Objective:To investigate the effect of anterior and posterior selective fusion strategy on evolution of coronal pattern in patients with Lenke 5C adolescent idiopathic scoliosis (AIS) and whether upper end vertebra (UEV)-1 strategy in anterior surgery would have an effect on postoperative coronal balance.Methods:A total of 108 Lenke 5C AIS patients with at least 2 years follow-up who underwent anterior or posterior selective thoracolumbar fusion surgery from January 2005 to December 2020 were enrolled, with 51 patients in the anterior group and 57 patients in the posterior group. The patients were categorized into three groups (type A, C 7PL-CSVL<20 mm; type B, C 7PL-CSVL ≥20 mm with C 7PL toward the concave side of the main curve; and type C, C 7PL-CSVL≥20 mm with C 7PL toward the convex side of the main curve) to investigate the evolution of coronal balance of each preoperative coronal pattern at the anterior and posterior groups. Parameters such as thoracolumbar Cobb angle, rate of coronal imbalance, and SRS-22 score were recorded at preoperative, 1 week postoperatively, and final follow-up in both groups. Results:The differences of basic date between the two groups were not statistically significant except for the fusion level (5.2±0.7 vs. 5.6±0.9, t=2.497, P=0.014). In the anterior group, a total of 27 patients with preoperative type A, 23 patients with preoperative type A maintained type A at the 1 week postoperatively, and 2 of them were converted to type C at the final follow-up. Four patients with preoperative type A converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 23 patients with preoperative type C, four patients with preoperative type C maintained type C at the 1 week postoperatively, and one of them maintained type C at the final follow-up. Nineteen patients with preoperative type C converted to type A at the 1 week postoperatively, and all of them maintained type A at the final follow-up. In the posterior group, a total of 26 patients with preoperative type A, 22 patients with preoperative type A maintained type A at the 1 week postoperatively, and only 2 of these patients converted to type C at the final follow-up. Four of the preoperative type A patients converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 29 patients with preoperative type C, thirteen patients with preoperative type C maintained type C at the 1 week postoperatively, and 7 of them maintained type C at the last follow-up. Sixteen patients with preoperative type C converted to type A at the 1 week postoperatively, of whom two converted to type C at the final follow-up. For patients with preoperative type C the rate of coronal imbalance was significantly lower in the anterior group than in the posterior group both in the immediate postoperative period (17% vs. 45%, P<0.05) and at the final follow-up (4% vs. 31%, P=0.038). The rate of coronal imbalance at final follow-up was significantly lower in the UEV-1 group than in the UEV group in the posterior approach (3% vs. 38%, P<0.05), and there was no difference between the two groups in the anterior approach. There were no significant differences in radiographic parameters and SRS-22 scores between the two groups, except for the thoracic Cobb angle at the final follow-up, which was greater in the anterior group than in the posterior group at the final follow-up (19.5±7.3 vs.16.4±5.6, t=2.427, P=0.017). Multivariate logistic regression analysis revealed that anterior surgery and Risser were risk factors for postoperative CIB of preoperative type C ( OR=21.138, P=0.030 and OR=0.406, P=0.048 respectively). Conclusion:For patients with preoperative type A, both anterior and posterior procedures lead to a satisfactory reconstruction of coronal balance. In patients with preoperative type C, anterior surgery acquire a better reconstruction of coronal balance. The strategy of proximal UEV-1 was similar to the strategy of UEV in terms of restoring coronary balance in anterior approach and it was unable to lower the rate of postoperative coronal imbalance. In contrast, UEV-1 strategy in posterior surgery was effective in reducing the rate of postoperative coronal imbalance.

Objective:To evaluate the relationship between postoperative changes in femoral head coverage (FHC) after S 2-Alar-Iliac (S 2AI) screw fixation and the development of sagittal imbalance during follow-up in patients with adult spinal deformity (ASD), providing insights for clinical assessment and treatment strategies. Methods:A consecutive cohort of 98 ASD patients who underwent S2AI fixation between September 2019 and September 2021 was retrospectively analyzed. Patients were divided into two groups based on changes in femoral head coverage (ΔFHC): the FHC-C group (upper quartile ΔFHC, 25 cases) and the FHC-NC group (lower quartile ΔFHC, 24 cases). Additionally, patients were classified into proximal junctional kyphosis (PJK) and non-PJK groups based on their clinical outcomes at the last follow-up. Standing full-spine anteroposterior and lateral X-rays were taken preoperatively, postoperatively, and at the two-year follow-up to measure and document the following spinal parameters: Cobb angle, proximal lumbar lordosis (PLL), distal lumbar lordosis (DLL), lumbar lordosis (LL), lordosis distribution index (LDI), sagittal vertical axis (SVA), coronal balance distance (CBD), thoracic kyphosis (TK), T 1 pelvic angle (T 1PA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), PI-LL, and proximal junctional angle (PJA). Parameters related to hip joint coverage included: femoral head coverage (FHC), lateral center-edge angle (LCE angle), acetabular index (AI), Sharp angle, and extrusion index (EI). Comparisons of radiographic indicators between the two groups were performed at preoperative, postoperative, and final follow-up assessments. The visual analogue scale (VAS) was used to evaluate the hip pain and back pain. Results:At final follow-up, the incidence of PJK was significantly higher in the FHC-NC group [37.5% (9/24)] compared to the FHC-C group [16.0% (4/25)] (χ 2=3.952, P=0.042). Moreover, the increase in sagittal vertical axis (ΔSVA) was significantly greater in the FHC-NC group (35.9±44.7 mm vs. 14.6±31.8 mm, t=2.216, P=0.031). Patients with PJK had significantly higher preoperative T 1PA (36.8°±10.8° vs. 31.9°±18.4°, t=2.150, P=0.034) and lower immediate postoperative ΔFHC (1.7%±1.5% vs. 3.3%±2.5%, t=2.987, P=0.004), as well as lower changes in lateral center-edge angle during follow-up (0.3°±3.0° vs. 1.1°±8.9°, t=2.334, P=0.022). Pearson correlation analysis revealed significant negative correlations between postoperative ΔFHC and both ΔSVA ( r=-0.374, P=0.008) and proximal junctional angle changes (ΔPJA, r=-0.429, P=0.006). Additionally, increases in VAS leg pain scores correlated negatively with immediate postoperative FHC ( r=-0.314, P=0.025) and ΔFHC ( r=-0.298, P=0.031). Logistic regression indicated that immediate postoperative ΔFHC was a protective factor against PJK [ OR=0.722, 95% CI (0.541, 0.963), P=0.009), with a ROC-determined optimal ΔFHC cut-off of 3.90% (AUC=0.723, Youden index=0.847). Conclusions:Postoperative evaluation of femoral head coverage is clinically important for ASD patients undergoing S2AI screw fixation. A pre-to-post ΔFHC below 3.90% may indicate reduced hip compensation capacity, increasing risks for hip pain, sagittal imbalance progression, and PJK postoperatively.

Objective:To evaluate the clinical outcomes of corrective surgery in patients with different subtypes of "Ω"-type severe scoliosis.Methods:A retrospective analysis was conducted on 79 patients with "Ω"-type severe scoliosis treated at Nanjing Drum Tower Hospital from August 2010 to July 2020. The cohort included 37 males and 42 females, with a mean age of 21.4±7.4 years (range, 8-52 years). The mean duration of preoperative halo traction was 72.6±27.5 days (range, 14-150 days). Etiologies included congenital scoliosis (33 cases), idiopathic scoliosis (27 cases), Marfan syndrome (9 cases), neurofibromatosis (8 cases), and neuromuscular disorders (2 cases). Based on the classification by Karikari et al., 58 patients were classified as type 2P, 13 as type 2D, and 8 as type 2PD. Outcome measures included coronal and kyphotic Cobb angles, the Scoliosis Research Society-22 (SRS-22) questionnaire, Oswestry disability index (ODI), and visual analog scale (VAS).Results:All surgical procedures were successfully completed, and all patients were followed up for an average of 27.5±3.9 months (range, 24 to 40 months). The duration of Halo gravity traction was 72.6±27.5 days (range, 14-150 days). In the 2D group, the changes after traction were 26.0°±12.5° for the coronal Cobb angle and 10.1°±7.9° for the kyphotic Cobb angle. In the 2PD group, the traction effect was 13.4°±5.7° for the coronal and 8.3°±5.9° for the kyphotic Cobb angle. In the 2P group, the preoperative coronal Cobb angle was 128.9°±29.1°, postoperative was 84.5°±24.5°, and at the last follow-up was 87.7°±25.0°, yielding a correction rate of 34%±12%. The kyphotic Cobb angle in this group changed from 112.9°±27.1° preoperatively to 77.6°±22.9° postoperatively, and 80.2°±22.8° at the final follow-up, corresponding to a correction rate of 30%±16%. In the 2D group, the coronal Cobb angle was 113.1°±19.9° preoperatively, 71.2°±16.3° postoperatively, and 73.8°±16.3° at the final follow-up, with a correction rate of 37%±11%. The kyphotic Cobb angle in this group was 87.2°±14.0° preoperatively, 61.6°±18.5° postoperatively, and 65.1°±18.5° at the final follow-up, with a correction rate of 31%±22%. In the 2PD group, the coronal Cobb angle improved from 119.6°±29.0° preoperatively to 78.3°±20.8° postoperatively, and 87.0°±23.0° at the last follow-up, corresponding to a correction rate of 35%±8%. The kyphotic Cobb angle in this group was 124.6°±16.8° preoperatively, 82.1°±19.9° postoperatively, and 90.9°±16.9° at the final follow-up, with a correction rate of 33%±16%. At the last follow-up, SRS-22 scores across all four domains had improved in all three groups compared to preoperative values. In the 2PD group, however, the differences in the pain and self-image domains before and after surgery were not statistically significant ( P>0.05), while improvements in the other domains were significant ( P<0.05). No statistically significant differences were observed among the three groups either preoperatively or at the final follow-up ( P>0.05). Conclusion:Combined Halo-gravity traction and spinal corrective surgery are effective in improving both radiographic and functional outcomes in patients with "Ω"-type severe scoliosis. Nonetheless, patients in the 2PD subtype demonstrate reduced traction responsiveness and relatively limited postoperative recovery compared to the 2P and 2D subtypes.

Smoking is a well-established risk factor for periodontitis, yet the precise mechanisms by which smoking contributes to periodontal disease remain poorly understood. Recent advances in spatial transcriptomics have enabled a deeper exploration of the periodontal tissue microenvironment at single-cell resolution, offering new opportunities to investigate these mechanisms. In this study, we utilized Visium HD single-cell spatial transcriptomics to profile gingival tissues from 12 individuals, including those with periodontitis, those with smoking-associated periodontitis, and healthy controls. Our analysis revealed that smoking disrupts the epithelial barrier integrity, induces fibroblast alterations, and dysregulates fibroblast-epithelial cell communication, thereby exacerbating periodontitis. The spatial analysis showed that endothelial cells and macrophages are in close proximity and interact, which further promotes the progression of smoking-induced periodontal disease. Importantly, we found that targeting the endothelial CXCL12 signalling pathway in smoking-associated periodontitis reduced the proinflammatory macrophage phenotype, alleviated epithelial inflammation, and reduced alveolar bone resorption. These findings provide novel insights into the pathogenesis of smoking-associated periodontitis and highlight the potential of targeting the endothelial-macrophage interaction as a therapeutic strategy. Furthermore, this study establishes an essential information resource for investigating the effects of smoking on periodontitis, providing a foundation for future research and therapeutic development for this prevalent and debilitating disease.
Humans ; Gingiva/cytology* ; Smoking/adverse effects* ; Male ; Periodontitis/pathology* ; Single-Cell Analysis ; Female ; Adult ; Middle Aged ; Macrophages ; Fibroblasts ; Endothelial Cells ; Case-Control Studies ; Chemokine CXCL12/metabolism*

Objective:To investigate the effect of anterior and posterior selective fusion strategy on evolution of coronal pattern in patients with Lenke 5C adolescent idiopathic scoliosis (AIS) and whether upper end vertebra (UEV)-1 strategy in anterior surgery would have an effect on postoperative coronal balance.Methods:A total of 108 Lenke 5C AIS patients with at least 2 years follow-up who underwent anterior or posterior selective thoracolumbar fusion surgery from January 2005 to December 2020 were enrolled, with 51 patients in the anterior group and 57 patients in the posterior group. The patients were categorized into three groups (type A, C 7PL-CSVL<20 mm; type B, C 7PL-CSVL ≥20 mm with C 7PL toward the concave side of the main curve; and type C, C 7PL-CSVL≥20 mm with C 7PL toward the convex side of the main curve) to investigate the evolution of coronal balance of each preoperative coronal pattern at the anterior and posterior groups. Parameters such as thoracolumbar Cobb angle, rate of coronal imbalance, and SRS-22 score were recorded at preoperative, 1 week postoperatively, and final follow-up in both groups. Results:The differences of basic date between the two groups were not statistically significant except for the fusion level (5.2±0.7 vs. 5.6±0.9, t=2.497, P=0.014). In the anterior group, a total of 27 patients with preoperative type A, 23 patients with preoperative type A maintained type A at the 1 week postoperatively, and 2 of them were converted to type C at the final follow-up. Four patients with preoperative type A converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 23 patients with preoperative type C, four patients with preoperative type C maintained type C at the 1 week postoperatively, and one of them maintained type C at the final follow-up. Nineteen patients with preoperative type C converted to type A at the 1 week postoperatively, and all of them maintained type A at the final follow-up. In the posterior group, a total of 26 patients with preoperative type A, 22 patients with preoperative type A maintained type A at the 1 week postoperatively, and only 2 of these patients converted to type C at the final follow-up. Four of the preoperative type A patients converted to type C at the 1 week postoperatively, and all of them returned to type A at the final follow-up. A total of 29 patients with preoperative type C, thirteen patients with preoperative type C maintained type C at the 1 week postoperatively, and 7 of them maintained type C at the last follow-up. Sixteen patients with preoperative type C converted to type A at the 1 week postoperatively, of whom two converted to type C at the final follow-up. For patients with preoperative type C the rate of coronal imbalance was significantly lower in the anterior group than in the posterior group both in the immediate postoperative period (17% vs. 45%, P<0.05) and at the final follow-up (4% vs. 31%, P=0.038). The rate of coronal imbalance at final follow-up was significantly lower in the UEV-1 group than in the UEV group in the posterior approach (3% vs. 38%, P<0.05), and there was no difference between the two groups in the anterior approach. There were no significant differences in radiographic parameters and SRS-22 scores between the two groups, except for the thoracic Cobb angle at the final follow-up, which was greater in the anterior group than in the posterior group at the final follow-up (19.5±7.3 vs.16.4±5.6, t=2.427, P=0.017). Multivariate logistic regression analysis revealed that anterior surgery and Risser were risk factors for postoperative CIB of preoperative type C ( OR=21.138, P=0.030 and OR=0.406, P=0.048 respectively). Conclusion:For patients with preoperative type A, both anterior and posterior procedures lead to a satisfactory reconstruction of coronal balance. In patients with preoperative type C, anterior surgery acquire a better reconstruction of coronal balance. The strategy of proximal UEV-1 was similar to the strategy of UEV in terms of restoring coronary balance in anterior approach and it was unable to lower the rate of postoperative coronal imbalance. In contrast, UEV-1 strategy in posterior surgery was effective in reducing the rate of postoperative coronal imbalance.

Objective:To evaluate the relationship between postoperative changes in femoral head coverage (FHC) after S 2-Alar-Iliac (S 2AI) screw fixation and the development of sagittal imbalance during follow-up in patients with adult spinal deformity (ASD), providing insights for clinical assessment and treatment strategies. Methods:A consecutive cohort of 98 ASD patients who underwent S2AI fixation between September 2019 and September 2021 was retrospectively analyzed. Patients were divided into two groups based on changes in femoral head coverage (ΔFHC): the FHC-C group (upper quartile ΔFHC, 25 cases) and the FHC-NC group (lower quartile ΔFHC, 24 cases). Additionally, patients were classified into proximal junctional kyphosis (PJK) and non-PJK groups based on their clinical outcomes at the last follow-up. Standing full-spine anteroposterior and lateral X-rays were taken preoperatively, postoperatively, and at the two-year follow-up to measure and document the following spinal parameters: Cobb angle, proximal lumbar lordosis (PLL), distal lumbar lordosis (DLL), lumbar lordosis (LL), lordosis distribution index (LDI), sagittal vertical axis (SVA), coronal balance distance (CBD), thoracic kyphosis (TK), T 1 pelvic angle (T 1PA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), PI-LL, and proximal junctional angle (PJA). Parameters related to hip joint coverage included: femoral head coverage (FHC), lateral center-edge angle (LCE angle), acetabular index (AI), Sharp angle, and extrusion index (EI). Comparisons of radiographic indicators between the two groups were performed at preoperative, postoperative, and final follow-up assessments. The visual analogue scale (VAS) was used to evaluate the hip pain and back pain. Results:At final follow-up, the incidence of PJK was significantly higher in the FHC-NC group [37.5% (9/24)] compared to the FHC-C group [16.0% (4/25)] (χ 2=3.952, P=0.042). Moreover, the increase in sagittal vertical axis (ΔSVA) was significantly greater in the FHC-NC group (35.9±44.7 mm vs. 14.6±31.8 mm, t=2.216, P=0.031). Patients with PJK had significantly higher preoperative T 1PA (36.8°±10.8° vs. 31.9°±18.4°, t=2.150, P=0.034) and lower immediate postoperative ΔFHC (1.7%±1.5% vs. 3.3%±2.5%, t=2.987, P=0.004), as well as lower changes in lateral center-edge angle during follow-up (0.3°±3.0° vs. 1.1°±8.9°, t=2.334, P=0.022). Pearson correlation analysis revealed significant negative correlations between postoperative ΔFHC and both ΔSVA ( r=-0.374, P=0.008) and proximal junctional angle changes (ΔPJA, r=-0.429, P=0.006). Additionally, increases in VAS leg pain scores correlated negatively with immediate postoperative FHC ( r=-0.314, P=0.025) and ΔFHC ( r=-0.298, P=0.031). Logistic regression indicated that immediate postoperative ΔFHC was a protective factor against PJK [ OR=0.722, 95% CI (0.541, 0.963), P=0.009), with a ROC-determined optimal ΔFHC cut-off of 3.90% (AUC=0.723, Youden index=0.847). Conclusions:Postoperative evaluation of femoral head coverage is clinically important for ASD patients undergoing S2AI screw fixation. A pre-to-post ΔFHC below 3.90% may indicate reduced hip compensation capacity, increasing risks for hip pain, sagittal imbalance progression, and PJK postoperatively.

Objective:To evaluate the clinical outcomes of corrective surgery in patients with different subtypes of "Ω"-type severe scoliosis.Methods:A retrospective analysis was conducted on 79 patients with "Ω"-type severe scoliosis treated at Nanjing Drum Tower Hospital from August 2010 to July 2020. The cohort included 37 males and 42 females, with a mean age of 21.4±7.4 years (range, 8-52 years). The mean duration of preoperative halo traction was 72.6±27.5 days (range, 14-150 days). Etiologies included congenital scoliosis (33 cases), idiopathic scoliosis (27 cases), Marfan syndrome (9 cases), neurofibromatosis (8 cases), and neuromuscular disorders (2 cases). Based on the classification by Karikari et al., 58 patients were classified as type 2P, 13 as type 2D, and 8 as type 2PD. Outcome measures included coronal and kyphotic Cobb angles, the Scoliosis Research Society-22 (SRS-22) questionnaire, Oswestry disability index (ODI), and visual analog scale (VAS).Results:All surgical procedures were successfully completed, and all patients were followed up for an average of 27.5±3.9 months (range, 24 to 40 months). The duration of Halo gravity traction was 72.6±27.5 days (range, 14-150 days). In the 2D group, the changes after traction were 26.0°±12.5° for the coronal Cobb angle and 10.1°±7.9° for the kyphotic Cobb angle. In the 2PD group, the traction effect was 13.4°±5.7° for the coronal and 8.3°±5.9° for the kyphotic Cobb angle. In the 2P group, the preoperative coronal Cobb angle was 128.9°±29.1°, postoperative was 84.5°±24.5°, and at the last follow-up was 87.7°±25.0°, yielding a correction rate of 34%±12%. The kyphotic Cobb angle in this group changed from 112.9°±27.1° preoperatively to 77.6°±22.9° postoperatively, and 80.2°±22.8° at the final follow-up, corresponding to a correction rate of 30%±16%. In the 2D group, the coronal Cobb angle was 113.1°±19.9° preoperatively, 71.2°±16.3° postoperatively, and 73.8°±16.3° at the final follow-up, with a correction rate of 37%±11%. The kyphotic Cobb angle in this group was 87.2°±14.0° preoperatively, 61.6°±18.5° postoperatively, and 65.1°±18.5° at the final follow-up, with a correction rate of 31%±22%. In the 2PD group, the coronal Cobb angle improved from 119.6°±29.0° preoperatively to 78.3°±20.8° postoperatively, and 87.0°±23.0° at the last follow-up, corresponding to a correction rate of 35%±8%. The kyphotic Cobb angle in this group was 124.6°±16.8° preoperatively, 82.1°±19.9° postoperatively, and 90.9°±16.9° at the final follow-up, with a correction rate of 33%±16%. At the last follow-up, SRS-22 scores across all four domains had improved in all three groups compared to preoperative values. In the 2PD group, however, the differences in the pain and self-image domains before and after surgery were not statistically significant ( P>0.05), while improvements in the other domains were significant ( P<0.05). No statistically significant differences were observed among the three groups either preoperatively or at the final follow-up ( P>0.05). Conclusion:Combined Halo-gravity traction and spinal corrective surgery are effective in improving both radiographic and functional outcomes in patients with "Ω"-type severe scoliosis. Nonetheless, patients in the 2PD subtype demonstrate reduced traction responsiveness and relatively limited postoperative recovery compared to the 2P and 2D subtypes.

Objective: To establish a novel classification system for predicting the risk of intraoperative neurophysiological monitoring (IONM) events in surgically-treated patients with kyphotic deformity. Methods: Patients with kyphotic deformity who underwent surgical correction of cervicothoracic, thoracic, or thoracolumbar kyphosis in our center from July 2005 to December 2020 were recruited. We proposed a classification system to describe the morphology of the spinal cord on T2-weighted sagittal magnetic resonance imaging: type A, circular/symmetric cord with visible cerebrospinal fluid (CSF) between the cord and vertebral body; type B, circular/oval/symmetric cord with no visible CSF between the cord and vertebral body; type C, spinal cord that is fattened/deformed by the vertebral body, with no visible CSF between the cord and vertebral body. Furthermore, based on type C, the spinal cord compression ratio (CR) < 50% was defined as the subtype C-, while the spinal cord CR ≥ 50% was defined as the subtype C+. IONM event was documented, and a comparative analysis was made to evaluate the prevalence of IONM events among patients with diverse spinal cord types. Results: A total of 294 patients were reviewed, including 73 in type A; 153 in type B; 53 in subtype C- and 15 in subtype C+. Lower extremity transcranial motor-evoked potentials and/or somatosensory evoked potentials were lost intraoperatively in 41 cases (13.9%), among which 4 patients with type C showed no return of spinal cord monitoring data. The 14 subtype C+ patients (93.3%) had IONM events. Univariate logistic regression analysis showed that patients with a type C spinal cord (subtype C-: odds ratio [OR], 10.390; 95% confidence interval [CI], 2.215–48.735; p = 0.003; subtype C+, OR, 497.000; 95% CI, 42.126– 5,863.611; p < 0.001) are at significantly higher risk of a positive IONM event during deformity correction compared to those with a type A. In further multiple logistic regression analysis, the spinal cord classification (OR, 5.371; 95% CI, 2.966–9.727; p < 0.001) was confirmed as an independent risk factor for IONM events. Conclusion We presented a new spinal cord classification system based on the relative position of the spinal cord and vertebrae to predict the risk of IONM events in patients with kyphotic deformity. In patients with type C spinal cord, especially those in C+ cases, it is essential to be aware of potential IONM events, and adopt standard operating procedures to facilitate neurological recovery.

Objective: To explore the changes in coronal imbalance (CIB) in Lenke 5C adolescent idiopathic scoliosis (AIS) after posterior selective fusion surgery and determine their implications for surgical decision-making. Methods: One hundred twenty patients were categorized according to the preoperative coronal pattern (type A, coronal balance distance [CBD]<20 mm; type B, CBD≥20 mm and coronal C7 plumbline [C7PL] shifted to the concave side of the curve; type C, CBD≥20 mm and C7PL shifted to the convex side of the curve). CIB group (CIB+) was defined as having a CBD≥20 mm at the 2-year follow-up. Results: Compared to type A patients, the prevalence of postoperative CIB was higher in type C patients both immediately postoperative (22% vs. 38%, p<0.05) and at the final follow-up (5% vs. 29%, p<0.05), whereas type A patients showed a greater improvement in CBD (9 of 12 vs. 6 of 24, p<0.05) at the final follow-up. The majority of patients in all groups had recovered to type A at the final follow-up (96 of 120). The proximal Cobb-1 strategy reduced the incidence of postoperative CIB (1 of 38) at the 2-year follow-up, especially in preoperative type C patients. Multivariate logistic regression analysis revealed that type C and overcorrection of the thoracolumbar curve were risk factors for CIB at the 2-year follow-up (p=0.007 and p=0.026, respectively). Conclusion Patients with type C CIB in AIS exhibited unsatisfactory restoration, with 29% of them exhibiting CIB at the final follow-up. The selective fusion strategy of proximal Cobb-1 may reduce the risk of postoperative CIB especially when the preoperative coronal pattern is type C.

Objective: To establish a novel classification system for predicting the risk of intraoperative neurophysiological monitoring (IONM) events in surgically-treated patients with kyphotic deformity. Methods: Patients with kyphotic deformity who underwent surgical correction of cervicothoracic, thoracic, or thoracolumbar kyphosis in our center from July 2005 to December 2020 were recruited. We proposed a classification system to describe the morphology of the spinal cord on T2-weighted sagittal magnetic resonance imaging: type A, circular/symmetric cord with visible cerebrospinal fluid (CSF) between the cord and vertebral body; type B, circular/oval/symmetric cord with no visible CSF between the cord and vertebral body; type C, spinal cord that is fattened/deformed by the vertebral body, with no visible CSF between the cord and vertebral body. Furthermore, based on type C, the spinal cord compression ratio (CR) < 50% was defined as the subtype C-, while the spinal cord CR ≥ 50% was defined as the subtype C+. IONM event was documented, and a comparative analysis was made to evaluate the prevalence of IONM events among patients with diverse spinal cord types. Results: A total of 294 patients were reviewed, including 73 in type A; 153 in type B; 53 in subtype C- and 15 in subtype C+. Lower extremity transcranial motor-evoked potentials and/or somatosensory evoked potentials were lost intraoperatively in 41 cases (13.9%), among which 4 patients with type C showed no return of spinal cord monitoring data. The 14 subtype C+ patients (93.3%) had IONM events. Univariate logistic regression analysis showed that patients with a type C spinal cord (subtype C-: odds ratio [OR], 10.390; 95% confidence interval [CI], 2.215–48.735; p = 0.003; subtype C+, OR, 497.000; 95% CI, 42.126– 5,863.611; p < 0.001) are at significantly higher risk of a positive IONM event during deformity correction compared to those with a type A. In further multiple logistic regression analysis, the spinal cord classification (OR, 5.371; 95% CI, 2.966–9.727; p < 0.001) was confirmed as an independent risk factor for IONM events. Conclusion We presented a new spinal cord classification system based on the relative position of the spinal cord and vertebrae to predict the risk of IONM events in patients with kyphotic deformity. In patients with type C spinal cord, especially those in C+ cases, it is essential to be aware of potential IONM events, and adopt standard operating procedures to facilitate neurological recovery.