Morphological description of sagittal lumbar spinal alignment using curve magnitude, span, and apex-the multiethnic alignment normative study (MEANS).

BACKGROUND CONTEXT: Current definition of lumbar lordosis uses the L1-S1 angle. Prevailing classification of sagittal spinal morphology, derived from a young adult population, classifies the spine into four subtypes defined by their sacral slope (SS) and curve morphology. PURPOSE: To describe physiological sagittal alignment of the lumbar spine across age groups using three main parameters that dictate the lumbar curve: angular magnitude, span, and apex. STUDY DESIGN: A large, multicenter, cross-sectional radiographic comparison study. PATIENT SAMPLE: Four hundred sixty-eight healthy, asymptomatic subjects aged 18 to 80 years from five countries (184 males, 284 females; 98 France, 119 Japan, 79 Singapore, 80 Tunisia, 92 USA, mean age 40.61±14.99 years). OUTCOME MEASURES: Sagittal lumbar profile subtypes clustered based on lumbar curve angular magnitude (ie, Cobb angle of the lumbar lordosis), span, and apex, and described by sagittal radiographic parameters. METHODS: Subjects underwent whole-body low-dose EOS stereoradiographs. Comparisons between conventional L1-S1 lumbar lordosis (cLL) and true lumbar lordosis (tLL, defined by the inflection-S1 angle) were conducted. Using the K-means clustering algorithm, lumbar curve angular magnitude, span and apex were used to classify sagittal spinal morphology into subtypes, stratified across age groups. Further univariate and multivariate analyses were conducted to compare radiographic parameters across subtypes, and identify predictors for the lumbar curve's angular magnitude, span and apex. RESULTS: Mean cLL was -57.27±11.37°, and tLL was -62.62±10.76°. Using tLL, instead of cLL, to describe sagittal spinal morphology, we found significant differences in terms of angular magnitude of the lumbar curve, the median thoracolumbar inflection vertebral level and pelvic incidence-lumbar lordosis mismatch Multivariate analysis found a larger SS, more positive T9 tilt, and more kyphotic T4-T12 predictive for a more lordotic tLL, while a larger overhang distance predicted for a less lordotic tLL (p-values<.001). In addition, a larger T9 tilt, less lordotic L1-L5 and smaller PT were predictors of a more caudal thoracolumbar inflection and lumbar apical vertebral levels (p-values<.001). Sagittal lumbar profiles of subjects age<30 years, 30≤age<60 years and age≥60 years, could be classified into 4, 6, and 3 subtypes, respectively. CONCLUSIONS: Sagittal lumbar profile subtypes vary across age groups, with more homogenous morphologies at the extremes of ages. Improved understanding of the morphological evolution of sagittal spinal profiles with age in asymptomatic individuals will help guide future individualized surgical treatment.

Patient decision support interventions for candidates considering elective surgeries: a systematic review and meta-analysis.

BACKGROUND: The increase in elective surgeries and varied postoperative patient outcomes has boosted the use of patient decision support interventions (PDSIs). However, evidence on the effectiveness of PDSIs are not updated. This systematic review aims to summarize the effects of PDSIs for surgical candidates considering elective surgeries and to identify their moderators with an emphasis on the type of targeted surgery. DESIGN: Systematic review and meta-analysis. METHODS: We searched eight electronic databases for randomized controlled trials evaluating PDSIs among elective surgical candidates. We documented the effects on invasive treatment choice, decision-making-related outcomes, patient-reported outcomes, and healthcare resource use. The Cochrane Risk of Bias Tool version 2 and Grading of Recommendations, Assessment, Development, and Evaluations were adopted to rate the risk of bias of individual trials and certainty of evidence, respectively. STATA 16 software was used to conduct the meta-analysis. RESULTS: Fifty-eight trials comprising 14 981 adults from 11 countries were included. Overall, PDSIs had no effect on invasive treatment choice (risk ratio=0.97; 95% CI: 0.90, 1.04), consultation time (mean difference=0.04 min; 95% CI: -0.17, 0.24), or patient-reported outcomes, but had a beneficial effect on decisional conflict (Hedges' g =-0.29; 95% CI: -0.41, -0.16), disease and treatment knowledge (Hedges' g =0.32; 95% CI: 0.15, 0.49), decision-making preparedness (Hedges' g =0.22; 95% CI: 0.09, 0.34), and decision quality (risk ratio=1.98; 95% CI: 1.15, 3.39). Treatment choice varied with surgery type and self-guided PDSIs had a greater effect on disease and treatment knowledge enhancement than clinician-delivered PDSIs. CONCLUSIONS: This review has demonstrated that PDSIs targeting individuals considering elective surgeries had benefited their decision-making by reducing decisional conflict and increasing disease and treatment knowledge, decision-making preparedness, and decision quality. These findings may be used to guide the development and evaluation of new PDSIs for elective surgical care.

Selective Thoracic Fusion for Idiopathic Scoliosis: A Comparison of Three Surgical Techniques with Minimum 5-year Follow-up.

STUDY DESIGN: Single-center retrospective review of outcomes among three surgical techniques in the treatment of thoracic idiopathic scoliosis (T-AIS) with a follow-up of at least 5 years. OBJECTIVE: To investigate how outcomes compare in video-assisted anterior thoracic instrumentation (VATS), all hooks/hook-pedicle screw hybrid instrumentation (HHF), and all pedicle screw instrumentation (PSF) techniques for T-AIS. SUMMARY OF BACKGROUND DATA: Studies comparing outcomes for anterior versus posterior fusion for T-AIS are few and with short follow-up. METHODS: Three groups of patients with T-AIS who underwent thoracic fusion were included in this study: 98 patients with mean curve of 49.0°â€Š±â€Š9.5° underwent VATS (Group 1); 44 patients with mean curve of 51.1°â€Š±â€Š7.4° underwent HHF (Group 2); and 47 patients with mean curve of 47.6°â€Š±â€Š9.9° underwent PSF (Group 3). Radiological outcomes were compared at preoperative, and up to 5 years. Surgical outcomes were noted until latest follow-up. RESULTS: Group 1 had less blood loss, less fusion levels, longer surgical time, and longer hospital stay compared with the other groups (P < 0.01). Groups 1 and 3 were comparable in all time periods with 78.8% and 78.2% immediate curve correction, and 72.9% and 72.1% at 5 years, respectively. Group 2 had lower correction in all time periods (P < 0.0001). Thoracic kyphosis and lumbar lordosis decreased in Group 3, but improved in both Groups 1 and 2 (P < 0.0001). Group 1 had more respiratory complications. The posterior groups had more deep wound infections. Two patients in Group 1 and one patient in Group 2 required revision surgery for implant-related complications. Reoperations for deep wound infections were noted only in the posterior groups. CONCLUSION: This is the first report comparing 5 year outcomes between anterior and posterior surgery for T-AIS. All three surgical methods resulted in significant and durable scoliosis correction; however, curve correction using HHF was inferior to both VATS and PSF with the latter two groups achieving similar coronal correction. However, VATS involved fewer segments, kyphosis improvement, and no deep wound infection, whereas PSF has less surgical time, shorter hospital stays, and no revision surgery from implant-related complications.Level of Evidence: 3.

Understanding the Pathophysiology of L5-S1 Loss of Lordosis and Retrolisthesis: An EOS Study of Lumbopelvic Movement Between Standing and Slump Sitting Postures.

OBJECTIVE: To understand the pathophysiology of L5-S1 loss of lordosis and retrolisthesis by comparing 2 commonly assumed physiological weight-bearing postures. METHODS: This was a prospective comparative study of whole-body standing and slump sitting EOS radiographs in clinic patients presenting with back pain or lower limb radicular pain. Patients with prior spinal intervention, malignancy, trauma, inflammatory diseases, transitional lumbosacral vertebra, pregnancy, and L5-S1 retrolisthesis or spondylolisthesis from nondegenerative causes were excluded. C7 sagittal vertical axis, global cervical angle, global thoracic angle, global lumbar angle, thoracolumbar angle, T1-slope, pelvic incidence, pelvic tilt, sacral slope, L5-S1 angle, L5-S1 vertebral translation, L5-S1 disc height, and presence of L4-5 vertebral translation were measured. Univariate and multivariate analyses were performed to identify predictors of L5-S1 lordosis loss and retrolisthesis. RESULTS: L5-S1 loss of lumbar lordosis (7.02 ± 9.90°, P < 0.001), retrolisthesis (0.07 ± 0.411 cm, P < 0.001), and loss of disc height (0.10 ± 0.23 cm, P < 0.001) occurred when changing from standing to slump sitting along with other sagittal profile changes (P < 0.001). Taller L5-S1 disc height (odds ratio [OR] 2.57, P = 0.04), larger lumbar range-of-motion change (OR 3.82, P = 0.012), lower sacral slope on sitting (OR 2.50, P = 0.043), and presence of L4-5 spondylolisthesis (OR 2.75, P = 0.032) were predictive of larger L5-S1 lordosis loss (>7°) on multivariate analysis, while larger lumbar range-of-motion change (OR 2.21, P = 0.050) and presence of L4-5 spondylolisthesis (OR 3.08, P = 0.023) were predictive of greater L5-S1 retrolisthesis (>0.07 cm). CONCLUSIONS: Degenerative L5-S1 loss of lordosis and retrolisthesis likely result from long-standing lower lumbar spine bending forces against the posterior ligamentous complex with slump sitting, predisposed by a negatively sloped sacrum and increased lumbar flexibility.

The Impact of Radiographic Lower Limb-Spinal Length Proportion on Whole-Body Sagittal Alignment.

STUDY DESIGN: A radiographic comparative study. OBJECTIVE: To investigate the influence of radiographic lower limb-spinal length proportion on sagittal radiographic parameters. SUMMARY OF BACKGROUND DATA: Although lordotic realignment of the lumbar spine is a well-established surgical strategy, its ideal target has not been fully understood. The widely used pelvic incidence-lumbar lordosis discrepancy (PI-LL) method to guide lordotic restoration of the lumber spine in the standing posture, may be further refined using the novel, radiographic lower limb-spinal length proportion parameter in selected subjects. METHODS: A 100 healthy subjects were imaged in the standing posture using EOS imaging to obtain whole-body lateral radiographs for the measurement of sagittal radiographic parameters. Univariate analyses were performed to compare radiographic parameters between groups with different radiographic lower limb-spinal length proportion. Multivariate analyses were performed to identify the associations between lower limb-spinal length proportions and other radiographic parameters. RESULTS: Regardless of lower limb-spinal length proportion (mean = 1.4), global lumbar angle (GLA) differed from spinal lordosis (SL), with the absolute means of SL and GLA larger and smaller than pelvic incidence (PI) respectively. Univariate analysis showed that patients with proportionately larger lower limb-spinal length proportion are more likely to have larger mean T1-slope, global thoracic angle (GTA), spinal kyphosis (SK), GLA, and SL. Multivariate analysis showed that a larger lower limb length-spinal length proportion is predictive of larger GLA is less than -47.69° (Odds Ratio (OR) 2.660, P = 0.026), and larger T1-slope of more than 18.84° (OR 3.695, P = 0.012). CONCLUSION: Larger radiographic lower limb-spinal length proportion results in naturally accentuated spinal curves. These patients balance with a larger lumbar lordosis that is closer to the PI and a higher T1-slope which should be considered for spinal realignment. SL differs from GLA and should be separately assessed.Level of Evidence: 3.

Understanding "Kyphosis" and "Lordosis" for Sagittal Balancing in Two Common Standing Postures.

STUDY DESIGN: Cross-sectional radiographic comparison study. OBJECTIVE: The aim of this study was to understand whole-body balancing in directed and natural standing postures, through comparison of kypholordotic ratios on whole-body radiographs of young, healthy subjects. SUMMARY OF BACKGROUND DATA: Recent studies highlighted the importance of understanding whole-body balancing, proposing the use of the more physiological natural standing posture, together with the conventional directed standing posture, for imaging. METHODS: Sixty healthy, 21-year-old subjects (36 males, 24 females) were recruited. EOS whole-body radiographs of subjects in directed and natural standing postures were obtained. Radiographic parameters compared include C2-sagittal vertical axis (C2-SVA), C7-SVA, C2-7-SVA, global cervical angles (C0-T1 and C2-C7), regional cervical angles (C0-C2, C2-C4, C4-C7), T1-slope, global thoracic angles (T1-T12 and T1-inflection vertebra [Inf]), thoracolumbar angle (T11-L2), global lumbar angles (T12-S1 and Inf-S1), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), spinocoxa angle (SCA), and femoral alignment angle (FAA). Kypholordotic ratios of T1-12/T12-S1, T1-Inf/Inf-S1, Tl-Inf/SCA, and (T1-Inf + FAA)/(T1-slope + SCA) were calculated and compared. RESULTS: Compared to directed standing, natural standing has greater C2-SVA and C7-SVA, more lordotic global and regional cervical angles (except C0-2 angle), higher T1-slope, larger T1- T12 and T1-Inf kyphotic angles, smaller T12-S1 and Inf-S1 lordotic angles, larger PT, more lordotic SCA, and smaller SS and FAA angles. T1-12/T12-S1 and T1-Inf/Inf-S1 ratios in natural standing, and (Tl-Inf + FAA)/(T1-slope + SCA) ratio in both postures approximate 1. There were significant differences between postures for Tl-l2/Tl2-Sl, Tl-Inf/Inf-Sl and Tl-Inf/SCA ratios. CONCLUSION: Whole-body balancing requires understanding of the balance between kyphosis and lordosis, which varies with the posture of patients. Analysis of kypholordotic ratios obtained in this study allude to the importance of performing whole-body imaging in the directed standing posture, and whole-spine or whole-body imaging in the natural standing posture, so as to fully understand spinal and whole body balancing for spinal realignment surgeries.Level of Evidence: Level 3.

Audit and Comparison Between Radiographic Markers of Gaze Direction Using EOS Imaging - An Essential Step to Streamline Existing Methods.

STUDY DESIGN: Retrospective cohort study on prospectively implemented EOS protocol. OBJECTIVE: This study aims to audit and compare existing radiological definitions of gaze direction-chin brow vertical angle (CBVA), McGregor slope (McGS), slope of line of sight (SLS), orbital-internal occipital protuberance (OIOP) slope angle, and Tangent to the hard palate (THP) in a neutral, healthy, and asymptomatic cohort. SUMMARY OF BACKGROUND DATA: The ability to accurately define direction of gaze is the first step when striving for horizontal gaze restoration in any affected individual with rigid sagittal deformity. Yet, the radiological definition of gaze direction remains poorly standardized. METHODS: Hundred healthy subjects who could achieve horizontal gaze underwent whole-body standing EOS radiographs taken under a strictly standardized protocol. Radiographic measurements of global spinal sagittal parameters and surrogate measures of horizontal gaze were analyzed and compared. RESULTS: The mean age was 45 ±â€Š15.9 years, with a balanced male-to-female-ratio. Their C7 SVA was -7.7 mm ±â€Š24.8 mm, PI was 51.0o ±â€Š11.4o, PI-LL was -0.9o ±â€Š13.0o and T1-slope was 21.2o ±â€Š9.2o. Measured horizontal gaze parameters were as follows: CBVA (1.07o ±â€Š5.48o), McGS (-3.23o ±â€Š5.63o), SLS (0.45o ±â€Š5.34o), OIOP (5.03o ±â€Š4.66o), THP (-0.17o ±â€Š6.27o). CBVA correlated strongly with McGS (r = 0.679, P < 0.001), SLS (r = 0.592, P < 0.001), OIOP (r = 0.697, P < 0.001), and THP (r = -0.504, P < 0.001). OIOP had the lowest variance amongst all parameters and showed less variability compared to CBVA (SD 4.66 Var 21.69 vs. SD 5.48 Var 30.08, P = .012). Multivariate analysis showed that C2-7 angle was the only parameter found to be associated with OIOP values (P = 0.006). CONCLUSION: OIOP is the least variable, and most robust radiological method in determining gaze direction. It uses easily recognizable anatomical landmarks and an angular criterion, which makes it advantageous both with x-rays or slot scanners.Level of Evidence: 3.

Addressing Coronavirus Disease 2019 in Spine Surgery: A Rapid National Consensus Using the Delphi Method via Teleconference.

The magnitude and potential duration of the current coronavirus disease 2019 (COVID-19) pandemic is something that most doctors currently in practice have yet to experience. While considerable information regarding COVID-19 is being published every day, it is challenging to filter out the most relevant or appropriate information for our individual practice. The Spine Society of Singapore convened via a teleconference on April 24, 2020 to collaborate on a national level and share collective wisdom in order to tackle the ongoing crisis. In the teleconference, 13 spine surgeons from across various hospitals in Singapore constituted the panel of experts. The following topics were discussed: repurposing of surgeons, continuity of spine services, introduction of telemedicine, triaging of spinal surgeries, preoperative testing, new challenges in performing spine surgery, and preparing for the post-pandemic era. While some issues required only the sharing of best practices, the Delphi panel method was adopted to form a consensus on others. Existing spine specific triage guidelines were debated and a locally accepted set of guidelines was established. Although preoperative testing is currently not performed routinely, the panel voted in favor of its implementation because they concluded that it is vital to protect themselves, their colleagues, and their patients. Solutions to operating room specific concerns were also discussed. This article reflects the opinions and insights shared during this meeting and reviews the evidence relevant to the issues that were raised. The rapid consensus reached during the teleconference has enabled us to be concerted, and thus stronger, in our national efforts to provide the best standard of care via our spine services in these challenging times. We believe that this article will provide some guidance for addressing COVID-19 in spine surgery and encourage other national/regional societies to conduct similar discussions that would help their navigation of this pandemic.

Characterization of Sagittal Spine Alignment With Reference to the Gravity Line and Vertebral Slopes: An Analysis of Different Roussouly Curves.

MINI: Spinal sagittal realignment necessitates a reference posture, and thus far this has only been defined for an "averaged" curve via horizontal offsets from the gravity line (GL). This prospective study of 169 healthy subjects demonstrates normative sagittal spatial orientation of each vertebra, for all Roussouly curve types, using vertebral slopes and horizontal offsets from the GL. STUDY DESIGN: Prospective study. OBJECTIVE: To map the healthy standing alignment of the adult spine, grouped according to Roussouly curve types, using both horizontal offset distance from the gravity line (GL), as well as vertebral slope measurements. SUMMARY OF BACKGROUND DATA: Spinal sagittal realignment requires a reference posture, and this has been defined in the literature via horizontal offsets from the GL. While useful, this does not provide information on the orientation of each vertebral segment, or distinguish between the various physiological curve types. METHODS: A total of 169 consecutive young adult subjects with healthy spines were recruited over a year. (EOS Imaging, Paris, France) whole body radiographs were performed. Radiographic measurements collected included sagittal vertical axis (SVA), T1-slope, global cervical angle (GCA), global thoracic angle (GTA), global lumbar angle (GLA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), apical and inflection vertebrae. Outcome measures comprised slope measurements, and distance offsets relative to the GL for individual vertebrae from T3 to S1. RESULTS: GLA, PI, PT, SS, apex of lordosis, and inflection vertebra were significantly different across groups, while SVA, T1-slope, GCA, GTA, and apex of kyphosis were not. Mean PI to LL discrepancy for Type I to IV groups were 8.0°, 2.3°, 4.8°, and 3.0°, respectively. Between groups, T3, T7 to T12, and L2 to S1 slopes and T9 to L3 offset distances from GL were significantly different, while the distance of the hip center from the GL was not. GLA was significantly different between curve types except between Type 1 and 2 curves, while the inflection vertebrae were not significantly different between Type 1 and 2 curves, as well as Type 3 and 4 curves. CONCLUSION: This study demonstrates normative sagittal spatial orientation of each vertebra in healthy adults, for each Roussouly type. Comparison across groups suggests the possibility of further refining the sagittal curve patterns described by Roussouly. LEVEL OF EVIDENCE: 3.

Prospective study. To map the healthy standing alignment of the adult spine, grouped according to Roussouly curve types, using both horizontal offset distance from the gravity line (GL), as well as vertebral slope measurements. Spinal sagittal realignment requires a reference posture, and this has been defined in the literature via horizontal offsets from the GL. While useful, this does not provide information on the orientation of each vertebral segment, or distinguish between the various physiological curve types. A total of 169 consecutive young adult subjects with healthy spines were recruited over a year. (EOS Imaging, Paris, France) whole body radiographs were performed. Radiographic measurements collected included sagittal vertical axis (SVA), T1-slope, global cervical angle (GCA), global thoracic angle (GTA), global lumbar angle (GLA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), apical and inflection vertebrae. Outcome measures comprised slope measurements, and distance offsets relative to the GL for individual vertebrae from T3 to S1. GLA, PI, PT, SS, apex of lordosis, and inflection vertebra were significantly different across groups, while SVA, T1-slope, GCA, GTA, and apex of kyphosis were not. Mean PI to LL discrepancy for Type I to IV groups were 8.0°, 2.3°, 4.8°, and 3.0°, respectively. Between groups, T3, T7 to T12, and L2 to S1 slopes and T9 to L3 offset distances from GL were significantly different, while the distance of the hip center from the GL was not. GLA was significantly different between curve types except between Type 1 and 2 curves, while the inflection vertebrae were not significantly different between Type 1 and 2 curves, as well as Type 3 and 4 curves. This study demonstrates normative sagittal spatial orientation of each vertebra in healthy adults, for each Roussouly type. Comparison across groups suggests the possibility of further refining the sagittal curve patterns described by Roussouly. Level of Evidence: 3.

A 10-Year Radiographic Study Comparing Anterior Versus Posterior Instrumented Spinal Fusion in Patients With Lenke Type 5 Adolescent Idiopathic Scoliosis.

MINI: This is a long-term prospective cohort study comparing the radiographic outcomes of anterior versus posterior instrumentation for Lenke 5 adolescent idiopathic scoliosis. Both approaches were comparable in terms of radiographic outcomes up to 10 years. The posterior approach is more prone to developing proximal junctional kyphosis. STUDY DESIGN: Prospective cohort study. OBJECTIVE: To compare the long-term, radiographic coronal and sagittal outcomes of these two approaches at 10-year follow-up. SUMMARY OF BACKGROUND DATA: Both anterior and posterior instrumented fusions have been found to be safe and effective treatments for Lenke 5 adolescent idiopathic scoliosis with up to 2 to 5 years of follow-up. Few studies follow patients beyond this duration. METHODS: 36 patients who underwent anterior (n = 25) or posterior instrumented spinal fusion (n = 11) for Lenke 5 adolescent idiopathic scoliosis over a 4-year period were recruited and followed for 10 years. Preoperative clinical data include patient's age and age of menarche. Operative data included instrumented levels, duration of surgery, and surgical blood loss. Postoperative data included duration of hospital stay, duration of intensive care unit stay, and complications. Pre- and postoperative radiographic data collected include coronal Cobb angles for structural thoracolumbar/lumbar curves, and sagittal angles-sagittal vertical axis, thoracic kyphosis, global lumbar angle, pelvic incidence, pelvic tilt, sacral slope, and upper and lower end vertebrae. RESULTS: Posterior surgery had a shorter operative time (P < 0.010) and hospital stay (P < 0.010). Coronal plane deformity improved by a mean of 74% in the anterior group and 71% in the posterior group. There was no significant change at 10 years in both groups (anterior P = 0.455 and posterior P = 0.325). Sagittal parameters remained unchanged. There was a higher incidence of proximal junctional kyphosis in the posterior (45%) compared to the anterior (16%) group (P < 0.010). CONCLUSION: Both anterior and posterior instrumentation and fusion are successful surgeries after 10 years of follow-up. They are comparable with regards to their ability to achieve and maintain good correction of scoliotic deformities and have a low rate of pseudoarthrosis and instrument failure. Ideal sagittal parameters are maintained up to 10 years of follow-up. LEVEL OF EVIDENCE: 3.

Prospective cohort study. To compare the long-term, radiographic coronal and sagittal outcomes of these two approaches at 10-year follow-up. Both anterior and posterior instrumented fusions have been found to be safe and effective treatments for Lenke 5 adolescent idiopathic scoliosis with up to 2 to 5 years of follow-up. Few studies follow patients beyond this duration. 36 patients who underwent anterior (n = 25) or posterior instrumented spinal fusion (n = 11) for Lenke 5 adolescent idiopathic scoliosis over a 4-year period were recruited and followed for 10 years. Preoperative clinical data include patient's age and age of menarche. Operative data included instrumented levels, duration of surgery, and surgical blood loss. Postoperative data included duration of hospital stay, duration of intensive care unit stay, and complications. Pre- and postoperative radiographic data collected include coronal Cobb angles for structural thoracolumbar/lumbar curves, and sagittal angles­sagittal vertical axis, thoracic kyphosis, global lumbar angle, pelvic incidence, pelvic tilt, sacral slope, and upper and lower end vertebrae. Posterior surgery had a shorter operative time (P < 0.010) and hospital stay (P < 0.010). Coronal plane deformity improved by a mean of 74% in the anterior group and 71% in the posterior group. There was no significant change at 10 years in both groups (anterior P = 0.455 and posterior P = 0.325). Sagittal parameters remained unchanged. There was a higher incidence of proximal junctional kyphosis in the posterior (45%) compared to the anterior (16%) group (P < 0.010). Both anterior and posterior instrumentation and fusion are successful surgeries after 10 years of follow-up. They are comparable with regards to their ability to achieve and maintain good correction of scoliotic deformities and have a low rate of pseudoarthrosis and instrument failure. Ideal sagittal parameters are maintained up to 10 years of follow-up. Level of Evidence: 3.

The Effectiveness of Full-body EOS Compared With Conventional Chest X-ray in Preoperative Evaluation of the Chest for Patients Undergoing Spine Operations: A Preliminary Study.

STUDY DESIGN: A prospective radiographic comparative study. OBJECTIVE: The aim of this study was to compare full-body EOS with conventional chest X-ray (CXR) for use in the preoperative evaluation of the chest in patients undergoing spine operations. SUMMARY OF BACKGROUND DATA: The full-body EOS reproduces an image of the chest similar to a routine CXR. The potential for the former replacing the latter is plausible. This is especially applicable in spine patients who would routinely have a preoperative full-body EOS performed. METHODS: A radiographic comparative study of 266 patients was conducted at a single tertiary center from January 2013 to July 2016. Each patient had EOS and CXR done in random order <2 weeks apart. Two radiologists reported the image findings using a checklist. A third radiologist was consulted in cases of discrepancy. Interobserver agreement was calculated using Gwet AC1 and a comparison between EOS and CXR findings was analyzed using paired Chi-squared test. Multivariate analysis was performed to identify predictors for abnormal radiological findings. The institutional ethics committee approved this prospective study and waiver of informed consent was obtained. RESULTS: There were 84 males (31.6%) and 182 females (68.4%). The mean age was 38.9 years (SD = 25.0 years). High interobserver agreement was found for EOS and CXR (Gwet AC1 0.993 and 0.988, respectively). There were no significant differences between both imaging modalities. Rare diagnoses precluded comparison of certain conditions. Age >18 years [odds ratio (OR) 7.69; P = 0.009] and American Society of Anesthesiologists physical status 3 (OR 6.64; P = 0.018) were independent predictors of abnormal radiological findings. CONCLUSION: EOS is not inferior to, and may be used to replace CXR in preoperative radiological screening of thoracic conditions especially in low-risk patients ≤18 years old and patients with ASA <3. Preoperative assessment should never rely on a single modality. High-risk patients should be sent for a thorough work-up before spine surgery. LEVEL OF EVIDENCE: 4.

Radiologically defining horizontal gaze using EOS imaging-a prospective study of healthy subjects and a retrospective audit.

BACKGROUND CONTEXT: As sagittal alignment of the cervical spine is important for maintaining horizontal gaze, it is important to determine the former for surgical correction. However, horizontal gaze remains poorly-defined from a radiological point of view. PURPOSE: The objective of this study was to establish radiological criteria to define horizontal gaze. STUDY DESIGN/SETTING: This study was conducted at a tertiary health-care institution over a 1-month period. PATIENT SAMPLE: A prospective cohort of healthy patients was used to determine the best radiological criteria for defining horizontal gaze. A retrospective cohort of patients without rigid spinal deformities was used to audit the incidence of horizontal gaze. OUTCOME MEASURES: Two categories of radiological parameters for determining horizontal gaze were tested: (1) the vertical offset distances of key identifiable structures from the horizontal gaze axis and (2) imaginary lines convergent with the horizontal gaze axis. MATERIALS AND METHODS: Sixty-seven healthy subjects underwent whole-body EOS radiographs taken in a directed standing posture. Horizontal gaze was radiologically defined using each parameter, as represented by their means, 95% confidence intervals (CIs), and associated 2 standard deviations (SDs). Subsequently, applying the radiological criteria, we conducted a retrospective audit of such radiographs (before the implementation of a strict radioimaging standardization). RESULTS: The mean age of our prospective cohort was 46.8 years, whereas that of our retrospective cohort was 37.2 years. Gender was evenly distributed across both cohorts. The four parameters with the lowest 95% CI and 2 SD were the distance offsets of the midpoint of the hard palate (A) and the base of the sella turcica (B), the horizontal convergents formed by the tangential line to the hard palate (C), and the line joining the center of the orbital orifice with the internal occipital protuberance (D). In the prospective cohort, good sensitivity (>98%) was attained when two or more parameters were used. Audit using Criterion B+D yielded compliance rates of 76.7%, a figure much closer to that of A+B+C+D (74.8%). From a practical viewpoint, Criterion B+D were most suitable for clinical use and could be simplified to the "3-6-12 rule" as a form of cursory assessment. Verbal instructions in the absence of stringent postural checks only ensured that ~75% of subjects achieved horizontal gaze. CONCLUSIONS: Fulfillment of Criterion B+D is sufficient to evaluate for horizontal gaze. Further criteria can be added to increase sensitivity. Verbal instructions alone yield high rates of inaccuracy when attempting to image patients in horizontal gaze. Apart from improving methods for obtaining radiographs, a radiological definition of horizontal gaze should be routinely applied for better evaluation of sagittal spinal alignment.

Cervical Alignment Variations in Different Postures and Predictors of Normal Cervical Kyphosis: A New Understanding.

STUDY DESIGN: Comparative study of prospectively collected radiographic data. OBJECTIVE: To predict physiological alignment of the cervical spine and study its morphology in different postures. SUMMARY OF BACKGROUND DATA: There is increasing evidence that normal cervical spinal alignment may vary from lordosis to neutral to kyphosis, or form S-shaped or reverse S-shaped curves. METHODS: Standing, erect sitting, and natural sitting whole-spine radiographs were obtained from 26 consecutive patients without cervical spine pathology. Sagittal vertical axis (SVA), global cervical lordosis, lower cervical alignment C4-T1, C0-C2 angle, T1 slope, C0-C7 SVA and C2-7SVA, SVA, thoracic kyphosis, thoracolumbar junctional angle, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence were measured. Statistical analysis was performed to elucidate differences in cervical alignment for all postures. Predictive values of T1 slope and SVA for cervical kyphosis were evaluated. RESULTS: Most patients (73.0%) do not have lordotic cervical alignment (C2-C7) upon standing (mean -0.6, standard deviation 11.1°). Lordosis increases significantly when transitioning from standing to erect sitting, as well as from erect to natural sitting (mean -17.2, standard deviation 12.1°). Transition from standing to natural sitting also produces concomitant increases in SVA (-8.8-65.2 mm) and T1-slope (17.4°-30.2°). T1 slope and SVA measured during standing significantly predicts angular cervical spine alignment in the same position. SVA < 10 mm significantly predicts C4-C7 kyphosis (P < 0.001), and to a lesser extent, C2-C7 kyphosis (P = 0.02). T1 slope <20° is both predictive of C2-C7 and C4-7 kyphosis (P = 0.001 and P = 0.023, respectively). For global cervical Cobb angle, T1 slope seems to be a more significant predictor of kyphosis than SVA (odds ratio 17.33, P = 0.001 vs odds ratio 11.67, P = 0.02, respectively). CONCLUSION: The cervical spine has variable normal morphology. Key determinants of its alignment include SVA and T1 slope. Lordotic correction of the cervical spine is not always physiological and thus correction targets should be individualized. LEVEL OF EVIDENCE: 3.

Slump sitting X-ray of the lumbar spine is superior to the conventional flexion view in assessing lumbar spine instability.

BACKGROUND CONTEXT: Flexion radiographs have been used to identify cases of spinal instability. However, current methods are not standardized and are not sufficiently sensitive or specific to identify instability. PURPOSE: This study aimed to introduce a new slump sitting method for performing lumbar spine flexion radiographs and comparison of the angular range of motions (ROMs) and displacements between the conventional method and this new method. STUDY DESIGN: This study used is a prospective study on radiological evaluation of the lumbar spine flexion ROMs and displacements using dynamic radiographs. PATIENT SAMPLE: Sixty patients were recruited from a single spine tertiary center. OUTCOME MEASURE: Angular and displacement measurements of lumbar spine flexion were carried out. METHOD: Participants were randomly allocated into two groups: those who did the new method first, followed by the conventional method versus those who did the conventional method first, followed by the new method. A comparison of the angular and displacement measurements of lumbar spine flexion between the conventional method and the new method was performed and tested for superiority and non-inferiority. RESULTS: The measurements of global lumbar angular ROM were, on average, 17.3° larger (p<.0001) using the new slump sitting method compared with the conventional method. They were most significant at the levels of L3-L4, L4-L5, and L5-S1 (p<.0001, p<.0001 and p=.001, respectively). There was no significant difference between both methods when measuring lumbar displacements (p=.814). CONCLUSION: The new method of slump sitting dynamic radiograph was shown to be superior to the conventional method in measuring the angular ROM and non-inferior to the conventional method in the measurement of displacement.

T9 versus T10 as the upper instrumented vertebra for correction of adult deformity-rationale and recommendations.

BACKGROUND CONTEXT: Adult spinal deformity correction sometimes involves long posterior pedicle screw constructs extending from the lumbosacral spine to the thoracic vertebra. As fusion obliterates motion and places supraphysiological stress on adjacent spinal segments, it is crucial to ascertain the ideal upper instrumented vertebra (UIV) to minimize risk of proximal junctional failure (PJF). The T10 vertebra is often chosen to allow bridging of the thoracolumbar junction into the immobile thoracic vertebrae on the basis that it is the lowest immobile thoracic vertebra strut by the rib cage. PURPOSE: This study aimed to characterize the range of motion (ROM) of each vertebral segment from T7 to S1 to determine if T10 is truly the lowest immobile thoracic vertebra. STUDY DESIGN/SETTING: This is a prospective, comparative study. PATIENT SAMPLE: Seventy-nine adults (mean age of 45.4 years) presenting with low back pain or lower limb radiculopathy or both, without previous spinal intervention, metastases, fractures, infection, or congenital deformities of the spine, were included in the study. OUTCOME MEASURES: A ROM >5° across two vertebral segments as determined by the Cobb method from radiographs. METHODS: Lumbar flexion-extension and neutral erect radiographs were obtained in randomized order using a slot scanner. Segmental ROM was measured from T7-T8 to L5-S1 and analyzed for significant differences using t tests. Age, gender, radiographical indices such as standard spinopelvic parameters, sagittal vertical axis (SVA), C7-T12 SVA, T1 slope, thoracic kyphosis (TK), and lumbar lordosis (LL) were studied via multivariate analysis to identify predictive factors for >5° change in ROM at the various segmental levels. There were no sources of funding and no conflicts of interest associated with this study. RESULTS: In the thoracolumbar spine, significant decreases in ROM when compared with the adjacent caudad segment occurs up to T9-T10, with mean total ROM of 1.98±1.47° (p<.001) seen in T9-T10, 2.19±1.67° (p<.001) in T10-T11, and 3.92±3.21°(p<.001) in T11-T12. The total ROM of T8-T9 (2.53±1.79°) was not significantly different from that of T9-T10 (p=.261). At the thoracolumbar junction, absence of scoliosis (OR 11.37, p=.020), high pelvic incidence (OR 1.14, p=.046), and low T1 slope (OR 1.45, p=.030) were predictive of ROM >5°. CONCLUSIONS: Lumbar spine flexion-extension ROM decreases as it approaches the thoracolumbar junction. T10 is indeed the lowest immobile thoracic vertebra strut by the rib cage, and the last significant decrease in ROM is observed at T9-T10, in relation to T10-T11. However, because this also implies that a UIV of T10 would mean there is only one level of fixation above the relatively mobile segment, while respecting other factors that influence UIV selection, we propose the T9 vertebra as a more ideal UIV to fulfill the biomechanical concept of bridge fixation. However, this decision should still be taken on a case-by-case basis.

Versatility of percutaneous pedicular screw fixation in metastatic spine tumor surgery: a prospective analysis.

BACKGROUND: Posterior percutaneous spinal fixation (PPSF) has evolved to address the problems associated with metastatic spinal disease (MSD). This study was designed to evaluate the feasibility and spectrum of application of PPSF in the management of MSD, highlighting its clinical advantages. METHODS: Twenty-seven consecutive patients with MSD treated with PPSF in our institution from January 2011 to June 2014 were studied. After a multidisciplinary assessment, all patients were considered for surgical intervention due to clinical presentation of either neural deficit, skeletal instability, or both. Some of these patients belonged to the poor prognostic category based on survival prognostic scoring systems. The patients were categorized into seven groups depending on the modality of PPSF used. Demographic data, operative details, and clinical outcomes were investigated for each category and compared pre- and postoperatively. RESULTS: The median age was 60 years (range 49-78 years). Generally, all patients either maintained or improved their neurological status and achieved pain alleviation. Ambulatory status and Eastern Cooperative Oncology Group (ECOG) scores were improved using any modality of PPSF. The pure-stabilization group had the lowest amount of mean blood loss, shortest operative time, and intensive care unit (ICU) and hospital stays, while the long-construct group was observed to have the greatest amount of blood loss, and longest operative time and ICU stay. CONCLUSIONS: For patients with MSD, even with predicted poor prognosis on survival prognostic scoring systems, it is possible to improve functional outcomes and quality of life with PPSF, keeping surgical morbidity to a minimum. PPSF allows patients with pure spinal instability to be addressed successfully with least morbidity.