Classification of coronal imbalance in adult scoliosis and spine deformity: a treatment-oriented guideline

Influence of postoperative coronal malalignment following long-instrumented fusion in patients with adult spinal deformity: evaluation of clinical outcomes and mechanical complications

BACKGROUND CONTEXT

Achieving satisfactory sagittal alignment in patients with adult spinal deformity (ASD) is a major goal of deformity correction, which leads to high health-related quality. However, compared with the literature on sagittal alignment, studies on postoperative coronal malalignment in ASD are limited.

PURPOSE

This study aimed to investigate the impact of coronal malalignment on clinical outcomes and mechanical complications after corrective surgery for ASD.

STUDY DESIGN/SETTING

Retrospective observational study.

PATIENT SAMPLE

Among patients who underwent deformity correction with ≥5-level fusion to the sacrum, this study focused on those who achieved optimal sagittal correction, defined as a pelvic incidence minus lumbar lordosis (PI-LL) of ≤10° postoperatively.

OUTCOME MEASURES

Incidence of coronal malalignment; clinical outcomes using the visual analog scale (VAS), Oswestry disability index (ODI), and Scoliosis Research Society Outcomes Questionnaire-22 (SRS-22); and mechanical complications such as proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and rod fracture.

METHODS

Coronal malalignment was evaluated using the coronal balance distance (CBD), defined as the horizontal distance between the C7 plumb line and the central sacral vertical line. Postoperative coronal malalignment was classified as CBD>3 cm. Patients were divided into two groups based on CBD as follows: the coronal balance (CB) group (balanced, CBD<3 cm) and the coronal imbalance (CI) group (imbalanced, CBD≥3 cm). Clinical outcomes and the incidence of mechanical complications were compared between the groups.

RESULTS

This study included 112 patients, with a mean follow-up duration of 46.8 months. Among them, 24 patients (21.4%) were included in the CI group, with a mean CBD of 3.6±0.4 cm, whereas 88 patients comprised the CB group, with a mean CBD of 1.1±0.7 cm. The back pain VAS scores indicated that the CI group had significantly worse clinical outcomes than the CB group (52.5±19.8 vs. 40.1±24.0, p=.022). The appearance domain of the SRS-22 was also significantly lower in the CI group than in the CB group (2.8±0.6 vs. 3.4±0.9, p=.002). However, no significant differences in leg pain VAS scores, ODI scores, or other SRS-22 domains, except appearance, were observed between the two groups. The incidences of PJK, PJF, and rod fractures were similar between the groups. However, the rate of revision surgery for rod fractures was significantly higher in the CI group than in the CB group (5/5 in the CI group vs. 5/29 in the CB group, p<.001).

CONCLUSIONS

After correction surgery for ASD, coronal malalignment demonstrated an association with increased back pain VAS scores and lower appearance scores on the SRS-22. The incidence of mechanical complications, including PJK, PJF, and rod fractures, was not influenced by coronal alignment. However, coronal malalignment significantly increased the risk of revision surgery for rod fractures.

Prevalence and Clinical Impact of Coronal Malalignment Following Circumferential Minimally Invasive Surgery (CMIS) for Adult Spinal Deformity Correction

Study DesignRetrospective study.ObjectivesTo determine prevalence and clinical importance of patients who had postoperative CM after CMIS for ASD correction.MethodsWe reviewed patients who underwent CMIS technique. Inclusion criteria were patients who were diagnosed with ASD, which is defined as having at least one of the following: coronal Cobb angle >20, SVA >50 mm, PI-LL >10, PT >20. They underwent >4 spinal levels fusion with CMIS technique and had at least 1-year follow-up. Preoperative and 1-year postoperative radiographs and clinical outcome measures (VAS, ODI, and SRS-22 scores) were used to make the comparisons.Results120 patients were included. Radiographic outcomes, including CVA, coronal Cobb angle, LSF curve, SVA, LL, and PI-LL, and clinical outcomes, were significantly improved postoperatively in each of the 3 preoperative subgroups (Bao type A, B, and C). At 1-year post-operation, 10 patients (12.4 %) of type A turned out to be CM, 4 patients (21.1%) of type B, and 8 patients (40%) of type C remained CM. Comparing coronally aligned (CA) to coronally mal-aligned patients at 1-year follow-up in each coronal subtype revealed that clinical and radiographic outcomes were comparable.ConclusionsCMIS technique significantly improves radiographic and clinical outcomes for ASD patients. Incidence rates of postoperative CM were similar to open surgery. Type C patients were at risk of postoperative CM than types A and B. However, most 1-year outcomes were not significantly different between postoperative CA and CM patients regardless of the preoperative coronal alignment characteristics except ODI scores in type A.

The correction range of lumbosacral curve vertebral body tilt in degenerative scoliosis for achieving postoperative coronal balance

PURPOSE

To explore the relationship between lumbosacral curve vertebral body tilt correction and postoperative coronal balance in adult degenerative scoliosis to determine the ideal target values for the tilt correction.

METHODS

We conducted a retrospective analysis of 144 patients who underwent surgery between January 2017 and December 2023. Patients were classified based on the preoperative Obeid classification and fixation segment length into Concave Long Segment (Concave-L, n = 41), Concave Short Segment (Concave-S, n = 33), Convex Long Segment (Convex-L, n = 39), and Convex Short Segment (Convex-S, n = 31). Changes in coronal and sagittal radiographic parameters and the correlation between the correction percentage of the most tilted vertebra (L4 or L5) and postoperative coronal balance distance (CBD) were assessed.

RESULTS

Significant postoperative improvements in CBD, maximum coronal tilt, and Cobb angle were observed in the Concave-L, Convex-L, and Convex-S groups. The Concave-S group exhibited significant changes only in Cobb angle and maximum coronal tilt, but not CBD. A significant negative correlation existed between postoperative CBD and the correction ratio of maximum coronal tilt in the convex malalignment (r=-0.629, P < 0.001), with the regression equation: Postoperative CBD = 32.99 - (28.82 × Correction Ratio of Coronal Tilt). A correction ratio exceeding 45% at L4 or L5 tilt predicted a postoperative CBD within 20 mm.

CONCLUSION

Both short and long segment fusions effectively correct convex coronal malalignment, but concave malalignment requires long segment fusion for adequate correction. Optimal coronal balance in convex malalignment is achieved when the maximum tilt correction ratio exceeds 45%.

The Role of Paraspinal Muscle in Postoperative Coronal Balance Transition in Degenerative Lumbar Scoliosis: A Two-Year Follow-Up Study

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

The purpose of this study was to determine whether paraspinal muscle could influence postoperative coronal balance and its transition in degenerative lumbar scoliosis (DLS).

SUMMARY OF BACKGROUND DATA

Although the importance of the paraspinal muscles (PSM) in sagittal alignment is well recognized, there is no information about its role in coronal balance.

METHODS

The study included 102 DLS patients. Evaluation of the PSM on magnetic resonance imaging were conducted at baseline. Coronal measurements included coronal balance distance (CBD), major Cobb angle, L4 coronal tilt, and L5 coronal tilt. The cohort was divided based on postoperative parameters into persistent coronal balance (PCB), worsened coronal imbalance (WCIB), recurrent coronal balance (RCB), and persistent coronal imbalance (PCIB) according to immediate postoperative and follow-up coronal balance. Multivariate logistic regression models for postoperative CIB, follow-up WCIB and follow-up RCB were utilized to identify statistically significant associations while accounting for confounders.

RESULTS

The cohort was divided into 57 with PCB, 13 with WCIB, 10 with RCB, and 22 with PCIB. The follow-up groups with CIB exhibited more severe fatty infiltration in the extensor muscle compared with the balanced groups. Specifically, the WCIB group demonstrated the most severe extensor muscle degeneration, particularly on the concave sides, and the most prominent asymmetric degeneration of the PSM among the four groups. Furthermore, patients with CIB had worse sagittal malalignment compared with those with CB at the last follow-up.

CONCLUSIONS

Patients exhibiting stronger extensor muscle mass were prone to immediate postoperative CB and more likely to experience spontaneous improvement or recurrence of coronal balance during follow-up. Severe extensor muscle degeneration and prominent asymmetric bilateral PSM degeneration represent potential risk factors for persistent CIB and recurrent CIB. It is crucial to assess the dynamic change during the follow-up period as long-term prognosis may be impacted if CB deteriorates, or otherwise develops during follow-up.

LEVEL OF EVIDENCE

3.

An Inter- and Intra-Rater Agreement Assessment of Two Novel Classification Systems for Coronal Imbalance in Adult Scoliosis and Spine Deformity

OBJECTIVE

Coronal malalignment is a common feature of adult spinal deformity, and accurate classification is essential for diagnosis and treatment planning. However, variations in interpretation among clinicians can impact classification consistency. By assessing the reliability and applicability of these systems across different medical experts, this study seeks to establish a standardized approach to enhance clinical outcomes. This study aimed to evaluate the inter- and intra-observer agreement of two classification systems for coronal malalignment in adult spinal deformity patients, as proposed by Qiu et al. and Obeid et al.

METHODS

We analyzed 70 cases of adult spinal deformity collected between January 1, 2010, and April 20, 2023, using the classification systems proposed by Qiu et al. and Obeid et al. To assess inter- and intra-rater agreement, the same group of researchers re-evaluated all cases in a random order after a 4-week interval. We used the kappa statistic (κ) for inter- and intra-rater agreement assessment.

RESULTS

Qiu's classification system: Inter-rater agreement: Substantial agreement (κ = 0.76; 95% CI: 0.72-0.80) for Type A, Type B, and Type C. Intra-rater agreement: Nearly perfect agreement (κ = 0.83; 95% CI: 0.78-0.89) within raters for Type A, Type B, and Type C. Obeid's classification system: Inter-rater agreement: Almost perfect agreement (κ = 0.85; 95% CI: 0.83-0.87) for Type 0, Type 1, and Type 2. Complete system: Substantial agreement (κ = 0.68; 95% CI: 0.65-0.71) for all types and subtypes. Intra-rater agreement: Almost perfect at the type level (κ = 0.88; 95% CI: 0.83-0.93) and substantial at the subtype level (κ = 0.75; 95% CI: 0.65-0.85).

CONCLUSIONS

The research findings indicate a high level of agreement between the classification system described by Qiu et al. and the classification system proposed by Obeid et al. This agreement supports the widespread adoption and utilization of these classification systems in future clinical studies.

Coronal Deformity is Associated With Uptake on Single Photon Emission Computed Tomography in Patients With Low Back Pain

Study DesignRetrospective Cohort Study.ObjectiveSingle Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) is emerging as a valuable imaging test for identifying pain generators within the lumbar spine. The relationship between radiotracer uptake on SPECT/CT and anatomic biomechanical parameters has not been previously studied.MethodsWe performed a retrospective review of all patients seen at our institution between 2021-2023 who obtained SPECT/CT scans for workup of thoracolumbar back pain. Patient data including demographic, clinical symptoms, and surgical history were collected. Radiology reports were reviewed for evidence of pathologic degeneration and increased bone metabolism on SPECT/CT. Biomechanical parameters were measured from standing scoliosis plain radiographs. Patients were stratified into two cohorts by either presence or absence of asymmetric coronal uptake on SPECT/CT.Results160 patients met inclusion criteria. Patients were primarily male (55%) with average age 55 ± 15 years. 87 (54%) patients demonstrated asymmetric uptake on SPECT/CT. These patients were older (P < 0.001), but with similar gender, prior fusion history, sacroiliitis, adjacent segment degeneration, and pseudoarthrosis (P > 0.05). This cohort had more disc disease, facet arthropathy, and greater degree of coronal scoliosis and coronal imbalance (P < 0.001). There were significantly more sites of uptake in the asymmetric cohort, and uptake was preferentially observed in the concavity of the lumbar curve (P < 0.001). There were no significant differences in sagittal balance or spinopelvic mismatch between cohorts (P > 0.05).ConclusionAsymmetric uptake on SPECT/CT was associated with coronal deformity in patients with low back pain. Further prospective studies are warranted to assess the effect of coronal deformity on pain generation.

Establishing a Threshold of Impairment to Define Preoperative Coronal Malalignment in Adult Spinal Deformity Patients

STUDY DESIGN

Single-center retrospective analysis.

OBJECTIVE

To establish an empirically derived threshold to define both coronal and sagittal malalignment (CM & SM) based on preoperative patient-reported outcomes (PROs).

SUMMARY OF BACKGROUND DATA

Currently, no radiographic alignment threshold defines preoperative CM in adult spinal deformity (ASD) patients based on disability. In a cohort of ASD patients undergoing corrective surgery, we sought to establish a threshold to define both CM and SM based on PRO and assess the clinical impact of CM and combined with SM.

METHODS

ASD patients with ≥6 level fusions were included. CVA and SVA were measured. PROs included preoperative ODI and SRS-22r scores. CVA and SVA thresholds were derived to accurately differentiate patients with ODI >40 and SRS-pain+function <5. Patients were then separated into 4 groups: (1) neutral alignment (NA); (2) CM; (3) SM; and (4) combined coronal and sagittal malalignment (CCSM).

RESULTS

Totally, 368 patients were included. Thresholds to distinguish patients with ODI ≥40 and SRS-pain/function <5 were: (1) CVA=3.96 cm (ODI) and 3.17 cm (SRS); (2) SVA=4.97 cm (ODI) and 7.52 cm (SRS). The lower numbers were chosen to define each threshold: CVA=3 cm and SVA=5 cm. Alignment breakdown was: NA=179 (48.6%), CM=66 (17.9%), SM=65 (17.7%), and CCSM=58 (15.8%). Both SM=(P=0.006) and CCSM (P<0.001) patients had significantly worse ODI scores than NA patients, and CCSM patients were significantly worse than SM alone (P=0.010). On the basis of preoperative total SRS-22r scores, only CCSM (P=0.003) patients were significantly worse than the NA group. CVA significantly correlated with 4/7 (57.1%) preoperative PROs (ODI/SRS-total/function/image), while SVA correlated with 5/7 (71.4%) preoperative PROs (ODI/SRS-total/function/image/pain). A linear relationship was seen between increasing CVA and worsening ODI (β=0.92, 95% CI: 0.37-1.48, P=0.001). A significant and slightly stronger relationship was seen between increasing SVA and worsening ODI (β=1.28, 95% CI: 1.00-1.56, P<0.001).

CONCLUSIONS

CM and SM thresholds that accurately distinguished ASD patients with severe pain and disability preoperatively were 3 cm for CVA and 5 cm for SVA, respectively. Preoperative CM was significantly associated with worse ODI, SRS-22r total/function/image scores. CCSM led to more disability than SM alone.

Machine learning can predict surgical indication: new clustering model from a large adult spine deformity database

PURPOSE

The choice of the best management for Adult Spine Deformity (ASD) is challenging. Health-related quality of life (HRQoL), comorbidities, symptoms and spine geometry, along with surgical risk and potential residual disability play a role, and a definite algorithm for patient management is lacking. Machine learning allows to analyse complex settings more efficiently than other available statistical tools. Aim of this study was to develop a machine-learning algorithm that, based on baseline data, would be able to predict whether an ASD patient would undergo surgery or not.

METHODS

Retrospective evaluation of prospectively collected data. Demographic data, HRQoL and radiographic parameters were collected. Two clustering methods were performed to differentiate groups of patients with similar characteristics. Three models were then used to identify the most relevant variables for management prediction.

RESULTS

Data from 1319 patients were available. Three clusters were identified: older subjects with sagittal imbalance and high PI, younger patients with greater coronal deformity and no sagittal imbalance, older patients with moderate sagittal imbalance and lower PI. The group of younger patients showed the highest error rate for the prediction (37%), which was lower for the other two groups (20-27%). For all groups, quality of life parameters such as the ODI and the SRS 22 and the Cobb angle of the major curve were the strongest predictors of surgical indication, albeit with different odds ratios in each group.

CONCLUSION

Three clusters could be identified along with the variables that, in each, are most likely to drive the choice of management.

A novel classification of congenital cervicothoracic scoliosis: identification of coronal subtypes and their prognostic significance

OBJECTIVE

To propose a novel classification system for stratifying coronal curve patterns in congenital cervicothoracic scoliosis with hemivertebrae (CTS-HV).

METHODS

Type A: regional cervicothoracic deformity only disturbing the balance of head-neck-shoulder complex; Type B: cervicothoracic deformity with significant trunk tilt to the convex side; Type C: cervicothoracic deformity with a significant compensatory thoracic curve. The reliability and reproducibility were assessed via the Kappa test. The differences among different subtypes in deformity parameters and bony structures were compared to identify the causative factors predisposing to different subtypes.

RESULTS

98 patients were classified into Type A (47 cases), Type B (31 cases), and Type C (20 cases). The Kappa test showed excellent reliability (Kappa value = 0.847) and reproducibility (Kappa value = 0.881). The proportions of Klippel-Feil syndrome in Types B (71.0%) and C (85.0%) were significantly higher than in Type A (46.8%; all P < 0.05). Type A (66.0%) and Type B (71.0%) predominantly had their hemivertebra (HV) at T3 or T4, while Type C (75%) mostly had HV at T1 or T2. Type B exhibited the most severe trunk tilt, head shift, neck tilt, head tilt, and coronal balance distance (all P < 0.05). Type C had the lowest T1 tilt and first rib angle despite the greatest cervicothoracic Cobb angle (all P < 0.05).

CONCLUSIONS

This novel reliable classification allows a better understanding of structural diversity and different coronal compensatory mechanisms for the natural progression of CTS-HV. It can contribute to determining the individualized treatment strategy and standardizing academic communication for this rare clinical entity.

Global Coronal Malalignment in Degenerative Lumbar Scoliosis and Priority-Matching Correction Technique to Prevent Postoperative Coronal Decompensation

STUDY DESIGN

A prospective case-control study.

OBJECTIVE

To analyze global coronal malalignment (GCM) in degenerative lumbar scoliosis (DLS) and to prospectively investigate the performance of priority-matching correction technique on preventing postoperative coronal imbalance.

METHODS

A total of 444 DLS inpatients and outpatients were recruited. GCMs were classified into 2 types: Type 1, GCM with thoracolumbar (TL/L) curve as the main contribution on coronal imbalance; Type 2, GCM with lumbosacral (LS) curve as the main contribution on coronal imbalance. Patients receiving priority-matching correction were assigned to Group P-M and receiving traditional correction were assigned to Group T form August 2020. The fundamental principle of priority-matching technique was to first correct the key curve contributing to coronal imbalance rather than the curve with greater magnitude.

RESULTS

Type 1 GCM accounted for 45% and Type 2 GCM accounted for 55% of patients. Type 2 GCM was detected to have greater LS Cobb angle and L4 tilt. At 1-year follow-up, 29.8% of patients with Type 2 GCM, whereas 11.7% of patients with Type 1 GCM were observed to have postoperative coronal decompensation. Patients with postoperative imbalance were revealed to have greater preoperative LS Cobb angle and L4 tilt and smaller correction extent of LS curve and L4 tilt. 6.25% of patients developed postoperative coronal imbalance in Group P-M, whereas 40.5% developed in Group T.

CONCLUSION

Highlighting priority and aggressive correction of the key curve to coronal imbalance, priority-matching technique was proved to be able to limit the development of postoperative coronal decompensation.

Global tilt angle in spinal alignment of asymptomatic older women with low bone mass

This study investigated the relationship between sagittal spinal alignment and musculoskeletal health in older women, particularly those exhibiting diminished bone density without apparent symptoms. The study assessed the impact of global tilt (GT) and the presence of coronal malalignment on spinal health. The research involved 165 asymptomatic older women with an average age of 68.91 ± 7.25 years and average body mass index of 24.26 ± 3.66 kg/m². Comprehensive standing anteroposterior and lateral spine radiographs were used for assessment. Through multivariate linear regression analysis, the study identified significant correlations between increased GT angles and various factors, including coronal malalignment, the C7 slope, and pelvic incidence. This led to the formulation of a predictive GT model: GT = -9.79 + 0.06 × menopausal period + 0.19 × body mass index (BMI)- 0.81 × average T score - 0.11 × grip strength + 3.03 × (presence of coronal malalignment) + 0.08 × sagittal vertical axis (SVA) + 0.12 × C7 slope - 0.35 × upper lumbar lordosis (ULL) - 0.43 × lower lumbar lordosis (LLL) + 0.70 × pelvic incidence (PI), with an adjusted R² of 0.816. The study findings highlight the prevalence of coronal malalignment in this demographic and its significant associations with critical spinal parameters. The proposed GT predictive model may enable development of personalized treatment plans for older women with low bone mass.

Coronal alignment in normal individuals and moderate scoliosis: Normative values, variation with age and comparison with sagittal alignment

Introduction

Global coronal alignment is mainly assessed by C7 plumbline and central sacral vertical line (CSVL), pelvic obliquity and shoulder alignment. A detailed analysis is mandatory when treating spinal deformity. It remains unclear to what extent mild scoliosis influences global coronal alignment.

Research question

The objective was to define a comprehensive set of coronal alignment parameters and to investigate differences between individuals without spinal deformity and with mild scoliosis. The relationship between coronal and sagittal alignment and the influence of age were studied.

Methods

Radiographs of 236 normal individuals (Group N) and 140 patients with scoliosis <35° (Group S) were prospectively collected. Coronal parameters were femoral head distance and angle, pelvic obliquity, Maloney angle, L4 and L5 inclinations, coronal T1 pelvic angle, C7-CSVL and odontoid CSVL offset, coracoid distance and angle. Sagittal cervical, spinopelvic, thoracolumbar and global parameters were measured.

Results

There was no significant difference between groups N and S for coronal parameters, except for L4 and L5 inclinations with a mean difference of 3,3° (p < 0,001). Global coronal alignment kept constant throughout age groups in N and S groups. Sagittal parameters varied with age: C2-C7 lordosis (p < 0,001), T1-T12 kyphosis (p < 0,001), pelvic incidence (p < 0,001). There was no correlation between global coronal and sagittal alignment: R-values ranging from -0.2 to 0.2.

Conclusion

Global coronal parameters were comparable in normal individuals and in scoliosis <35°. Coronal plane parameters were not influenced by age. Sagittal plane parameters varied significantly with age. There was no direct link between coronal et sagittal alignment.

Orthopedic research productivity of KSA: First bibliometric analysis

Purpose

Medical research is a crucial indicator of a nation's reputation and development. However, there are concerns about the limited orthopedic research in Kingdom of Saudi Arabia (KSA). Therefore, this study conducted bibliometric analysis to investigate orthopedic research output from KSA.

Methods

PubMed database for orthopedic articles, with a minimum of one KSA-affiliated orthopedic author published from the year 2000 onwards, was searched. This excluded duplicate articles, corrections, letters, editorials, commentaries, and brief communications. The titles of the included articles, publication years, first and corresponding authors' primary affiliations and countries, countries and institutes of research, and total citations were noted. Thereafter, year-wise research contribution, top contributing and collaborating nations, top contributing affiliations, study types, levels of evidence, journal distribution, their impact factor, h-index and quartile-related information, and citation trends were analyzed.

Results

The search strategy yielded 1047 eligible articles. An increasing trend in research contributions in recent years was observed, with the least number of articles (8) contributed in 2005 and the most (140) in 2023. The research was conducted in KSA for most articles (83.48%). Authors from Canada collaborated in 3.44% of the articles. King Saud University was the top contributing institution (17.38% of all articles). There were 66 (6.30%) basic science studies and 873 (83.3%) clinical studies. Among non-basic science studies, 84.51% had level IV evidence. Overall, 73.83% of articles had either first/corresponding or both authorships from KSA-affiliated orthopedic authors. The eligible articles were published in 303 journals, with a mean impact factor of 3.04 (range 0.4-51.1, 165 journals) and a mean h-index of 59.2 (range 1-367, 277 journals). Overall, 31.23% of articles with quartile information available were published in first-quartile journals.

Conclusions

The orthopedic research productivity in KSA is limited. However, there has been an increasing trend in orthopedic research in recent years. Nevertheless, the quality of clinical research, particularly the level of evidence, needs improvement. Therefore, further efforts should be made to strengthen research opportunities and encourage research participation among orthopedic and medical institutes.

The Lumbosacral Fractional Curve vs Maximum Coronal Cobb Angle in Adult Spinal Deformity Patients with Coronal Malalignment: Which Matters More?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

In patients undergoing adult spinal deformity (ASD) surgery we sought to: 1) report preoperative and postoperative lumbosacral fractional (LSF) curve and maximum coronal Cobb angles and 2) determine their impact on radiographic, clinical, and patient-reported outcomes (PROs).

METHODS

A single-institution cohort study was undertaken. The LSF curve was the cobb angle between the sacrum and most tilted lower lumbar vertebra. Coronal/sagittal vertical axis (CVA/SVA) were collected. Patients were compared between 4 groups: 1) Neutral Alignment (NA); 2) coronal malalignment only (CM); 3) Sagittal malalignment only (SM); and 4) Combined-Coronal-Sagittal-Malalignment (CCSM). Outcomes including postoperative CM, postoperative coronal vertical axis, complications, readmissions, reoperation, and PROs.

RESULTS

A total of 243 patients underwent ASD surgery with mean total instrumented levels of 13.5. Mean LSF curve was 12.1±9.9°(0.2-62.3) and mean max Cobb angle was 43.0±26.5° (0.0-134.3). The largest mean LSF curves were seen in patients with CM (14.6°) and CCSM (13.1°) compared to NA (12.1°) and SM (9.5°) (p=0.100). A higher LSF curve was seen in patients with fusion to the sacrum and instrumentation to the pelvis (p=0.009), and a higher LSF curve was associated with more TLIFs (p=0.031). Postoperatively, more TLIFs were associated with greater amount of LSF curve correction (p<0.001). Comparing the LSF and the max Cob angle among Qiu types, the highest mean max Cobb angle was in Qiu Type B patients (p=0.025), whereas the highest mean LSF curve was in Qiu Type C patients (p=0.037). Moreover, 82.7% of patients had a LSF curve opposite the max Cobb angle. The LSF curve was larger than the max Cobb angle in 22/243 (9.1%) patients, and most of these 22 patients were Qiu Type A (59.1%). Regarding correction, the max Cobb angle achieved more correction than the LSF curve, judged by the percent improved from preop (54.5% Cobb vs. 46.5% LSF, p=0.025) in patients with max cobb>20° and LSF curve >5°. The LSF curve underwent greater correction in Qiu Type C patients (9.2°) compared to Type A (5.7°) and Type B (5.1°) (p=0.023); however, the max Cobb angle was similarly corrected among Qiu Types: Type A 21.8°, Type B 24.6°, and Type C 25.4° (p=0.602). Minimal differences were seen comparing the preop/postop/change in LSF curve and max Cobb angle regarding postop CM, postop CVA, complications, readmissions, reoperation, and PROs.

CONCLUSIONS

The LSF curve was highest in patients with CM, CCSM, and Qiu Type C curves. Most patients had a LSF curve opposite the max Cobb angle. The max Cobb angle was more often corrected than the LSF curve. The LSF curve underwent greater correction among Qiu Type C patients, whereas the max Cobb angle was similarly corrected among all Qiu Types. No clear trend was seen regarding postoperative complications and PROs between the LSF curve and max Cobb angle.

Postoperative Coronal Imbalance in Lenke 5C Adolescent Idiopathic Scoliosis: Evolution, Risk Factors, and Clinical Implications

OBJECTIVE

To explore the changes in coronal imbalance (CIB) in Lenke 5C adolescent idiopathic scoliosis (AIS) after posterior selective fusion surgery and determine their implications for surgical decision-making.

METHODS

One hundred twenty patients were categorized according to the preoperative coronal pattern (type A, coronal balance distance [CBD]<20 mm; type B, CBD≥20 mm and coronal C7 plumbline [C7PL] shifted to the concave side of the curve; type C, CBD≥20 mm and C7PL shifted to the convex side of the curve). CIB group (CIB+) was defined as having a CBD≥20 mm at the 2-year follow-up.

RESULTS

Compared to type A patients, the prevalence of postoperative CIB was higher in type C patients both immediately postoperative (22% vs. 38%, p<0.05) and at the final follow-up (5% vs. 29%, p<0.05), whereas type A patients showed a greater improvement in CBD (9 of 12 vs. 6 of 24, p<0.05) at the final follow-up. The majority of patients in all groups had recovered to type A at the final follow-up (96 of 120). The proximal Cobb-1 strategy reduced the incidence of postoperative CIB (1 of 38) at the 2-year follow-up, especially in preoperative type C patients. Multivariate logistic regression analysis revealed that type C and overcorrection of the thoracolumbar curve were risk factors for CIB at the 2-year follow-up (p=0.007 and p=0.026, respectively).

CONCLUSION

Patients with type C CIB in AIS exhibited unsatisfactory restoration, with 29% of them exhibiting CIB at the final follow-up. The selective fusion strategy of proximal Cobb-1 may reduce the risk of postoperative CIB especially when the preoperative coronal pattern is type C.

Lumbar pedicle subtraction osteotomy: techniques and outcomes

Pedicle subtraction osteotomy has been thoroughly described and studied over the past 2 decades, being applied mainly in the lumbar spine, followed by the thoracic spine. Our better understanding of alignment biomechanics, and the progressive refinements of the surgical technique over time made it a very efficient procedure for the management of fixed sagittal malalignment. However, a long learning curve is mandatory to mitigate the associated risks particularly neurological deficits and achieve satisfactory clinical and radiological outcomes with an acceptable rate of complications.

Comparison of the Odontoid and Orbital-Coronal Vertical Axis Lines in Evaluating Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery

STUDY DESIGN

Asymptomatic Multi-Ethnic Alignment Normative Study (MEANS) cohort: cross-sectional, multicenter. Symptomatic cohort: retrospective, multisurgeon, single-center.

OBJECTIVE

To assess the association of odontoid-coronal vertical axis (OD-CVA) and orbital-coronal vertical axis (ORB-CVA) with radiographic parameters, patient-reported outcomes, and clinical outcomes.

SUMMARY OF BACKGROUND DATA

Previous literature studied the OD-CVA in an asymptomatic cohort and ORB-CVA in a symptomatic cohort, demonstrating their correlations with radiographic parameters and ORB-CVA with outcomes.

MATERIALS AND METHODS

A total of 468 asymptomatic adult participants were prospectively enrolled in the MEANS cohort. 174 symptomatic patients with adult spinal deformity with ≥6 fused levels and 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. The association between OD-CVA and ORB-CVA, and radiographic parameters, perioperative variables, PROs, and outcomes were analyzed. Pearson correlation was used to assess correlation and logistic regression odds of outcomes.

RESULTS

In the MEANS cohort, the ORB-CVA correlated with C7-CVA ( r = 0.58) and OD-CVA ( r = 0.74). In the symptomatic cohort, preoperative ORB-CVA correlated better with leg length discrepancy; r = 0.17, P = 0.029), whereas preoperative OD-CVA correlated better with C7-CVA ( r = 0.90, P < 0.001). Postoperative ORB-CVA correlated with postoperative C7-CVA ( r = 0.66, P < 0.001), and postoperative OD-CVA correlated strongly with postoperative C7-CVA ( r = 0.81, P < 0.001). Both preoperative OD-CVA ( r = 0.199) and ORB-CVA ( r = 0.208) correlated with the preoperative Oswestry Disability Index. ORB-CVA correlated better than OD-CVA in the preoperative Scoliosis Research Society-22r pain category but worse in total and other subcategories. Preoperative ORB-CVA was associated with increased odds of intraoperative complication (odds ratio = 1.28, 1.01-1.22), like OD-CVA (odds ratio = 1.30, 1.12-1.53). Neither preoperative ORB-CVA nor OD-CVA was associated with reoperations and readmissions after multivariate analysis. Preoperative OD-ORB mismatch >1.5 cm was not associated with increased odds of intraoperative and postoperative complications, reoperations, or readmissions.

CONCLUSION

ORB-CVA and OD-CVA correlated with radiographic parameters, patient-reported outcomes, and intraoperative complications. ORB-CVA and OD-CVA can be used interchangeably as cranial coronal parameters in adult spinal deformity surgery.

Spinopelvic Parameters in the Elderly: Does Inadequate Correction Portend Worse Outcomes?

Introduction

This study aimed to compare the outcomes of corrective fusion for adult spinal deformity (ASD) in older people using two different sagittal correction goals: the conventional formula of "pelvic incidence (PI)-lumbar lordosis (LL) mismatch <10°" and an undercorrection strategy based on the range of 10°≤PI-LL≤20°.

Methods

A total of 102 consecutive patients (11 male and 91 female patients; mean age, 72.0 years) aged above 65 years with scoliosis >20° or LL<20° who had undergone long-segment fusion from the lower thoracic spine to the pelvis for ASD and had been followed-up for a minimum of two years at our institution since March 2013 were included in this retrospective study. After excluding patients with PI-LL≤-10° on postoperative standing radiographs, the remaining patients were divided into two groups: 31 patients with 10°≤PI-LL≤20° (U group) and 63 patients with -10°

Results

The incidence of proximal junctional kyphosis and mechanical failure was not significantly different between the groups (p=0.659 and 1.000, respectively). After excluding patients who underwent reoperation due to mechanical failure, there were no differences in the Oswestry Disability Index (ODI) and each domain of the Visual Analog Scale score, Scoliosis Research Society-22r patient questionnaire (SRS-22r), or the short form 36 health survey questionnaire at the final observation between the U (n=27) and M (n=57) groups. In addition, the non-inferiority and equivalence of the U group to the M group were demonstrated in all domains of the SRS-22r and ODI. Furthermore, the superiority of the U group was demonstrated by the functional domain of SRS-22r.

Conclusions

For the sagittal correction goal in corrective fusion surgery for ASD in the elderly, strict adherence to "PI-LL mismatch <10°" is not necessary and "PI-LL≤20°" may be acceptable.

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Key Words

• Scoliosis Research Society-Schwab classification
• adult spinal deformity
• elderly patients with spinal deformity
• extensive corrective fusion
• pelvic incidence minus lumbar lordosis mismatch
• sagittal corrective goal
• undercorrection

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Affiliation(s)

Masanari Takami Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shunji Tsutsui Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Keiji Nagata Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Iwasaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Akihito Minamide Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Dokkyo Medical University Nikko Medical Center, Nikko, Japan
Yasutsugu Yukawa Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Nagoya Kyoritsu Hospital, Nagoya, Japan
Motohiro Okada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Department of Orthopaedic Surgery, Sumiya Orthopaedic Hospital, Wakayama, Japan
Ryo Taiji Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shizumasa Murata Department of Orthopaedic Surgery, Shingu Municipal Medical Center, Shingu, Japan
Takuhei Kozaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Hashizume Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Yamada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan

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The kickstand rod technique for correction of coronal malalignment in patients with adult spinal deformity: a systematic review and pooled analysis of 97 cases

Coronal malalignment (CM) has recently gained focus as a key predictor of functional outcomes in patients with adult spinal deformity (ASD). The kickstand rod technique has been described as a novel technique for CM correction using an accessory rod on the convex side of the deformity. This review aimed to evaluate the surgical technique and outcomes of corrective surgery using this technique. The literature search was conducted on three databases (PubMed, EMBASE, and Scopus). After reviewing the search results, six studies were shortlisted for data extraction and pooled analysis. Weighted means for surgical duration, length of stay, amount of coronal correction, and sagittal parameters were calculated. The studies included in the review were published between 2018 and 2023, with a total sample size of 97 patients. The mean age of the study cohort was 61.1 years, with female preponderance. The mean operative time was 333.6 minutes. The mean correction of CM was 5.1 cm (95% confidence interval [CI], 3.6-6.6), the mean sagittal correction was 5.6 cm (95% CI, 4.1-7.1), and the mean change in lumbar lordosis was 17° (95% CI, 10.4-24.1). Preoperative coronal imbalance and mean correction achieved postoperatively were directly related with age. The reoperation rate was 13.2%. The kickstand rod technique compares favorably with conventional techniques such as asymmetric osteotomies in CM management. This technique provides an additional accessory rod that helps increase construct stiffness. Because of limited data, definitive conclusions cannot be drawn from this review; however, this technique is a valuable tool for a surgeon dealing with ASD.

Pedicle Subtraction Osteotomy Versus Multilevel Anterior Lumbar Interbody Fusion and Lateral Lumbar Interbody Fusion in the Treatment of Adult Spinal Deformity: Trends, Outcomes, and Cost

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the outcomes of pedicle subtraction osteotomy (PSO) with multilevel anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) in posterior long-segment fusion.

BACKGROUND

PSO and ALIF/LLIF are 2 techniques used to restore lumbar lordosis and correct sagittal alignment, with each holding its unique advantages and disadvantages. As there are situations where both techniques can be employed, it is important to compare the risks and benefits of both.

PATIENTS AND METHODS

Patients aged 18 years or older who underwent PSO or multilevel ALIF/LLIF with posterior fusion of 7-12 levels and pelvic fixation were identified. 1:1 propensity score was used to match PSO and ALIF/LLIF cohorts for age, sex, and relevant comorbidities, including smoking status. Logistic regression was used to compare medical and surgical outcomes. Trends and costs were generated for both groups as well.

RESULTS

ALIF/LLIF utilization in posterior long fusion has been steadily increasing since 2010, whereas PSO utilization has significantly dropped since 2017. PSO was associated with an increased risk of durotomy ( P < 0.001) and neurological injury ( P = 0.018). ALIF/LLIF was associated with increased rates of postoperative radiculopathy ( P = 0.005). Patients who underwent PSO had higher rates of pseudarthrosis within 1 and 2 years ( P = 0.015; P = 0.010), 1-year hardware failure ( P = 0.028), and 2-year reinsertion of instrumentation ( P = 0.009). Reoperation rates for both approaches were not statistically different at any time point throughout the 5-year period. In addition, there were no significant differences in both procedural and 90-day postoperative costs.

CONCLUSIONS

PSO was associated with higher rates of surgical complications compared with anterior approaches. However, there was no significant difference in overall reoperation rates. Spine surgeons should select the optimal technique for a given patient and the type of lordotic correction required.

Assessing the Fractional Curve for Proper Management of Adult Degenerative Scoliosis

Adult degenerative scoliosis (ADS) is a coronal plane deformity often accompanied by sagittal plane malalignment. Surgical correction may involve the major and/or distally-located fractional curves (FCs). Correction of the FC has been increasingly recognized as key to ameliorating radicular pain localized to the FC levels. The present study aims to summarize the literature on the rationale for FC correction in ADS. Three databases were systematically reviewed to identify all primary studies reporting the rationale for correcting the FC in ADS. Articles were included if they were English full-text studies with primary data from ADS ( ≥ 18 years old) patients. Seventy-four articles were identified, of which 12 were included after full-text review. Findings suggest FC correction with long-segment fusion terminating at L5 increases the risk of distal junctional degeneration as compared to constructs instrumenting the sacrum. Additionally, circumferential fusion offers greater FC correction, lower reoperation risk, and shorter construct length. Minimally invasive surgery (MIS) techniques may offer effective radiographic correction and improve leg pain associated with foraminal stenosis on the FC concavity, though experiences are limited. Open surgery may be necessary to achieve adequate correction of severe, highly rigid deformities. Current data support major curve correction in ASD where the FC concavity and truncal shift are concordant, suggesting that the FC contributes to the patient's overall deformity. Circumferential fusion and the use of kickstand rods can improve correction and enhance the stability and durability of long constructs. Last, MIS techniques show promise for milder deformities but require further investigation.

Research of Global Tilt and Functional Independence: Insights into Spinal Health of Older Women

Spinal alignment intricately influences functional independence, particularly in older women with osteopenia experiencing mild neck and back pain. This study elucidates the interplay between spinal alignment, bone mineral density (BMD), and muscle strength in elderly women presenting with mild neck and back pain. Focusing on a cohort of 189 older women, we examined the associations among global tilt (GT), coronal and sagittal alignment, BMD, grip strength, and functional independence as gauged by the Barthel index. Our findings indicate significant associations between functional capacity and grip strength, bone density, GT, and pelvic tilt (PT). Elderly women with a Barthel Index above 80 demonstrated higher grip strength and better bone quality, reflected by less negative average T scores. These individuals also exhibited lower values of GT and PT, suggesting a better sagittal alignment compared to those with a Barthel index of 80 or below. The results highlight that deviations in GT and PT are significantly associated with decreased functional independence. These insights emphasize the importance of maintaining optimal spinal alignment and muscle strength to support functional independence in elderly women. This study underscores the potential for targeted interventions that improve postural stability and manage pain effectively in this vulnerable population.

Coronal Alignment in Adult Spine Surgery

Coronal realignment is an important goal in adult spine surgery that has been overshadowed by emphasis on the sagittal plane. As coronal malalignment drives considerable functional disability, a fundamental understanding of its clinical and radiographic evaluation and surgical techniques to prevent its development is of utmost importance. In this study, we review etiologies of coronal malalignment and their radiographic and clinical assessments, risk factors for and functional implications of postoperative coronal malalignment, and surgical strategies to optimize appropriate coronal realignment in adult spine surgery.

Practical Methods of Assessing Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery: A Comparative Analysis

STUDY DESIGN

Asymptomatic cohort: prospective, cross-sectional, multicenter. Symptomatic: retrospective, multisurgeon, single-center.

OBJECTIVE

To assess the association between cranial coronal alignment and adult spinal deformity (ASD) surgical risk and outcomes.

SUMMARY OF BACKGROUND DATA

ASD leads to decreased quality of life. Studies have shown that coronal malignment (CM) is associated with worse surgical outcomes.

MATERIALS AND METHODS

A total of 468 adult participants were prospectively enrolled in the asymptomatic cohort. Totally, 172 symptomatic ASD patients with 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. Three cranial plumb line parameters: the positions of the plumb lines from the midpoint between the medial orbital rims (ORB-L5), the odontoid (OD-L5), and the C7 centroid (C7-L5) relative to the L5 pedicle, were measured. Each subject had plumb line medial (M), touching (T), or lateral (L) to either pedicle. The association between each group of patients and radiographic parameters, intraoperative variables, patient-reported outcomes, and clinical outcomes were analyzed.

RESULTS

In the asymptomatic cohort, OD-L5 was medial to or touching the L5 pedicle in 98.3% of volunteers. In the symptomatic patients, preoperative OD-L5-L exhibited higher mean age (56.2±14.0), odontoid-coronal vertical axis (OD-CVA) (5.5±3.3 cm), Oswestry disability index (ODI) score (40.6±18.4), pelvic fixation rate (56/62, 90.3%), OR time (528.4±144.6 min), median estimated blood loss (1300 ml), and durotomy rate (24/62, 38.7%). A similar pattern of higher CVA, preoperative ODI, intraoperative pelvic fixation rate, OR time, estimated blood loss, and durotomy rate was observed in ORB-L5-L and C7-L5-L patients. Final follow-up postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis (13.0%) and pseudarthrosis (17.4%).

CONCLUSION

Preoperative OD-L5, ORB-L5, and C7-L5 lateral to pedicles were associated with worse preoperative ODI and higher intraoperative complexity. Postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis and pseudarthrosis. Postoperative CM, approximated by the cranial plumb line lateral to the L5 pedicles, was associated with sagittal plane complications.

Scoliosis and Lower Limb Inequality: To Lift or Not to Lift, That Is the Question

In subjects with scoliotic alterations of the spine, asymmetrical lengths of the lower limbs are frequently observed, a condition commonly referred to as leg length inequality (LLI) or discrepancy (LLD). This asymmetry can induce pelvic misalignments, manifested by an asymmetric height of the iliac crests, and consequently an alteration of the spine's axis. Although correcting this discrepancy might appear to be a straightforward solution, further investigation may reveal other indications. The purpose of this article is to aid clinicians confronted with the decision of whether to compensate for an LLI in individuals with scoliosis, encompassing both adolescents and adults. It presents a literature review on the incidence of LLIs in the general population, distinguishing between structural LLI (sLLI) and functional LLI (fLLI) types of LLIs, and quantifying their magnitude with clinical and instrumental evaluation. Additionally, it links these two types of LLIs to the type of scoliosis (structural or functional). From a clinical perspective, it also examines the compensatory mechanisms employed by the pelvis in the presence of structural or functional LLIs in order to draw useful indications for therapeutic decisions. Moreover, it proposes an additional evaluation parameter in the coronal plane, namely the central sacral vertical line (CSVL), to aid in the decision-making process regarding LLI compensation. Although this parameter has been documented in the literature, it has been little associated with LLIs. The findings indicate that scoliotic discrepancies should be compensated (conservatively or surgically) only when the imbalance of the femoral heads is on the same side as the imbalance of the sacrum and the iliac crests; this corrective action should result in a reduction of the overhang in the coronal plane.

The Importance of Pelvic Obliquity in Assessing Spinal Coronal Alignment: Normative Values, Demographic, and Radiographic Correlations

STUDY DESIGN

Prospective, cross-sectional study.

OBJECTIVE

In a geographically diverse population of asymptomatic volunteers, we sought to report the incidence of pelvic obliquity (PO), establish normative values of PO across patient factors, and assess the correlation of PO with radiographic parameters.

SUMMARY OF BACKGROUND DATA

PO is defined as the misalignment of the pelvis and can be assessed through several anatomic landmarks. Significant PO, whether caused by leg-length discrepancy or not, can lead to coronal malalignment which causes severe pain and disability. Significant emphasis has been placed on achieving appropriate sagittal alignment in recent decades; however, a greater understanding of coronal alignment is needed, and PO is a crucial aspect of evaluating the coronal plane in adult spinal deformity patients.

METHODS

Asymptomatic adult volunteers, ages 18-80 years, enrolled patients from 5 countries (France, Japan, Singapore, Tunisia, and the United States) in the "multiethnic alignment normative study" cohort (IRB 201812144). The included volunteers had no known spinal disorder(s), no significant neck or back pain (Visual Analog Scale: ≤2; Oswestry Disability Index: ≤20), and no abnormal alignment (Cobb ≤20°). PO was measured in the frontal plane as the distance between the highest points of each acetabulum, calculated along the vertical axis in millimeters (mm). The incidence of PO was defined as PO ≥10 mm. Kruskal-Wallis, Wilcoxon rank-sum, Pearson correlation, and linear regression were used.

RESULTS

A total of 467 patients were included, and PO values by age, sex, body mass index, and country were provided. The overall incidence of PO ≥10 mm was 4.3%, and a nonsignificant trend toward increased PO with age was seen ( P = 0.077). No significant differences were seen in PO between sex, ethnicity, or body mass index groups. No significant correlation existed between PO and other commonly used coronal radiographic measurements.

CONCLUSION

PO ≥10 mm occurred in 4.3% of asymptomatic volunteers. Despite the importance of recognizing PO in preventing coronal malalignment, PO did not seem to be associated with other radiographic and demographic information, which underscores the importance of intentionally assessing for any PO before surgery. These results in an asymptomatic population provide a foundation for studying PO in patients with spinal pathology.

Placement of a Kickstand Rod in Adult Spinal Deformity Surgery: A Simple 8-Step Process With Intraoperative Images and Video

BACKGROUND AND OBJECTIVES

In adult spinal deformity (ASD) surgery, operative correction of coronal malalignment remains a challenging surgical task. Given the proven effectiveness and longevity of the kickstand rod (KSR) technique and its powerful ability to correct coronal malalignment, this technique is an important tool to have available. Therefore, we sought to provide a simple 8-step description of the KSR technique using intraoperative images and video in a patient undergoing combined sagittal and coronal malalignment correction.

METHODS

A 68-year-old female with a previous history of T11-S1 posterior spinal fusion presented with mid thoracic back pain, leg paresthesias, and a right-leaning posture. The patient underwent a T4-pelvis extension of fusion, T8-11 posterior column osteotomies, and placement of a right-sided KSR to address her coronal malalignment.

RESULTS

The KSR technique is summarized in the following steps: (1) place kickstand screw, (2) place contralateral main rod and tighten all set plugs, (3) place ipsilateral main rod and keep rod long distally, (4) place a domino in the lower/mid thoracic area, (5) place the KSR and leave the rod long proximally, (6) tighten the ipsilateral main rod above the domino, (7) loosen the ipsilateral main rod below the domino, and (8) place a rod gripper below the domino and distract. Postoperatively, the coronal vertical axis improved from 4.8 to 0.6 cm, and the sagittal vertical axis improved from 9.5 to 3.9 cm.

CONCLUSION

The current case report provides a simple 8-step description of the KSR technique to improve coronal malalignment accompanied by intraoperative images and video.

Will coronal alignment postoperatively be deteriorating in adult spinal deformity after long-fusion surgery?

BACKGROUND

To investigate whether the coronal alignment (CA) will deteriorate, and identify the risk factors for coronal malalignment (CM) developing in adult spinal deformity (ASD) after long-fusion surgery.

METHODS

A multi-center retrospective study was performed, which included a total of 161 ASD patients who had undergone the surgical procedure of long-fusion (≥ 5 vertebras) with instrumentations in three medical centers. All of the participants were retrospectively reviewed, and subsequently assigned into the consistency group (C7 plumb line (C7PL) shifting towards the convex side of the main curve), and the opposition group (C7PL shifting towards the concave side). CM was considered if the coronal balance distance (CBD) being over 30 mm. A Kaplan-Meier curve and log-rank test were used to analyze the differences in CM-free survival during follow-up. Multivariate analysis via a Cox proportional hazards test was used to analyze the risk factors.

RESULTS

Patients showing CM equaled 35 (21.7%) at the pre-operation, and that increased significantly up to 51 (31.7%) at the final follow-up (P = 0.04). In the consistency group, the incidence of CM at the final follow-up was much higher than that preoperatively (35:16, P = 0.002). CM-free survival time decreased significantly in patients with larger CBD correction, pelvic fixation and more instrumented segments, respectively, during follow-up (P < 0.05, log-rank test). Age ≥ 60 years, the consistency CA, pelvic fixation, CBD-correction ≥ 30 mm and fixed-vertebra ≥ 8 were risk factors for CM happening after surgery using multivariate regression analysis (P < 0.05).

CONCLUSIONS

The coronal alignments in ASD patients underwent long-fusion surgeries may deteriorate during follow-up, for which the risk factors include the consistency CA, age ≥ 60, fixed-vertebra ≥ 8, CBD-correction ≥ 30 mm and pelvic fixation.

Anterior lumbar interbody fusion versus transforaminal lumbar interbody fusion for correction of lumbosacral fractional curves in adult (thoraco)lumbar scoliosis: A systematic review

Background

Anterior lumbar interbody fusion (ALIF) or transforaminal lumbar interbody fusion (TLIF) may be used to correct the lumbosacral fractional curve (LsFC) in de novo adult (thoraco) lumbar scoliosis. Yet, the relative benefits of ALIF and TLIF for LsFC correction remain largely undetermined.

Purpose

To compare the currently available data comparing radiographic correction of the LsFC provided by ALIF and TLIF of LsFC in adult (thoraco)lumbar scoliosis.

Methods

A systematic review was performed on original articles discussing fractional curve correction of lumbosacral spinal deformity (using search criteria: "lumbar" and "fractional curve"). Articles which discussed TLIF or ALIF for LsFC correction were presented and radiographic results for TLIF and ALIF were compared.

Results

Thirty-one articles were returned in the original search criteria, with 7 articles included in the systematic review criteria. All 7 articles presented radiographic results using TLIF for LsFC correction. Three of these articles also discussed results for patients whose LsFC were treated with ALIFs; 2 articles directly compared TLIF and ALIF for LsFC correction. Level III and level IV evidence indicated ALIF as advantageous for reducing the coronal Cobb angle of the LsFC. There were mixed results on relative efficacy of ALIF and TLIF in the LsFC for restoration of adequate global coronal alignment.

Conclusions

Limited level III and IV evidence suggests ALIF as advantageous for reducing the coronal Cobb angle of the LsFC in de novo adult (thoraco) lumbar scoliosis. Relative efficacy of ALIF and TLIF in the LsFC for restoration of global coronal alignment may be dictated by several factors, including directionality and magnitude of preoperative coronal deformity. Given the limited and low-quality evidence, additional research is warranted to determine the ideal interbody support strategies to address the LsFC in adult (thoraco) lumbar scoliosis.

How coronal malalignment affects the surgical outcome in corrective spine surgery for adult symptomatic lumbar deformity

PURPOSE

The importance of coronal alignment is unclear, while the importance of sagittal alignment in the treatment of adult patients with spinal deformities is well described. This study sought to elucidate the impact of global coronal malalignment (GCMA) in surgically treated adult symptomatic lumbar deformity (ASLD) patients.

METHODS

A multicentre retrospective analysis of a prospective ASD database. GCMA was defined as GCA (C7PL-CSVL) ≥ 3 cm. GCMA is categorized based on the Obeid-Coronal Malalignment Classification (O-CM). Demographic, surgical, radiographic, HRQOL, and complication data were analysed. The risk for postoperative GCMA was analysed by univariate and multivariate analyses.

RESULTS

Of 230 surgically treated ASLD patients, 96 patients showed GCMA preoperatively and baseline GCA was correlated with the baseline SRS-22 pain domain score (r = - 30). Postoperatively, 62 patients (27%, O-CM type 1: 41[18%], type 2: 21[9%]) developed GCMA. The multivariate risk analysis indicated dementia (OR 20.1[1.2-304.4]), diabetes (OR 5.9[1.3-27.3]), and baseline O-CM type 2 (OR 2.1[1.3-3.4]) as independent risk factors for postoperative GCMA. The 2-year SRS-22 score was not different between the 2 groups, while 4 GCMA patients required revision surgery within 1 year after surgery due to coronal decompensation (GCMA+ vs. GCMA- function: 3.6 ± 0.6 vs. 3.7 ± 0.7, pain: 3.7 ± 0.8 vs. 3.8 ± 0.8, self-image: 3.6 ± 0.8 vs. 3.6 ± 0.8, mental health: 3.7 ± 0.8 vs. 3.8 ± 0.9, satisfaction: 3.9 ± 0.9 vs. 3.9 ± 0.8, total: 3.7 ± 0.7 vs. 3.7 ± 0.7). Additionally, the comparisons of 2-yr SRS-22 between GCMA ± showed no difference in any UIV and LIV level or O-CM type.

CONCLUSIONS

In ASLD patients with corrective spine surgery, GCMA at 2 years did not affect HRQOL or major complications at any spinal fusion extent or O-CM type of malalignment, whereas GCA correlated with pain intensity before surgery. These findings may warrant further study of the impact of GCMA on HRQOL in the surgical treatment of ASLD patients.

Oblique lateral interbody fusion for lumbosacral fractional curve correction in degenerative lumbar scoliosis

PURPOSE

In combined anterior-posterior adult spinal deformity surgery, the optimal combination of anterior and posterior procedures remains unclear. We aimed to demonstrate the radiological outcomes and relevant factors in oblique lateral interbody fusion (OLIF) for lumbosacral fractional curve (FC) correction combined with open posterior surgery in degenerative lumbar scoliosis (DLS).

METHODS

This study involved 42 consecutive patients with DLS who had a major curve (MC) ≥ 20° and an FC (L4 to S1) ≥ 10°, and underwent a combined anterior-posterior surgery Changes in the MC, FC, coronal balance distance, type of coronal imbalance, coronal/sagittal disc angle at L4-5 and L5-S1, L4 and L5 tilt, and sagittal parameters were examined. The associations between FC correction and demographic, surgical, and radiological factors were analysed.

RESULTS

The FC decreased from 16.9 ± 7.3° preoperatively to 6.6 ± 4.4° at the last follow-up (P < 0.001). The coronal disc angle at L4-5 and L5-S1 were, respectively, 6.8 ± 2.2° and 6.0 ± 4.1° preoperatively and decreased to 2.2 ± 2.1 and 1.2 ± 1.3° at the last follow-up (both P < 0.001). The changes in FC were greater in uppermost instrumented level > T10 (P < 0.001), and associated with the preoperative FC (r = 0.820, P < 0.001), L4 tilt (r = 0.434, P = 0.007), and L5 tilt (r = 0.462, P = 0.003).

CONCLUSION

OLIF at the FC combined with open posterior surgery is an effective combined anterior-posterior correction strategy in DLS.

Risk Factors of Postoperative Coronal Balance Transition in Degenerative Lumbar Scoliosis

STUDY DESIGN

Retrospective radiographic study.

OBJECTIVE

To determine the potential risk factors influencing the transition of postoperative coronal balance in degenerative lumbar scoliosis (DLS) patients.

SUMMARY OF BACKGROUND DATA

As time passes after surgery, the spinal sequence of DLS patients may dynamically shift from coronal balance to imbalance, causing clinical symptoms. However, the transition of postoperative coronal balance and its risk factors have not been effectively investigated.

MATERIALS AND METHODS

We included 156 DLS patients. The cohort was divided into immediate postoperative coronal balance with follow-up balance (N=73) and follow-up imbalance (N=21), immediate postoperative coronal imbalance (CIB) with follow-up balance (N=23), and follow-up imbalance (N=39). Parameters included age, sex, classification of coronal balance, coronal balance distance, fusion of L5 or S1, location of apical vertebra, apical vertebral translation (AVT), Cobb angle of the main curve and lumbar-sacral curve, tilt and direction of L4/5, tilt and direction of upper instrumented vertebra (UIV), and Cobb angle of T1-UIV. Statistical testing was performed using chi-square/Fisher exact test, t tests or nonparametric tests, correlation testing, and stepwise logistic regression.

RESULTS

We identified a significant difference in preoperative AVT, preoperative Cobb angle, and immediate postoperative UIV tilt between patients with and without follow-up balance. Logistic regression analysis demonstrated factors associated with follow-up CIB included preoperative AVT ( P =0.015), preoperative Cobb angle ( P =0.002), and tilt of immediate postoperative UIV ( P =0.018). Factors associated with immediate postoperative CIB in patients with follow-up coronal balance were sex, correction ratio of the main curve, and direction of L4. Logistic regression analysis further identified a correction ratio of main curve ≤0.7 ( P =0.009) as an important predictive factor.

CONCLUSION

Patients with immediate postoperative coronal balance and higher preoperative AVT, preoperative Cobb angle, and tilt of immediate postoperative UIV were more likely to experience follow-up CIB. A correction ratio of the main curve ≤0.7 was an independent predictor of follow-up CIB.

LEVEL OF EVIDENCE

3.

Sex-based differences in clinical and radiological presentation of patients with degenerative lumbar scoliosis: a cross-sectional study

BACKGROUND

To evaluate the sex-based differences in clinical and radiological presentation of patients with degenerative lumbar scoliosis (DLS) and to explore whether the difference is helpful in investigating the etiology and progression of DLS.

METHOD

A retrospective review of 199 patients (41 males, 158 females) with DLS was included. Patient demographics including age, gender, bone mineral density were collected. Back and leg pain was assessed by visual analog scale, and general physical condition was assessed by Oswestry Disability Index. Cobb's angle was measured, and direction of scoliosis, position of the superior, inferior and apex vertebrae, number of vertebrae included in the scoliosis, rotation of apex vertebrae (Nash-Mo index), translation of apex vertebrae were recorded. Sagittal longitudinal axis, thoracolumbar kyphosis, lumbar lordosis (LL), pelvic incidence angle (PI), sacral slope, apex of lumbar lordosis and coronal balance distance were measured by whole spine lateral radiographs, and type of coronal imbalance was evaluated in all patients. Fat infiltration rate (FIR) of the paraspinal muscles at the vertebral apex was measured by MRI.

RESULT

Compared to female patients, male patients showed more back and leg pain on clinical presentation and smaller Cobb angle, less parietal rotation, larger LL, smaller PI-LL and lower paravertebral muscle FIR on radiologic features.

CONCLUSION

Gender differences do exist in DLS patients with regard to clinical and radiological presentation, low back pain was more pronounced in male patients, and scoliosis was more severe in female patients based on this cross-sectional study.

The iliac kickstand screw: anatomic CT analysis of screw trajectory and osseous corridor for screw placement

INTRODUCTION

The 'kickstand screw-rod' technique has been recently described for correction of coronal malalignment. This technique utilizes powerful 'construct-to-ilium' distraction between a fixed multi-screw thoracic construct and the ilium, facilitated by a novel 'iliac kickstand screw'. The 'iliac kickstand screw' traverses a previously undescribed osseous corridor in the ilium.

OBJECTIVE

Using a radiographic CT study, the objective is to describe a large osseous corridor within the ilium to accommodate the novel iliac kickstand screw.

METHODS

50 consecutive patients with pelvic CTs at an academic medical center were queried. Simulated iliac kickstand screw trajectories for the left and right hemipelvis were analyzed with 3D visualization software. Maximal screw lengths and dimensions, and trajectories in the osseous corridor were measured.

RESULTS

50 patients' (31 female, 19 male) pelvic CTs were measured with a total of 100 simulated screws. The mean age was 52.4 years and BMI 28.1 ± 7.9. The average length is 119.7 ± 6.6 mm (range 98.7 - 135.3). The narrowest width (maximum potential screw diameter) is 17.8 ± 2.9 mm (coronal) and 20.8 ± 5.3 mm (sagittal). The starting point to the top of the iliac crest is 66.4 mm lateral to midline, and 15.9° caudal in the sagittal and 6.1° lateral in the coronal planes.

CONCLUSIONS

The novel iliac kickstand screw traverses a consistent and large osseous corridor within the ilium. The average simulated screw length is 119.7 mm and maximum potential diameter of 17.8 mm. Starting points relative to the iliac crest are identified.

Fixed coronal malalignment (CM) in the lumbar spine independently impacts disability in adult spinal deformity (ASD) patients when considering the obeid-CM (O-CM) classification

BACKGROUND

Postoperative flatback has been described in detail for sagittal plane considerations over the past 2 decades, and its correlations with disability are now accepted. Fixed Coronal Malalignment (CM) has been less described, and some authors report no significant association with the clinical outcome. The O-CM classification analyses CM and incorporates specific modifiers for each curve type.

PURPOSE

This study evaluates the O-CM classification modifiers according to age, sagittal alignment, and patient-reported outcome measures (PROMs). Our hypothesis is that fixed CM correlates with PROMs independently from sagittal alignment and age.

STUDY DESIGN

Retrospective analysis of a large adult spinal deformity (ASD) database prospectively collected.

PATIENT SAMPLE

We included 747 patients from the database with long lumbar fusion (more than 3 levels), with at least two years of follow-up. Three categories of patients met the inclusion criteria (prior surgery at baseline and no revision surgery afterward, prior surgery at baseline and revision afterward, no prior surgery at baseline but fusion>3 levels and 2 years follow-up).

OUTCOME MEASURES

All patients completed the Oswestry Disability Index (ODI), Short Form 36 (SF36), and Scoliosis Research Society 22 scores.

METHODS

The patients were classified according to the six modifiers of the O-CM classification. Central Sacral Vertical Line (CSVL) above 2, 3, and 4 cm's impact on PROMs was analyzed. Multivariate analysis was performed on the relationship between PROMS and age, global tilt (GT), and CM modifiers.

RESULTS

After multivariate analysis using age and GT as confounding factors, we found that CM independently affects PROMs starting at 2 cm offset. Disability increases linearly with CSVL. Patients classified with 2B modifiers have the worst SRS-22 total score, social life, and self-image.

CONCLUSION

In a fused spine, CM independently affects disability in ASD patients. Disability increases linearly with CSVL. Despite previous reports that failed to find correlations of CM with PROMs, our study showed that fixed postoperative CM, according to O-CM classification, correlates independently from sagittal malalignment with worse PROMs.

LEVEL OF EVIDENCE

III.

Adherence to the Obeid coronal malalignment classification and a residual malalignment below 20 mm can improve surgical outcomes in adult spine deformity surgery

PURPOSE

Coronal balance is a major factor impacting the surgical outcomes in adult spinal deformity (ASD). The Obeid coronal malalignment (O-CM) classification has been proposed to improve the coronal alignment in ASD surgery. Aim of this study was to investigate whether a postoperative CM < 20 mm and adherence to the O-CM classification could improve surgical outcomes and decrease the rate of mechanical failure in a cohort of ASD patients.

METHODS

Multicenter retrospective analysis of prospectively collected data on all ASD patients who underwent surgical management and had a preoperative CM > 20 mm and a 2-year follow-up. Patients were divided in two groups according to whether or not surgery had been performed in adherence to the guidelines of the O-CM classification and according to whether or not the residual CM was < 20 mm. The outcomes of interest were radiographic data, rate of mechanical complications and Patient-Reported Outcome Measures.

RESULTS

At 2 years, adherence to the O-CM classification led to a lower rate of mechanical complications (40 vs. 60%). A coronal correction of the CM < 20 mm allowed for a significant improvement in SRS-22 and SF-36 scores and was associated with a 3.5 times greater odd of achieving the minimal clinical important difference for the SRS-22.

CONCLUSION

Adherence to the O-CM classification could reduce the risk of mechanic complications 2 years after ASD surgery. Patients with a residual CM < 20 mm showed better functional outcomes and a 3.5 times greater odd of achieving the MCID for the SRS-22 score.

Rod angulation does not reflect sagittal curvature in adult spinal deformity surgery: comparison of lumbar lordosis and rod contouring

STUDY DESIGN

A retrospective study.

OBJECTIVE

Relationship between rod and spinal shape in the sagittal plane in adult spinal deformity (ASD) surgery.

BACKGROUND

Corrective surgery for adult spinal deformity (ASD) involves the use of contoured rods to correct and modify the spinal curvatures. Adequate rod bending is crucial for achieving optimal correction. The correlation between rods and spinal shape in long constructs has not been reported previously.

METHODS

We conducted a retrospective analysis of a prospective, multicenter database of patients who underwent surgery for ASD. The inclusion criteria were patients who underwent pelvic fixation and had an upper instrumented vertebra at or above T12. Pre- and post-operative standing radiographs were used to assess lumbar lordosis at the L4S1 and L1S1 levels. The angle between the tangents to the rod at the L1, L4, and S1 pedicles was calculated to determine the L4S1 and L1S1 rod lordosis. The difference between the lumbar lordosis (LL) and the rod lordosis (RL) was calculated as ΔL = LL-RL. The correlation between this difference (ΔL) and various characteristics was analyzed using descriptive and statistical methods.

RESULTS

Eighty-three patients were included in the study, resulting in 166 analyzed differences (ΔL) between the rod and spinal lordosis. The values for rod lordosis were found to be both greater and lesser than those of the spine but were mostly lower. The range for total ΔL was -24 °-30.9 °, with a mean absolute ΔL of 7.8 ° for L1S1 (standard deviation (SD) = 6.0) and 9.1 ° for L4S1 (SD = 6.8). In 46% of patients, both rods had a ΔL of over 5 °, and over 60% had at least one rod with a ΔL difference of over 5 °. Factors found to be related to a higher ΔL included postoperative higher lumbar lordosis, presence of osteotomies, higher corrected degrees, older age, and thinner rods. Multivariate analysis correlated only higher postoperative L1S1 lordosis with higher ΔL. No correlation was found between a higher ΔL and sagittal imbalance.

CONCLUSIONS

Variations between spinal and rod curvatures were observed despite the linear regression correlation. The shape of the rod does not seem to be predictive of the shape of the spine in the sagittal plane in ASD long-construct surgeries. Several factors, other than rod contouring, are involved in explaining the postoperative shape of the spine. The observed variation calls into question the fundamentals of the ideal rod concept.

Preoperative Optimization: Risk Factors for Perioperative Complications and Preoperative Modification

Adult spinal deformity (ASD) is common and the complication rate in ASD surgery is high due to its invasiveness. There are several factors that increase the risk of complications with ASD surgery. These include age, past medical history, frailty, osteoporosis, or operative invasiveness. Risk factors for perioperative complications can be categorized as modifiable and non-modifiable. The purpose of this article is to present the current available evidence on risk factors for perioperative complications, with a focus on frailty, osteoporosis, surgical site infection prevention, and hip-spine syndrome. In addition, we present the latest evidence for patient-specific surgical risk assessment and surgical planning.

Evaluation of intraoperative coronal alignment using a computer-assisted rod bending system (CARBS) without intraoperative radiation exposure in adult spinal deformity surgery: a technical note and preliminary results

PURPOSE

Intraoperative radiographs and fluoroscopy are used in adult spinal deformity (ASD) surgery to prevent postoperative coronal malalignment but with limited accuracy. Therefore, we applied a computer-assisted rod bending system (CARBS: Bendini®) for an intraoperative coronal alignment evaluation. The purpose of this study is to introduce this novel technique and validate its accuracy.

METHODS

Fifteen ASD patients were included in the study. The heads of the bilateral S1 pedicle screws (S1), the S1 spinous process, and the bilateral greater trochanter (GT) and the C7 spinous process were recorded with CARBS for an intraoperative coronal alignment evaluation. The lines which connect the bilateral S1 and GT were used as references. The C7-center sacral vertical line (C7-CSVL) on the CARBS monitor was checked, and the C7-CSVL from the intraoperative CARBS recording and postoperative standing whole spine radiograph were compared.

RESULTS

Intraoperative C7-CSVL with CARBS was 35.1 ± 31.6 mm when the S1 pedicle screws were used as the reference line and was 16.6 ± 17.8 mm when the GTs were used. Postoperative C7-CSVL by radiograph was 15.1 ± 16.5 mm. In addition, the intraoperative C7-CSVL with CARBS and the postoperative C7-CSVL showed a strong positive correlation in both GT (R = 0.86, p < 0.01) and in S1(R = 0.79, p < 0.01), with a better correlation found in GT than in S1.

CONCLUSION

Intraoperative C7-CSVL with CARBS was found to be highly accurate in ASD surgery. Our results suggest that this novel technique can be useful as an alternative to intraoperative radiography and fluoroscopy and may reduce radiation exposure.

New Effective Intraoperative Techniques for the Prevention of Coronal Imbalance after Circumferential Minimally Invasive Correction Surgery for Adult Spinal Deformity

This study aimed to devise measures and investigate their effect on coronal imbalance (CI) after circumferential minimally invasive correction surgery (CMIS) with lateral lumbar interbody fusion and percutaneous pedicle screw for adult spinal deformity (ASD). A total of 115 patients with ASD who underwent CMIS from the lower thoracic spine to the ilium were included. Patients were stratified based on the distance between the spinous process of the upper instrumented vertebra and central sacrum vertical line (UIV-CSVL) after the first intraoperative rod application into groups P (UIV-CSVL > 10 mm, n = 50) and G (UIV-CSVL < 10 mm, n = 65). Measures to correct postoperative CI introduced during surgery, preoperative and postoperative UIV-CSVL, and changes in UIV-CSVL after various measures (ΔUIV-CSVL) were investigated in group P. Rod rotation (RR), S2 alar-iliac screw distraction (SD), and kickstand-rod (KR) technique were performed in group P. Group P was further divided into group RR (n = 38), group SD (RR and SD) (n = 7), and group KR (RR and KR) (n = 5); the ΔUIV-CSVLs were 13.9 mm, 20.1 mm, and 24.4 mm in these three groups, respectively. Postoperative C7-CSVL < 10 mm was achieved in all three correction groups. In conclusion, our measures enabled sufficient correction of the UIV-CSVL and are useful for preventing CI after CMIS for ASD.

Scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and fixation

Purpose

To explore scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and internal fixation.

Methods

We retrospectively analyzed 56 children with dysplastic spondylolisthesis who underwent surgical reduction and internal fixation. Patients were grouped according to presence of scoliosis before surgery. Radiographic parameters measured before surgery included pelvic incidence, pelvic tilt, sacral slope, coronal Cobb angle, slip percentage, Dubousset's lumbosacral angle, lumbar lordosis, sagittal vertical axis, and Spinal Deformity Study Group index. Groups were compared using logistic regression. Receiver operating characteristic analysis was performed to determine the optimal Spinal Deformity Study Group index cut-off value. All patients were followed up for at least 2 years.

Results

The scoliosis group comprises 36 patients (mean age: 9.6 ± 2.7 years), while the no scoliosis group comprises 20 (mean age: 9.1 ± 2.4 years). Slip percentage and Spinal Deformity Study Group index were significantly higher in the scoliosis group (p < 0.01). Sacral slope and pelvic incidence were lower in the scoliosis group (p < 0.05). Univariate logistic regression analysis showed that slip percentage, Spinal Deformity Study Group index, pelvic incidence, and sacral slope were significantly associated with scoliosis. In the multivariate logistic regression analysis, only Spinal Deformity Study Group index was an independent risk factor for scoliosis. The optimal cut-off value for Spinal Deformity Study Group index was 0.288. Mean Cobb angle decreased from 20.3° ± 8.8° before surgery to 8.5° ± 8.9° at last follow-up; the mean scoliosis correction rate was 59.3%.

Conclusion

Severe S1 dysplasia and high slip percentage may be risk factors for developing scoliosis in patients with dysplastic spondylolisthesis. Scoliosis resolved spontaneously after spondylolisthesis reduction and fixation in most patients.

Level of evidence

3.

AO Spine Adult Spinal Deformity Patient Profile: A Paradigm Shift in Comprehensive Patient Evaluation in Order to Optimize Treatment and Improve Patient Care

STUDY DESIGN

Modified Delphi study.

OBJECTIVE

Adult spinal deformity (ASD) is an increasingly recognized condition, comprising a spectrum of pathologies considerably impacting patients' health and functional status. Patients present with a combination of pain, disability, comorbidities and radiological deformity. The study aims to propose a systematic approach of gathering information on the factors that drive decision-making by developing a patient profile.

METHODS

The present study comprises of 3 parts. Part 1: Development of prototype of patient profile: The data from the Core Outcome Study on SCOlisis (COSSCO) by Scoliosis Research Society (SRS) was categorized into a conceptual framework. Part 2: Modified Delphi study: Items reaching >70% agreement were included in a 4 round iterative process with 51 panellists across the globe. Part 3: Pilot testing-feasibility: Content validity and usability were evaluated quantitatively.

RESULTS

The profile consisted of 4 domains. 1. General health with demographics and comorbidities, 2.Spine-specific health with spine related health and neurological status, 3. Imaging with radiographic and MRI parameters and 4. Deformity type. Each domain consisted of 1 or 2 components with various factors and their measuring instruments. Profile was found to have an excellent content validity (I-CVIr 0.78-1.00; Ave-CVI 0.92) appropriateness, relevance and usefulness.

CONCLUSIONS

The present study, is first to provide a universally applicable multimodal ASD patient profile to methodically describe patients. Physicians are encouraged to assess ASD patients holistically using this profile and not just based on radiographic findings.

Independent Risk Factors of Postoperative Coronal Imbalance after Adult Spinal Deformity Surgery

The aim of the present study is to elucidate preoperative risk factors for inadequate correction of coronal imbalance and/or creation of new postoperative coronal imbalance (iatrogenic CIB) in patients who undergo surgery for Adult Spinal Deformity (ASD). A retrospective review of adults who underwent posterior spinal fusion (>5 levels) for ASD was performed. Patients were divided into groups according to the Nanjing classification: type A (CSVL < 3 cm), type B (CSVL > 3 cm and C7 plumb line shifted to major curve concavity), and type C (CSVL > 3 cm and C7 plumb line shifted to major curve convexity). They were also divided according to postoperative coronal balance in balanced (CB) vs. imbalanced (CIB) and according to iatrogenic coronal imbalance (iCIB). Preoperative, postoperative, and last follow-up radiographical parameters and intraoperative data were recorded. A multivariate analysis was performed to identify independent risk factors for CIB. A total of 127 patients were included (85 type A, 30 type B, 12 type C). They all underwent long (average levels fused 13.3 ± 2.7) all-posterior fusion. Type C patients were more at risk of developing postoperative CIB (p = 0.04). Multivariate regression analysis indicated L5 tilt angle as a preoperative risk factor for CIB (p = 0.007) and indicated L5 tilt angle and age as a preoperative independent risk factors for iatrogenic CIB (p = 0.01 and p = 0.008). Patients with a preoperative trunk shift towards the convexity of the main curve (type C) are more prone to postoperative CIB and leveling the L4 and L5 vertebrae is the key to achieve coronal alignment preventing the "takeoff phenomenon".

Postoperative Radiological Improvement after Staged Surgery Using Lateral Lumbar Interbody Fusion for Preoperative Coronal Malalignment in Patients with Adult Spinal Deformity

This retrospective observational study evaluated improvement in coronal malalignment (CM) after anteroposterior staged surgery using lateral lumbar interbody fusion (LLIF) in patients with coronal lumbar curve adult spinal deformity (ASD). Sixty patients with ASD underwent surgery; 34 had SRS-Schwab type L lumbar curve. Patients with a coronal balance distance (CBD) ≥20 mm were diagnosed with CM. Using the Obeid CM classification, we classified the preoperative coronal pattern as concave CM (type 1) or convex CM (type 2). Demographic, surgical, and radiological parameters were compared. Whole-spine standing radiographs were assessed preoperatively and postoperatively. Twenty-three patients had type 1A, six had type 2A, five had no CM, and none had type 1B or 2B according to the Obeid CM classification. Compared with patients with Obeid type 1A, those with Obeid type 2A had significantly higher preoperative and postoperative coronal L4 tilts and a smaller change in corrected CBD (Δ|CBD|) (76.6 mm vs. 24.1 mm, p < 0.001). At the final follow-up, 58.6% (17/29 patients) of patients with SRS-Schwab type L CM showed improvement after corrective fusion using LLIF. Although the difference was not statistically significant, CM improved in 69.6% (16/23 patients) of patients with Obeid type 1A type but only 16.7% (1/6 patients) of those with Obeid type 2A type (p = 0.056). CM was more likely to remain after anteroposterior staged surgery using LLIF in patients with preoperative Obeid type 2A ASD.

A comparative study of supine traction, supine side-bending radiographs, and supine MRI to determine coronal flexibility in degenerative lumbar scoliosis patients

PURPOSE

The purpose of this study was to compare curve correction in degenerative lumbar scoliosis using supine traction radiographs, supine side-bending radiographs, and supine MRI.

METHODS

A prospective analysis of Cobb angles from patients diagnosed with degenerative lumbar scoliosis who underwent supine traction radiography (TR), side-bending radiography (SB), and supine MRI. The Cobb angles at thoracic (T), thoracolumbar/lumbar (TL/L), and lumbosacral (LS) levels were measured, and the curve correction in percentages compared with standing AP radiography was calculated as corrective flexibility. Differences in curve correction were analyzed.

RESULTS

In total, 33 patients with an age range of 50-80 years were eligible for inclusion. Traction radiography provided the greatest accuracy in curve correction, with a significant difference from side-bending radiography and supine MRI in T, TL/L, and LS levels (P < 0.001). The difference between side-bending radiography and supine MRI in TL/L and LS levels was not significant (P = 0.721, P = 0.654, respectively). A moderate correlation was found between the corrective flexibility of TR and SB at the T level (0.563, P = 0.001), a strong correlation was observed between the corrective flexibility of TR and SB at the TL/L level (0.709, P < 0.001), and at the TL/L level, a moderate correlation was identified between TR and supine MRI corrective flexibility (0.425, P = 0.014).

CONCLUSIONS

Traction radiographs significantly outperformed side-bending radiographs and supine MRI in terms of access curve flexibility in degenerative lumbar scoliosis.

The Obeid-coronal malalignment classification is reliable and helps guiding decision-making and surgical management of adult spinal deformities: letter to the editor of BMC Musculoskeletal Disorders

A recently published article by Zhang et al. in BMC Musculoskeletal Disorders reported that the classification of coronal deformity based on preoperative global coronal malalignment for adult spinal deformity is questionable. The aim of the paper was to specifically discredit the Obeid-Coronal Malalignment (O-CM) classification. In this correspondence, we thought it judicious to clarify misunderstood concepts by the authors. We highlight several limitations of their study, and explain the deep interest of the classification from our perspective in order to avoid misleading the readers. Overarching, we aim to help the colleagues through a constructive rather than destructive approach to better understand the foundations of a coronal malalignment classification.

Post-Maturity Progression in Adolescent Idiopathic Scoliosis Curves of 40° to 50°

BACKGROUND

Adolescent idiopathic scoliosis (AIS) curves of 50° to 75° are inclined to progress and are thus indicated for surgery. Nevertheless, the natural history of curves of 40° to 50° following skeletal maturity remains uncertain and presents a clinical dilemma. The aim of this study was to determine the prevalence, rate, and prognostic indicators of curve progression within this patient group.

METHODS

This was a retrospective study of 73 skeletally mature patients with AIS. Following yearly or more frequent follow-up, patients were stratified as having no progression (<5° increase) or progression (≥5° increase). Those with progression were further differentiated as having standard progression (<2° increase/year) or fast progression (≥2° increase/year). Radiographic parameters (coronal balance, sagittal balance, truncal shift, apical translation, T1 tilt, apical vertebral wedging) and height were determined on skeletal maturity. Parameters that were significantly associated with progression were subject to receiver operating characteristic (ROC) curve analysis.

RESULTS

The average period of post-maturity follow-up was 11.8 years. The prevalence of progression was 61.6%. Among those with progression, the curve increased by a mean of 1.47° ± 1.22° per year, and among those with fast progression, by 3.0° ± 1.2° per year. Thoracic apical vertebral wedging (concave/convex vertebral height × 100) was more apparent in those with progression than in those without progression (84.1 ± 7.5 versus 88.6 ± 3.1; p = 0.003). Increased coronal imbalance (C7 plumb line to central sacral vertebral line) differentiated those with fast progression from others (16.0 ± 11.0 versus 8.7 ± 7.7 mm; p = 0.007). An ROC curve of height-corrected coronal balance demonstrated an area under the curve (AUC) of 0.722, sensitivity of 75.0%, and specificity of 72.5% in identifying fast progression. An ROC curve of height-corrected coronal balance together with apical vertebral wedging to identify those with progression demonstrated an AUC of 0.746, with specificity of 93.7% and sensitivity of 64.5%.

CONCLUSIONS

While the majority of curves progressed, the average rate of progression was slow, and thus, yearly observation was a reasonable management approach. Upon validation in larger cohorts, apical wedging and coronal imbalance may identity patients suited for closer monitoring and early spinal fusion.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Patients With Coronal Malalignment Undergoing Adult Spinal Deformity Surgery: Does Coronal Alignment Change From Immediately Postoperative to 2-years?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The objectives were to: (1) characterize the changes in coronal vertical axis (CVA) after adult spinal deformity (ASD) surgery from immediate postoperative to 2-years postoperative, and (2) assess for predictors of CVA change from immediate postoperative to 2-years postoperative.

SUMMARY OF BACKGROUND DATA

It is unknown whether coronal correction obtained immediately postoperative accurately reflects long-term coronal alignment.

MATERIALS AND METHODS

A retrospective, single-institution registry was queried for patients undergoing ASD surgery from 2015-2019, including patients undergoing ≥6-level fusions with preoperative coronal malalignment (CM), defined as CVA≥3 cm. A clinically significant change in CVA was defined a priori as ≥1 cm. Radiographic variables were obtained preoperatively, immediately postoperative, and at 2-years postoperative.

RESULTS

Of 368 patients undergoing ASD surgery, 124 (33.7%) had preoperative CM, and 64 (17.0%) completed 2-years follow-up. Among 64 patients, mean age was 53.6±15.4 years. Preoperatively, absolute mean CVA was 5.4±3.1 cm, which improved to 2.3±2.0 cm ( P <0.001) immediately postoperative and 2.2±1.6 cm ( P <0.001) at 2-years. The mean change in CVA from preoperative to immediately postoperative was 2.2±1.9 cm (0.3-14.4). During the immediate postoperative to 2-years interval, 29/64 (45.3%) patients experienced a significant change of CVA by ≥1 cm, of which 22/29 (76%) improved by a mean of 1.7 cm and 7/29 (24%) worsened by a mean of 3.5 cm. No preoperative or surgical factors were associated with changed CVA from immediately postoperative to 2-years.

CONCLUSION

Among 64 patients undergoing ASD surgery with preoperative CM, 45.3% experienced a significant (≥1 cm) change in their CVA from immediately postoperative to 2-years postoperative. Of these 29 patients, 22/29 (76%) improved, whereas 7/29 (24%) worsened. Although no factors were associated with undergoing a change in CVA, this information is useful in understanding the evolution and spontaneous coronal alignment changes that take place after major ASD coronal plane correction.

The top 100 most-cited articles on adult spinal deformity: The most popular topics are still sagittal plane parameters and complications

Purpose

This study aimed to summarize the characteristics of the 100 most-cited articles on adult spinal deformity (ASD) and to analyze past and current research hotspots and trends.

Methods

Literature searches (from inception to 28 April 2022) using Web of Science databases were conducted to identify ASD-related articles. The top 100 most-cited articles were collected for further analysis. Meanwhile, author keywords from articles published in the last 5 years were selected for further analysis.

Results

The top 100 most-cited articles on ASD were selected from 3,354 papers. The publication year ranged from 1979 to 2017, and all papers were written in English. The citation count among them ranged from 100 to 1,145, and the mean citation number was 215.2. The foremost productive first author was Schwab F. University of Washington had the largest number of publications. The United States of America had the largest number of published articles (n = 84) in this field. Spine was the most popular journal. Complications were the most studied themes. The visualization analysis of author keywords from the literature in the recent 5 years showed that complications, sagittal plane parameters, and surgical techniques are still the research hotspots, and minimally invasive surgery will continue to develop rapidly.

Conclusion

Based on a comparative analysis of the results of bibliometric and visualization, complications and sagittal plane parameters are still the major topics of research at present and even later, and minimally invasive surgery has a growth trend in this field of ASD.

The "kickstand rod" technique for correction of coronal malalignment: two-year clinical and radiographic outcomes

PURPOSE

Restoring coronal alignment in spine deformity patients has been shown to play an important role in improving patient reported outcomes (PRO). Recently, the "kickstand rod" (KSR) technique was developed as a novel coronal correction method in complex spine deformity cases. The goal of the present study was to assess outcomes of this technique at two years of follow-up.

METHODS

Consecutive, unique adult patients who underwent KSR constructs for coronal spinal malalignment between 2015 and 2019 with a minimum 2 year clinical and radiographic follow-up were identified. A KSR construct includes a more laterally placed iliac screw and additional rod that effectively depresses the ipsilateral ilium/pelvis for coronal correction, while serving as a buttress to prevent future loss of correction. Outcomes included revision for instrumentation-related complications, radiographic alignment, and PROs.

RESULTS

Twenty patients were included with a mean age of 54 years [range: 20-73 years]. Mean follow-up time was 2.5 years [range: 2.0-5.0]. Mean number of levels fused was 17.3 [range: 10-24]. There were significant improvements in coronal alignment (CVA: 5.8 cm ± 2.6 cm vs. 1.7 cm ± 1.5 cm), sagittal alignment (SVA: 5.6 cm ± 5.9 cm vs. 1.6 cm ± 2.5 cm) and major Cobb angle (55º ± 32 vs. 26º ± 21) maintained at 2 years (p < 0.05). One patient experienced an asymptomatic fracture at the shank of the KSR iliac screw. There were significant improvements in Oswestry Disability Index and SRS-22 domains (p < 0.05).

CONCLUSION

The KSR technique is a safe and effective method for correcting coronal malalignment in complex spinal deformity patients with no revisions specific for the KSR or iliac screw and significantly improved PROs at a minimum two-year follow-up.