: Many surgeons have encountered patients who could not immediately undergo surgery to treat spinal fractures because they had associated injuries. 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 intracanal fragment in the treatment for thoracolumbar burst fracture.

Aims: The purpose of this study is to investigate the risk factors for insufficient reduction of intracanal fragment after short-segment fixation for thoracolumbar burst fractures.

Methods: Our multicenter study included 241 patients who sustained a single traumatic thoracolumbar burst fracture and underwent short-segment fixation. We measured canal compromise ratio (CCR) of intracanal fragment on CT before and after surgery, and then calculated the reduction rate of the fragment by using the following formula: (Preoperative CCR − Postoperative CCR)/Preoperative CCR × 100. A multiple logistical regression analysis was performed to identify risk factors for insufficient reduction of intracanal fragment. 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 A3.A4 or B1.B2), and preoperative CCR.

Results: There were 132 male and 109 female patients, with an average age of 44 years, and the mean time elapsed between injury and surgery was 3.8 days. Combination of vertebroplasty was performed in 114 patients. Mean preoperative CCR was 42% and improved to 24% after surgery. The mean LSS was 6.4 points. Multiple linear regression analysis revealed that T12 and L1 fracture and AO type B fracture had better reduction rate compared to L2 and L3 fracture and AO type A fracture. The time elapsed from injury to surgery had no relation to the quality of fracture reduction.

Conclusions: Patients with L1 and L2 fracture and AO type B fracture had better reduction of intracanal fragment for treatment of thoracolumbar burst fracture by short-segment fixation. Because the timing of surgery did not affect the results of fragment reduction, few delays are acceptable, and we might not need to hurry surgical reduction of intracanal fragment in the acute phase, unless there was neurologic reduction.