Nrf-2/ROS/NF-κB pathway is modulated by cynarin in human mesenchymal stem cells in vitro from ankylosing spondylitis.

Ankylosing spondylitis (AS) is an immune chronic inflammatory disease, resulting in back pain, stiffness, and thoracolumbar kyphotic deformity. Based on the reported anti-inflammatory and antioxidant capacities of cynarin (Cyn), this study explored its protective role and molecular mechanisms in mesenchymal stem cells (MSCs) from AS. The target pathways and genes were verified using Western blotting, quantitative real-time polymerase chain reaction, and immunofluorescent staining, while molecular docking analysis was conducted. In AS-MSCs, we found that the expression levels of p-NF-κB, IL-6, IL-1ß, and TNF-α were higher and IκB-α, Nrf-2, and HO-1 were lower compared with healthy control (HC)-MSCs. With molecular docking analysis, the biding affinities between Cyn and Keap1-Nrf-2 and p65-IκB-α were predicted. The mRNA and protein expression of p-NF-κB, IL-6, IL-1ß, and TNF-α and the reactive oxygen species (ROS) generation were downregulated following Cyn administration. Meanwhile, the expression level of IκB-α, Nrf-2, and HO-1 were significantly increased after Cyn pretreatment. The results suggested that the protective mechanisms of Cyn in AS-MSCs were based on enhancing the antioxidation and suppression of excessive inflammatory responses via Nrf-2/ROS/NF-κB axis. Our findings demonstrate that Cyn is a potential candidate for alleviating inflammation in AS.

The Use of Osteobiologics in Single versus Multi-Level Anterior Cervical Discectomy and Fusion: A Systematic Review.

STUDY DESIGN: Systematic literature review. OBJECTIVES: In this study we assessed evidence for the use of osteobiologics in single vs multi-level anterior cervical discectomy and fusion (ACDF) in patients with cervical spine degeneration. The primary objective was to compare fusion rates after single and multi-level surgery with different osteobiologics. Secondary objectives were to compare differences in patient reported outcome measures (PROMs) and complications. METHODS: After a global team of reviewers was selected, a systematic review using different repositories was performed, confirming to PRISMA and GRADE guidelines. In total 1206 articles were identified and after applying inclusion and exclusion criteria, 11 articles were eligible for analysis. Extracted data included fusion rates, definition of fusion, patient reported outcome measures, types of osteobiologics used, complications, adverse events and revisions. RESULTS: Fusion rates ranged from 87.7% to 100% for bone morphogenetic protein 2 (BMP-2) and 88.6% to 94.7% for demineralized bone matrix, while fusion rates reported for other osteobiologics were lower. All included studies showed PROMs improved significantly for each osteobiologic. However, no differences were reported when comparing osteobiologics, or when comparing single vs multi-level surgery specifically. CONCLUSION: The highest fusion rates after 2-level ACDF for cervical spine degeneration were reported when BMP-2 was used. However, PROMs did not differ between the different osteobiologics. Further blinded randomized trials should be performed to compare the use of BMP-2 in single vs multi-level ACDF specifically.

Is the pelvic incidence a determinant factor for kyphosis curve patterns of ankylosing spondylitis patients?

To investigate the influence of pelvic incidence (PI) on the kyphosis curve patterns and clinical outcomes in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis and to construct a classification of AS according to the PI value for surgical decision-making. 107 AS patients underwent single-level lumbar pedicle subtraction osteotomy (PSO) and finished a minimal of 2-year follow-up. All patients were divided into three groups: low PI (PI ≤ 40°), moderate PI (40° < PI ≤ 60°), and high PI (PI > 60°). Standing lateral radiographs were taken to evaluate the location of kyphotic apex, thoracic kyphosis (TK), lumbar lordosis (LL), C7 sagittal vertical axis (SVA), spino-sacral angle (SSA), global kyphosis (GK), PI, sacral slope (SS), and pelvic tilt (PT). Visual Analogue Scale (VAS) score, Oswestry Disability Index (ODI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were used to evaluate quality of life. Before surgery, a significant difference was shown in the average LL and the mean GK in high PI group was the largest among the three groups. Correction of SVA, GK and LL in high PI group was the smallest among the three group. No significant difference in clinical outcomes was found among the three groups before surgery and at the final follow-up. Regarding the preoperative sagittal profile, the kyphosis curve pattern of moderate PI group is similar to that of low PI group. For AS patients in these two groups, harmonious sagittal alignment can be restored by a single-level PSO. However, the sagittal imbalance is insufficiently realigned by a single-level PSO in a patient with high PI.

Junctional Kyphosis after Correction with Long Instrumentation for Late Posttraumatic Thoracolumbar Kyphosis: Characteristics and Risk Factors.

OBJECTIVE: Junctional kyphosis is a common complication after corrective long spinal fusion for adult spinal deformity. Whereas there is still a paucity of data on junctional kyphosis, specifically among late posttraumatic thoracolumbar kyphosis (LPTK) patients. Thus, the aim of this study was to investigate the characteristics and risk factors of junctional kyphosis in LPTK patients receiving long segmental instrumented fusion. METHODS: We retrospectively reviewed a cohort of LPTK patients who had received long segmental instrumented fusion (>4 segments) in our center between January 2012 and January 2019. Radiographic assessments included the sagittal alignment, pelvic parameters, bone quality on CT images, and measurements of the cross-sectional area (CSA, cross-sectional area of muscle-vertebral body ratio × 100) and fat saturation fraction (FSF, cross-sectional area of fat-muscle body ratio × 100) of paraspinal muscles. Patients in this study were divided into those with junctional kyphosis or failure (Group J) and those without (Group NJ) during follow-up. Group J included patients with junctional kyphosis (Group JK) and patients with junctional failure (Group JF). RESULTS: A total of 65 patients (16 males and 49 females, average age 56.5 ± 23.4 years) were enrolled in this study. After (32.7 ± 8.5) months follow-up, 15 patients (23.1%) experienced junctional kyphosis, and four of them deteriorated into junctional failure. Eighty percent (12/15) of junctional kyphosis was identified within 6 months after surgery. In comparison with Group NJ, Group J were older (P = 0.026), longer fusion levels (P < 0.001), greater thoracic kyphosis (P = 0.01), greater global kyphosis (P = 0.023), lower bone quality (P < 0.001), less CSA (P = 0.005) and higher FSF (P <0.001) of paraspinal muscles. Preoperative global kyphosis more than 48.5° (P = 0.001, odds ratio 1.793) and FSF more than 48.4 (P = 0.010, odds ratio 2.916) were identified as independent risk factors of junctional kyphosis. Based on the statistical differences among Group NJ, Group JK and Group JF (P < 0.001), Group JF had lower bone quality than Group NJ (P < 0.001) and Group JK (P = 0.015). In terms of patient-reported outcomes, patients in Group JF had worse outcomes in ODI and VAS scores, and PCS and MCS of SF-36 than Group NJ and group JK CONCLUSION: The prevalence of junctional kyphosis was 23.1% in LPTK patients after long segmental instrumented fusion. Preoperative hyperkyphosis and advanced fatty degeneration of paraspinal muscles were independent risk factors of junctional kyphosis. Patients with lower bone quality were more likely to develop junctional failure.

Remodeling morphology of the subluxated osteotomy vertebra in closing-opening wedge osteotomy in ankylosing spondylitis: would the anterior bony beak blunt?

INTRODUCTION: To investigate the remodeling morphology of subluxated osteotomy vertebra in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis after single-level closing-opening wedge osteotomy (COWO). MATERIALS AND METHODS: Standing lateral radiographs were taken to evaluate sagittal parameters including lumbar lordosis (LL), C7 sagittal vertical axis (SVA), global kyphosis (GK), sacral slope (SS), and pelvic tilt (PT). Radiographic parameters of the osteotomy vertebra included osteotomized vertebra angle (OVA), sagittal translation (ST), anterior height (AH), posterior height (PH), and middle height (MH) of the osteotomy vertebrae. Furthermore, lateral projection area of the vertebral body was also measured to evaluate the remodeling of the osteotomy vertebrae. RESULTS: Sixty AS patients who underwent single-level lumbar COWO with a minimal 2-year follow-up were included. The cohort consisted of 54 males and 6 females with an average age of 36.6 years. All patients were divided into two groups according to the development of vertebral subluxation (VS): 15 in VS group (ST ≥ 5 mm), 45 in non-VS group (ST < 5 mm). There was significant difference in the correction of GK, SVA, and the loss of correction of SVA between AS patients with and without VS. Significant difference in vertebra-related parameters regarding AH and OVA was found between VS group and non-VS group (P < 0.05). CONCLUSIONS: After COWO, new bone formation narrowing the gap and adaptive resorption of the anterior bony beak at the osteotomy level during follow-up was surprisingly favorable. However, the ability of spinal canal remodeling is limited in patients complicated with VS.

Pedicle Morphology of Lower Thoracic and Lumbar Spine in Ankylosing Spondylitis Patients with Thoracolumbar Kyphosis: A Comparison with Fracture Patients.

OBJECTIVE: The pedicle morphology of ankylosing spondylitis (AS)-related thoracolumbar kyphosis patients may be different from that of individuals with normal spine due to the ectopic ossification and kyphotic deformity. However, there was no literature analyzing the pedicle morphology of AS patients with thoracolumbar kyphosis. Therefore, the present study aimed to investigate the pedicle morphology of lower thoracic and lumbar spine (T9-L5) in ankylosing spondylitis (AS)-related thoracolumbar kyphosis patients. METHODS: A retrospective review of AS patients with thoracolumbar kyphosis (AS group) and the patients with spinal or rib fracture (fracture group) who underwent CT scans of the lower thoracic and lumbar spine between February 2017 and September 2018 was performed. Patients with spinal tumor, spinal tuberculosis, severe degenerative spinal diseases including degenerative scoliosis, degenerative spondylolisthesis, degenerative spinal stenosis or history of previous spine surgery, or AS patients with pseudarthrosis which influenced the measurement of pedicle parameters were excluded. The measured parameters on CT images included transverse pedicle angle (TPA), transverse pedicle width (TPW), chord length (CL), pedicle length (PL), and sagittal pedicle angle (SPA). The intraclass correlation coefficient (ICC) was used to evaluate the agreement of radiographic parameters between observers. The independent sample t test was applied for the comparison of pedicle parameters between the two groups. The gender distribution between the two groups were compared using the Fisher's exact test. RESULTS: A total of 1444 pedicles of 53 AS-related thoracolumbar kyphosis patients and 30 patients with fracture were analyzed. TPA was significantly smaller in AS group (p < 0.05). Significantly larger TPW was found in AS group in the lumbar spine (p < 0.05). TPW ≥ 7.5 mm was observed in 95.3%-98.1% of the pedicles at the levels of L3-L5 in AS group. The CL and PL were significantly larger in AS group at the levels of T9-L5 (p < 0.05). The CL ≥ 50 mm was found in 84.0%-96.2% of the pedicles in mid-to-lower lumbar spine in AS group. Significantly smaller SPA was found in AS group at the levels from L3 to L5 (p < 0.05). CONCLUSIONS: Pedicle screws with relatively large diameter of 7.5 mm and length of 50 mm could be used in mid-to-lower lumbar spine in the majority of AS-related thoracolumbar kyphosis patients. Also, the insertion angle of pedicle screws in both the transverse and sagittal plane should be appropriately reduced in these patients. This study may help surgeons select the pedicle screws of appropriate size in AS patients.

Scoliosis: an unusual clinical presentation of paraspinal ganglioneuroma.

PURPOSE: To comprehensively present the clinical characteristics and treatment strategies in patients with scoliosis secondary to ganglioneuroma (S-GN). METHODS: Six patients with S-GN treated surgically at a median age of 12 years were retrospectively reviewed and the median follow-up period was 6 years (4-14 years). The radiological features of GN and the associated scoliosis were evaluated. The surgical strategies and the corresponding outcomes were investigated. RESULTS: All patients had a delayed diagnosis age of GN than scoliosis (12 vs. 9 years). GN was located at the posterior mediastinum in four patients (66.7%) and at retroperitoneum in two, respectively. Tumor occupancies were frequently detected on the X-ray films for four patients (66.7%), being uniformly on the convexity of the main curve. All patients complained of rapid progressive deformities during the growth period. Five patients (83.3%) received total tumor resections, one accepted partial resection. Deformity correction was implemented for all patients with an average rate of 66.4% on the main curve. No recurrence of the GN was detected for all totally tumor-resected patients at the latest follow-up. CONCLUSION: S-GN is often misdiagnosed clinically. Paravertebral mass neighboring the apex of scoliosis can be meticulously detected from the X-ray films. Total tumor resection should be aggressively performed if possible. The deformity correction could be satisfactorily obtained and the risk of recurrence of the GN was relatively low.

Improvement of Pulmonary Function in Arthrogryposis Multiplex Congenita Patients Undergoing Posterior Spinal Fusion Surgery for Concomitant Scoliosis: A Minimum of 3-Year Follow-up.

OBJECTIVE: We sought to investigate the long-term outcome of pulmonary function for arthrogryposis multiplex congenita (AMC) patients undergoing posterior spinal fusion (PSF) and to further determine influential factors. METHODS: Eighteen AMC patients with a minimum of 3-year follow-up after PSF were prospectively collected. All the patients underwent a pulmonary function test before surgery and at the final follow-up. The percentage predicted values of vital capacity (VC%) and forced vital capacity (FVC%) were recorded. The following radiographic parameters were collected including Cobb angle and thoracic kyphosis. The total lung volumes (TLV) were measured on the image of 3-dimensional computed tomography scan by the reconstruction software. RESULTS: There were 10 males and 8 females with a mean age of 13.8 ± 6.1 years. The mean preoperative VC% and FVC% were 40.5% ± 7.6% and 39.5% ± 4.7%, which were significantly increased to 52.0% ± 7.5% and 51.2% ± 6.8% at the final follow-up (P < 0.001). Besides, there was remarkable improvement in terms of TLV (1.57 ± 0.2 L vs. 2.39 ± 0.6 L, P < 0.001). Remarkable correlations were observed between TLV and pulmonary function tests (r = 0.79, P < 0.001 for VC%; r = 0.78, P < 0.001 for FVC%). Multiple regression analysis showed that 2 variables including Δ thoracic kyphosis and Δ Cobb angle were independently associated with the improvement of pulmonary function. CONCLUSIONS: The pulmonary function of AMC patients can be well improved through PSF surgery. It was remarkably associated with the correction of curve magnitude and restoration of thoracic kyphosis.

Does the Level of Pedicle Subtraction Osteotomy Affect the Surgical Outcomes in Ankylosing Spondylitis-Related Thoracolumbar Kyphosis With the Same Curve Pattern?

STUDY DESIGN: A retrospective study. OBJECTIVE: To investigate the effect of pedicle subtraction osteotomy (PSO) level on the surgical outcomes in ankylosing spondylitis-related thoracolumbar kyphosis with the same curve pattern. METHODS: ankylosing spondylitis (AS) patients with thoracolumbar kyphosis, who underwent 1-level lumbar PSO between March 2006 and June 2017, were retrospectively reviewed. Criteria for curve-matched thoracolumbar kyphosis were: (1) have same level of preoperative apex (pre-apex); (2) have similar global kyphosis (GK, the angle between the superior/inferior endplate of the maximally tilted upper and lower end vertebra) (the difference of GK less than 15˚). The radiographic parameters measured were sagittal vertical axis (SVA, the horizontal distance between the C7 plumb line and the posterosuperior corner of the S1), GK, thoracic kyphosis (TK, the angle between the T5 superior endplate and the T12 inferior endplate), lumbar lordosis (LL, the angle between the L1 and S1 superior endplate), sacral slope (SS, the angle between the sacral endplate and the horizontal line), pelvic tilt (PT, the angle between the vertical and the line joining the midpoint of the sacral plate and hip axis), and pelvic incidence (PI, the angle between the line vertical to the superior margin of S1 and the line connecting the sacral plate midpoint with the hip joint axis). All of these parameters and health-related quality of life (HRQoL, evaluated by preoperative and the last follow-up questionnaires including ODI and VAS) scores were collected before surgery and at the last follow-up. According to their osteotomy level, patients were devided into 2 sub-groups (L1 group and L2 group), and differences of these mentioned parameters between 2 groups were compared. RESULTS: 26 curve-matched patients were recruited with a mean follow-up of 37.2 months. All patients improved significantly after surgery in HRQoL scores (VAS 1.6 vs 5.4, P < 0.001; ODI 11.9 vs 26.4, P < 0.001). Except for TK and PI, those radiographic parameters were also observed to be significantly changed after surgery. Compared to L2 group, PSO at L1 may have larger correction of TK (ΔTK -6.8 vs -0.3°, P = 0.164), PI (ΔPI -7.4 vs -0.7°, P = 0.364) and smaller correction of SVA (ΔSVA -105.3 vs -128.5 mm, P = 0.096), LL (ΔLL -31.1 vs -43.0°, P = 0.307) and SS (ΔSS 6.9 vs 12.2°, P = 0.279) but had no statistical significance. CONCLUSION: The results of this investigation showed that in AS-related thoracolumbar kyphosis patients with the same curve pattern, the different levels of osteotomy had little effect on the improvement of surgical outcomes. However, osteotomy at L2 is more likely to obtain a larger correction of SVA compared to osteotomy at L1.

Low expression of TCP1 (T-Complex 1) and PSMC1 (Proteasome 26S subunit, ATPase 1) in heterotopic ossification during ankylosing spondylitis.

Heterotopic ossification (HO) is frequently seen in patients with spinal injuries. Therefore, this study aimed to characterize the association of HO with ankylosing spondylitis (AS) through gene expression profiling. The human transcriptomic datasets (GSE73754 and GSE94683) were obtained from the Gene Expression Omnibus database for analysis. Overlapping differentially expressed genes (DEGs) were identified between AS and HO disease states. Subsequently, weighted gene co-expression network analysis (WGCNA) was performed for constructing and identifying hub genes for each condition. Finally, a consensus of the overlapping DEGs and the hub genes in AS and HO was taken for determining the key genes involved in AS-induced HO. Quantitative real-time polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels in mesenchymal stem cells of AS patients and controls. Additionally, immunohistochemistry was performed on interspinous ligament samples for experimental validation of genes. DEG analysis identified 355 overlapping genes between HO and AS. WGCNA indicated that the salmon module of the 22 modules constructed, was most significantly correlated with AS-induced HO. Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of the salmon module indicated the presence of genes enriched in proteasome regulatory particle and proteasome pathways. mRNA expression analysis identified TCP1 and PSMC1 as the key genes in AS-induced HO. Further validation of these genes could help elucidate their role in the complex association of AS and HO.

Failure patterns and related risk factors of sagittal reconstruction following pedicle subtraction osteotomy in patients with ankylosing spondylitis and thoracolumbar kyphosis.

OBJECTIVE: The aim of this study was to analyze the specific patterns and risk factors of sagittal reconstruction failure in ankylosing spondylitis (AS)-related thoracolumbar kyphosis after pedicle subtraction osteotomy (PSO). METHODS: A retrospective study was performed in patients with AS and thoracolumbar kyphosis after lumbar PSO with a minimum follow-up of 2 years. Patients were classified as having successful realignment (group A), inadequate correction immediately postoperatively (group B), and sagittal decompensation during follow-up (group C) according to the immediately postoperative and latest follow-up sagittal vertical axis (SVA). Radiographic parameters and clinical outcomes were collected. Pelvic tilt (PT) was used to assess the magnitude of pelvic backward rotation. Hip structural damage and ossification of the anterior longitudinal ligament (ALL) at the proximal junction, PSO level, and distal junction were also evaluated on radiographs. RESULTS: Overall, 109 patients with a mean age of 35.3 years were included. Patients in both group B (n = 16) and group C (n = 13) were older than those in group A (n = 80) (mean ages 43.6 vs 32.9 years, p < 0.011; and 39.2 vs 32.9 years, p = 0.018; respectively). Age (OR 1.102, p = 0.011), and preoperative PT (OR 1.171, p = 0.041) and SVA (OR 1.041, p = 0.016) were identified as independent risk factors of inadequate correction. Additionally, a higher distribution of patients with adequate ALL ossification at the PSO level was found in group B than in group A (37.5% vs 22.5%, p = 0.003). Age (OR 1.101, p = 0.011) and preoperative SVA (OR 1.013, p = 0.020) were identified as independent risk factors of sagittal decompensation. Furthermore, compared with group A, group C showed a higher distribution of patients with severe hip structural damage (15.4% vs 0, p = 0.018) and higher incidences of rod fracture (RF) (38.5% vs 8.8%, p = 0.011) and pseudarthrosis (15.4% vs 0, p = 0.018). Additionally, the incidence of RF (19.6% vs 6.9%, p = 0.045) and changes in the proximal junctional angle (0.5° vs 2.2°, p = 0.027) and the distal junctional angle (0.3° vs 2.2°, p = 0.019) were lower during follow-up in patients with adequate ALL ossification than in those without adequate ossification. CONCLUSIONS: Sagittal reconstruction failure in patients with AS could be attributed to inadequate correction immediately after surgery (14.7%) and sagittal decompensation during follow-up (11.9%). Adequate ALL ossification was a risk factor of inadequate correction. However, adequate ALL ossification could decrease the development of RF and relieve the junctional kyphotic change during follow-up. Older age and greater baseline SVA were independent risk factors for both inadequate correction and sagittal decompensation.

Variation patterns of cervical alignment in ankylosing spondylitis-related thoracolumbar kyphosis following pedicle subtraction osteotomy in the sitting position: an EOS-based investigation.

OBJECTIVE: Both unchanged upper cervical lordosis combined with decreased lower cervical lordosis and decreased upper cervical lordosis combined with decreased lower cervical lordosis have been reported to occur after correction surgery for adult spinal deformity. However, variations in cervical alignment after correction surgery in patients with ankylosing spondylitis (AS) have not been investigated. The current study aimed to investigate the variations in cervical alignment following the correction surgery in AS patients with thoracolumbar kyphosis. METHODS: Patients with AS who underwent pedicle subtraction osteotomy (PSO) for thoracolumbar kyphosis from June 2016 to June 2019 with a minimum of 1-year follow-up were reviewed. Patients were grouped according to the presence (ossified group) and absence (non-ossified group) of total ossification of the anterior longitudinal ligament (ALL) in the lower cervical spine. Radiographic parameters, including thoracolumbar, craniocervical, and global radiographic parameters, were measured on lateral sitting EOS images. RESULTS: Thirty-two patients (27 males and 5 females) with a mean follow-up of 1.5 years were identified. There were 21 patients in the non-ossified group and 11 patients in the ossified group. After PSO, both groups showed a decrease in the occiput-C7 angle (p < 0.001 for both). In the non-ossified group, the C2-7 angle decreased significantly (p < 0.001), while the occiput-C2 angle remained unchanged (p = 0.570). In the ossified group, the occiput-C2 angle decreased significantly (p < 0.001), while C2-7 angle remained unchanged (p = 0.311). In addition, the change in occiput-C2 was correlated with the osteotomy angle in the ossified group (R = 0.776, p = 0.005). CONCLUSIONS: The variation patterns of cervical alignment following correction surgery for AS-related thoracolumbar kyphosis were different based on patients with or without total ossification of ALL in the lower cervical spine. When planning PSO for patients in the ossified group, restoration of the physiological upper cervical lordosis angle could be achieved by adjusting the osteotomy angle.

Distal Adding-on Phenomenon in Scoliosis Secondary to Chiari Malformation Type I: Incidence and Risk Factors.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to investigate the incidence and risk factors for distal adding-on (AO) phenomenon after posterior spinal fusion (PSF) in scoliosis secondary to Chiari malformation type I (CMS) patients with right major thoracic curve. SUMMARY OF BACKGROUND DATA: Distal AO phenomenon is a common complication observed in adolescent idiopathic scoliosis (AIS), which is significantly associated with unsatisfactory outcomes. However, few studies specifically focused on the incidence and risk factors of distal AO in CMS. METHODS: Seventy-eight CMS adolescents were included with a minimum of 2-year follow-up after PSF. patients with distal AO at the final follow-up were divided into AO group and those without were No-AO group. The coronal and sagittal parameters were evaluated preoperatively, immediately after surgery, and at the last follow-up. Clinical outcome was analyzed using the Chicago Chiari Outcome Scale (CCOS). RESULTS: Distal AO was observed in 18 of 78 patients (23.1%). Compared with No-AO group, patients with distal AO had significantly lower Risser sign (P = 0.001), more flexibility of lumbar curve (P = 0.021), higher incidence of lowest instrumented vertebra-last substantially touched vertebra (LIV-LSTV) ≤0 (P = 0.001), smaller postoperative Cobb angle of lumbar curve (P < 0.001), and greater correction rate of lumbar curve (P = 0.001). Logistic regression analysis revealed that low Risser sign (Grade 1-2, odds ratio [OR] = 5.7, P = 0.029) and LIV-LSTV ≤0 (OR = 6.4, P = 0.019) were independent risk factors for distal AO. There was no significant difference of CCOS scores between two groups at the final follow-up (P > 0.05 for all). CONCLUSION: The incidence of distal AO was 23.1% in CMS patients after PSF. Patients with low Risser sign and LIV-LSTV ≤0 were high risk factors for distal AO.Level of Evidence: 3.

Can fusion to S1 maintain favorable surgical outcomes following one-level pedicle subtraction osteotomy in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis?

PURPOSE: To compare the surgical outcomes between ankylosing spondylitis (AS)-related thoracolumbar kyphosis patients with the lowest instrumented vertebra (LIV) at S1 or above following one-level pedicle subtraction osteotomy (PSO). METHODS: One hundred and two AS patients undergoing one-level PSO with a minimum of 2-year follow-up were included. Twenty-two patients were in group S1 (LIV at S1), and eighty were in group non-S1 (LIV above S1). Radiographic parameters including lumbar lordosis (LL), sacral slope (SS), pelvic incidence (PI), and sagittal vertical axis (SVA) were measured. Oswestry Disability Index (ODI) and visual analog scale (VAS) were applied for clinical assessment. RESULTS: In both S1 and non-S1 groups, the radiographic parameters and clinical outcomes were significantly improved after surgery (P < 0.05). Patients undergoing distal fusion to S1 had significantly larger preoperative PI-LL mismatch, SVA, and smaller preoperative LL and SS compared to those in group non-S1 (P < 0.05). No significant difference was found between the two groups regarding preoperative and final follow-up ODI and VAS (P > 0.05), as well as the improvement in ODI and VAS (P > 0.05). The incidence of overall complications and each type of complication including the implant failure was similar between group S1 and non-S1 (P > 0.05). CONCLUSION: Selecting S1 as the LIV without pelvic fixation following one-level PSO in thoracolumbar kyphosis caused by AS could achieve satisfactory surgical outcomes and might not increase the complications. Patients with relatively severe sagittal imbalance, loss of LL, PI-LL mismatch, and small SS might be the potential candidates for distal fusion to S1 following one-level PSO.

An analysis of the interactions between the spine, pelvis, and lower limbs in asymptomatic adults with limited pelvic compensation.

BACKGROUND: The interactions between the spine, pelvis, and lower limbs are dynamic based on the "cone of economy" concept; thus, different global radiographic parameters could be regarded as reflections of different centers of gravity. We conducted this retrospective study to evaluate the offsets of different centers of gravity in asymptomatic populations and to investigate how the global sagittal alignment is supported. METHODS: The following parameters were measured: cervical lordosis, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), the ratio between PT and PI (PT/PI), sacral slope, PI minus LL (PI-LL), the sagittal vertical axis (SVA), cranial SVA to ankle center (Cr-A), CrSVA to the femoral head center (Cr-FH), C2SVA to the femoral head center (C2-FH), pelvic translation (P. Shift), and knee angle (KA). Participants were divided into subgroups based on the PT/PI ratio. Mean values were compared using the t-test, and correlations were assessed using Pearson's coefficient. RESULTS: A total of 82 asymptomatic adults were enrolled. The average PT/PI in subgroup 1 was the smallest, showing that individuals in this group may have limited pelvic retroversion. No significant differences in Cr-FH, Cr-A, or C2-FH were found between subgroups (all P>0.1), implying that global alignment was well supported in each group. Specifically, C2-FH showed minor changes between subgroups (P=0.998), showing that C2-FH may be a target for sagittal compensation. There were positive correlations between PT/PI and both P. Shift and SVA (r=0.930 and r=0.606, respectively). However, Cr-FH, Cr-A, and C2-FH were not significantly correlated with P. Shift or PT/PI (all P>0.05). Weak correlations existed between Cr-A, Cr-FH, and age (all P>0.2). CONCLUSIONS: This study revealed that the Cr-FH and C2-FH offsets are stable across the population and could be maintained by regulating only the sagittal spinal curvature when pelvic compensation is limited. Cr-FH is not affected by age in the asymptomatic population. Thus, the stable Cr-FH and C2-FH could provide references for surgeons during the surgical decision-making process in patients with adult spinal deformity with sagittal malalignment.

Scoliosis Research Society-Schwab Grade 6 Osteotomy for Severe Congenital Angular Kyphoscoliosis: An Analysis of 17 Cases With a Minimum 2-Year Follow-up.

BACKGROUND: For some patients with severe congenital angular kyphoscoliosis (SCAK), 1-level vertebral column resection is insufficient and the Scoliosis Research Society (SRS)-Schwab Grade 6 osteotomy may be necessary. However, the indications and clinical outcomes of SRS-Schwab Grade 6 osteotomy in patients with SCAK have not been investigated in depth. OBJECTIVE: To investigate the middle-term radiographic and clinical outcomes, and to evaluate the safety of this high technique-demanding procedure. METHODS: Patients with SCAK undergoing SRS-Schwab Grade 6 osteotomy from 2005 to 2016 followed up at least 2 yr were retrospectively reviewed. The potential indications of SRS-Schwab Grade 6 osteotomy were analyzed. The coronal Cobb angle, segmental kyphosis (SK), deformity angular ratio (DAR), coronal balance, and sagittal vertical axis (SVA) were measured in the preoperative, postoperative, and final follow-up. The intraoperative and postoperative complications were recorded. RESULTS: A total of 17 patients with SCAK (10 M and 7F) were included, and the mean follow-up was 30.8 ± 16.4 mo. The indications of SRS-Schwab Grade 6 osteotomy were as follows: multiple "pushed-out" hemivertebrae (13, 76.5%) and multilevel anterior block (4, 23.5%). Compared with preoperation, the coronal Cobb angle, SK and SVA at postoperation were significantly improved (P < .05 for all). The mean total DAR was 33.4 ± 9.9 at preoperation. Three patients were found to have postoperative neurological deficit. Rod breakage occurred in 3 patients at 15- to 48-mo follow-up, and revision surgeries were performed. At the last follow-up, firm bony fusion was observed in all patients. CONCLUSION: The technique-demanding SRS-Schwab Grade 6 osteotomy, if well indicated, could provide satisfying correction of the SCAK deformity.

Is Any Correlation Present Between the Severity of Syndesmophytes and Spinopelvic and Clinical Parameters in Advanced Ankylosing Spondylitis?

OBJECTIVE: The present study evaluated the severity of syndesmophytes and its correlation with the spinopelvic and clinical outcomes in patients with ankylosing spondylitis (AS). METHODS: The data from 41 consecutive patients with AS who had undergone pedicle subtraction osteotomy surgery at our institution were reviewed. The computed tomography syndesmophyte score (CTSS), a novel method of evaluating the severity of syndesmophytes, was applied to assess the syndesmophytes of the whole, cervical, thoracic, and lumbar spine. The measured spinopelvic parameters included global kyphosis, sagittal vertical axis, lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The Oswestry disability index questionnaire, C-reactive protein, and erythrocyte sedimentation rate were used to evaluate the clinical outcome. The Pearson correlation test was performed to identify correlations between syndesmophyte severity and the spinopelvic and clinical parameters. RESULTS: The Pearson correlation analysis demonstrated that the whole CTSS (WCTSS), cervical CTSS, thoracic CTSS, and lumbar CTSS (LCTSS) correlated significantly with each other (P < 0.05). All the CTSSs correlated positively with age, disease duration, and pelvic tilt (P < 0.05). In addition, both sagittal vertical axis and lumbar lordosis were significantly related to the WCTSS, cervical CTSS, and LCTSS (P < 0.05). The Oswestry disability index correlated negatively with the WCTSS (r = -0.312; P < 0.05), thoracic CTSS (r = -0.314; P < 0.05), and LCTSS (r = -0.343; P < 0.05). CONCLUSIONS: In advanced AS, old age and a long disease duration are risk factors for the progression of syndesmophytes. The progression of syndesmophytes might contribute to spinal sagittal malalignment. With serious syndesmophytes, pelvic retroversion seems to be the major compensatory mechanism for spinal sagittal malalignment.

Impact of cervical range of motion on the global spinal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following pedicle subtraction osteotomy.

BACKGROUND CONTEXT: The head's center of gravity (COG) plumb line (PL) and C7 PL could be simultaneously positioned over the pelvis in adult spinal deformity with normal cervical mobility. However, the position of the head in relation to the global spinal alignment has yet to be investigated in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. PURPOSE: The objective of this study was to analyze the position of head in relation to the global spinal alignment in AS-related thoracolumbar kyphosis. STUDY DESIGN/SETTING: Retrospective single-center study. PATIENT SAMPLE: AS patients who underwent lumbar pedicle subtraction osteotomy for thoracolumbar kyphosis from January 2010 to August 2016 were reviewed. Only patients with a visible ear canal on the preoperative, immediate postoperative, and final follow-up radiographs were included. OUTCOME MEASURES: The chin-brow angle, cervical range of motion (ROM), lumbar lordosis (LL), thoracolumbar angle, thoracic kyphosis (TK), L1 pelvic angle, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), TK+LL+PI, PI-LL, maximal kyphosis (MK), deformity angular rate, T1 pelvic angle, T1 tilt, spinosacral angle, sagittal vertical axis (SVA) COG-C7, SVA COG-femoral head (FH), and SVA C7-S were evaluated. Data regarding the health-related quality of life, including the Oswestry disability index (ODI) and visual analogue scale (VAS)-back score, were also collected preoperatively, 2 years postoperatively, and at the latest follow-up. METHODS: The cohort was divided into patients with occiput-trunk (OT) concordance or with OT discordance according to the SVA COG-C7 ≤30 mm or >30 mm, respectively. There was no funding in this study and there are no conflict of interest-associated biases. RESULTS: A total of 43 patients (36 males and 7 females) with a mean age of 34.2 years (range, 18-59 years) were identified. There were 17 patients accompanied with OT concordance and 26 patients with OT discordance preoperatively. The cervical ROM was significantly lower (24.0° vs 56.1°, p<.001) and SVA COG-C7 was significantly larger (71.7 mm vs 7.4 mm, p<.001) in patients with OT discordance. Furthermore, the PT was larger (41.0° vs 33.5°, p=.010) in patients with OT discordance. After surgery, the whole cohort showed an improvement in LL (-8.6° vs -52.8°, p<.001). Moreover, the CBVA (25.4° vs 1.3°, p<.001) and SVA COG-C7 (46.2 mm vs 21.6 mm, p<.001) were significantly decreased following lumbar PSO. There were 13 patients accompanied with OT discordance postoperatively, and the cervical ROM was still lower (22.5° vs 42.8°, p=.024) in these patients. Postoperative PT was larger (26.5° vs 20.1°, p=.033) in the patients with OT discordance. At the latest follow-up, there were 17 patients accompanied with OT discordance. In these 17 patients, the cervical ROM was significantly lower (21.0° vs 47.0°, p=.001) and PT was significantly higher (26.2° vs 19.2°, p=.012). The ODI and VAS-back scores demonstrated no significant differences between the two groups preoperatively, 2 years postoperatively, or at the latest follow-up. CONCLUSIONS: OT discordance in AS-related thoracolumbar kyphosis could be caused by the reduced cervical ROM. To maintain global spinal balance, the pelvis rotated further backward in response to the larger SVA COG-C7. Moreover, the larger SVA COG-C7 could be decreased after the lumbar PSO. Although there were radiographic differences between the patients with OT concordance and with OT discordance, there was no difference in clinical outcomes, and that a larger sample size and longer follow-up are needed.

Sequential correction technique to avoid postoperative global coronal decompensation in rigid adult spinal deformity: a technical note and preliminary results.

PURPOSE: This study aims to evaluate this new sequential correction technique for preventing postoperative coronal imbalance. METHODS: Adult Spinal deformity (ASD) patients were stratifies into two types: primary thoracolumbar/lumbar (TL/L) curve with compensatory lumbosacral (LS) curve (Type I) and primary LS curve with compensatory TL/L curve (Type II): for Type I patients: correction of major TL/L curve and one- or two-level segmental rod installed at the convexity of the TL/L curve, L4-S1 TLIF to correct fractional curve and a short rod installed on the contralateral side and installation of long rods; for Type II patients: horizontalize L4 and L5, short rod installation at the convexity of the LS curve, distraction of curve with regional rod and installation of long rods. ASD patients were enrolled with inclusion criteria: with pre-op TL/L Cobb angle more than 30°, with pelvic fixation and with UIV over T10. Radiographic parameters were analyzed. RESULTS: Twenty-one patients were recruited (14 patients Type I and 7 Type II patients). Both Cobb angle and coronal offset were significantly improved after surgery. In Type I patients, Cobb angle was improved from 50.48° to 26.91° and coronal offset from 2.94 to 0.95 cm; in Type II patients, Cobb angle was improved from 61.42° to 28.48° and coronal offset from 2.82 to 1.38 cm. In the 10 patients with baseline coronal imbalance, 9 were corrected to coronal balance after surgery. CONCLUSION: The sequential correction technique allows decomposing the complex correction surgery into several steps, and each step focuses only on one task. It can also reduce the difficulty of rod installation due to the separated maneuvers and multi-rod system. LEVEL OF EVIDENCE: IV These slides can be retrieved under Electronic Supplementary Material.

[Comparison of sagittal plane morphology of spine and pelvis in adolescents with L5S1 developmental spondylolisthesis and isthmic spondylolisthesis].

OBJECTIVE: To compare the sagittal morphological features of the spine and pelvis between L5S1 dysplastic spondylolisthesis and isthmus spondylolisthesis in adolescent. METHODS: Retrospective analysis of 24 cases of adolescent L5S1 spondylolisthesis with complete imaging data from May 2002 to December 2016. Those included 8 males and 16 females, aged from 10 to 18 years old with an average of (13.4±2.0) years. Among them, 9 cases were diagnosed as dysplastic spondylolisthesis (dysplasia group) and 15 cases isthmic spondylolisthesis (ischemic group). Radiographic parameters including slippage distance, slippage degree, slippage angle, sagittal vertical axis(SVA), thoracic kyphosis(TK), lumbar lordosis(LL), L5 incidence(L5I), pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS), sagittal pelvic thickness(SPT), lumbosacral angle (LSA), sacral table angle (STA) were measured on the spinal lateral X-ray of the standing position. Independent-samples t-test was used in the comparison of each variable between two groups. P<0.05 was considered statistically significant. RESULTS: There were no significant differences in slippage distance, slippage rate, slippage angle between two groups. In dysplasia group, SVA, L5I, PT, SPT were (37.0±48.4) mm, (57.0±14.8)°, (42.3±15.4)°, (56.1±21.2) mm, respectively, and (-11.0±22.2) mm, (31.7±19.3) °, ( 15.5±10.2)°, (31.4±19.1) mm in ischemic group; and the differences between the two groups were significant(P<0.05). In ischemic group, SS, LSA, STA were (44.1±12.6)°, (103.9±21.7)°, (92.7±9.9)°, respectively, and (25.9±20.2) °, (75.4±16.4) °, (75.4±9.7) ° in dysplasia group; and the differences between the two groups were significant(P<0.05). There was no significant difference in TK, LL between two groups(P>0.05). CONCLUSIONS: Significant different from isthmic spondylolisthesis, adolescents with dysplastic spondylolisthesis present a different spino-pelvic sagittal alignment, characterized with trunk forward leaning and pelvic retroversion. In case of sagittal imbalance, early surgical intervention is required to restore a balanced spino-pelvic alignment.