High Sagittal Vertical Axis Research Articles

Incidence and risk factors of proximal junctional kyphosis after internal fixation for adult spinal deformity: a systematic evaluation and meta-analysis.

To investigate the factors associated with proximal junctional kyphosis (PJK). A systematic search was performed. The weighted mean difference (WMD) was pooled for continuous variables, and the odds ratio (OR) was calculated for dichotomous variables. The PJK group had higher values for age (WMD = 2.53, 95%CI = 1.38 ~ 3.68, P <0.001), female gender (OR = 1.56, 95%CI = 1.29 ~ 1.87, P <0.001), and diagnosed osteoporosis (OR = 1.58, 95%CI = 1.11 ~ 2.26, P =0.01). Preoperatively, significant differences were detected in sagittal vertical axis (SVA) (WMD = 19.29, 95%CI = 16.60 ~ 21.98, P <0.001), pelvic incidence minus lumbar lordosis (PI-LL) (WMD = 2.71, 95%CI = 0.25 ~ 5.18, P =0.03), pelvic tilt (PT) (WMD = 2.64, 95%CI = 1.38 ~ 3.90, P <0.001), lumbar lordosis (LL) (WMD = - 1.76, 95%CI = - 2.73 ~ -0.79, P <0.001), and sacral slope (SS) (WMD = - 2.80, 95%CI = - 5.57 ~ -0.04, P =0.001). At follow-up, the following were higher in the PJK group: thoracic kyphosis (TK) (WMD = 5.51, 95%CI = 2.23 ~ 8.80, P <0.001), proximal junctional angle (PJA) (WMD = 9.07, 95%CI = 4.21 ~ 13.92, P <0.001), and PT (WMD = 1.51, 95%CI = 0.31 ~ 2.72, P =0.01). However, there was no significant difference in SS (P = 0.49), and SVA (P = 0.11) between groups. Fusion to S1 or pelvis significantly increased the risk of PJK (OR = 2.08, P <0.001). Ligament augmentation reduced the risk of PJK (OR = 0.34, 95%CI = 0.21 ~ 0.53, P <0.001) better than the use of laminar hook (OR = 0.46, P <0.001). Although no difference was detected for preoperative SRS-22 score (P = 0.056), a lower score (WMD = - 0.24, 95%CI = - 0.35 ~ -0.14, P <0.001) was detected in PJK group at follow-up. The elderly female ASD patients were more susceptible to PJK, especially for those with osteoporosis, high preoperative SVA, low LL, large PT, and LIV extended to pelvis. The use of laminar hook and ligament reinforcement at the proximal end might prevent PJK.

Influence of the Sagittal Vertical Axis on the Risk of Falls in Community-Dwelling Elderly People: A Retrospective Longitudinal Study.

Introduction Falling is an age-related problem that increases with age. Compared with younger people, elderly people possess increased risk factors for falls, and falling among the elderly is associated with increased mortality. Risk factors for falls have been reported in elderly outpatients; however, whether sagittal spinal posture affect the risk of falls in community residents remains unclear. Therefore, we aimed to investigate the influence of sagittal spinal posture on the risk of falls in elderly community-dwelling people using spino-plevic sagittal parameters in a retrospective longitudinal study. Methods A total of 463 volunteers (96 men and 367 women; mean age, 72.8 years) who underwent a routine physical checkup were evaluated. Baseline whole spine and lower limb radiography, physical tests, bone mineral density (BMD), number of medications and comorbidities, patient-reported outcomes (PROs), and a history of falls in the previous four years period were examined. Results Univariate analysis revealed older age, lower height and weight, higher prevalence of vertebral fractures, higher number of medications, poor physical test scores including one-leg standing test and prone trunk extension, poor PROs, a higher sagittal vertical axis, and higher pelvic tilt (PT) as factors significantly associated with the risk of falls, and multivariate analysis revealed a higher sagittal vertical axis [odds ratio (OR), 1.08; 95% confidence interval (CI), 1.002-1.013; P = 0.02] and locomotive syndrome assessed using the 25-Question Geriatric Locomotive Function Scale score (OR, 1.028; 95% CI, 1.004-1.053; P = 0.03) to be associated with the risk of falls, independent of other factors in the univariate analysis. Conclusions The sagittal vertical axis was an independent risk factor for falls, and the prevalence of vertebral fractures and prone truck extension correlated with the sagittal vertical axis. Prospective and intervention studies are needed to prevent future falls in elderly community volunteers with a higher sagittal vertical axis.

Factors predicting loss of cervical lordosis following cervical laminoplasty: A critical review

Background:Laminoplasty is a method of posterior cervical decompression which indirectly decompresses the spinal column. Unfortunately, many patients undergoing laminoplasty develops postoperative loss of cervical lordosis (LCL) or kyphotic alignment of cervical spine even though they have sufficient preoperative lordosis which results in poor surgical outcome.Objective:We would like to highlight the relationship between various radiological parameters of cervical alignment and postoperative LCL in patients undergoing laminoplasty.Methods:We performed extensive literature search using PubMed, Google Scholar, and Web of Science for relevant articles that report factors affecting cervical alignment following laminoplasty.Results:On reviewing the literature, patients with high T1 slope have more lordotic alignment of cervical spine preoperatively. They also have more chances of LCL following laminoplasty. C2–C7 sagittal vertical axis (SVA) has no role in predicting LCL following laminoplasty though patients with low T1 slope (≤20°) and high C2–C7 SVA (>22 mm) had correction of kyphotic deformity following laminoplasty. C2–C7 lordosis, Neck Tilt, cervical range of motion, and thoracic kyphosis has no predictive value for LCL. Lower value of T1 slope (T1S-CL) and CL/T1S has more incidence of developing LCL following laminoplasty. The role of C2–C3 disc angle has not yet been evaluated in patients undergoing laminoplasty. Dynamic extension reserve determines the contraction reserve of SPMLC and lower dynamic extension reserve is associated with higher chances of LCL following laminoplasty.Conclusions:Cervical lordotic alignment is important in maintaining cervical sagittal balance which ultimately is responsible for global spinal sagittal balance and horizontal gaze. Among various radiological parameters, T1 Slope has been reported to be the most important factor affecting cervical alignment following laminoplasty.

Does Cervical Sagittal Balance Affect the Preoperative Neck Disability Index in Patients With Cervical Myelopathy?

This was a retrospective study. This study aimed to ascertain the relationship between preoperative Neck Disability Index (NDI) scores and cervical sagittal alignment in patients with cervical spondylotic myelopathy (CSM). Cervical alignment may influence postoperative clinical outcomes. However, the effect of preoperative sagittal balance on the preoperative status in CSM patients remains uncertain. From 2010 to 2016, 90 patients who underwent cervical surgery for CSM were enrolled. The inclusion criteria for this study included preoperative standing cervical radiographs and a preoperative NDI score. The following radiographic parameters were measured: (1) C0-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (SVA), (4) neck tilt, (5) thoracic inlet angle, (6) T1 slope, and (7) T1 slope minus cervical lordosis (T1S-CL). The Pearson product-moment correlation coefficients were calculated between all radiographic variables and the NDI scores, and multiple regression analysis was performed to determine the independent predictors of high preoperative NDI scores. Both C2-C7 SVA and T1S-CL were positively correlated with NDI scores (r=0.732, P<0.001 and r=0.333, P=0.001). Cervical lordosis was negatively correlated with NDI scores (r=-0.267, P=0.011). Significant correlations were found between C2-C7 SVA and the C0-C2 Cobb angle (r=0.244, P=0.020), C2-C7 SVA and the C2-C7 Cobb angle (r=-0.359, P=0.001), the C2-C7 Cobb angle and the C0-C2 Cobb angle (r=-0.457, P<0.001), and the C2-C7 Cobb angle and T1 slope (r=-0.385, P<0.001). The disability of the neck increased with increasing C2-C7 SVA and T1S-CL and decreasing cervical lordosis before surgical reconstruction. High C2-C7 SVA, low thoracic inlet angle, and high neck tilt values are independent predictors of high preoperative NDI scores.

71. High preoperative T1 slope is a marker for global sagittal malalignment

BACKGROUND CONTEXT T1 slope (T1S) is a parameter typically discussed in the context of cervical deformity and is correlated with health-related quality of life outcomes. Although prior research has suggested that T1S is related to global alignment, a definition for “high” T1S has not been established. Most patients undergoing cervical surgery do not receive full spine imaging. Therefore, it would be beneficial to have a parameter obtained from cervical radiographs that is associated with thoracolumbar malalignment. PURPOSE To define a threshold for T1S that is associated with thoracolumbar malalignment STUDY DESIGN/SETTING Retrospective review of a prospective adult spinal deformity(ASD) database PATIENT SAMPLE A total of 226 preoperative ASD patients. OUTCOME MEASURES Baseline sagittal alignment: T1S, thoracic kyphosis(TK), C7 sagittal vertical axis (SVA), T1 pelvic angle (TPA), pelvic tilt (PT), pelvic incidence-lumbar lordosis mismatch (PI-LL). METHODS A database of preoperative ASD patients was analyzed. Patients without preoperative full-spine images were excluded. Measures obtained from standing lateral radiographs included: T1S, TK, SVA, TPA, PT, and PI-LL. T1S was correlated to each of these parameters. Decision tree analysis was then used to determine the T1S corresponding to published thresholds for high TK (40°), SVA (40mm), TPA (25°), and PT (25°). Alignment between high and normal T1S patients was compared via t-tests and chi-square tests. RESULTS A total of 226 preoperative ASD patients were included (mean 58±16y 62% F). At baseline, 30% had high TK, 54% had high SVA, 46% had high TPA, and 46% had high PT. Larger T1S was significantly correlated with greater SVA (R=.365) TPA (R=.302), TK (R=.606), and PT (R=.230)(all p 30° had higher TK (41.5° vs 25.8°), SVA (78.7mm vs 33.7mm), TPA (27.6° vs 18.3°), and PT (26.3° vs 20.8°), and PI-LL (18.2° vs 11.7°)(all p 25° (T1S 20° (T1S CONCLUSIONS Similar to previous studies higher T1S was associated with worse global alignment. T1S was most strongly associated with TK. A T1S=30° corresponds to thresholds for high TK, SVA, TPA, and PT. Therefore, surgeons should consider obtaining full-spine radiographs if a T1S>30° is present on cervical imaging. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Surgical, Radiographic, and Patient-Related Risk Factors for Proximal Junctional Kyphosis: A Meta-Analysis.

Study Design:Meta-analysis.Objective:Proximal junctional kyphosis (PJK) is a complication of surgical management for adult spinal deformity with a multifactorial etiology. Many risk factors are controversial and their relative importance are not fully understood. We aimed to identify the surgical, radiographic, and patient-related risk factors associated with PJK and proximal junctional failure (PJF).Methods:A systematic literature search was performed using PubMed, Cochrane Database of Systematic Reviews, and EMBASE. The inclusion criteria included prospective randomized control trials and prospective/retrospective cohort studies of adult patients with radiographic evidence of PJK, which was defined as a proximal junctional sagittal Cobb angle ≥10° and at least 10° greater than the preoperative measurement. Studies required a minimum of 10 patients and 12 months of follow-up.Results:A total of 14 unique studies, including 1908 patients were included. The pooled analysis showed significant differences between the PJK and non-PJK groups in age (weighted mean difference [WMD] −3.80; P = .03), prevalence of osteopenia/osteoporosis (odds ratio [OR] 1.99; P = .0004), preoperative sagittal vertical axis (SVA) (WMD −17.52; P = .02), preoperative lumbar lordosis (LL) (WMD −1.22; P = .002), pedicle screw instrumentation at the upper instrumented vertebra (UIV) (OR 1.67; P = .02), change in SVA (WMD −11.87; P = .01), fusion to sacrum/pelvis/ilium (OR 2.14; P < .00 001), change in LL (WMD −5.61; P = .01), and postoperative SVA (WMD −7.79; P = .008).Conclusions:Our meta-analysis suggests that age, osteopenia/osteoporosis, high preoperative SVA, high postoperative SVA, low preoperative LL, use of pedicle screws at the UIV, SVA change/correction, LL change/correction, and fusion to sacrum/pelvis/iliac region are risk factors for PJK.

Radiological severity of hip osteoarthritis in patients with adult spinal deformity: the effect on spinopelvic and lower extremity compensatory mechanisms.

Sagittal spinal deformity (SSD) patients utilize pelvic tilt (PT) and their lower extremities in order to compensate for malalignment. This study examines the effect of hip osteoarthritis (OA) on compensatory mechanisms in SSD patients. Patients≥18years with SSD were included for analysis. Spinopelvic, lower extremity, and cervical alignment were assessed on standing full-body stereoradiographs. Hip OA severity was graded by Kellgren-Lawrence scale (0-4). Patients were categorized as limited osteoarthritis (LOA: grade 0-2) and severe osteoarthritis (SOA: grade 3-4). Patients were matched for age and T1-pelvic angle (TPA). Spinopelvic [sagittal vertical axis (SVA), T1-pelvic angle, thoracic kyphosis (TK), pelvic tilt (PT), lumbar lordosis (LL), pelvic incidence minus lumbar lordosis (PI-LL), T1-spinopelvic inclination (T1SPi)] and lower extremity parameters [sacrofemoral angle, knee angle, ankle angle, posterior pelvic shift (P. Shift), global sagittal axis (GSA)] were compared between groups using independent sample t test. 136 patients (LOA=68, SOA=68) were included in the study. SOA had less pelvic tilt (p=0.011), thoracic kyphosis (p=0.007), and higher SVA and T1Spi (p<0.001) than LOA. SOA had lower sacrofemoral angle (p<0.001) and ankle angle (p=0.043), increased P. Shift (p<0.001) and increased GSA (p<0.001) compared to LOA. There were no differences in PI-LL, LL, knee angle, or cervical alignment (p>0.05). Patients with coexisting spinal malalignment and SOA compensate by pelvic shift and thoracic hypokyphosis rather than PT, likely as a result of limited hip extension secondary to SOA. As a result, SOA had worse global sagittal alignment than their LOA counterparts. These slides can be retrieved under Electronic Supplementary Material.

Effect of global postural alignment on gait: A study on 145 asymptomatic subjects with a large age range

Introduction Global postural alignment parameters have been shown to be major determinants of quality of life [1] . Gait is an essential task of functionality during daily living activities. It is still unknown how global postural alignment can influence gait. The aim was to investigate how global postural alignment can influence gait in asymptomatic subjects. Materiel et methodes Overall, 145 asymptomatic subjects (age: 29.2 ± 11 years [18–59], 70F) underwent 3D gait analysis followed by full body biplanar X-rays. Kinematics of lower limb segments (pelvis, hip, knee, ankle and foot) were extracted in the 3 planes during the gait cycle. Full body 3D reconstructions were obtained from the biplanar X-rays and global postural alignment was evaluated by calculating: sagittal vertical axis (SVA), center of the auditory meatus plumbline to the hip axis, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic parameters (PI, PT, SS). Agglomerative hierarchical clustering (AHC) was performed on each postural parameter to classify subjects into homogeneous groups. Differences in gait parameters between groups were evaluated using ANCOVA while adjusting for demographic confounding factors (age, weight, height and sex). Resultats The most discriminant postural parameter in gait kinematics was the SVA. AHC differentiated 3 groups of SVA: Gr1: 10 mm, n = 55. Weight, height and sex were statistically different between groups (Gr1 vs. Gr3: 68 ± 16 vs. 77 ± 13 kg, 167, n 10 vs. 173 ± 10 cm, 39F/23 M vs. 6F/22 M, p Discussion This is the first study demonstrating the influence of postural alignment parameters on gait. While interindividual variations of TK and LL were not shown to impact gait, subjects with elevated SVA had their general gait modified even after correcting for confounding factors: higher duration with larger knee flexion during shock absorption phase at the beginning of gait cycle. While these results were shown in asymptomatic subjects with high SVA (> 10 cm), higher SVA in subjects with spinal deformities could be a cause for more altered gait kinematics.

Magnitude, Location, and Factors Related to Regional and Global Sagittal Alignment Change in Long Adult Deformity Constructs: Report of 183 Patients With 2-Year Follow-up.

This is a retrospective review of a prospective multicenter adult spinal deformity (ASD) database. To quantify the location and magnitude of sagittal alignment changes within instrumented and noninstrumented spinal segments and to investigate the factors associated with these changes after surgery for ASD. Spinal realignment is one of the major goals in ASD surgery and changes in the alignment are common following surgical correction. Inclusion criteria: operative patients with age above 18, coronal Cobb angle ≥20 degrees, sagittal vertical axis (SVA) ≥5 cm, pelvic tilt ≥25 degrees, and/or thoracic kyphosis ≥60 degrees. revision surgery 6 weeks postoperatively. Standard sagittal radiographic spinal deformity parameters were evaluated. Changes in sagittal parameters between 6 weeks and 2 years postoperatively were assessed within and outside instrumented segments. Associations between changes in sagittal alignment and age, preoperative SVA, rod diameters, rod material, presence of 3-column osteotomy, and the use of interbody fusions were evaluated. Patients were also stratified by >5- and >10-degree changes in alignment. In total, 183 patients (male:29, female:154, average age: 56±14.8 y) met inclusion criteria. A total of 45(24.6%) patients had increase in pelvic tilt >5 degrees, 74(40.4%) had increase in pelvic incidence and lumbar lordosis (LL) >5 degrees, and 76 (41.5%) had increase in SVA >2 cm. Mean change of thoracic sagittal alignment was +8 degrees; 70 (60%) patients had increases of >5 degrees and 31 (27%) had increases of >10 degrees. Noninstrumented thoracic segments had significantly more increase than instrumented thoracic segments (P=0.02). Mean loss of LL was -6 degrees; 49(47%) patients had worsening >5 degrees and 13(13%) >10 degrees. Noninstrumented lumbar segments had significantly less loss of lordosis than instrumented segments (P<0.01). Risks for loss of LL were: age 65 years and above [odds ratio (OR) 9.4; 95% confidence interval (CI), 3.5-25.2; P<0.01], preoperative SVA>5 cm (OR, 2.4; 95% CI, 1.3-4.4; P<0.01), and lumbar interbody fusion (OR, 2.3; 95% CI, 1.2-4.2; P<0.01). Smaller rods (4.5 mm) were associated with a lower probability of worsening LL compared with 5.5-mm rods (OR, 0.15; 95% CI, 0.04-0.58; P<0.01) and 6.0-mm rods (OR, 0.36; 95% CI, 0.18-0.72; P<0.01). The presence of a 3-column osteotomy and rod material were not significant factors in alignment changes (P>0.05). After correction of ASD, increases in thoracic and decreases in lumbar alignment is common. Loss of thoracic sagittal alignment primarily occurs in noninstrumented thoracic segments, whereas instrumented lumbar levels in elderly patients ( above 65 y) with high preoperative SVA, interbody fusions, and larger rods have significantly higher rates of postoperative sagittal alignment changes in the lumbar spine.

A Novel Tool for Deformity Surgery Planning: Determining the Magnitude of Lordotic Correction Required to Achieve a Desired Sagittal Vertical Axis.

We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordosis (PI-LL) correction necessary to achieve a desired change in sagittal vertical axis (SVA). A retrospective review was conducted of a prospectively maintained multicenter adult spinal deformity database collected by the International Spine Study Group between 2009 and 2014. The independent variable of interest was the degree of correction achieved in the PI-LL mismatch 6 weeks after surgery. Primary outcome was the change in global sagittal alignment 6 weeks and 1 year after surgery. We used a linear mixed-effects model to determine the extent to which corrections in the PI-LL relationship affected postoperative changes in SVA. A total of 1053 adult patients were identified. Of these patients, 590 were managed surgically. Eighty-seven surgically managed patients were excluded because of incomplete or missing PI-LL measurements on follow-up; the remaining 503 patients were selected for inclusion. For each degree of improvement in the PI-LL mismatch at 6 weeks, the SVA decreased by 2.18 mm (95% confidence interval,-2.56,-1.79; P < 0.01) and 1.67 mm (95% confidence interval,-2.07,-1.27; P < 0.01) at 6 weeks and 12 months, respectively. A high SVA measurement (>50 mm) 1 year after surgery was negatively associated with health-related quality of life as measured by the Scoliosis Research Society 22 outcomes assessment. We describe a novel model that shows how surgical correction of the PI-LL relationship affects postoperative changes in SVA. This model may enable surgeons to determine preoperatively the amount of LL necessary to achieve a desired change in SVA.

The impact of obesity on compensatory mechanisms in response to progressive sagittal malalignment

Background ContextObesity's impact on standing sagittal alignment remains poorly understood, especially with respect to the role of the lower limbs. Given energetic expenditure in standing, a complete understanding of compensation in obese patients with sagittal malalignment remains relevant. PurposeThis study compares obese and non-obese patients with progressive sagittal malalignment for differences in recruitment of pelvic and lower-limb mechanisms. Study Design/SettingSingle-center retrospective review. Patient SampleA total of 554 patients (277 obese, 277 non-obese) were identified for analysis. Outcome MeasuresUpper body alignment parameters: sagittal vertical axis (SVA) and T1 spinopelvic inclination (T1SPi). Compensatory lower-limb mechanisms: pelvic translation (pelvic shift [PS]), knee (KA) and ankle (AA) flexion, hip extension (sacrofemoral angle [SFA]), and global sagittal angle (GSA). MethodsInclusion criteria were patients ≥18 years who underwent full-body stereographic x-rays. Included patients were categorized as non-obese (N-Ob: body mass index [BMI]<30 kg/m2) or obese (Ob: BMI≥30 kg/m2). To control for potential confounders, groups were propensity score matched by age, gender, and baseline pelvic incidence (PI), and subsequently categorized by increasing spinopelvic (pelvic incidence minus lumbar lordosis [PI−LL]) mismatch: <10°, 10°–20°, >20°. Independent t tests and linear regression models compared sagittal (SVA, T1SPi) and lower limb (PS, KA, AA, SFA, GSA) parameters between obesity cohorts. ResultsA total of 554 patients (277 Ob, 277 N-Ob) were included for analysis and were stratified to the following mismatch categories: <10°: n=367; 10°–20°: n=91; >20°: n=96. Obese patients had higher SVA, KA, PS, and GSA than N-Ob patients (p<.001 all). Low PI−LL mismatch Ob patients had greater SVA with lower SFA (142.22° vs. 156.66°, p=.032), higher KA (5.22° vs. 2.93°, p=.004), and higher PS (4.91 vs. −5.20 mm, p<.001) than N-Ob patients. With moderate PI−LL mismatch, Ob patients similarly demonstrated greater SVA, KA, and PS, combined with significantly lower PT (23.69° vs. 27.14°, p=.012). Obese patients of highest (>20°) PI−LL mismatch showed greatest forward malalignment (SVA, T1SPi) with significantly greater PS, and a concomitantly high GSA (12.86° vs. 9.67°, p=.005). Regression analysis for lower-limb compensation revealed that increasing BMI and PI−LL predicted KA (r2=0.234) and GSA (r2=0.563). ConclusionsWith progressive sagittal malalignment, obese patients differentially recruit lower extremity compensatory mechanisms, whereas non-obese patients preferentially recruit pelvic mechanisms. The ability to compensate for progressive sagittal malalignment with the pelvic retroversion is limited by obesity.

Impact of Cervical Sagittal Alignment Parameters on Neck Disability.

Retrospective cross-sectional study. Determine if pre-operative cervical alignment serves as an independent predictor of pre-operative disability as measured by the neck disability index (NDI). There is growing interest in the relationship between cervical sagittal alignment and clinical outcomes. While prior studies have shown that C2-C7 sagittal vertical axis (SVA) correlates with worse NDI scores in post-operative patients, no studies to date have examined the impact of cervical sagittal parameters on pre-operative disability in patients indicated for surgery. Patients with pre-operative standing cervical radiographs, no prior cervical spine procedures and a pre-operative NDI score were identified. Measurements were made by two observers at two different time points. Parameters measured were: Occiput-C2 angle, C1-C2 angle, C2-C7 angle (CL), T1 slope (TS), TS minus CL (TS-CL), C2-C7 SVA, and C1-C7 SVA. Intra- and inter-observer reliability was calculated. Subgroup analyses of myelopathy vs. radiculopathy and deformity vs. no deformity was performed. A multivariate linear regression was performed. Ninety patients were included. Indications included cervical myelopathy (n = 63), cervical radiculopathy (n = 25), cervical stenosis (n = 9), and others (n = 5). CL averaged -13.7 ± 14.9 degrees. TS averaged 30.7 ± 10.4 degrees and C2-C7 SVA averaged 28.8 ± 13.2 mm. Intra- and inter-observer reliability was good to excellent (ICC > 0.8). Increasing CL (r = 0.277, P = 0.009), increasing TS (r = -0.273, P = 0.011) and increasing TS-CL (r = -0.301, P = 0.005) were correlated with decreasing NDI. CL, TS and TS-CL were also strongly correlated with each other (r > 0.65, P < 0.001 for all bivariate correlations). A multivariate regression adjusting for age and indication showed TS-CL (P = 0.040) and C2-C7 SVA (P = 0.015) were independent predictors of NDI. Increasing CL, increasing TS and increasing TS-CL are correlated with decreasing pre-operative NDI. Low TS-CL and high C2-C7 SVA are independent predictors of high pre-operative NDI. 4.

Clinical Implications of Spino-pelvic Parameters for the Outcome of Spinal Surgery for Lumbar Degenerative Diseases

Study Design: A review of the literature. Objectives: To discuss how to evaluate, interpret, and utilize measurements of spino-pelvic alignment before and after spinal surgery in patients with lumbar degenerative disease. Summary of Literature Review: Various spino-pelvic parameters are currently utilized in the evaluation of spinal patients; however, interpretation of these parameters is not easy. Materials and Methods: Each spino-pelvic parameter and factors affecting its value, and how to interpret and utilize the spino-pelvic parameters before and after spinal surgery were discussed for patients with lumbar degenerative disease with and without sagittal spinal deformity. Results: Sagittal modifiers in the SRS-Schwab classification including pelvic incidence minus lumbar lordosis (PI-LL), sagittal vertical axis (SVA), and pelvic tilt (PT) are widely accepted in the evaluation of lumbar degenerative disease with sagittal deformity. Surgery for sagittal realignment is meant to restore both the SVA and PT by restoring the LL in reference to the PI. However, patients with an extremely high SVA and PT or those with a high SVA and low PT can end up with postoperative residual malalignment. In patients without deformity, PI-LL mismatch (> 10°) should be highlighted and should be actively corrected by restoring the lordosis of the pathologic segment. Conclusions: Sagittal modifiers are beneficial for their simplicity and comprehensibility; however, they are insufficient for evaluating sub-regional spinal deformity. Spino-pelvic parameters can be useful for evaluating spinal patients in a clinical setting, but the measurements are greatly affected by confounding factors such as poor patient posture, unqualified testers, and manual measurement techniques.

Analysis of an unexplored group of sagittal deformity patients: low pelvic tilt despite positive sagittal malalignment.

In adult spinal deformity (ASD), patients increase pelvic tilt (PT) to maintain standing alignment. Previously, ASD patients with low PT and high disability were described. This study investigates this unusual population in terms of demographic, radiographic, and clinical features after three-column osteotomy (3CO). In this multicenter retrospective study, ASD patients underwent single lumbar 3CO. Since PT is proportional to pelvic incidence (PI), the low PT group (LowPT) was defined as having a baseline (BL) PT/PI <25th percentile. HRQOL and full spine x-rays were analyzed at BL and 1year. LowPT patients were compared to those with high PT/PI (HighPT) in a matched range of T1 pelvic angle. LowPT group had PT/PI <0.4 (n=31). High disability was reported at baseline for both groups with significant improvement postoperatively, but without difference between groups. LowPT had significantly smaller lack lumbar lordosis but larger SVA, T1 spinopelvic inclination. Postoperatively, there were improvements in all sagittal modifiers except PT in LowPT. 33% of LowPT had an increase in PT (>5°) postoperatively. This subset had more deformity at baseline, achieving good T1SPi postoperative correction but without achieving the SRS-Schwab target SVA at 1year. LowPT group had high levels of disability. After 3CO surgery, low PT patients experience only partial improvements in sagittal vertical axis (SVA) and 33% of the group increased their PT. Further work is necessary to determine optimal realignment approaches for this unusual set of patients. It is unclear if neuromuscular pathology plays a role in the setting of high SVA without pelvic retroversion.

Magnitude of preoperative cervical lordotic compensation and C2–T3 angle are correlated to increased risk of postoperative sagittal spinal pelvic malalignment in adult thoracolumbar deformity patients at 2-year follow-up

Background contextCervical deformity (CD) is prevalent among patients with adult spinal deformity (ASD). The effect of baseline cervical alignment on achieving optimal thoracolumbar alignment in ASD surgery is unclear. PurposeThis study assesses the relationship between preoperative (preop) cervical spinal parameters and global alignment after thoracolumbar ASD surgery at 2-year follow-up. Study design/settingThis study is a retrospective review of a multicenter, prospective database. Patient sampleSurgical ASD patients with 2-year follow-up and cervical X-rays were included. Outcome measuresThe outcome measures were radiographic parameters and self-reported health-related quality-of-life measures (Short-Form 36 [SF-36], Oswestry Disability Index [ODI], and Scoliosis Research Society 22 [SRS-22]). MethodsSurgical ASD patients of 18 years and older with scoliosis greater than or equal to 20° and one of the following radiographic parameters were included: sagittal vertical axis (SVA) greater than or equal to 5 cm, pelvic tilt (PT) greater than or equal to 25°, or thoracic kyphosis (TK) greater than 60°. The SRS-Schwab sagittal modifiers (PT, global alignment, and pelvic incidence and lumbar lordosis [PI-LL]) were assessed at 2-year postoperatively as either normal (“0”) or abnormal (“+” or “++”). Patients were classified in the aligned group (AG) or malaligned group (MG) at 2-year follow-up if all three sagittal modifiers were normal or abnormal, respectively. Patients were assessed for CD based on the following criteria: C2–C7 SVA greater than 4 cm, C2–C7 SVA less than 4 cm, cervical kyphosis (CL greater than 0), cervical lordosis (CL less than 0), any deformity (C2–C7 SVA greater than 4 cm or CL greater than 0), and both CD (C2–C7 SVA greater than 4 cm and CL greater than 0). Univariate testing was performed using t or chi-square test, looking at the following preop parameters: CD, C2–C7 SVA, C2–T3 SVA, CL, T1 slope (T1S), T1S-CL, C2–T3 angle, LL, TK, PT, C7–S1 SVA, and PI-LL. ResultsOne hundred four patients met the initial inclusion criteria with 70 in the AG and 34 in MG. Preoperative, patients in the MG had a higher CL (11.7 vs. 4.9, p=.03), higher C2–T3 angle (13.59 vs 4.9 p=.01), higher PT (p<.0001), higher SVA (p<.0001), and higher PI-LL (p<.0001) compared with the AG. Interestingly, the prevalence of CD at baseline was similar for both groups. There was no statistically significant difference among groups in the amount of improvement more than 2 years on the ODI or the Physical Component Summary of SF-36. ConclusionsPatients with sagittal spinal malalignment associated with significant cervical compensatory lordosis are at increased risk of realignment failure at 2-year follow-up. Assessment of the degree of cervical compensation may be helpful in preop evaluation to assist in realignment outcome prediction.

Sagittal spinopelvic malalignment in Parkinson disease: prevalence and associations with disease severity.

Prospective study. Our objectives were to evaluate the prevalence of sagittal spinopelvic malalignment in a consecutive series of patients with Parkinson disease (PD) and to identify factors associated with sagittal spinopelvic deformity in this population. PD is a degenerative neurological condition characterized by tremor, rigidity, bradykinesia, and loss of postural reflexes. The prevalence of spinal deformity in PD is higher than that of age-matched adults without PD. This study was a prospective assessment of consecutive patients with PD presenting to a neurology clinic during 12 months. Inclusion criteria included age more than 21 years and diagnosis of PD. Age- and sex-matched control group was selected from patients with cervical spondylosis. Clinical and demographic factors were collected including Unified Parkinson Disease Rating Scale score and Hoehn and Yahr stage. Full-length standing spine radiographs were assessed. Patients were grouped into either low C7 sagittal vertical axis (SVA) (<5 cm) or high C7 SVA (≥5 cm) and into matched (≤10°) or mismatched (>10°) pelvic incidence (PI)-lumbar lordosis. Eighty-nine patients met criteria (41 males/48 females), including 52 with low C7 SVA and 37 with high C7 SVA. Significantly higher prevalence of high C7 SVA was found in PD (41.6 vs. 16.8%; P < 0.001). The high C7 SVA group was significantly older (72.4 vs. 65.1 yr; P < 0.001) and had a higher proportion of females (68% vs. 44%; P = 0.034), greater severity of PD based on Hoehn and Yahr stage (1.89 vs. 1.37; P < 0.001) and Unified Parkinson Disease Rating Scale (30.5 vs. 17.2; P = 0.002. Unified Parkinson Disease Rating Scale significantly correlated with C7 SVA (r = 0.474). Compared with the matched (≤10°) PI-lumbar lordosis group, the mismatch PI-lumbar lordosis group had higher C7 SVA, higher PI, higher pelvic tilt, lower lumbar lordosis, and lower thoracic kyphosis (P ≤ 0.003). Patients with PD have a high prevalence of sagittal spinopelvic malalignment than control group patients. Greater severity of PD is associated with sagittal spinopelvic malalignment. 3.

Reciprocal changes in cervical spine alignment after corrective thoracolumbar deformity surgery.

To identify changes in cervical alignment parameters following surgical correction of thoracolumbar deformity and then assess the preoperative parameters which induce changes in cervical alignment following corrective thoracolumbar deformity surgery. A retrospective study of 49 patients treated for thoracolumbar deformity with preoperative planning of an acceptably aligned coronal and sagittal plane in each case. We compared cervical spine parameters in two distinct low [preoperative C7 sagittal vertical axis (SVA) ≤ 6 cm] and high (preoperative C7 SVA ≥ 9 cm) C7 SVA groups. Multilinear regression analysis was performed and revealed the relationship between postoperative cervical lordosis and preoperative spinopelvic parameters and surgical plans. In the lower C7 SVA group, cervical lordosis was significantly increased after thoracic/lumbar deformity correction (p < 0.01). In contrast, the high C7 SVA group showed decreased cervical lordosis postoperatively (p < 0.01). Multilinear regression analysis demonstrated the preoperative parameters (preoperative C2-7 angle, T1 slope, surgical plan for PT and C7 SVA), which determine the postoperative cervical lordosis. In spinal deformity procedures, preoperative spinal alignment parameters, and surgical plans could affect postoperative cervical spine alignment.

Identification of Decision Criteria for Revision Surgery Among Patients With Proximal Junctional Failure After Surgical Treatment of Spinal Deformity

Multicenter, retrospective, consecutive case series. This study aims to identify demographic and radiographical characteristics that influence the decision to perform revision surgery among patients with proximal junctional failure (PJF). Revision rates after PJF remain relatively high, yet the decision criteria for performing revision surgical procedures are not uniform and vary by surgeon. A better understanding of the factors that impact the decision to perform revision surgery is important in order to improve efficiency of surgical treatment of adult spinal deformity. A cohort of 57 patients with PJF was identified retrospectively from 1218 consecutive patients with adult spinal deformity. PJF was identified on the basis of 10° postoperative increase in kyphosis between upper instrumented vertebra (UIV) and UIV +2, along with 1 or more of the following: fracture of the vertebral body of UIV or UIV +1, posterior osseoligamentous disruption, or pullout of instrumentation at the UIV. Univariate statistical analysis was performed using t tests and Fisher exact tests. Multivariate analysis was performed using logistic regression. Twenty-seven (47.4%) patients underwent revision surgery within 6 months of the index operation. Regression results revealed that patients with combined posterior/anterior approaches at index were significantly more likely to undergo revision (P = 0.001) as were patients with more extreme proximal junctional kyphosis angulation (P = 0.034). Patients sustaining trauma were also significantly more likely to undergo revision (P = 0.019). Variables approaching but not reaching significance as predictors of revision included female sex (P = 0.066) and higher sagittal vertical axis (SVA) (P = 0.090). The decision to perform revision surgery is complicated and varies by surgeon. Factors that seem to influence this decision include traumatic etiology of PJF, severity of proximal junctional kyphosis angulation, higher SVA, and female sex. Factors that were expected to influence revision but had no statistical effect included soft tissue versus bony mode of failure, age, levels fused, and upper thoracic versus thoracolumbar proximal junction.