The Global Spine Care Initiative: model of care and implementation.

PURPOSE: Spine-related disorders are a leading cause of global disability and are a burden on society and to public health. Currently, there is no comprehensive, evidence-based model of care for spine-related disorders, which includes back and neck pain, deformity, spine injury, neurological conditions, spinal diseases, and pathology, that could be applied in global health care settings. The purposes of this paper are to propose: (1) principles to transform the delivery of spine care; (2) an evidence-based model that could be applied globally; and (3) implementation suggestions. METHODS: The Global Spine Care Initiative (GSCI) meetings and literature reviews were synthesized into a seed document and distributed to spine care experts. After three rounds of a modified Delphi process, all participants reached consensus on the final model of care and implementation steps. RESULTS: Sixty-six experts representing 24 countries participated. The GSCI model of care has eight core principles: person-centered, people-centered, biopsychosocial, proactive, evidence-based, integrative, collaborative, and self-sustaining. The model of care includes a classification system and care pathway, levels of care, and a focus on the patient's journey. The six steps for implementation are initiation and preparation; assessment of the current situation; planning and designing solutions; implementation; assessment and evaluation of program; and sustain program and scale up. CONCLUSION: The GSCI proposes an evidence-based, practical, sustainable, and scalable model of care representing eight core principles with a six-step implementation plan. The aim of this model is to help transform spine care globally, especially in low- and middle-income countries and underserved communities. These slides can be retrieved under Electronic Supplementary Material.

The Global Spine Care Initiative: methodology, contributors, and disclosures.

PURPOSE: The purpose of this report is to describe the Global Spine Care Initiative (GSCI) contributors, disclosures, and methods for reporting transparency on the development of the recommendations. METHODS: World Spine Care convened the GSCI to develop an evidence-based, practical, and sustainable healthcare model for spinal care. The initiative aims to improve the management, prevention, and public health for spine-related disorders worldwide; thus, global representation was essential. A series of meetings established the initiative's mission and goals. Electronic surveys collected contributorship and demographic information, and experiences with spinal conditions to better understand perceptions and potential biases that were contributing to the model of care. RESULTS: Sixty-eight clinicians and scientists participated in the deliberations and are authors of one or more of the GSCI articles. Of these experts, 57 reported providing spine care in 34 countries, (i.e., low-, middle-, and high-income countries, as well as underserved communities in high-income countries.) The majority reported personally experiencing or having a close family member with one or more spinal concerns including: spine-related trauma or injury, spinal problems that required emergency or surgical intervention, spinal pain referred from non-spine sources, spinal deformity, spinal pathology or disease, neurological problems, and/or mild, moderate, or severe back or neck pain. There were no substantial reported conflicts of interest. CONCLUSION: The GSCI participants have broad professional experience and wide international distribution with no discipline dominating the deliberations. The GSCI believes this set of papers has the potential to inform and improve spine care globally. These slides can be retrieved under Electronic Supplementary Material.

The Global Spine Care Initiative: World Spine Care executive summary on reducing spine-related disability in low- and middle-income communities.

PURPOSE: Spinal disorders, including back and neck pain, are major causes of disability, economic hardship, and morbidity, especially in underserved communities and low- and middle-income countries. Currently, there is no model of care to address this issue. This paper provides an overview of the papers from the Global Spine Care Initiative (GSCI), which was convened to develop an evidence-based, practical, and sustainable, spinal healthcare model for communities around the world with various levels of resources. METHODS: Leading spine clinicians and scientists around the world were invited to participate. The interprofessional, international team consisted of 68 members from 24 countries, representing most disciplines that study or care for patients with spinal symptoms, including family physicians, spine surgeons, rheumatologists, chiropractors, physical therapists, epidemiologists, research methodologists, and other stakeholders. RESULTS: Literature reviews on the burden of spinal disorders and six categories of evidence-based interventions for spinal disorders (assessment, public health, psychosocial, noninvasive, invasive, and the management of osteoporosis) were completed. In addition, participants developed a stratification system for surgical intervention, a classification system for spinal disorders, an evidence-based care pathway, and lists of resources and recommendations to implement the GSCI model of care. CONCLUSION: The GSCI proposes an evidence-based model that is consistent with recent calls for action to reduce the global burden of spinal disorders. The model requires testing to determine feasibility. If it proves to be implementable, this model holds great promise to reduce the tremendous global burden of spinal disorders. These slides can be retrieved under Electronic Supplementary Material.

The comprehensive anatomical spinal osteotomy classification.

BACKGROUND: 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.

Partial facetectomy for lumbar foraminal stenosis.

Background. Several different techniques exist to address the pain and disability caused by isolated nerve root impingement. Failure to adequately decompress the lumbar foramen may lead to failed back surgery syndrome. However, aggressive treatment often causes spinal instability or may require fusion for satisfactory results. We describe a novel technique for decompression of the lumbar nerve root and demonstrate its effectiveness in relief of radicular symptoms. Methods. Partial facetectomy was performed by removal of the medial portion of the superior facet in patients with lumbar foraminal stenosis. 47 patients underwent the procedure from 2001 to 2010. Those who demonstrated neurogenic claudication without spinal instability or central canal stenosis and failed conservative management were eligible for the procedure. Functional level was recorded for each patient. These patients were followed for an average of 3.9 years to evaluate outcomes. Results. 27 of 47 patients (57%) reported no back pain and no functional limitations. Eight of 47 patients (17%) reported moderate pain, but had no limitations. Six of 47 patients (13%) continued to experience degenerative symptoms. Five of 47 patients (11%) required additional surgery. Conclusions. Partial facetectomy is an effective means to decompress the lumbar nerve root foramen without causing spinal instability.

The comprehensive anatomical spinal osteotomy classification.

BACKGROUND: 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.

Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis.

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.

Comparative analysis of surgical approaches and osteotomies for the correction of sagittal plane spinal deformity in adults.

STUDY DESIGN: A retrospective review. OBJECTIVE: To compare the radiographical and clinical profiles between 2 surgical approaches for the correction of sagittal plane spinal deformity. SUMMARY OF BACKGROUND DATA: Sagittal plane decompensation is the radiographical parameter that carries the greatest impact on adverse outcomes. Surgical correction methods are heterogeneous, and opposing views pervade the spine community in consideration of the most effective approach and techniques to achieve correction. METHODS: A total of 33 cases with sagittal spinal deformity were assessed according to their surgical approach, posterior only versus combined anteroposterior group. Comparison was based on the demographic data, and radiographical parameters included pelvic tilt, pelvic incidence, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis. RESULTS: Twenty two subjects were identified for the posterior-only and 11 subjects for the anteroposterior group. Average age was 58.7 years in the posterior-only and 55.7 years for the combined approach. Preoperative mean sagittal vertical axis was 186.6 and 147.7 mm, for the posterior-only and combined approaches, respectively (P = 0.1). Preoperative mean pelvic tilt was 34.2° for the posterior-only and 36.9° for the combined approach group (P = 0.5). A greater operative time for the combined approach was significant, 535 versus 333 minutes for the posterior-only approach (P < 0.001). In the posterior-only group, 8 of 22 patients and 7 of 11 patients in the combined-approach cohort experienced a postoperative complication (P = 0.16). The average follow-up was 41.8 and 47.7 months for the posterior-only and combined approaches, respectively (P = 0.4). CONCLUSION: A posterior-only or combined surgical approach had comparable radiographical outcomes. Higher morbidity was significant in regard to operative time in the combined-approach group. Deciding on the approach best suited for achieving correction in the sagittal plane likely resides on the surgeon's experience and expertise.

Impact of magnitude and percentage of global sagittal plane correction on health-related quality of life at 2-years follow-up.

BACKGROUND: 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.

Sagittal realignment failures following pedicle subtraction osteotomy surgery: are we doing enough?: Clinical article.

OBJECT: Pedicle subtraction osteotomy (PSO) is a surgical procedure that is frequently performed on patients with sagittal spinopelvic malalignment. Although it allows for substantial spinopelvic realignment, suboptimal realignment outcomes have been reported in up to 33% of patients. The authors' objective in the present study was to identify differences in radiographic profiles and surgical procedures between patients achieving successful versus failed spinopelvic realignment following PSO. METHODS: This study is a multicenter retrospective consecutive PSO case series. The authors evaluated 99 cases involving patients who underwent PSO for sagittal spinopelvic malalignment. Because precise cutoffs of acceptable residual postoperative sagittal vertical axis (SVA) values have not been well defined, comparisons were focused between patient groups with a postoperative SVA that could be clearly considered either a success or a failure. Only cases in which the patients had a postoperative SVA of less than 50 mm (successful PSO realignment) or more than 100 mm (failed PSO realignment) were included in the analysis. Radiographic measures and PSO parameters were compared between successful and failed PSO realignments. RESULTS: Seventy-nine patients met the inclusion criteria. Successful realignment was achieved in 61 patients (77%), while realignment failed in 18 (23%). Patients with failed realignment had larger preoperative SVA (mean 217.9 vs 106.7 mm, p < 0.01), larger pelvic tilt (mean 36.9° vs 30.7°, p < 0.01), larger pelvic incidence (mean 64.2° vs 53.7°, p < 0.01), and greater lumbar lordosis-pelvic incidence mismatch (-47.1° vs -30.9°, p < 0.01) compared with those in whom realignment was successful. Failed and successful realignments were similar regarding the vertebral level of the PSO, the median size of wedge resection 22.0° (interquartile range 16.5°-28.5°), and the numerical changes in pre- and postoperative spinopelvic parameters (p > 0.05). CONCLUSIONS: Patients with failed PSO realignments had significantly larger preoperative spinopelvic deformity than patients in whom realignment was successful. Despite their apparent need for greater correction, the patients in the failed realignment group only received the same amount of correction as those in the successfully realigned patients. A single-level standard PSO may not achieve optimal outcome in patients with high preoperative spinopelvic sagittal malalignment. Patients with large spinopelvic deformities should receive larger osteotomies or additional corrective procedures beyond PSOs to avoid undercorrection.

Impact of unilateral corrective tethering on the histology of the growth plate in an established porcine model for thoracic scoliosis.

STUDY DESIGN: Histological growth plate analysis. OBJECTIVE.: To evaluate the histological effects on vertebral growth plates following corrective mechanical tethering in the porcine scoliosis model. SUMMARY OF BACKGROUND DATA: Theoretically, growth modulation allows progressive vertebral correction in the setting of scoliosis (Hueter-Volkmann principle). METHODS: This IACUC-approved study divided 9 immature Yorkshire pigs into 2 groups: deforming tether release (TR, n = 4) group and anterior corrective (AC, n = 5) tether group. Once 50° coronal Cobb was demonstrated, TR had release of the deforming tether, whereas AC had release of the deforming tether and additional placement of a corrective tether. After 20 weeks of observation, pigs were killed, spines were removed, and apical samples were prepared for histological study. Growth plate analysis included the following histological parameters: proliferative zone height, hypertrophic zone height, and cell heights within the hypertrophic zone. Student t test was used to evaluate differences within and between groups. RESULTS: No significant differences were found within the release group on the concave versus convex side in terms of proliferative zone height, hypertrophic zone height, and cell heights in the hypertrophic zone. In the anterior correction group, the proliferative zone height was significantly smaller on the concave side than on the convex side (P < 0.01); no significant differences were found in AC on the concave versus convex side in terms of hypertrophic zone height and cell heights in the hypertrophic zone. No significant differences were found in any parameters between TR and AC on either the concave or the convex side. CONCLUSION: No significant decrease in any of the measured parameters was observed in the anterior correction group compared with the tether release group. These histological findings are consistent with preservation of growth potential.

Sacro-femoral-pubic angle: a coronal parameter to estimate pelvic tilt.

INTRODUCTION: Pelvic tilt is an established measure of position which has been tied to sagittal plane spinal deformity. Increased tilt is noted in the setting of the aging spine and sagittal malalignment syndromes such as flatback (compensatory mechanism). However, the femoral heads are often poorly visualized on sagittal films of scoliosis series in adults, limiting the ability to determine pelvic incidence and tilt. There is a need to establish a coronal plane (better visualization) pelvic parameter which correlates closely with pelvic tilt. METHODS: This is a retrospective review of 71 adult patients (47 females and 24 males) with full-length standing spine radiographs. Visualization of all spinal and pelvic landmarks was available coronally and sagittally (including pelvis and acetabuli). Pelvic tilt was calculated through validated digital analysis software (SpineView(®)). A new parameter, the sacro-femoral-pubic angle (midpoint of S1 endplate to centroid of acetabuli to superior border of the pubic symphysis) was analyzed for correlation (and predictive ability) with sagittal pelvic tilt. RESULTS: The sacro-femoral-pubic angle (SFP angle) was highly correlated to PT, and according to this analysis, pelvic tilt could be estimated by the formula: PT = 75 - (SFP angle). A Pearson's correlation coefficient of 0.74 (p < 0.005) and predictive ability of 76% accuracy was obtained (±7.5°). The correlation and predictive ability was greater for males compared to females (male: r = 0.87 and predictive model = 93%; female: r = 0.67 and predictive model = 67%). CONCLUSION: The pelvic tilt is an essential measure in the context of radiographic evaluation of spinal deformity and malalignment. Given the routinely excellent visibility of coronal films this study established the SFP as a coronal parameter which can reliably estimate pelvic tilt. The high correlation and predictive ability of the SFP angle should prompt further study and clinical application when lateral radiographs do not permit assessment of pelvic parameters.

Does removing the spinal tether in a porcine scoliosis model result in persistent deformity? A pilot study.

BACKGROUND: Using a tethering technique, a porcine model of scoliosis has been created. Ideally, tether release before placement and evaluation of corrective therapies would lead to persistent scoliosis. QUESTIONS/PURPOSES: Does release of the spinal tether result in persistent deformity? METHODS: Using a unilateral spinal tether and ipsilateral rib cage tethering, scoliosis was initiated on seven pigs. The spinal tether was released after progression to a Cobb angle of 50°. Biweekly radiographs were taken for 18 weeks after tether release to evaluate longitudinal changes in coronal and sagittal Cobb angles. Postmortem fine-cut CT scans were used to evaluate vertebral and disc wedging and axial rotation; results were compared to a previously published data set of 11 animals euthanized before release of the tether (control group). RESULTS: Radiographic analysis demonstrated two responses to tether release: a persistent deformity group and an autocorrective group. Differences between these two groups included number of days with the tether in place before reaching a Cobb angle of 50° and degree of deformity immediately after scoliosis induction. CT analysis of the tether release versus tether intact groups demonstrated progression in vertebral body wedging without differences in apical rotation. CONCLUSIONS: With the appropriate inducing parameters, release of the spinal tether does not systematically result in deformity correction. Tether release resulted in a reduction in Cobb angle in the first several weeks followed by steady curve progression. Deformity progression was confirmed using detailed CT morphometric analysis.

Spino-pelvic parameters after surgery can be predicted: a preliminary formula and validation of standing alignment.

STUDY DESIGN: Prospective and retrospective radiographic study of adult patients with spinal deformities. OBJECTIVE: Construct predictive models for pelvic tilt (PT) and global sagittal balance (sagittal vertical axis [SVA]) and evaluate the effectiveness of these predictive models against a group of patients after pedicle subtraction osteotomy. SUMMARY OF BACKGROUND DATA: Spinal balance involves a complex interaction between the pelvis and vertebral column. In the setting of adult spinal deformity, prediction of postoperative alignment can be challenging. METHODS: The study included 219 adult patients treated for spinal deformity. Full-length standing films were available for all subjects. Multilinear models with a stepwise condition were used on the first group of patients (n = 179) to predict PT and global sagittal balance (measured by the SVA). Prediction models were then applied on a second group of patients (n = 40) to estimate postoperative radiographic parameters after pedicle subtraction osteotomy surgery. Differences between estimated parameters and real values were evaluated. RESULTS: Multilinear regression analysis applied on the first group of patients led to a predictive formula for PT (r = 0.93, standard error = 4.4°) using the following parameters: pelvic incidence, maximal lordosis, and maximal kyphosis. These parameters with the addition of the predicted PT were then used to predict the SVA (r = 0.89, standard error = 32 mm). Validation of predictive models (second group of patients) used pelvic incidence and postoperative sagittal curves. Postoperative PT was predicted with a mean error of 4.3° (SD 3.5°) and postoperative SVA was predicted with a mean error of 29 mm (SD = 23 mm). CONCLUSION: This is the first study to develop and validate pragmatic predictive models for key spino-pelvic parameters (PT and SVA) in the setting of adult spinal deformity. Using a morphologic pelvic parameter (pelvic incidence) and spinal parameters modifiable through surgery (lumbar lordosis and thoracic kyphosis), postoperative sagittal alignment can be predicted.

Does vertebral level of pedicle subtraction osteotomy correlate with degree of spinopelvic parameter correction?

OBJECT: Pedicle subtraction osteotomy (PSO) is a spinal realignment technique that may be used to correct sagittal spinal imbalance. Theoretically, the level and degree of resection via a PSO should impact the degree of sagittal plane correction in the setting of deformity. However, the quantitative effect of PSO level and focal angular change on postoperative spinopelvic parameters has not been well described. The purpose of this study is to analyze the relationship between the level/degree of PSO and changes in global sagittal balance and spinopelvic parameters. METHODS: In this multicenter retrospective study, 70 patients (54 women and 16 men) underwent lumbar PSO surgery for spinal imbalance. Preoperative and postoperative free-standing sagittal radiographs were obtained and analyzed by regional curves (lumbar, thoracic, and thoracolumbar), pelvic parameters (pelvic incidence and pelvic tilt [PT]) and global balance (sagittal vertical axis [SVA] and T-1 spinopelvic inclination). Correlations between PSO parameters (level and degree of change in angle between the 2 adjacent vertebrae) and spinopelvic measurements were analyzed. RESULTS: Pedicle subtraction osteotomy distribution by level and degree of correction was as follows: L-1 (6 patients, 24°), L-2 (15 patients, 24°), L-3 (29 patients, 25°), and L-4 (20 patients, 22°). There was no significant difference in the focal correction achieved by PSO by level. All patients demonstrated changes in preoperative to postoperative parameters including increased lumbar lordosis (from 20° to 49°, p < 0.001), increased thoracic kyphosis (from 30° to 38°, p < 0.001), decreased SVA and T-1 spinopelvic inclination (from 122 to 34 mm, p < 0.001 and from +3° to -4°, p < 0.001, respectively), and decreased PT (from 31° to 23°, p < 0.001). More caudal PSO was correlated with greater PT reduction (r = -0.410, p < 0.05). No correlation was found between SVA correction and PSO location. The PSO degree was correlated with change in thoracic kyphosis (r = -0.474, p < 0.001), lumbar lordosis (r = 0.667, p < 0.001), sacral slope (r = 0.426, p < 0.001), and PT (r = -0.358, p < 0.005). CONCLUSIONS: The degree of PSO resection correlates more with spinopelvic parameters (lumbar lordosis, thoracic kyphosis, PT, and sacral slope) than PSO level. More importantly, PSO level impacts postoperative PT correction but not SVA.

Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery.

STUDY DESIGN: Current concepts review. OBJECTIVE: Outline the basic principles in the evaluation and treatment of adult spinal deformity patients with a focus on goals to achieve during surgical realignment surgery. SUMMARY OF BACKGROUND DATA: Proper global alignment of the spine is critical in maintaining standing posture and balance in an efficient and pain-free manner. Outcomes data demonstrate the clinical effect of spinopelvic malalignment and form a basis for realignment strategies. METHODS: Correlation between certain radiographic parameters and patient self-reported pain and disability has been established. Using normative values for several important spinopelvic parameters (including sagittal vertical axis, pelvic tilt, and lumbar lordosis), spinopelvic radiographic realignment objectives were identified as a tool for clinical application. Because of the complex relationship between the spine and the pelvis in maintaining posture and the wide range of "normal" values for the associated parameters, a focus on global alignment, with proportionality of individual parameters to each other, was pursued to provide clinical relevance to planning realignment for deformity across a range of clinical cases. CONCLUSION: Good clinical outcome requires achieving proper spinopelvic alignment in the treatment of adult spinal deformity. Although variations in pelvic morphology exist, a framework has been established to determine ideal values for regional and global parameter in an individualized patient approach. When planning realignment surgery for adult spinal deformity, restoring low sagittal vertical axis and pelvic tilt values are critical goals, and should be combined with proportional lumbar lordosis to pelvic incidence.

Computed tomographic validation of the porcine model for thoracic scoliosis.

STUDY DESIGN: Computed Tomographic Analysis of the Porcine Scoliosis Model. OBJECTIVE: To describe the spinal and rib cage modifications using computed tomography (CT). SUMMARY OF BACKGROUND DATA: Optimal development of nonfusion techniques for treatment of adolescent idiopathic scoliosis (AIS) requires a reliable large animal model that achieves spinal and rib cage modifications similar to AIS. Previous work has described the global 3-dimensional nature of the progressive deformity. METHODS: This IACUC-approved study includes 11 extracted scoliotic spines from a previous investigation. Scoliosis was induced through unilateral posterior ligament tethering of the spine via pedicle screw fixation, and ipsilateral rib cage tethering. CT analysis was used to quantify rib cage asymmetry, axial rotation, and wedging of the apical functional unit (2 vertebrae and intervening disc) for each specimen. RESULTS: The mean coronal Cobb angle was 55.7 degrees (n = 11). Vertebral and intervertebral heights of the apical functional unit demonstrated convex heights (untethered) were always larger than concave (tethered) heights (P < 0.05). Axial rotation was maximal (mean, 20 degrees ) at 1 to 2 levels distal to the coronal apex. Maximal rib cage asymmetry was demonstrated at the transverse apex with significant coupling of the rotational and rib cage modifications (r = 0.82). A large initial Cobb index (tether tension) was significantly correlated with vertebral and intervertebral wedging and coronal curve progression. CONCLUSION: The present study has used CT analysis to analyze spinal and rib cage modifications in the Porcine Scoliosis Model. Placement of a unilateral ligamentous spinal tether combined with concave rib cage ligament tethering during the rapid growth stage of the Yorkshire pig results in significant apical vertebral and intervertebral wedging and rotational and rib cage modifications. The porcine model is a reliable and duplicable model for scoliosis, which bears significant similarities to AIS.

Pelvic tilt and truncal inclination: two key radiographic parameters in the setting of adults with spinal deformity.

STUDY DESIGN: Prospective radiographic and clinical analysis. OBJECTIVE: Investigate the relationship between spino-pelvic parameters and patient self reported outcomes on adult subjects with spinal deformities. SUMMARY OF BACKGROUND DATA: It is becoming increasingly recognized that the study of spinal alignment should include pelvic position. While pelvic incidence determines lumbar lordosis, pelvic tilt (PT) is a positional parameter reflecting compensation to spinal deformity. Correlation between plumbline offset (sagittal vertical axis [SVA]) and Health Related Quality of Life (HRQOL) measures has been demonstrated, but such a study is lacking for PT. METHODS: This prospective study was carried out on 125 adult patients suffering from spinal deformity (mean age: 57 years). Full-length free-standing radiographs including the spine and pelvis were available for all patients. HRQOL instruments included: Oswestry Disability Index, Short Form-12, Scoliosis Research Society. Correlation analysis between radiographic spinopelvic parameters and HRQOL measures was pursued. RESULTS: Correlation analysis revealed no significance pertaining to coronal plane parameters. Significant sagittal plane correlations were identified. SVA and truncal inclination measured by T1 spinopelvic inclination (T1-SPI) (angle between T1-hip axis and vertical) correlated with: Scoliosis Research Society (appearance, activity, total score), Oswestry Disability Index, and Short Form-12 (physical component score). Correlation coefficients ranged from 0.42 < r < 0.55 (P < 0.0001). T1-SPI revealed greater correlation with HRQOL compared to SVA. PT showed correlation with HRQOL (0.28 < r < 0.42) and with SVA (r = 0.64, P < 0.0001). CONCLUSION: This study confirms that pelvic position measured via PT correlates with HRQOL in the setting of adult deformity. High values of PT express compensatory pelvic retroversion for sagittal spinal malalignment. This study also demonstrates significant T1-SPI correlation with HRQOL measures and outperforms SVA. This parameter carries the advantage of being an angular measurement which avoids the error inherent in measuring offsets in noncalibrated radiographs.

Sagittal plane considerations and the pelvis in the adult patient.

STUDY DESIGN: Research update, focused review. OBJECTIVE: Identify the role of the pelvis in the setting of adults with spinal deformity. SUMMARY OF BACKGROUND DATA: Sagittal plane alignment is increasingly recognized as a critical parameter in the setting of adult spinal deformity. Additionally, pelvic parameters reveal to be a key component in the regulation of sagittal alignment. METHODS: Analysis of the pelvis in the sagittal plane is commonly assessed by 3 angular measurements: the pelvic incidence (morphologic parameter directly linked to sagittal morphotypes), the pelvic tilt (or pelvis retroversion used to maintain an upright posture in the setting of spinal deformity), and the sacral slope. Recent work using force plate technology has revealed that in the setting of anterior trunk inclination ("spinal imbalance"), the pelvis shifted posteriorly (toward the heels) in order to maintain a balanced mass distribution. The complex relationship between pelvic and spinal parameter were investigated in order to construct predictive formulas of postoperative spinopelvic alignment. It has emerged that pelvic tilt is highly correlated with patient self reported function (ODI, SF-12, and SRS). CONCLUSION: It has become evident that good clinical outcome in the treatment of spinal deformity requires proper alignment. Pelvis parameters play an essential role not only in terms of spine morphotypes but also in regulating standing balance and postoperative alignment. Thus, optimal treatment of a patient with spinal deformity requires integration of the pelvis in the preoperative evaluation and treatment plan.

A porcine model for progressive thoracic scoliosis.

STUDY DESIGN: An IACUC-approved study to create a scoliotic deformity representative of adolescent idiopathic scoliosis. OBJECTIVE: The goal of this study was to develop a reliable porcine scoliosis model and to evaluate the three-dimensional progression of the deformity. SUMMARY OF BACKGROUND DATA: Optimal development of nonfusion techniques for treatment of adolescent idiopathic scoliosis requires a reliable large animal model that achieves a progressive three-dimensional (frontal, sagittal, axial) deformity. Limitations in previous work have led our team to the development of a porcine model. METHODS: This IACUC-approved study included 18 Yorkshire pigs, obtained at 11 weeks old. Scoliosis was induced through unilateral posterior ligament tethering of the spine via pedicle screw fixation, and ipsilateral ribcage tethering. Progressive deformity was documented with biweekly radiographs. Frontal, sagittal, and axial modifications were assessed using the Cobb method. Animals were observed until severe deformity (>50 degrees) developed, then killed. RESULTS: Animals were observed for a mean 11 weeks. The mean coronal Cobb angle was 25 degrees immediately postoperatively and 55 degrees at 11 weeks. The mean lordosis increased from 4 degrees postoperative to 24 degrees at final follow-up. Apical axial rotation (posterior elements into concavity) increased from 4% postoperative to 27% at 11 weeks. Rate of coronal curve progression was significantly correlated with the initial Cobb index. CONCLUSION: This study establishes a porcine scoliosis model. With placement of a unilateral ligamentous spinal tether combined with concave ribcage ligament tethering a three-dimensional (frontal, sagittal, and axial) spinal deformity can be obtained. The speed of the progressive deformity leaves significant remaining skeletal growth to assess growth modulating therapies for correction. This work forms the basis for a number of investigative efforts at developing new fusionless therapies for patients suffering from adolescent scoliosis.