Trapezoidal Vertebral Body and Spine-Pelvis Sagittal Alignment in Patients with Lumber Spondylolisthesis.

BACKGROUND Trapezoidal changes of the vertebral body are more common in patients with lumbar spondylolisthesis than in others. However, we lack an understanding of factors predisposing to the development of a marked trapezoidal deformity. Also, no associations between a trapezoidal vertebrae (TV) and spine-pelvis sagittal parameters have been previously reported. MATERIAL AND METHODS A total of 73 subjects with lumbar spondylolisthesis were enrolled and we collected their clinical data. Vertebral body parameters and spine-pelvis sagittal alignment parameters were measured via lumbar spine X-ray. Using the lumbar index (LI), patients were divided into a TV group (LI >0.8, n=24) and a control group (LI >0.8, n=49). The clinical data and spine-pelvic sagittal parameters of the 2 groups were compared using the t test or chi-squared test. Pearson's correlation analysis and multiple linear regression were used to determine relationships among the parameters. RESULTS The TV and control groups differed significantly in terms of the slipped segment, extent of slippage, intervertebral disc height (IDH), and sagittal parameters (all P<0.05). Pearson's correlation analysis and multiple linear regression analysis showed that the slipped segment (r=-0.606), extent of slippage (r=-0.660), and IDH (r=0.698) were risk factors for the development of a TV body. Also, vertebral trapezoidal deformation was closely associated with sagittal parameters. CONCLUSIONS The vertebral body affected by lumbar spondylolisthesis exhibits a trapezoidal change closely associated with the slipped segment, the extent of slippage, and IDH. The TV group exhibited greater pelvic incidence values and lumbar lordosis, which may have caused wedging of the slipped vertebra.