Purpose
Regarding the close interaction between the spinal alignment and the pelvis orientation, no parameter is routinely used to describe and to evaluate the global spinopelvic balance, taking into ...account simultaneously the spinal part and the pelvic part of the global alignment. We described the global tilt (GT) that could analyze malalignment considering the spine and the pelvis simultaneously. From a geometrical point of view, the global tilt is the sum of the pelvic tilt (PT) and the C7 vertical tilt (angular value of sagittal vertical axis). The aim of this study is to evaluate the global tilt with comparison to PT and sagittal vertical axis (SVA), with the hypothesis that GT would be the least sensitive to positional changes.
Methods
A cohort of 22 patients with sagittal malalignment was identified from a multicentric database of adult spinal deformities (ASD). Inclusion criteria were age >30 years, SVA > 40 mm and/or PT > 20°. All patients had full spine EOS radiographs in positions 1 and 2 (P1 and P2), in which the patient was asked to stand and put his hands on his shoulders without any effort (P1), or to make an effort to be as straight as possible (P2). PT, SVA and GT were measured in both positions and changes between P1 and P2 were calculated and compared using Student’s
t
test with significance level at
p
< 0.05.
Results
No significant changes were observed for GT; SVA and PT were significantly influenced by patient positioning. SVA decreased and PT increased for all cases in P2 whereas the changes in GT were in either direction. The average increase in PT was 7.1° (±5.4) or 30.8 % (±24.9); decrease in SVA was 45.1 mm (±25.6) or 60.0 % (±44.2) while the change in GT was 4.4° (±3.3) or 12.6 % (±9.3).
Discussion
GT appears to be less affected by the patient’s position compared to SVA and PT. This seems logical because GT contains both spinal alignment and pelvic compensation; it is not affected by their changes in opposing directions.
Conclusion
GT appears to be the most reliable single sagittal plane parameter in ASD. It is the least affected by patient position and incorporates both the pelvic and the spinal alignment within one measure.
Adolescent Idiopathic Scoliosis (AIS) is a complex three dimensional deformity the treatment of which remains to be surgical correction of the deformity as it had progressed over certain thresholds. ...The main focus in surgical treatment had, for decades, been the amount of correction in the coronal plane whereas corrections in sagittal and rotational (axial) planes have also been recognized as almost as important as the coronal over the recent decades.
The hypotheses presented and discussed in this study is the virtual adversity between the rates of correction in these two (sagittal and axial) planes. Namely, we are suggesting that due to an elongated anterior spinal column as an intrinsic component of AIS, posterior surgery cannot correct both the axial plane deformity and the thoracic hypokyphosis in the sagittal plane at the same time, unless the posterior spinal column is substantially lengthened. This hypothesis is supported by 3D modeling of the AIS spine as well as the relative inability in changing the sagittal alignment of the thoracic spine demonstrated by a literature search by us.
Understanding and internalization of this hypothesis by AIS surgeons is important as it suggests that by posterior instrumentation, unless a riskier approach of substantially lengthening the spinal column is taken, surgeons need to make the choice of correcting the hypokyphosis OR axial rotation.
Introduction
The Core Outcome Measures Index for the back (COMI-back) is a very brief instrument for assessing the main outcomes of importance to patients with back problems (pain, function, ...symptom-specific well-being, quality of life, disability). However, it might be expected to be less responsive than a disease-specific instrument when evaluating specific pathologies. In patients with adult spinal deformity, we compared the performance of COMI-back with the widely accepted SRS-22 questionnaire.
Methods
At baseline and 12 months after non-operative (
N
= 121) and surgical (
N
= 83) treatment, patients (175 F, 29 M) completed the following: COMI-back, SRS-22, Oswestry Disability Index (ODI) and SF-36 PCS. At 12 months' follow-up, patients also indicated on a 15-point Global Rating of Change Scale (GRCS) how their back problem had changed relative to 1 year ago. Construct validity for the COMI-back was assessed by the correlation between its scores and those of the comparator instruments; responsiveness was assessed with receiver operating characteristics (ROC) analysis of COMI-back change scores versus the criterion ‘treatment success’ (dichotomized GRCS).
Results
Baseline values for the COMI-back showed significant (
p
< 0.0001) correlations with SRS-22 (
r
= −0.85), ODI (
r
= 0.83), and SF-36 PCS (
r
= −0.82) scores; significantly worse scores for all measures were recorded in the surgical group. The correlation between the change scores (baseline to 12 months) for COMI and SRS-22 was 0.74, and between each of these change scores and the external criterion of treatment success were: COMI-back,
r
= 0.58; SRS-22,
r
= −0.58 (each
p
< 0.0001). The ROC areas under the curve for the COMI-back and SRS-22 change scores were 0.79 and 0.82, respectively.
Conclusion
Both baseline and change scores for the COMI-back correlated strongly with those of the SRS-22, and differed significantly in surgical and non-operative patients, suggesting good construct validity. With the “change in the back problem” serving as external criterion, COMI-back showed similar external responsiveness to SRS-22. The COMI-back was well able to detect important change. Coupled with its brevity, which minimizes patient burden, these favourable psychometric properties suggest the COMI-back is a suitable instrument for use in registries and can serve as a valid instrument in clinical studies emerging from such data pools.
Purpose
To determine if responses given to each question of the Scoliosis Research Society-22 (SRS22), Oswestry disability index (ODI) and Short Form-36 (SF-36) questionnaires are influenced by the ...radiological parameters.
Methods
Patients enrolled in a multi-centre prospectively collected adult spinal deformity database who had complete SRS22, ODI and SF-36 data at baseline and at one-year follow-up were analysed. The presence of a differential item function of each question within each score in relation to radiological parameters was analysed using a mixed Rasch model with the radiological threshold value(s) determined.
Results
Of those patients analysed (
n
= 1745; 1406 female, average age 51.0 ± 19.8 years), 944 were surgically and 801 were non-surgically treated. For the SRS22, questions (
Q
) 3, 5 and 18 were sensitive to almost all radiological parameters and the overall score was found sensitive to the Cobb angle. For the ODI, Q3, 6, 9 and 10 were not sensitive to any radiologic parameters whereas Q4 and 5 were sensitive to most. In contrast, only 3 of the SF-36 items were sensitive to radiological parameters.
Conclusions
78% of the SRS-22, 60% of the ODI and 8% of the questions in the SF-36 are sensitive to radiological parameters. Sagittal imbalance is independently associated with a poor overall outcome, but affects mental status and function more than pain and self-image. The assembly of questions responsive to radiological parameters may be useful in establishing a connection between changes in radiologic parameters and HRQL.
Purpose
The aim of this study was to evaluate factors that distinguish between patients with adult spinal deformity (ASD) with and without an indication for surgery, irrespective of their final ...treatment.
Methods
Baseline variables (demographics, medical history, outcome measures, coronal, sagittal and neurologic parameters) were evaluated in a multicentre, prospective cohort of patients with ASD. Multivariable analyses were carried out for idiopathic and degenerative patients separately with the dependent variable being “indication for surgery” and baseline parameters as independent variables.
Results
In total, 342 patients with degenerative ASD and 624 patients with idiopathic ASD were included in the multivariable models. In patients with degenerative ASD, the parameters associated with having an indication for surgery were greater self-rated disability on the Oswestry Disability Index odds ratio (OR) 1.04, 95% confidence interval (CI) 1.02–1.07 and a lower thoracic kyphosis (OR 0.97 95% CI 0.95–0.99), whereas in patients with idiopathic ASD, it was lower (worse) SRS self-image scores (OR 0.45 95% CI 0.32–0.64), a higher value for the major Cobb angle (OR 1.03 95% CI 1.01–1.05), lower age (OR 0.96 95% CI 0.95–0.98), prior decompression (OR 3.76 95% CI 1.00–14.08), prior infiltration (OR 2.23 95% CI 1.12–4.43), and the presence of rotatory subluxation (OR 1.98 95% CI 1.11–3.54) and sagittal subluxation (OR 4.38 95% CI 1.61–11.95).
Conclusion
Specific sets of variables were found to be associated with an indication for surgery in patients with ASD. These should be investigated in relation to patient outcomes for their potential to guide the future development of decision aids in the treatment of ASD.
Graphical abstract
These slides can be retrieved under Electronic Supplementary Material.
Purpose
Designed for patients with adolescent idiopathic scoliosis, the SRS-22 is now widely used as an outcome instrument in patients with adult spinal deformity (ASD). No studies have confirmed the ...four-factor structure (pain, function, self-image, mental health) of the SRS-22 in ASD and under different contexts. Factorial invariance of an instrument over time and in different languages is essential to allow for precise interpretations of treatment success and comparisons across studies. This study sought to evaluate the invariance of the SRS-22 structure across different languages and sub-groups of ASD patients.
Methods
Confirmatory factor analysis was performed on the 20 non-management items of the SRS-22 with data from 245 American English-, 428 Spanish-, 229 Turkish-, 95 French-, and 195 German-speaking patients. Item loading invariance was compared across languages, age groups, etiologies, treatment groups, and assessment times. A separate sample of SRS-22 data from 772 American surgical patients with ASD was used for cross-validation.
Results
The factor structure fitted significantly better to the proposed four-factor solution than to a unifactorial solution. However, items 14 (personal relationships), 15 (financial difficulties), and 17 (days off work) consistently showed weak item loading within their factors across all language versions and in both baseline and follow-up datasets. A trimmed SRS (16 non-management items) that used the four least problematic items in each of the four domains yielded better-fitting models across all languages, but equivalence was still not reached. With this shorter version there was equivalence of item loading with respect to treatment (surgery vs conservative), time of assessment (baseline vs 12 months follow-up), and etiology (degenerative vs idiopathic), but not age (< vs ≥50 years). All findings were confirmed in the cross-validation sample.
Conclusion
We recommend removal of the worst-fitting items from each of the four domains of the SRS-instrument (items 3, 14, 15, 17), together with adaptation and standardization of other items across language versions, to provide an improved version of the instrument with just 16 non-management items.
The capacitance–voltage–frequency (C–V–f) and conductance–voltage–frequency (G/w–V–f) characteristics of Al/perylene/p-Si Schottky barrier diodes (SBDs) fabricated with spin coating system have been ...investigated in the frequency range of 30 kHz–2 MHz at room temperature. In order to elucidate the electrical characteristics of SBDs with perylene interface, the voltage and frequency dependent series resistance (Rs), frequency dependent density distribution profile of interface state (Nss) were obtained. The measurements of C and G/w were found to be strongly dependent on bias voltage and frequency for Al/perylene/p-Si SBDs. For each frequency, the Rs–V plot gives a peak, decreasing with increasing frequencies. Also, it has been shown that the interface states density exponentially decreases with increasing frequency. The C–V–f and G/w–V–f characteristics confirm that the Nss and Rs of the diode are important parameters that strongly influence the electric parameters in metal/polymer/semiconductor (MPS) structure.
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Samples of human lumbar (L3-L4) anulus fibrosus from four different anatomic sites (anterior outer, posterolateral inner), ranging from normal to severely degenerate, were studied in uniaxial tension ...and measured for water content.
To evaluate the effects of aging and degeneration on the tensile properties and hydration of the anulus fibrosus in a site-specific manner. The relationship between hydration and parameters of the tensile behavior were investigated.
Degeneration and aging have been shown to be related to dramatic changes in the composition and structure of the anulus fibrosus. The associated changes in the tensile, compressive, and shear properties of the anulus fibrosus have not been documented. Numerical studies using finite element models have attempted to simulate the degenerative process by incorporating estimated mechanical properties meant to represent the degenerate anulus fibrosus. Their results present findings that suggest that altered material properties of the anulus fibrosus affect the mechanics of the entire intervertebral disc.
Samples of human lumbar anulus fibrosus were classified by grade of degeneration based on a morphologic grading scheme. Multiple layer anulus specimens from four sites in the disc were tested in uniaxial tension under quasistatic conditions in a physiologic saline bath. The tensile modules, Poisson's ratio, failure stress and strain, the strain energy density to failure, and the corresponding hydration were determined for each sample.
The Poisson's ratio, failure stress, and strain energy density of the anulus fibrosus were found to be affected significantly by degeneration, with some evidence of a sensitivity of the tensile modulus to grade of degeneration. All material properties were found to exhibit a significant and greater dependence on site within the disc than on degenerative grade. Weak correlations between aging and the Poisson's ratio and strain energy density were observed. Water content of anulus fibrosus tissue was not affected by degeneration or aging, although correlations with tensile properties were observed.
The dramatic changes in morphology, composition, and structure that occur in anulus fibrosus with aging and degeneration are accompanied by specific variations in the tensile properties, which were generally small in magnitude. Position of the anulus fibrosus within the intervertebral disc, particularly in the radial direction, appeared to be the most important variable affecting anulus fibrosus tensile properties. This dependence on position did not change with either aging or degeneration. Results from the present study may be useful in future finite element models to assess how altered material properties of the anulus fibrosus during degeneration and aging may affect the mechanics of the entire intervertebral disc.
Multicenter, prospective study of consecutive adult spinal deformity (ASD) patients.
To Validate Schwab's classification accuracy for surgical indication, and to evaluate a simplified sagittal ...modifier.
The SRS-Schwab Radiologic Classification based on clinical impact parameters, offers 27 different sagittal classification possibilities regarding sagittal vertical alignment (SVA), pelvic tilt (PT), and pelvic incidence-lumbar lordosis (PI-LL). The high number of classification possibilities makes it complex to use.
Inclusion criteria were ASD patients, presenting at least 1 criteria: Cobb ≥ 20°, SVA ≥ 5 cm, thoracic kyphosis ≥ 60°, or PT ≥ 25°. A total of 1,004 patients (410 nonoperative and 594 operative) were classified regarding SVA, PT, and PI-LL (0, +, ++), and 27 possibilities were identified. Categories were formed by adding the number of + signs, considering PT, SVA, and PI-LL. Three specific categories were identified: Aligned: 0 +; Moderate deformity: 1 to 3+; and Severe deformity: 4 to 6+. A χ-square test was performed for surgical indication (operated or not) and an analysis of variance was performed to evaluate the relationship between categories and Oswestry Disability Index (ODI). Probability <.05 was considered significant.
Significant differences for HRQoL scores and surgical indication were found in the 27 sagittal parameter possibilities. For nonoperative patients, 230 (56.1%) were classified as aligned, 145 (35.4%) as moderate, and 35 (8.5%) as severe. For operative patients, there were 200 (33.7%), 215 (36.2%), and 179 (30.1%) in each respective subgroup. For HRQoL scores and surgical indication, no significant differences were found within each category, but significant differences were found when comparing the subgroups.
Despite the correlation between SRS-Schwab classification and surgical indication, it is complex to use, with a total of 27 possibilities regarding sagittal modifiers. This simplification into three categories offers more readability, without losing any significant information, and could replace Schwab sagittal modifiers. In association with other parameters, they could be used for decision-making.
Level II.
Purpose
Achieving an adequate level of patient’s satisfaction with results is one of the goals of adult spinal deformity (ASD) surgery. However, it is unclear whether the same factors affect ...satisfaction in all patient populations. Patients’ age influences the postoperative course and prevalence of complications after ASD surgery. The purpose of this study was to determine the factors predicting satisfaction 2 years after ASD surgery in younger and older patients.
Methods
A total of 119 patients under 40 years old, 155 patients 40 to 65 years old, and 148 patients over 65 years old at surgery who were followed for a minimum of 2 years after surgery were included. Multivariate analysis was used to determine independent related factors with maximum AUC for satisfaction 2 years after surgery in each group. A propensity-matched cohort under equivalent demographic and clinical characteristics was used to confirm the results.
Results
Logistic regression analyses revealed satisfaction among the under-40 group corresponded to prior spine surgery, complications, and self-image. That among the 40-to-65 group corresponded to neurologic complication, revision surgery, pain, and sagittal vertical axis restoration. Among the over-65 group satisfaction correlated with revision surgery, standing ability, and lumbar lordosis index restoration. Propensity score matching confirmed that sagittal alignment correction led to substantial satisfaction.
Conclusions
In younger patients, avoiding complications and improving patients’ self-image were essential for substantial satisfaction levels. In older patients, revision, standing ability, as well as sagittal spinopelvic alignment restoration, were the key factors. Surgeons should consider the differences in goals of each patient.
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