Characterization of the influence of spinopelvic parameters on thoracolumbar trauma

OBJECTIVE The current Roussouly classification identifies four groups of “normal” sagittal spine morphology, which has greatly expanded the understanding of normal heterogeneity of the spine. While there has been extensive characterization of the influence of spinopelvic parameters on outcomes after degenerative spine surgery, the influence of spinopelvic parameters on thoracolumbar trauma has yet to be described. The goal of this study was to determine if spinopelvic parameters and global spine morphology influence fracture location, fracture morphology, and rate of neurological deficit in the setting of thoracolumbar trauma. METHODS Of 2896 patients reviewed in the authors’ institutional spine database between January 2014 and April 2020 with an ICD-9/10 diagnosis of thoracolumbar trauma, 514 met the inclusion criteria of acute thoracolumbar fracture on CT and visible femoral heads on sagittal CT. Pelvic incidence (PI) was calculated on sagittal CT. Demographic and clinical data including age, sex, BMI, smoking status, concomitant cervical fracture, mechanism of injury, major fracture location, neurological deficit, AO Spine thoracolumbar injury classification, and management type (operative vs nonoperative) were collected. Patients were stratified into high-PI (≥ 50°) and low-PI (< 50°) groups. RESULTS Patients with high PI had a lower incidence of fractures in the lower lumbar spine (below L2) compared with patients with low PI (16% vs 8%, p < 0.01). The last lordotic vertebrae were observed between T10 and L4, and of fractures that occurred at these levels, 75% were at the last lordotic vertebrae. Fall from height was the most common cause of neurological deficit, accounting for 47%. Of the patients presenting with a fall from height, AO Spine type B distraction injuries were more common in the high-PI group (41% vs 18%, p = 0.01). Similarly, within the same subgroup, AO Spine type A compression injuries were more common in the low-PI group (73% vs 53%, p = 0.01). CONCLUSIONS Spinopelvic parameters and sagittal balance influence the location and morphology of thoracolumbar fractures. Fractures of the thoracolumbar junction are strongly associated with the inflection point, which is defined by sagittal alignment. While the importance of considering sagittal balance is known for decision-making in degenerative spinal pathology, further studies are required to determine if spinopelvic parameters and sagittal balance should play a role in the decision-making for management of thoracolumbar fractures.