Peculiarities of the sagittal balance of patients with post-traumatic deformities of the thoracic and lumbar spine

Purpose To determine the specificity of sagittal compensatory mechanisms in patients with post-traumatic deformities of the thoracic and lumbar spine, and also to study their correlation with pain and the life quality of patients. Materials and methods Using X-ray analysis of growth profile spondylograms of 103 patients we studied the effect of segmental post-traumatic deformity (SD) and anatomic shape of the spine (Roussouly type) on regional (TK, LL), pelvic (SS, PT) and global (SVA) parameters of sagittal balance. In addition, the analysis of dependence of pain (VAS) and the life quality of patients (ODI, SF-36) on the above parameters was done. Results SD of the thoracic spine (Th1-Th10) increased TK, which led to hyperextension of LL and a decrease in SS. These compensatory mechanisms were reflected in significant correlations SD-TK, TK-LL, TK-SS, and LL-SS. In the thoracolumbar spine (Th11-L2) SD at the level of Th11 and Th12 increased TK (SD-TK r = 0.553), and at the level of L1 and L2 they caused reactive hypokyphosis (SD-TK r = -0.687). A compensatory increase in LL was typical for injuries of Th11-Th12 (TK-LL r = 0.831) and L1 (TK-LL r = -0.629). Deformities at the L2 level led to hypolordosis (SD-LL r = -0.710), the magnitude of which, in turn, significantly influenced the TK, SS, and PT (LL-TK r = 0.690; LL-SS r = 0.832; SS-PT r = 0.597). The effectiveness of sagittal alignment in thoracic and thoracolumbar SD was confirmed by normal SVA values, as well as their lack of correlation with TK, LL and SS. In the lumbar spine (L3-L5), SD in 75 % of cases led to a critical decrease in LL and sagittal imbalance, which was reflected in significant correlations SD-LL, SD-PT, and SD-SVA. Compensatory correction of regional (TK, LL) and pelvic sagittal parameters (SS, PT) depended on the anatomical features of the spine (PI, Roussouly type) at all levels of the spinal column. However, a significant effect of PI on global sagittal alignment was noted only in lumbar SD (SVA-PI r = -0.617). Correlation of sagittal modifiers with pain intensity and quality of life was also typical only for patients with SD of the lumbar spine (PT-VAS r = 0.777; PT-ODI r = 0.752; PT-SF36 (PH) r = 0.651; SVA-VAS r = 0.775; SVA-ODI r = 0.762; SVA-SF36 (PH) r = 0.703). Conclusion Sagittal balance in fixed thoracic and thoracolumbar kyphosis is satisfactorily supported by changes in the curvature of adjacent parts of the spine, in contrast to lumbar deformities, in which in 75 % of cases, decompensation of the spine profile alignment occurs.