Central Sacral Vertical Line Research Articles

The Incidence of Adding-On or Distal Junctional Kyphosis in Adolescent Idiopathic Scoliosis Treated by Anterior Spinal Fusion to L3 Was Significantly Higher Than by Posterior Spinal Fusion to L3.

ObjectiveTo compare and identify risk factors for distal adding-on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by anterior- (ASF) and posterior spinal fusion (PSF) to L3. MethodsAIS patients undergoing ASF versus PSF to L3 from 2000–2010 were analyzed. Distal AO and DJK were deemed poor radiographic results. New stable (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. ResultsTwenty of 42 (ASF group: 47.6%) and 8 of 72 patients (PSF group: 11.1%) showed poor radiographic outcome. Fused vertebrae, correction rate of main curve, coronal reduction rate of L3 were significantly higher in PSF group. Multiple logistic regression results indicated that preoperative SV-3 at L3 in standing and side benders (odds ratio [OR], 2.7 and 3.7, respectively), TS score -5, -6 at L3 (OR, 4.9), rigid disc at L3–4 (OR, 3.7), lowest instrumented vertebra (LIV) rotation > 15° (OR, 3.3), LIV deviation > 2 cm from center sacral vertical line (OR, 3.1) and ASF (OR, 13.4; p<0.001) were independent predictive factors. There was significant improvement of the Scoliosis Research Society (SRS)-22 average scores only in PSF group. Furthermore, the ultimate scores of PSF group were significantly superior to ASF group. ConclusionThe prevalence of AO or DJK at ultimate follow-up for AIS with LIV at L3 was significantly higher in ASF group. Ultimate SRS-22 scores were significantly better in PSF group.

How do spine instrumentation parameters influence the 3D correction of thoracic adolescent idiopathic scoliosis? A patient-specific biomechanical study

BackgroundPatient-specific models promises to support the surgical decision-making process, particularly in adolescent idiopathic scoliosis. The present computational biomechanical study investigates how specific instrumentation parameters impact 3D deformity correction in thoracic scoliosis. Methods1080 instrumentation simulations of a representative patient were run. The independent instrumentation parameters were: screw pattern, upper and lower instrumented vertebrae, rod curvature and rod stiffness. ANOVA and correlation analyses analyzed how the instrumentation parameters influenced the 3D correction. FindingsCoronal plane correction was affected by the lower instrumented vertebra and rod stiffness (explaining 84% and 11%, respectively, of its overall variance). The sagittal profile was controlled by rod curvature and the upper vertebra (56% and 36%). The transverse plane vertebral rotation was influenced by lower, upper instrumented vertebra and screw pattern (35%, 32% and 19%). The Cobb angle correction was strongly correlated with the number of fused vertebrae, particularly when grouped by the upper instrumented vertebra (r = −0.91) and rod stiffness (r = −0.73). Thoracic kyphosis was strongly correlated with the number of fused vertebrae grouped by rod curvature (r = 0.84). Apical vertebral rotation was moderately correlated with the number of fused vertebrae grouped by upper/lower instrumented vertebra (r = 0.55/0.58), although variations were minimal. InterpretationInstrumenting the last vertebra touching the central sacral vertical line improves 3D correction. A trade-off between a more cranial vs. caudal upper instrumented vertebra, respectively beneficial for coronal/sagittal vs. transverse plane correction, is required. High rod stiffness, differential rod contouring, and screw pattern were effective for coronal correction, thoracic kyphosis, and axial vertebral derotation, respectively.

Intraoperative versus postoperative radiographic coronal balance for adult spinal deformity surgery.

Coronal malalignment in adult spinal deformity (ASD) has a close relationship with patient clinical outcomes. The purpose of this study is to evaluate the relationship between intra- and postoperative coronal radiographic parameters. A novel parameter, the central sacral pelvic line (CSPL), and its relation to the central sacral vertical line (CSVL) is explored. CSPL is a measure of spinal alignment referenced to the patient's pelvis as an intraoperative proxy for CSVL. CSVL is difficult to measure intraoperatively, because a C7-plumb line (referenced to gravity) cannot be drawn in the supine position. 47 subjects ≥ 18years old undergoing a spinal fusion of ≥ 6 levels from 2015 to 2017 were enrolled. The CSPL is defined as the perpendicular line bisecting the midpoint of the line that connects the superior aspects of the acetabuli. Two metrics describing coronal alignment were derived from each radiograph: (1) horizontal distance between the C7-plumb line and the CSPL at C7 (C7-CSPL) and (2) horizontal distance between the C7-plumb line and CSVL (C7-CSVL). Pearson's correlation and linear regression analysis was used to study the relationship between the intraoperative C7-CSPL and the postoperative C7-CSVL. On average, the intraoperative C7-CSPL distance was 32.1mm, postoperative C7-CSPL 20.8mm, and postoperative C7-CSVL 18.9mm. 15/47 (32%) had intraoperative C7-CSPL measurements > 4cm, requiring intraoperative correction. Of those 15, 10 patients (67%) still had a postoperative C7-CSVL < 4cm. Linear regression modeling indicates that when intraoperative CSPL is < 7.7cm on average, the postoperative C7-CSVL will < 4cm-our threshold for adequate coronal alignment. Patients with intraoperative C7-CSPL > 5cm had a 50% chance of having a postoperative C7-CSVL > 4cm; patients with intraoperative C7-CSPL < 5cm had a 3% chance of having coronal malalignment. There is a strong positive relationship between postoperative C7-CSPL and C7-CSVL (r = 0.80 and 0.85, respectively). In adult spinal surgery, the intraoperative coronal alignment measured using the novel C7-CSPL distance correlates well with postoperative C7-CSVL distance. This gives the surgeon an objective measurement of the correction they need after assessing initial intraoperative imaging. Our findings suggest an intraoperative C7-CSPL distance < 5cm as a threshold value to predict postoperative C7-CSVL < 4cm in 97% of patients tested.

A Retrospective Study of Factors Associated with Restoration of Thoracic Kyphosis in 43 Patients with Adolescent Idiopathic Scoliosis with Lenke Type 1 Curvature.

BackgroundThis retrospective study aimed to identify the factors associated with successful surgical correction of thoracic kyphosis (TK) in 43 patients with adolescent idiopathic scoliosis (AIS) with Lenke type 1 curvature, in which the major curve with the largest Cobb angle was mainly in the thoracic region.Material/MethodsWe collected data from patients with Lenke 1 AIS. The following parameters were measured: Cobb angle, side-bending Cobb angle, cervical lordosis (CL), TK, lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), the sagittal vertical axis (SVA), the center of a C7 plumb line to the center sacral vertical line (C7-CSVL), correction rate, Ponte osteotomy, flexibility, and screw density. Univariate analysis and multivariate logistic regression analyses were performed.ResultsAmong the 43 cases analyzed, the mean postoperative Cobb angle at the last follow-up, C7-CSVL, SVA, CL, TK, LL, PI, SS, and PT were respectively 21.33±9.47°, 10.41±8.45 mm, 19.68±14.33 mm, 16.19±7.45°, 23.12±7.45°, 50.33±11.37°, 49.70±9.83°, 39.42±8.11°, and 10.16±6.63°. Univariate analysis suggested that preoperative TK, preoperative LL, and Ponte osteotomy were statistically significant (P<0.05), and multivariate analysis suggested that preoperative LL and Ponte osteotomy were statistically significant (P<0.05).ConclusionsThe results of this study demonstrated that preoperative TK, preoperative LL, and Ponte osteotomy were related factors for maintaining normal TK. Multivariate analysis suggested that preoperative LL and the use of Ponte osteotomy with full-thickness segmental resection of the spinal posterior column resulted in the successful surgical correction of TK in patients with AIS with Lenke type 1 curvature.

Using Satellite Rod Technique in Patients with Severe Kyphoscoliosis Undergoing Three-Column Osteotomy: A Minimum of 2 Years' Follow-up.

ObjectiveTo introduce the satellite rod technique utilized in severe spinal deformity after three‐column osteotomy (3CO) and to evaluate the radiographic and clinical outcomes at 2‐year follow‐up, further discussing its utilization in this particular cohort.MethodsA total of 32 (19 females and 13 males) with an average age of 32.9 ± 18.3 years from December 2012 to March 2016 were retrospectively reviewed. Radiographic measurements were performed on standing full‐spine anteroposterior and lateral radiographs preoperatively, postoperatively, and at last follow‐up. The coronal parameters including Cobb angle and distance between C7 plumb line and center sacral vertical line (C7PL‐CSVL), as well as the sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were measured at three time points. The Scoliosis Research Society‐22 questionnaire (SRS‐22) was fulfilled preoperatively and at each follow‐up. Paired t test would be used to determine whether there was a significant difference between time points.ResultsA total of 32 patients were enrolled in this study with mean age of 32.9 ± 18.3 (range, 12 to 66) years old. Twenty patients underwent pedicle subluxation osteotomy (PSO) and 12 patients underwent vertebral column resection (VCR). The pathogenesis of this cohort included neuromuscular scoliosis (11 cases), congenital kyphoscoliosis (seven with hemivertebrae and five with segmentation failure), degenerative spinal deformity (five cases), and thoracolumbar tuberculosis with angular kyphosis (four cases). The post‐operative Cobb angle decreased significantly from 49.1° ± 28.0° to 19.0° ± 16.7° with a correction rate of 65.2% ± 21.8%. At final follow‐up, the average Cobb angle was 19.4° ± 16.9° and no obvious loss of correction was found. The preoperative, postoperative, and last follow‐up C7PL‐CSVL were 23.9 ± 14.5 mm, 15.7 ± 11.1 mm, and 12.1 ± 7.4 mm, respectively. Significant postoperative improvement was attained while there was no change observed at last follow‐up. Postoperative GK significantly improved from 73.8° ± 28.1° to 23.2° ± 11.7° with the correction rate of 66.0% ± 17.9%. SVA decreased significantly from 42.9 ± 33.9 mm to 24.1 ± 21.1 mm. The average GK and SVA at final follow‐up were 22.7° ± 10.1° and 23.5 ± 21.1 mm, respectively and no obvious loss of correction was observed of them during follow‐up. In addition, no change or loss of motor or somatosensory evoked potential occurred during surgery. During the follow‐up, two malposition screws and one rod breakage were found.ConclusionThe satellite rod used in patients with severe kyphoscoliosis undergoing 3CO could yield favorable radiological and clinical outcomes. With the utilization of this technique, the coronal and sagittal balance could be well‐maintained during follow‐up.

A New Global Spinal Balance Classification Based on Individual Pelvic Anatomical Measurements in Patients With Adult Spinal Deformity.

A retrospective study. This study aims to establish a new, easy-to-implement global spinal balance (GSB) classification based on individual pelvic anatomical measurements in adult spinal deformity patients, and to validate this classification in terms of patients' quality of life (QOL). Coronal (central sacral vertical line) and sagittal (C7 sagittal vertical axis [C7 SVA]) lines are standard parameters to evaluate GSB. However, these parameters do not consider individual differences in height and physique. Therefore, a new classification to more simply evaluate GSB related to QOL would be a beneficial tool. This study included 279 patients with adult spinal deformity. The enrollment criteria included age >18 years and scoliosis >30°. GSB was evaluated based on C7 coronal vertical axis and C7 SVA, and was graded with our sagittal (Grades 1-3) and coronal classifications (Grades 1-3), where larger values represented worse GSB. In addition, total global balance classification (Grades 1-3) was also established based on both coronal and sagittal classifications. Patient self-assessment measures of health status were collected using the Scoliosis Research Society patient questionnaire (SRS-22). The relationships between responses to the SRS-22 and GSB were evaluated using partial correlation coefficients, adjusted by age. A newly described coronal classification correlated with the preoperative function (P < 0.02), pain (P = 0.001), subtotal (P < 0.001) domains in the SRS-22, whereas a newly described sagittal classification was correlated with the preoperative subtotal domain (P < 0.001). There were also significant correlations between total global balance and the preoperative function (P = 0.03) and subtotal domains (P < 0.001) in the SRS-22. We present a simple new classification for GSB that strongly correlates with QOL in patients with adult spinal deformity, thereby translating clinical data into meaningful patient outcomes and livelihoods.Level of Evidence: 4.

Factors related to postoperative coronal imbalance in adult lumbar scoliosis.

The object of this study was to analyze the prevalence of postoperative coronal imbalance (CIB) and related factors in patients with adult lumbar scoliosis. This was a retrospective single-center study of data from patients with adult spinal deformity (ASD) who had undergone corrective surgery performed by a single surgeon between 2009 and 2017. The inclusion criteria were as follows: 1) age at surgery > 40 years, 2) Cobb angles of the thoracolumbar/lumbar (TL/L) curve > 40°, 3) upper instrumented vertebra of T9 or T10, 4) lowest instrumented vertebra of L5 or the pelvis, and 5) minimum 2-year follow-up period. Radiographic parameters were measured before surgery, 2 weeks after surgery, and at the latest follow-up. Curve flexibility was also assessed using side bending radiographs. Clinical outcomes were evaluated using the 22-Item Scoliosis Research Society Outcomes Questionnaire (SRS-22) and the SF-36. CIB was considered to have occurred if the C7 plumbline was more than 2.5 cm lateral to the central sacral vertical line (i.e., coronal vertical axis [CVA] > 2.5 cm) at the final follow-up. Parameters between the patients with (CIB group) and without (coronal balance [CB] group) CIB were compared, and factors related to CIB were evaluated. From among 66 consecutively treated ASD patients, a total of 37 patients (mean age at surgery 66.3 years, average follow-up 63 months) met the study inclusion criteria. CIB was found in 6 patients at the final follow-up (16.2%), and the CVA of all patients in the CIB group shifted to the convex side of the TL/L curve. A comparative analysis between the CB and CIB groups, respectively, at the final follow-up indicated the following factors were related to CIB: lumbosacral (LS) curve, 11.0°/16.5° (p = 0.02); LS correction rate (CR), 61%/47% (p = 0.02); and CR ratio (LS vs TL/L), 0.93/0.67 (p = 0.0002). Regarding clinical outcomes, the satisfaction domain of the SRS-22 (CB 4.4 vs CIB 3.5) showed a significant difference between the CIB and CB groups (p = 0.02), and patients in the CB group tended to score better on the pain domain (CB 4.3 vs CIB 3.7), but the difference was not significant (p = 0.06). Postoperative CIB negatively impacted patients' HRQOL. An imbalanced correction ratio between the TL/L and LS curves may cause postoperative CIB. Therefore, adequate correction of the LS curve may prevent postoperative CIB.

Free-hand technique of S(2) alar iliac screw placement for sacropelvic fusion in lumbar degenerative scoliosis

Objective: To evaluate the feasibility of placement of S(2) alar iliac screw (S(2)AI) using free-hand technique for sacrapelvic fusion in lumbar degenerative scoliosis. Methods: Eighteen patients with Lumbar Degenerative Scoliosis treated by S(2)AI screw fixation at Department of Orthopedics, General Hospital of Southern Theater Command of People's Liberation Army and Department of Orthopedics, 89th hospital of People's Liberation Army from August 2014 to October 2018 were analyzed retrospectively. There were 5 males and 13 females, aged 63.2 years old (range:55 to 71 years old).Parameters of spine including: Cobb Angle, C(7) plumb line -center sacral vertical line (C(7)PL-CSVL), lumbar lordosis(LL), sagittal vertical axis(SVA), pelvic incidence(PI), pelvic tilt(PT), sacral slope (SS) and pI-LL were measured on the whole spine X-ray before operation and at final follow-up. Pelvic CT scan was performed postoperatively to assess the accuracy of S(2)AI placement. Oswestry disability Index (ODI) was also recorded. The data were compared by paired t test or Wilcoxon tests. Results: All patients were followed up for 23.7 months (range: 12~62 months).At the last follow up, Cobb Angle decreased from (32.28±4.97) °preoperative to (6.56±3.20) ° (t=41.142, P<0.01) and C(7)PL-CSVL deceased from (1.11±2.07) cm preoperative to (0.18±1.08) cm (t=41.142, P=0.06) .LL improved from (-22.39±13.07) °preoperative to (-36.39±4.29) ° (t=4.470, P<0.01) , PI-LL decreased from (26.83±14.83)°preoperative to (13.72±8.3)° (t=4.396, P<0.01) , PT decreased from (27.94±4.26) °to (23.39±6.08) ° (t=2.680, P=0.02) , and SS increased from (22.22±6.36) °to (26.28±7.24) ° (t=-2.178, P=0.04) .SVA decreased from (6.54±4.51) cm preoperative to (2.62±1.29) cm (t=3.052, P=0.01) .ODI decreased from 0.58(0.40) (M(Q(R))) to 0.18 (0.15) (Z=-4.567, P<0.01) .No complications such as nerve and blood vessel injury occurred during the operation. A total of 32 S(2)AI screws were placed, 3 screws were placed with mild to moderate cortical breaches, 2 were perforated the pelvis ventrally, 1 was perforated posteriorly, with no clinically notable neurovascular or visceral complications. Eight patients finished the SRS-22 questionnaire, with mean score of 4.4 in terms of satisfaction with management. Conclusions: Free-hand technique of S(2)AI screw placement for sacrapelvic fusion in degenerative lumbar scoliosis is safe and feasible.S(2)AI fixation in DLS can provide great correction of deformity, maintain the stability of lumbo-pelvic area and improve the clinical symptoms.

P100. Upper instrumented vertebral pelvic angle and risk of proximal junctional kyphosis at 2- year follow-up

BACKGROUND CONTEXT There remains a need for practical radiographic parameters to help predict risk of proximal junctional kyphosis (PJK) in adult patients undergoing multilevel posterior fusion. The upper instrumented vertebral pelvic angle (UIVPA) is a novel measure of sagittal alignment that is easy to measure and can account for both spinal inclination and pelvic retroversion. We hypothesize that the further the UIV is from the center of gravity, the higher the risk of PJK. PURPOSE The purpose of this study is to evaluate the association between UIVPA and risk of PJK in adult patients undergoing 6-level fusion. STUDY DESIGN/SETTING Retrospective cohort study at single academic institution. PATIENT SAMPLE Adult patients with minimum two-year follow-up who underwent ≥6 level posterior spinal fusion. OUTCOME MEASURES PJK, proximal junctional failure (PJF). METHODS In this retrospective cohort study, adult patients with two-year follow-up and ≥6 levels of posterior fusion for spinal deformity were included. The UIVPA was measured between a line from the UIV centroid to the center of the femoral head to a line from the center of the sacrum to the center of the femoral head. PJK was defined as a >10° kyphotic angle between the UIV and the vertebra 2 levels above. Proximal junctional failure (PJF) was defined as PJK that required surgery. Patients who developed PJK and those who did not were compared with respect to UIVPA, T1 pelvic angle (T1PA), pelvic tilt, sagittal vertical axis and central sacral vertical line. RESULTS There were 291 patients with an average 3.0 years follow-up enrolled in the study. Fifty (17%) patients were diagnosed with PJK and 29 (10%) qualified for PJF. The average UIVPA for all patients was 19.5° preop. Patients with PJK had significantly higher preoperative UIVPA than those without PJK or PJF (25.6 vs 16.2 p CONCLUSIONS UIV pelvic angle correlates well with established measures of sagittal spinopelvic alignment, such as T1PA, SVA and pelvic tilt. Patients with PJK and PJF at least two years from surgery were more likely to have a significantly higher preoperative UIVPA than their counterparts. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Selecting the "Touched Vertebra" as the Lowest Instrumented Vertebra in Patients with Lenke Type-1 and 2 Curves: Radiographic Results After a Minimum 5-Year Follow-up.

The selection of the lowest instrumented vertebra (LIV) in patients with adolescent idiopathic scoliosis (AIS) is still controversial. Although multiple radiographic methods have been proposed, there is no universally accepted guideline for appropriate selection of the LIV. We developed a simple and reproducible method for selection of the LIV in patients with Lenke type-1 (main thoracic) and 2 (double thoracic) curves and investigated its effectiveness in producing optimal positioning of the LIV at 5 years of follow-up. The radiographs for 299 patients with Lenke type-1 or 2 AIS curves that were included in a multicenter database were evaluated after a minimum duration of follow-up of 5 years. The "touched vertebra" (TV) was selected on preoperative radiographs by 2 independent examiners. The LIV on postoperative radiographs was compared with the preoperative TV. The final LIV position in relation to the center sacral vertical line (CSVL) was assessed. The CSVL-LIV distance and coronal balance in patients who had fusion to the TV were compared with those in patients who had fusion cephalad and caudad to the TV. The sagittal plane was also reviewed. In 86.6% of patients, the LIV was selected at or immediately adjacent to the TV. Among patients with an "A" lumbar modifier, those who had fusion cephalad to the TV had a significantly greater CSVL-LIV distance than those who had fusion to the TV (p = 0.006) or caudad to the TV (p = 0.002). In the groups with "B" (p = 0.424) and "C" (p = 0.326) lumbar modifiers, there were no differences among the TV groups. We recommend the TV rule as a third modifier in the Lenke AIS classification system. Selecting the TV as the LIV in patients with Lenke type-1 and 2 curves provides acceptable positioning of the LIV at long-term follow-up. The position of the LIV was not different when fusion was performed caudad to the TV but came at the expense of fewer motion segments. Patients with lumbar modifier "A" who had fusion cephalad to the TV had greater translation of the LIV, putting these patients at risk for poor long-term outcomes. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Postoperative Distal Coronal Decompensation After Fusion to L3 for Adolescent Idiopathic Scoliosis Is Affected by Sagittal Pelvic Parameters.

Retrospective study. To identify on early postoperative radiographs the risk factors for late distal decompensation in adolescent idiopathic scoliosis (AIS) patients undergoing posterior fusion surgery to L3. Sparing distal fusion levels in AIS surgery is considered beneficial for postoperative mobility and outcomes; nonetheless, late distal decompensation is of concern. L3 is often advocated as lower instrumented vertebra in posterior fusion, but progressive angulation of the L3/4 disc is commonly observed. A retrospective analysis was conducted on 78 AIS patients who underwent posterior fusion to L3 from 2007 to 2014. Patients' demographic data, early and 2-year postoperative standing radiographs by biplanar imaging system were investigated. Late decompensation was defined as progressive increase of L3-4 disc wedging angle at 2-year follow-up. Coronal, sagittal, and rotational radiographic parameters were compared between those with and without decompensation. SRS-30 scores were reviewed. Mean age was 14.5-year, and fusion levels averaged 12.0 (range: 6-15); 43 out of 78 patients (55%) experienced progressive L3-4 disc wedging, with 6 showing wedging >5°. L3 translation from the central sacral vertical line (13.9 vs. 11.1 mm, P = 0.13) and increased pelvic tilt (13.3° vs. 8.6°, P = 0.06) on the early postoperative radiograph were associated with increased L3-4 disc wedging. Multivariate analysis revealed that larger pelvic tilt was a significant risk factor for decompensation (odds ratio = 1.1 per 1°, 95% confidence interval: 1.0-1.1, P = 0.04). SRS-30 scores did not differ significantly between the two groups (4.0 vs. 4.1, P = 0.44). Pelvic retroversion and increased translation of L3 from the central sacral line on the early postoperative radiograph were associated with late L3-4 disc wedging in AIS fusions to L3. Careful surgical planning and correction of sagittal alignment are imperative to ensure the long-term outcomes. 4.

The Impact of Posterior Spinal Fusion (PSF) on Coronal Balance in Adolescent Idiopathic Scoliosis (AIS): A New Classification and Trends in the Postoperative Period.

One of the primary goals of scoliosis surgery is to balance the head over the pelvis (or avoid creating imbalance). Historically, a normal coronal balance was defined as the C7 plumb line (C7PL) within 2 cm of the central sacral vertical line (CSVL); however, there is limited published information regarding the speed/magnitude and success/failure of balancing, rebalancing, or unbalancing in the postoperative period. The purpose of this study is to classify and quantify coronal plane balance postoperatively in adolescent idiopathic scoliosis when using pedicle screw instrumentation. Evaluated patients with adolescent idiopathic scoliosis who had a posterior spinal fusion withstanding 2-view, posteroanterior and lateral radiographs of the entire spine performed at first erect visit, 6, 12, and 24 months. To measure coronal balance, a C7PL was measured and compared with the CSVL. A negative value denotes the leftward deviation of the C7PL and a positive value a rightward deviation. The authors then created a novel coronal balance classification system. A total of 954 patients met the inclusion criteria. There was a strong trend toward improving coronal balance, especially between first erect and 6 months; the proportion of out of balance patients declined throughout the 2-year period: preoperative 372 of 954 (39%), first erect 297 of 954 (31.1%), 6 months 167 of 954 (17.5%), 1 year 136 of 954 (14.3%), and 2 years 115 of 954 (12.0%). Analyzing the patients most out of balance immediately after posterior spinal fusion, 35 of 50 (70%) in group 3 regained balance by 2 years. Out of the remaining 15 patients, 12 corrected to group 1 (24%), 2 patients to group 2 (4%), and 1 patient remained in group 3 (2%). This large, longitudinal postoperative study of coronal balance documents a strong trend toward postoperative rebalancing, with the largest gains between first erect image and 6 months. The 31% of patients out of balance at first erect declined to only 12.1% at 2 years.

Posterior Spinal Fusion With Multilevel Posterolateral Convex Disc Releases for the Treatment of Severe Thoracolumbar Scoliosis.

Severe, rigid thoracolumbar scoliosis presents a surgical challenge to achieve 3-dimensional correction, maximize distal motion segments, and avoid operative morbidity conferred by combined anterior-posterior approaches or 3-column osteotomies. We present a new approach for releasing these curves, using multilevel posterolateral convex disc release (PCDR) and posterior instrumented fusion. There were 3 adults and 1 adolescent (mean age, 31.8 years; 2 females) with severe progressive thoracic and transforaminal lumbar (major) idiopathic scoliosis (IS) who were treated with 3-level PCDR, multiple posterior column osteotomies, and posterior instrumented thoracolumbar fusion with all-pedicle screw constructs. Restoration of global coronal and sagittal alignment was achieved for all patients (minimum 2-year follow-up). Lowest instrumented vertebra (LIV) was L4 in 2 patients and L3 in the remaining 2. All except 1 were fused to the lower end vertebra. Postoperatively, mean thoracolumbar curve was reduced from 77.3° (range, 69°-91°) to 21.8° (72%Δ), LIV tilt decreased from 26.8° to 8.3°, and LIV translation improved (2.5-1.2 cm; 58%Δ), whereas lumbar lordosis remained unchanged. Average central sacral vertical line shift measured via C7 sagittal vertical axis changed from 1.4 to -0.7 cm. There were no complications except for dysesthesias in the lower extremity on the side of the PCDR in 1 patient, which resolved after 3 months. Severe thoracolumbar IS presents a surgical challenge to achieve 3-dimensional correction, minimize fusion levels, and avoid procedural morbidity. PCDR is a novel technique that may facilitate this correction with minimal procedure-related morbidity.

The Effect of Cervicodorsal Hemivertebra Resection on Head Tilt and Trunk Shift in Children With Congenital Scoliosis.

Congenital scoliosis due to hemivertebra of the cervicodorsal spine is a rare disorder. It might be accompanied by impaired cosmetic appearances such as head tilt and trunk shift. Little is known about the effect of correction of the major curve on head tilt and trunk shift in children. The purpose of this study was to assess radiographic changes of head tilt and trunk shift following posterior hemivertebra resection (PHVR). Retrospectively, all children who underwent PHVR at the cervicodorsal spine (C6-Th6) with pedicle screw fixation with a minimum radiographic follow-up of 1 year were identified for further assessment. A total of 5 radiographic parameters were assessed on preoperative, postoperative, and final follow-up radiographs. (1) Head tilt was defined as the angle between the horizontal line and the line through both molars of the maxillary, (2) trunk shift as the angle between the line of the center of C7 to the sacrum and the central sacral vertical line, (3) Cobb angle was used to assess the major curve, (4) cranial, and (5) caudal compensatory curvature. Seven boys and 10 girls with a mean age of 9.0 years at surgery were evaluated. The mean radiographic follow-up was 89.5 months (range: 12 to 166 mo). The mean head tilt reoriented from 6.9 to 1.9 degrees (P<0.001); trunk shift improved from 4.3 to 2.5 degrees after surgery (P=0.100). There was a significant correlation between head tilt and trunk shift on preoperative and postoperative radiographs (P=0.030/0.031). The major curve, and compensatory curvatures were all significantly corrected (P<0.001). Head reorientation was significantly influenced by patient age at surgery. Repeated procedures due to decompensation of the compensatory curvature were performed in 2 cases. PHVR and pedicle screw fixation is an effective treatment for patients with congenital scoliosis. Surgery achieves a significant correction of the major curve and reorientation of the head postoperatively, and till the last follow-up. Level IV.

Posterior techniques for correcting deformity in adolescent idiopathic scoliosis––How much correction is optimal?

The optimal surgical treatment of adolescent idiopathic scoliosis is heavily debated in the literature. This study aimed to review posterior surgical techniques in the treatment of adolescent idiopathic scoliosis. Literature review was performed. In treating adolescent idiopathic scoliosis with posterior spine fusion, there are many factors to consider when determining where to start and end the fusion construct: skeletal maturity, stress/bending radiographs, and assessment of vertebral rotation and translation. When considering selective thoracic fusion, the relative magnitudes of the main thoracic (MT) and thoracolumbar/lumbar (TL/L) curves and the overall sagittal profile of the thoracolumbar junction are assessed. Selective thoracic fusion can be appropriate if two of the three are found to be true: the MT-to-TL/L Cobb angle ratio is >1.2, the MT-to-TL/L apical vertebral translation (AVT) ratio is >1.2, and/or the MT-to-TL/L apical vertebral rotation (AVR) ratio is >1.2. Moreover, selective thoracic fusion can be an option in the presence of a nonstructural lumbar curve (bending Cobb angle <25°) with thoracolumbar (T10-L2) kyphosis <20°. When choosing the uppermost and lowest instrumented vertebra, one must consider standing coronal balance and regional kyphosis to lessen risk of postoperative complication. The uppermost instrumented vertebra should be a stable, neutral vertebra with <5° of junctional kyphosis; and the lowest instrument vertebra should be touched by the central sacral vertical line and within two vertebrae proximal to the neutral vertebra. To aid in correction, the addition of posterior surgical releases improves the mobility of spine, especially in more rigid curves, but may increase intraoperative blood loss and operative time. Rod derotation and vertebral translation appear to have similar results in correcting coronal and sagittal deformities. The addition of direct vertebral rotation and segmental rotation plays a role in surgical correction as well.

Efficacy of sequential correction based on satellite rod techniquein degenerative scoliosis with B-type coronal imbalance

Objective: To evaluate the radiographic and clinical outcomes of sequential correction based on satellite rod technique in degenerative scoliosis (DS) with B-type coronal imbalance, and to investigate the efficacy of sequential correction in this cohort. Methods: Twenty-one DS patients with B-type coronal imbalance applying sequential correction from December 2015 to July 2017 in Nanjing Drum Tower Hospital were retrospectively reviewed. There were 4 males and 17 females in this group, the average age was (63±8) years. The coronal parameters including Cobb angle of main curve and distance between C(7) plumb line and center sacral vertical line (C(7)PL-CSVL), as well as sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were assessed pre-operatively, post-operatively and at the last follow-up. The Scoliosis Research Society-22 (SRS-22) questionnaire was fulfilled before the operation and at each follow-up to evaluate the quality of life. Paired t test was performed for statistical analysis. Results: The patients were followed-up for (20±8) months. The post-operative Cobb angle of main curve was significantly improved from 52°±12° to 19°±7° (t=13.886, P<0.01), and it was 19°±8° at the last follow-up and no significant correction loss was attained (t=1.101, P=0.284). The values of C(7)PL-CSVL before the operation, after the operation and at the final follow-up were (46±11) mm, (12±7) mm and (12±7) mm, respectively; significant post-operative improvement achieved (t=19.718, P<0.01) while there was no correction loss at last follow-up (t=-1.393, P=0.179). After sequential correction, 20 patients (95.2%) improved to A-type coronal imbalance while 1 patient (4.8%) remained with B-type coronal imbalance. Significant post-operative improvements were found in terms of GK and SVA and no significant correction loss was found during follow-up. The scores of pain and self-image showed significant improvement at the last follow-up (t=8.706, 3.104, both P<0.01). In addition, there was no implant failure during follow-up. Conclusion: The sequential correction based on satellite rod technique in DS patients with B-type coronal imbalance corrects the deformity, relieves the clinical symptoms, improves the quality of life, and decreases the rates of post-operative coronal imbalance as well as implant-related complications.

The Lumbosacral Takeoff Angle Can Be Used to Predict the Postoperative Lumbar Cobb Angle Following Selective Thoracic Fusion in Patients with Adolescent Idiopathic Scoliosis.

Selective fusion of double curves in patients with scoliosis is considered to spare fusion levels. In 2011, we studied the lumbosacral takeoff angle, defined as the angle between the center-sacral vertical line and a line through the centra of S1, L5, and L4. The lumbosacral takeoff angle was shown to moderately correlate with the lumbar Cobb angle, and a predictive equation was developed to predict the lumbar Cobb angle after selective fusions. The purposes of the present study were to validate that equation in a separate cohort and to assess differences in outcomes following selective and nonselective fusion. Patients with Lenke 1B, 1C, 3B, or 3C curve patterns undergoing fusion (both selective and nonselective) with pedicle screw constructs and a minimum of 2 years of follow-up were included. Selective fusion was defined as a lowest level of fixation cephalad to or at the apex of the lumbar curve. To validate the previously derived equation, we used this data set and analysis of variance to check for differences between the actual and calculated postoperative lumbar Cobb angles. Pearson correlation, multiple linear regression, and t tests were used to explore relationships and differences between the selective and nonselective fusion groups. The mean calculated postoperative lumbar Cobb angle (and standard deviation) (22.35° ± 3.82°) was not significantly different from the actual postoperative lumbar Cobb angle (21.08° ± 7.75°), with an average model error of -1.268° (95% confidence interval, -2.649° to 0.112°). The preoperative lumbar Cobb angle was larger in patients with deformities that were chosen for nonselective fusion (50.2° versus 38.9°; p < 0.001). Performing selective fusion resulted in a 3.5° correction of the lumbosacral takeoff angle (p < 0.001), whereas nonselective fusion resulted in a 9.3° correction (p < 0.001). The lumbosacral takeoff angle can be used to predict the residual lumbar Cobb angle and may be used by surgeons to aid in the decision between selective and nonselective fusion. The change in the lumbosacral takeoff angle following selective fusion is small. Improvement in the lumbosacral takeoff angle and coronal balance is greater in association with nonselective fusion. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Surgical strategy and clinical outcomes in degenerative lumbar scoliosis with type C coronal imbalance

Objective To illustrate the surgical strategy of sequential correction in degenerative lumbar scoliosis (DLS) with type C coronal imbalance, and to evaluate the clinical outcomes and advances of sequential correction technique. Methods Twelve patients (2 males and 10 females) applying sequential correction technique from January 2015 to August 2017 were retrospectively reviewed. The ages of the cohort ranged 48-74 years and the average value was 52.3±8.4 years. The sequential correction technique was mainly applied in 3 steps: correction of local kyphoscoliosis with satellite rod on convex side of lumbar spine; correction of lumbosacral curve with L 4-S1 Intervertebral fusion and satellite rod on convex side of lumbosacral spine; correction of global deformity with bilateral long rods. The coronal parameters including Cobb angle and distance between C7 plumb line and center sacral vertical line (C7PL-CSVL), and the sagittal parameters including global kyphosis (GK) and sagittal vertical axis (SVA) were assessed at pre-operation, post-operationand last follow-up. The quality of life was evaluated using SF-36 questionnaire, and paired t test was used for the statistical analysis. Results The average follow-up period was 16.7±4.8 months. The Cobb angles at pre-operation and post-operation were 59.6°±18.7° and 25.6°±12.4° (t=3.705, P<0.001), respectively. At last follow-up, the average Cobb angle was 27.5°±13.0°, and there was no significant loss of correction (t=0.366, P=0.718). Post-operative C7PL-CSVL changed from 48.5±17.2 mm to 9.7±4.3 mm (t=5.842, P<0.001), of which the average value was 10.1±4.5 mm at last follow-up (t=0.223, P=0.826). At post-operation, 11 patients were with type A coronal imbalance, and 1 patient was still with type C coronal imbalance. The scores of bodily pain, general health, and social functioning were 8.4±1.9, 78.1±9.4 and 76.7±8.4 at pre-operation, 10.2±2.0 (t=2.260, P=0.034) , 89.5±7.6 (t=3.267, P=0.004) and 84.5±9.3 (t=2.156, P=0.042) at post-operation. In addition, there was no implant-related complications during follow-up. Conclusion The sequential correction technique could be well used in adult degenerative lumbar scoliosis patients with type C coronal imbalance, which can simplify the surgical procedure, decrease the rates of post-operative coronal imbalance, and obtain rigid internal fixation. Key words: Adult; Lumbar vertebrae; Intervertebral disc degeneration; Scoliosis; Spinal fusion

Correlation between spinal coronal balance and static baropodometry in children with adolescent idiopathic scoliosis

BackgroundScoliosis is accepted as a 3-dimensional deformity involving axial, sagittal and frontal planes. Research questionTo evaluate the correlation between baropodometric parameters and coronal balance status for idiopathic scoliosis. Methods44 patients (7 males and 37 females) of Adolescent Idiopathic Scoliosis (AIS) were recruited. All participants should have scoliosis confirmed by a spine X-ray performed less than one month ahead of the baropodometric study. Radiographic studies including Cobb angle, offset between Central Sacral Vertical Line (CSVL) and C7 Vertebra Plumb Line (C7PL) (considered as global coronal balance, GCB), Apical Translation of the major curve (AT, considered as regional coronal balance) as well as Lateral Pelvic Tilt (LPT) were examined. A static baropodometry was performed for each patient. The contact surface and load ratio (to the entire load of both feet) were measured. ResultsOn both sides, the surface of the forefoot was significantly larger than that of the rearfoot (P < 0.001) and the load ratio of the forefoot was significantly smaller than that of the rearfoot (P < 0.001). On the major curve side, GCB showed a positive correlation with the contact surface of the forefoot (r = 0.36, P = 0.019), as well as the load ratio (r = 0.40, P = 0.008). AT also showed a positive correlation with the load ratio of the forefoot (r = 0.331, P = 0.03) but no correlation with contact surface. SignificanceIn scoliosis, coronal balance is correlated to plantar pressure distribution. Apical translation of the major curve and offset between CSVL and C7PL are the best describers of coronal balance.

P142. Management of coronal malalignment in the setting of fractional curve correction

BACKGROUND CONTEXT Sagittal malalignment has been discussed extensively in adult spinal deformity (ASD) literature, while coronal malalignment (CM) and fractional curve (FC) have received less attention. As a result, little guidance currently exists for surgical indications in managing CM, despite it being a relatively common occurrence that can considerably impact patient wellbeing. Patients with CM significantly affected by FC are at particular risk for continued CM postoperatively, along with its complications. PURPOSE Assess types of approach to fusion of the fractional curve in ASD surgery and their relation to coronal alignment and sagittal alignment. STUDY DESIGN/SETTING Retrospective review at single institution. PATIENT SAMPLE A total of 82 ASD patients undergoing primary spinal fusion of 4 or more levels to sacrum or pelvis. OUTCOME MEASURES Baseline (BL), 1-year (Y1) postoperatively and BL-Y1 difference (ΔBL-Y1) in magnitudes of FC, coronal alignment (CA) and sagittal alignment (SA) parameters: pelvic incidence-LL (PI-LL), cervical sagittal vertical axis (cSVA), T1 pelvic angle (TPA). METHODS Patients ≥18 years old undergoing primary ≥4-level fusion to sacrum/pelvis between October 2011 and January 2018 with minimum 6-month follow-up included. Chart review performed for operative dates and details and patient follow-up information. Coronal and sagittal parameters measured using deformity measuring software program. FC measured as segmental angle between L4 and S1. CA measured as distance between C7 plumb line and central sacral vertical line. CA≥20mm designated as CM, per guidelines in literature. Chi-squared test used to compare percentages and ANOVA used to compare means, with significance set at p RESULTS A total of 82 patients studied (68.3%F, age 62.6±13.3, BMI 28.1±6.6, Charlson comorbidity index 0.80±1.16). Nine patients (10.98%) had anterior-posterior fusion (AP), 41 (50%) posterior-only fusion with interbody device (PIB), 32 (39.02%) PSF without interbody (PSF). Twenty-three patients (28.04%) had FC≥15° at BL, 7 (8.54%) at Y1. Forty-one patients (50%) had CM at BL, 35 (42.68%) at Y1. AP fusion patients had least levels fused (6.4 AP, 11.4 PIB, 11.8 PSF, p CONCLUSIONS Fusion to the sacrum/pelvis improves sagittal alignment, fractional curve and coronal alignment in most patients. However, while fractional curve and sagittal alignment are better corrected, coronal malalignment, particularly more severe malalignment at baseline, tends to persist postoperatively. Type of approach and use of interbody device does not appear to significantly impact these results. This should be considered in preoperative planning for patients with coronal deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.