RÉSUMÉ
Objective@#To review and compare radiological parameters between degenerative lumbar kyphoscoliosis (DLKS) and degenerative lumbar kyphosis (DLK), and analyze the relationships between coronal and sagittal deformities and compensatory mechanisms of sagittal balance.@*Methods@#A total of 82 patients with lumbar degenerative deformities were enrolled for our radiographic study at Department of Spinal Surgery, Peking University People′s Hospital from January 2016 to May 2017. These patients were divided into two groups: DLKS group (39 patients) with lumbar coronal and sagittal deformities, and DLK group (43 patients) just with lumbar sagittal deformity. Complete spinopelvic radiographic parameters were compared.@*Results@#The Cobb angle and lumbar lordosis of DLKS group were (23.0±11.8)° and (18.2±12.1)°, while the lumbar lordosis of DLK group was (20.4±10.2)°. In DLKS group, Cobb angle had correlations with lumbar lordosis(r=-0.338, P=0.035), and central sacral vertical line distance had significant correlations with thoracolumbar junctional angle (r=0.488, P=0.002) . Moreover, no significant differences of all sagittal spinopelvic parameters were found between two groups (P>0.05). In DLKS group, significant correlations between lumbar lordosis and sacral slope (r=0.617, P=0.000), and correlations between lumbar lordosis and thoracic kyphosis(r=-0.363, P=0.023) were observed. In DLK group, lumbar lordosis showed significant correlations with thoracic kyphosis(r=-0.341, P=0.025) and sacral slope (r=0.772, P=0.000). According to Nash-Moe grading scale of apical vertebral rotation, 10 patients were with Ⅰ-Ⅱ grade while 29 patients with Ⅲ-Ⅴ grade in DLKS group.@*Conclusions@#Both as typical lumbar degenerative deformities, there are some correlations between scoliosis and kyphosis. However, coronal scoliosis may not influent sagittal morphological parameters for DLKS patients. Thoracic curve changes and pelvic backtilt are both important for maintaining the sagittal balance in patients with degenerative lumbar kyphoscoliosis.
RÉSUMÉ
<p><b>BACKGROUND</b>Thoracolumbar junction (TLJ) is the transitional area between the lower thoracic spine and the upper lumbar spine. Vertebral compression fractures and proximal junctional kyphosis following spine surgery often occur in this area. Therefore, the study of development and mechanisms of thoracolumbar junctional degeneration is important for planning surgical management. This study aimed to review radiological parameters of thoracolumbar junctional degenerative kyphosis (TLJDK) in patients with lumbar degenerative kyphosis and to analyze compensatory mechanisms of sagittal balance.</p><p><b>METHODS</b>From January 2016 to March 2017, patients with lumbar degenerative kyphosis were enrolled in this radiographic study. Patients were divided into two groups according to thoracolumbar junctional angle (TLJA): the non-TLJDK (NTLJDK) group (TLJA <10°) and the TLJDK group (TLJA ≥10°). Complete spinopelvic radiographic parameters were analyzed and compared between two groups. Pearson or Spearman correlation coefficients and independent two-sample t-test or Mann-Whitney U-test were used.</p><p><b>RESULTS</b>A total of 77 patients with symptomatic sagittal imbalance due to lumbar degenerative kyphosis were enrolled in this study. There were 34 patients in NTLJDK group (TLJA <10°) and 43 patients in TLJDK group (TLJA ≥10°). The median angle of lumbar lordosis (LL) in the NTLJDK or TLJDK groups was 23.40° (18.50°, 29.48°) or 19.50° (13.30°, 24.55°), respectively. The median TLJAs in all patients and both groups were -11.20° (-14.60°, -4.80°), -3.70° (-7.53°, -1.73°), and -14.30° (-17.45°, -13.00°), respectively. In the NTLJDK group, LL was correlated with thoracic kyphosis (TK; r = -0.400, P = 0.019), sacral slope (SS; r = 0.681, P < 0.001), and C7-sagittal vertical axis (r = -0.402, P = 0.018). In the TLJDK group, LL was correlated with TK (r = -0.345, P = 0.024), SS (r = 0.595, P < 0.001), and pelvic tilt (r = -0.363, P = 0.017). There were significant differences in LL, TLJA, TK, SS, and pelvic incidence (PI) between two groups.</p><p><b>CONCLUSIONS</b>Although TLJDK is common in patients with lumbar degenerative kyphosis, it might be generated by special characteristics of morphology and biomechanics of the TLJ. To maintain sagittal balance, pelvis back tilt might be more important in patients with TLJDK, whereas thoracic curve changes might be more important in patients without TLJDK.</p>