Browsing by Author "Blondel, Benjamin"
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Item Open Access Cervical radiographical alignment: comprehensive assessment techniques and potential importance in cervical myelopathy.(Spine, 2013-10) Ames, Christopher P; Blondel, Benjamin; Scheer, Justin K; Schwab, Frank J; Le Huec, Jean-Charles; Massicotte, Eric M; Patel, Alpesh A; Traynelis, Vincent C; Kim, Han Jo; Shaffrey, Christopher I; Smith, Justin S; Lafage, VirginieStudy design
Narrative review.Objective
To provide a comprehensive narrative review of cervical alignment parameters, the methods for quantifying cervical alignment, normal cervical alignment values, and how alignment is associated with cervical deformity and myelopathy with discussions of health-related quality of life.Summary of background data
Indications for surgery to correct cervical alignment are not well-defined and there is no set standard to address the amount of correction to be achieved. In addition, classifications of cervical deformity have yet to be fully established and treatment options defined and clarified.Methods
A survey of the cervical spine literature was conducted.Results
New normative cervical alignment values from an asymptomatic volunteer population are introduced, updated methods for quantifying cervical alignment are discussed, and describing the relationship between cervical alignment, disability, and myelopathy are outlined. Specifically, methods used to quantify cervical alignment include cervical lordosis, cervical sagittal vertical axis, and horizontal gaze with the chin-brow vertical angle. Updated methods include T1 slope. Evidence from a few recent studies suggests correlations between radiographical parameters in the cervical spine and health-related quality of life. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is emerging and critical. Cervical myelopathy and sagittal alignment of the cervical spine are closely related as cervical deformity can lead to spinal cord compression and tension.Conclusion
Cervical deformity correction should take on a comprehensive approach in assessing global cervical-pelvic relationships and the radiographical parameters that effect health-related quality of life scores are not well-defined. Cervical alignment may be important in assessment and treatment of cervical myelopathy. Future work should concentrate on correlation of cervical alignment parameters to disability scores and myelopathy outcomes. SUMMARY STATEMENTS: STATEMENT 1: Cervical sagittal alignment (cervical SVA and kyphosis) is related to thoracolumbar spinal pelvic alignment and to T1 slope. STATEMENT 2: When significant deformity is clinically or radiographically suspected, regional cervical and relative global spinal alignment should be evaluated preoperatively via standing 3-foot scoliosis X-rays for appropriate operative planning. STATEMENT 3: Cervical sagittal alignment (C2-C7 SVA) is correlated to regional disability, general health scores and to myelopathy severity. STATEMENT 4: When performing decompressive surgery for CSM, consideration should be given to correction of cervical kyphosis and cervical sagittal imbalance (C2-C7 SVA) when present.Item Open Access Cervical spine alignment, sagittal deformity, and clinical implications: a review.(Journal of neurosurgery. Spine, 2013-08) Scheer, Justin K; Tang, Jessica A; Smith, Justin S; Acosta, Frank L; Protopsaltis, Themistocles S; Blondel, Benjamin; Bess, Shay; Shaffrey, Christopher I; Deviren, Vedat; Lafage, Virginie; Schwab, Frank; Ames, Christopher P; International Spine Study GroupThis paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical deformity, myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL). Popular methods currently used to quantify cervical alignment are discussed including cervical lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle. Cervical deformity is examined in detail as deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment. Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD. Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical myelopathy as cervical deformity can lead to spinal cord compression and cord tension. Surgical correction of cervical myelopathy should always take into consideration cervical sagittal alignment, as decompression alone may not decrease cord tension induced by kyphosis. Awareness of the development of postlaminectomy kyphosis is critical as it relates to cervical myelopathy. The future direction of cervical deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar lordosis was crucial in building our knowledge of thoracolumbar deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical deformity correction.Item Open Access Impact of magnitude and percentage of global sagittal plane correction on health-related quality of life at 2-years follow-up.(Neurosurgery, 2012-08) Blondel, Benjamin; Schwab, Frank; Ungar, Benjamin; Smith, Justin; Bridwell, Keith; Glassman, Steven; Shaffrey, Christopher; Farcy, Jean-Pierre; Lafage, VirginieBackground
Sagittal plane malalignment has been established as the main radiographic driver of disability in adult spinal deformity (ASD).Objective
To evaluate the amount of sagittal correction needed for a patient to perceive improvement (minimal clinically important difference, MCID) in health-related quality of life (HRQOL) scores.Methods
This was a multicenter, retrospective analysis of prospectively consecutively enrolled ASD patients. Inclusion criterion was a sagittal vertical axis (SVA) >80 mm. Demographic, radiographic, and HRQOL preoperative and 2-year postsurgery data were collected. Surgical treatment was categorized based on SVA correction: <60 mm, 60 mm to 120 mm, and >120 mm. Changes in parameters were analyzed using paired t test, 1-way analysis of variance, and χ2 test.Results
Seventy-six patients (preoperative SVA = 140 mm) were analyzed; each subgroup revealed significant HRQOL improvements following surgery. Compared with the <60 mm correction group, the likelihood of reaching MCID was significantly improved for the >120 mm group (Oswestry Disability Index) but not for the 60 mm to 120 mm group. A significantly greater likelihood of reaching MCID thresholds was observed for corrections above 66% of preoperative SVA.Conclusion
Best HRQOL outcomes for ASD patients with severe sagittal plane deformity were obtained with a correction >120 mm for SVA and at least 66% of correction. Although lesser amounts of SVA correction yielded clinical improvement, the rate of MCID threshold improvement was not significantly different for mild or modest corrections. These results underline the need for complete sagittal plane deformity correction if high rates of HRQOL benefit are sought for patients with marked sagittal plane deformity.Item Open Access Posterior global malalignment after osteotomy for sagittal plane deformity: it happens and here is why.(Spine, 2013-04) Blondel, Benjamin; Schwab, Frank; Bess, Shay; Ames, Christopher; Mummaneni, Praveen V; Hart, Robert; Smith, Justin S; Shaffrey, Christopher I; Burton, Douglas; Boachie-Adjei, Oheneba; Lafage, VirginieStudy design
Multicenter, retrospective analysis of 183 consecutive patients undergoing lumbar osteotomy.Objective
To evaluate cause and impact of posterior postoperative alignment.Summary of background data
Sagittal malalignment in the setting of adult spinal deformity (ASD) has shown significant correlation with pain and disability. Surgical treatment often entails correction of deformity by pedicle subtraction osteotomies (PSO). Key radiographical spinopelvic objectives to reach improvement in clinical outcomes have been previously reported. Although anterior alignment is a cause of poor outcomes, the impact and cause of posterior spinal alignment by PSO has not been reported.Methods
The patient inclusion criteria were age, more than 18 years, with a diagnosis of sagittal plane deformity (C7 plumbline offset >5 cm, a pelvic tilt >20°, or a lumbar lordosis to pelvic incidence mismatch of ≥10°) requiring a surgical procedure involving a lumbar posterior osteotomy and a long fusion. Patients were divided into 3 groups based on postoperative sagittal vertical axis (SVA): neutral alignment (0 < SVA < 50 mm), anterior alignment (SVA > 50 mm), and posterior alignment (SVA < 0 mm). All patients underwent pre- and postoperative full-length sagittal spine radiography. Differences between groups were evaluated using ANOVA and χ² analysis.Results
Seventy-six patients were postoperatively classified in the anterior group: 59 in the neutral group and 48 in the posterior group. These groups were comparable preoperatively in terms of surgical status (revision vs. primary surgery) and regional alignment (lumbar lordosis and thoracic kyphosis). The patients with posterior alignment were younger and had a significantly lower pelvic incidence (53° vs. 62°), preoperative pelvic tilt (30 vs. 36°), SVA (94 vs. 185 mm) and cervical lordosis (16° vs. 25°) than patients in the anterior alignment group. No significant differences were found in terms surgical procedure. Patients in the posterior alignment group demonstrated a significantly greater change in SVA and pelvic tilt correction (P < 0.05) but with a lower gain in thoracic kyphosis (5 vs. 12°) and reduction of cervical lordosis (4° vs. 22°).Conclusion
A significantly lower pelvic incidence and lack of restoration of thoracic kyphosis may lead to sagittal overcorrection with a posterior alignment. Although the clinical significance of posterior malalignment is still unclear, this study showed a compensatory loss of cervical lordosis in these patients. Particular attention must be paid to preoperative planning before sagittal realignment procedures. Further study will be necessary to evaluate long-term clinical outcomes of these patients.Item Open Access Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis.(Spine, 2013-06) Schwab, Frank J; Blondel, Benjamin; Bess, Shay; Hostin, Richard; Shaffrey, Christopher I; Smith, Justin S; Boachie-Adjei, Oheneba; Burton, Douglas C; Akbarnia, Behrooz A; Mundis, Gregory M; Ames, Christopher P; Kebaish, Khaled; Hart, Robert A; Farcy, Jean-Pierre; Lafage, Virginie; International Spine Study Group (ISSG)Study design
Prospective multicenter study evaluating operative (OP) versus nonoperative (NONOP) treatment for adult spinal deformity (ASD).Objective
Evaluate correlations between spinopelvic parameters and health-related quality of life (HRQOL) scores in patients with ASD.Summary of background data
Sagittal spinal deformity is commonly defined by an increased sagittal vertical axis (SVA); however, SVA alone may underestimate the severity of the deformity. Spinopelvic parameters provide a more complete assessment of the sagittal plane but only limited data are available that correlate spinopelvic parameters with disability. METHODS.: Baseline demographic, radiographical, and HRQOL data were obtained for all patients enrolled in a multicenter consecutive database. Inclusion criteria were: age more than 18 years and radiographical diagnosis of ASD. Radiographical evaluation was conducted on the frontal and lateral planes and HRQOL questionnaires (Oswestry Disability Index [ODI], Scoliosis Research Society-22r and Short Form [SF]-12) were completed. Radiographical parameters demonstrating highest correlation with HRQOL values were evaluated to determine thresholds predictive of ODI more than 40.Results
Four hundred ninety-two consecutive patients with ASD (mean age, 51.9 yr) were enrolled. Patients from the OP group (n = 178) were older (55 vs. 50.1 yr, P < 0.05), had greater SVA (5.5 vs. 1.7 cm, P < 0.05), greater pelvic tilt (PT; 22° vs. 11°, P < 0.05), and greater pelvic incidence/lumbar lordosis PI/LL mismatch (PI-LL; 12.2 vs. 4.3; P < 0.05) than NONOP group (n = 314). OP group demonstrated greater disability on all HRQOL measures compared with NONOP group (ODI = 41.4 vs. 23.9, P < 0.05; Scoliosis Research Society score total = 2.9 vs. 3.5, P < 0.05). Pearson analysis demonstrated that among all parameters, PT, SVA, and PI-LL correlated most strongly with disability for both OP and NONOP groups (P < 0.001). Linear regression models demonstrated threshold radiographical spinopelvic parameters for ODI more than 40 to be: PT 22° or more (r = 0.38), SVA 47 mm or more (r = 0.47), PI - LL 11° or more (r = 0.45).Conclusion
ASD is a disabling condition. Prospective analysis of consecutively enrolled patients with ASD demonstrated that PT and PI-LL combined with SVA can predict patient disability and provide a guide for patient assessment for appropriate therapeutic decision making. Threshold values for severe disability (ODI > 40) included: PT 22° or more, SVA 47 mm or more, and PI - LL 11° or more.Item Open Access Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study.(Spine, 2012-05) Schwab, Frank; Ungar, Benjamin; Blondel, Benjamin; Buchowski, Jacob; Coe, Jeffrey; Deinlein, Donald; DeWald, Christopher; Mehdian, Hossein; Shaffrey, Christopher; Tribus, Clifford; Lafage, VirginieStudy design
Inter- and intra-rater variability study.Objective
On the basis of a Scoliosis Research Society effort, this study seeks to determine whether the new adult spinal deformity (ASD) classification system is clear and reliable.Summary of background data
A classification of adult ASD can serve several purposes, including consistent characterization of a clinical entity, a basis for comparing different treatments, and recommended treatments. Although pediatric scoliosis classifications are well established, an ASD classification is still being developed. A previous classification developed by Schwab et al has met with clinical relevance but did not include pelvic parameters, which have shown substantial correlation with health-related quality of life measures in recent studies.Methods
Initiated by the Scoliosis Research Society Adult Deformity Committee, this study revised a previously published classification to include pelvic parameters. Modifier cutoffs were determined using health-related quality of life analysis from a multicenter database of adult deformity patients. Nine readers graded 21 premarked cases twice each, approximately 1 week apart. Inter- and intra-rater variability and agreement were determined for curve type and each modifier separately. Fleiss' kappa was used for reliability measures, with values of 0.00 to 0.20 considered slight, 0.21 to 0.40 fair, 0.41 to 0.60 moderate, 0.61 to 0.80 substantial, and 0.81 to 1.00 almost perfect agreement.Results
Inter-rater kappa for curve type was 0.80 and 0.87 for the 2 readings, respectively, with modifier kappas of 0.75 and 0.86, 0.97 and 0.98, and 0.96 and 0.96 for pelvic incidence minus lumbar lordosis (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA), respectively. By the second reading, curve type was identified by all readers consistently in 66.7%, PI-LL in 71.4%, PT in 95.2%, and SVA in 90.5% of cases. Intra-rater kappa averaged 0.94 for curve type, 0.88 for PI-LL, 0.97 for PT, and 0.97 for SVA across all readers.Conclusion
Data from this study show that there is excellent inter- and intra-rater reliability and inter-rater agreement for curve type and each modifier. The high degree of reliability demonstrates that applying the classification system is easy and consistent.Item Open Access Spontaneous improvement of cervical alignment after correction of global sagittal balance following pedicle subtraction osteotomy.(Journal of neurosurgery. Spine, 2012-10) Smith, Justin S; Shaffrey, Christopher I; Lafage, Virginie; Blondel, Benjamin; Schwab, Frank; Hostin, Richard; Hart, Robert; O'Shaughnessy, Brian; Bess, Shay; Hu, Serena S; Deviren, Vedat; Ames, Christopher P; International Spine Study GroupObject
Sagittal spinopelvic malalignment is a significant cause of pain and disability in patients with adult spinal deformity. Surgical correction of spinopelvic malalignment can result in compensatory changes in spinal alignment outside of the fused spinal segments. These compensatory changes, termed reciprocal changes, have been defined for thoracic and lumbar regions but not for the cervical spine. The object of this study was to evaluate postoperative reciprocal changes within the cervical spine following lumbar pedicle subtraction osteotomy (PSO).Methods
This was a multicenter retrospective radiographic analysis of patients from International Spine Study Group centers. Inclusion criteria were as follows: adults (>18 years old) with spinal deformity treated using lumbar PSO, a preoperative C7-S1 plumb line greater than 5 cm, and availability of pre- and postoperative full-length standing radiographs.Results
Seventy-five patients (60 women, mean age 59 years) were included. The lumbar PSO significantly improved sagittal alignment, including the C7-S1 plumb line, C7-T12 inclination, and pelvic tilt (p <0.001). After lumbar PSO, reciprocal changes were seen to occur in C2-7 cervical lordosis (from 30.8° to 21.6°, p <0.001), C2-7 plumb line (from 27.0 mm to 22.9 mm), and T-1 slope (from -38.9° to -30.4°, p <0.001). Ideal correction of sagittal malalignment (postoperative sagittal vertical alignment < 50 mm) was associated with the greatest relaxation of cervical hyperlordosis (-12.4° vs -5.7°, p = 0.037). A change in cervical lordosis correlated with changes in T-1 slope (r = -0.621, p <0.001), C7-T12 inclination (r = 0.418, p <0.001), T12-S1 angle (r = -0.339, p = 0.005), and C7-S1 plumb line (r = 0.289, p = 0.018). Radiographic parameters that correlated with changes in cervical lordosis on multivariate linear regression analysis included change in T-1 slope and change in C2-7 plumb line (r(2) = 0.53, p <0.001).Conclusions
Adults with positive sagittal spinopelvic malalignment compensate with abnormally increased cervical lordosis in an effort to maintain horizontal gaze. Surgical correction of sagittal malalignment results in improvement of the abnormal cervical hyperlordosis through reciprocal changes.Item Open Access The comprehensive anatomical spinal osteotomy classification.(Neurosurgery, 2014-01) Schwab, Frank; Blondel, Benjamin; Chay, Edward; Demakakos, Jason; Lenke, Lawrence; Tropiano, Patrick; Ames, Christopher; Smith, Justin S; Shaffrey, Christopher I; Glassman, Steven; Farcy, Jean-Pierre; Lafage, VirginieBackground
Global sagittal malalignment is significantly correlated with health-related quality-of-life scores in the setting of spinal deformity. In order to address rigid deformity patterns, the use of spinal osteotomies has seen a substantial increase. Unfortunately, variations of established techniques and hybrid combinations of osteotomies have made comparisons of outcomes difficult.Objective
To propose a classification system of anatomically-based spinal osteotomies and provide a common language among spine specialists.Methods
The proposed classification system is based on 6 anatomic grades of resection (1 through 6) corresponding to the extent of bone resection and increasing degree of destabilizing potential. In addition, a surgical approach modifier is added (posterior approach or combined anterior and posterior approaches). Reliability of the classification system was evaluated by an analysis of 16 clinical cases, rated 2 times by 8 different readers, and calculation of Fleiss kappa coefficients.Results
Intraobserver reliability was classified as "almost perfect"; Fleiss kappa coefficient averaged 0.96 (range, 0.92-1.0) for resection type and 0.90 (0.71-1.0) for the approach modifier. Results from the interobserver reliability for the classification were 0.96 for resection type and 0.88 for the approach modifier.Conclusion
This proposed anatomically based classification system provides a consistent description of the various osteotomies performed in spinal deformity correction surgery. The reliability study confirmed that the classification is simple and consistent. Further development of its use will provide a common frame for osteotomy assessment and permit comparative analysis of different treatments.Item Open Access The comprehensive anatomical spinal osteotomy classification.(Neurosurgery, 2015-03) Schwab, Frank; Blondel, Benjamin; Chay, Edward; Demakakos, Jason; Lenke, Lawrence; Tropiano, Patrick; Ames, Christopher; Smith, Justin S; Shaffrey, Christopher I; Glassman, Steven; Farcy, Jean-Pierre; Lafage, VirginieBackground
Global sagittal malalignment is significantly correlated with health-related quality-of-life scores in the setting of spinal deformity. In order to address rigid deformity patterns, the use of spinal osteotomies has seen a substantial increase. Unfortunately, variations of established techniques and hybrid combinations of osteotomies have made comparisons of outcomes difficult.Objective
To propose a classification system of anatomically-based spinal osteotomies and provide a common language among spine specialists.Methods
The proposed classification system is based on 6 anatomic grades of resection (1 through 6) corresponding to the extent of bone resection and increasing degree of destabilizing potential. In addition, a surgical approach modifier is added (posterior approach or combined anterior and posterior approaches). Reliability of the classification system was evaluated by an analysis of 16 clinical cases, rated 2 times by 8 different readers, and calculation of Fleiss kappa coefficients.Results
Intraobserver reliability was classified as 'almost perfect'; Fleiss kappa coefficient averaged 0.96 (range, 0.92-1.0) for resection type and 0.90 (0.71-1.0) for the approach modifier. Results from the interobserver reliability for the classification were 0.96 for resection type and 0.88 for the approach modifier.Conclusion
This proposed anatomically based classification system provides a consistent description of the various osteotomies performed in spinal deformity correction surgery. The reliability study confirmed that the classification is simple and consistent. Further development of its use will provide a common frame for osteotomy assessment and permit comparative analysis of different treatments.