Preoperative Sagittal Spinal Profile of Adolescent Idiopathic Scoliosis Lenke Types and Non-Scoliotic Adolescents: A Systematic Review and Meta-Analysis

Is sagittal spinopelvic alignment a cause of low back pain in pediatric spine pathologies? A review

Purpose

Altered spinopelvic morphology is observed in many spine pathologies occurring during growth. The aim of the study is to better understand the sagittal compensatory mechanisms and their possible influence on the occurrence of pain in selected pediatric spine pathologies.

Methods

A bibliographic search in the PubMed database included articles published between September 1965 and July 2023. The keywords contained in the search were "spondylolysis," "spondylolisthesis," "scoliosis," "kypho," "sagittal," "pediatric," "child," "adolescent," "grow," "development," and "pain."

Results

The largest diversity in sagittal alignment patterns was reported in idiopathic scoliosis, with global flattening of the spine being the most common. Kyphotic deformations occurring during growth are characterized by structural thoracic or thoracolumbar kyphosis compensated by lumbar hyperlordosis and lower pelvic incidence. Whereas in spondylolisthesis, altered morphology of the spinopelvic junction with high values of pelvic incidence is observed. Pain does not seem to be related to sagittal alignment in idiopathic scoliosis. In Scheuermann disease, it is localized at the apex of the deformity and is associated with the curve pattern, whereas in spondylolisthesis, sagittal alignment correlates with pain scores only in high-grade slips.

Conclusion

Most of the patients with spine disorders that occurred during growth present a clinically balanced posture in the sagittal plane. It suggests that compensatory mechanisms before achieving skeletal maturity are really significant. A comprehension of sagittal alignment in spine deformities and its relationship to pain is essential for the proper assessment and treatment of these disorders.

PRE- AND POSTOPERATIVE COMPARATIVE ANALYSIS OF THE SPINOPELVIC AND GLOBAL SAGITTAL PARAMETERS OF PATIENTS WITH ADOLESCENT IDIOPATHIC SCOLIOSIS

ABSTRACT Objective: To analyze the pre- and postoperative spinopelvic parameters and global sagittal balance of patients with adolescent idiopathic scoliosis (AIS) divided into 3 groups (Group 1 – thoracic arthrodesis, Group 2 - thoracolumbar arthrodesis, and Group 3 – lumbar arthrodesis), observing differences in these two moments and whether the parameter values are maintained or not over a period of up to 2 years following surgery. Methods: We analyzed the radiographs from a single-center database of 99 patients who underwent arthrodesis with posterior instrumentation. Pelvic incidence, pelvic version, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis values were measured in the pre- and postoperative radiographies of each patient. Results: The parameters of pelvic incidence, pelvic version, sacral slope, and sagittal vertical axis did not show statistically significant differences among the 3 groups. There was a difference in preoperative lumbar lordosis between the 3 groups (p = 0.049). Thoracic kyphosis showed differences both in the pre- (p = 0.015) and postoperative (p = 0.042) values, in addition to demonstrating a relationship of dependence between the pre- and postoperative values in the final statistical analysis. Conclusion: The evaluation of the parameters analyzed shows that the study groups have similar values of individual balance, with the exception of thoracic kyphosis and lumbar lordosis, which are measurements that depend on the surgical technique and compensatory mechanisms, but remained within normal ranges. These factors allow the surgeon to be attentive to both the coronal and sagittal planes when planning the correction in order to achieve the equilibrium of the trunk in addition to correction of the deformity. Level of Evidence IIIA: Comparative retrospective study.

Morphology, Development and Deformation of the Spine in Mild and Moderate Scoliosis: Are Changes in the Spine Primary or Secondary?

Introduction and aim of the study: We aim to determine whether the changes in the spine in scoliogenesis of idiopathic scoliosis (IS), are primary/inherent or secondary. There is limited information on this issue in the literature. We studied the sagittal profile of the spine in IS using surface topography. Material and methods: After approval of the ethics committee of the hospital, we studied 45 children, 4 boys and 41 girls, with an average age of 12.5 years (range 7.5–16.4 years), referred to the scoliosis clinic by our school screening program. These children were divided in two groups: A and B. Group A included 17 children with IS, 15 girls and 2 boys. All of them had a trunk asymmetry, measured with a scoliometer, greater than or equal to 5 degrees. Group B, (control group) included 26 children, 15 girls and 11 boys, with no trunk asymmetry and scoliometer measurement less than 2 degrees. The height and weight of children were measured. The Prujis scoliometer was used in standing Adam test in the thoracic (T), thoraco-lumbar (TL) and lumbar (L) regions. All IS children had an ATR greater than or equal to 5 degrees. The Cobb angle was assessed in the postero-anterior radiographs in Group A. A posterior truncal surface topogram, using the “Formetric 4” apparatus, was also performed and the distance from the vertebra prominence (VP) to the apex of the kyphosis (KA), and similarly to the apex of the lumbar lordosis (LA) was calculated. The ratio of the distances (VP-KA) for (PV-LA) was calculated. The averages of the parameters were studied, and the correlation of the ratio of distances (VP-KA) to (VP-KA) with the scoliometer and Cobb angle measurements were assessed, respectively (Pearson corr. Coeff. r), in both groups and between them. Results: Regarding group A (IS), the average height was 1.55 m (range 1.37, 1.71), weight 47.76 kg (range 33, 65). The IS children had right (Rt) T or TL curves. The mean T Cobb angle was 24 degrees and 26 in L. In the same group, the kyphotic apex (KA (VPDM)) distance was −125.82 mm (range −26, −184) and the lordotic apex (LA (VPDM)) distance was −321.65 mm (range −237, −417). The correlations of the ratio of distances (KA (VPDM))/(LA (VPDM)) with the Major Curve Cobb angle measurement and scoliometer findings were non-statistically significant (Pearson r = 0.077, −0.211, p: 0.768, 0.416, respectively. Similarly, in the control group, KA (VPDM))/(LA (VPDM) was not significantly correlated with scoliometer findings (Pearson r = −0.016, −p: 0.939). Discussion and conclusions: The lateral profile of the spine was commonly considered to be a primary aetiological factor of IS due to the fact that the kyphotic thoracic apex in IS is located in a higher thoracic vertebra (more vertebrae are posteriorly inclined), thus creating conditions of greater rotational instability and therefore greater vulnerability for IS development. Our findings do not confirm this hypothesis, since the correlation of the (VP-KA) to (VP-KA) ratio with the truncal asymmetry, assessed with the scoliometer and Cobb angle measurements, is non-statistically significant, in both groups A and B. In addition, the aforementioned ratio did not differ significantly between the two groups in our sample (0.39 ± 0.11 vs. 0.44 ± 0.08, p: 0.134). It is clear that hypokyphosis is not a primary causal factor for the commencing, mild or moderate scoliotic curve, as published elsewhere. We consider that the small thoracic hypokyphosis in developing scoliosis adds to the view that the reduced kyphosis, facilitating the axial rotation, could be considered as a permissive factor rather than a causal one, in the pathogenesis of IS. This view is consistent with previously published views and it is obviously the result of gravity, growth and muscle tone.

Assessment of sagittal spinopelvic alignment in asymptomatic Chinese juveniles and adolescents: a large cohort study and comparative meta-analysis

STUDY DESIGN

Retrospective study and comparative meta-analysis.

OBJECTIVE

To document the sagittal spinopelvic alignment in a large cohort study in asymptomatic Chinese juveniles and adolescents, and to explore whether these parameters were different from various regions using meta-analysis.

METHODS

Medical records of 656 asymptomatic Chinese juveniles and adolescents were reviewed, whose mean age was 13.14 ± 3.41 years old, including 254 male and 402 female volunteers. Demographic and lateral radiological parameters were evaluated. Furthermore, a systematic online search was performed to identify eligible studies. Weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate whether these sagittal parameters were different from various regions.

RESULTS

The mean value of sagittal spinopelvic alignment in this study was calculated and analyzed respectively. Significant differences of PI (34.20 ± 4.00 vs. 43.18 ± 7.12, P < 0.001) and PT (3.99 ± 6.04 vs. 8.42 ± 7.08, P < 0.001) were found between juveniles and adolescents. A total of 17 studies were recruited for meta-analysis. For juvenile populations, TK, PI and SS of Caucasians were significantly larger than those of our study (all P < 0.001). As for adolescent populations, PI (P = 0.017), TK (P = 0.017) and SS (P < 0.001) of Caucasians was found to be greater when compared with that of our study. All in all, TK, PI and SS in Chinese pre-adult populations were significantly smaller than those populations in Caucasian regions (all P < 0.001).

CONCLUSION

Our study was the first large-scale study that reported the mean values of sagittal parameters in asymptomatic Chinese juveniles and adolescents. There were significant differences in TK, PI and SS between our study and other previous reported populations, which reminded us for using specific mean values in different populations when restoring a relatively normal sagittal spinopelvic balance in spinal deformity.

Sagittal curvature of the spine as a predictor of the pediatric spinal deformity development

BACKGROUND

The sagittal curvature of the spine is hypothesized to play an important role in induction of spinal deformities in adolescent idiopathic scoliosis. We previously showed an S shaped flexible rod, with the same curvature as the pediatric sagittal spinal curve, produces scoliotic-like deformities under physiologic loading. Yet, detailed characteristics of the pediatric sagittal spinal curves associated with higher risk of scoliosis are not well defined.

METHODS

A total of 32 patients in a population with a high prevalence of idiopathic-like scoliosis, 22q11.2 deletion syndrome (22q), were included and followed up for at least two-years. We developed a reduced order finite element model (FEM) of the sagittal profile of these 32 patients where the spine was modeled as an S shaped elastic rod. We related the geometrical parameters of the sagittal curves and the deformed FEM of the corresponding S shaped rods to the risk of scoliosis development at two-year follow-up in this cohort.

RESULTS

Variations in the sagittal curvature in the cohort of 22q patients resulted in five different deformity patterns shown by finite element analyses. Two sagittal plane deformity pattern groups had high rate of scoliosis development (86% and 100%) whereas the other 3 groups had less than 50% rate of scoliosis development (40%, 33%, and 0%). The pre-scoliotic position of the inflection point (where lordosis turns into kyphosis), the ratio of the spinal curvatures above and below the inflection point, and the length of the spinal curve above and below the inflection point were significantly different between the five deformity patterns groups, p < 0.05.

CONCLUSION

Combination of geometrical parameters of the sagittal profile prior to onset of scoliosis can relate to the development of spinal deformity in pediatric population.

A reduced-order model of the spine to study pediatric scoliosis

The S-shaped curvature of the spine has been hypothesized as the underlying mechanical cause of adolescent idiopathic scoliosis. In earlier work, we proposed a reduced-order model in which the spine was viewed as an S-shaped elastic rod under torsion and bending. Here, we simulate the deformation of S-shaped rods of a wide range of curvatures and inflection points under a fixed mechanical loading. Our analysis determines three distinct axial projection patterns of these S-shaped rods: two loop (in opposite directions) patterns and one Lemniscate pattern. We further identify the curve characteristics associated with each deformation pattern, showing that for rods deforming in a Loop1 shape the position of the inflection point is the highest and the curvature of the rod is smaller compared to the other two types. For rods deforming in the Loop2 shape, the position of the inflection point is the lowest (closer to the fixed base) and the curvatures are higher than the other two types. These patterns matched the common clinically observed scoliotic curves-Lenke 1 and Lenke 5. Our S-shaped elastic rod model generates deformations that are similar to those of a pediatric spine with the same sagittal curvature characteristics and it can differentiate between the clinically observed deformation patterns.

Validity of a one-item drawing-based instrument to assess trunk deformity perception in kyphotic deformities

INTRODUCTION

Body image and trunk appearance perception are two crucial attributes in determining the quality of life of individuals with spinal deformities. The Trunk Appearance Perception Scale (TAPS) is a drawing-based instrument used to evaluate this feature. The TAPS does not include a sagittal view of the trunk so it is never been used to assess trunk deformity perception in hyperkyphotic patients. This study aims to analyze the effect of introducing a new drawing on the TAPS scale representing the trunk view in the sagittal plane.

PATIENTS

170 non-surgical patients were included (mean age 16.9 years and 77.4% women) distributed in three groups. CONTROL group (no deformity): 22 cases; KYPHOSIS group (sagittal deformity): 49 cases and SCOLIOSIS group (coronal deformity): 99 cases (mean Cobb 42.4º).

METHOD

Cross-sectional study. A new drawing (TAPS4) was designed to represent the deformity in the sagittal plane with five response options. Clinical (SRS-22 and TAPS 4-items) and radiological (kyphosis T4-T12) data were collected in all patients. The statistical analysis consisted in determining for each group the internal consistency of the 3-items TAPS vs 4-items TAPS, as well as the discriminant validity (correlation with kyphosis magnitude) and convergent validity (correlation with the SRS-22 image subscale). In addition, test-retest reliability of new item 4 was determined in a subgroup of 30 kyphotic patients. During control visit, the patients received a complete physical examination and a full-spine AP and lateral X-ray in standing position using a low-radiation technique and fulfilled instruments TAPS 4 items and SRS-22r.

RESULTS

The three groups were found to have statistically significant differences in the magnitude of kyphosis, quality of life, body image perception, the 3-items TAPS, 4-items TAPS and new item 4 score. The addition of the item 4 to TAPS 3 items did not cause a significant change in the internal consistency of the scales (Cronbach's alpha) (TAPS 3-items 0.8 vs. TAPS 4-items 0.8). Kyphosis magnitude was not correlated with the 3-items TAPS and 4-items TAPS scores; however, in the KYPHOSIS group, a significant negative correlation was observed between kyphosis and item 4 (Rho = - 0.4, p = 0.0001). A significant correlation was found in all groups between TAPS 3-items and TAPS 4-items and SRS-22 image domain; the correlation between item 4 and SRS-22 body image domain was 0.3 in the Scoliosis group and 0.7 in the Kyphosis group.

CONCLUSIONS

The 4-items TAPS scale does not provide advantages in the assessment of trunk deformity over the 3-items scale. However, in patients with kyphosis, the item 4 (Kypho-TAPS) alone is a valid and reliable instrument to monitor the perception of the trunk deformity.

Whole body balance control in Lenke 1 thoracic adolescent idiopathic scoliosis during level walking

Introduction

Altered trunk shape and body alignment in Lenke 1 thoracic adolescent idiopathic scoliosis (AIS) may affect the body’s balance control during activities. The current study aimed to identify the effects of Lenke 1 thoracic AIS on the balance control during level walking in terms of the inclination angles (IA) of the center of mass (COM) relative to the center of pressure (COP), the rate of change of IA (RCIA), and the jerk index of IA. The association between the Cobb angle, IA and RCIA was also evaluated.

Materials and methods

Sixteen adolescents with AIS (age: 14.0±1.8 years, height: 154.8±4.7 cm, mass: 42.0±7.5 kg) and sixteen healthy controls (age: 14.4±2.0 years, height: 158.4±6.2 cm, body mass: 48.6±8.9 kg) performed level walking in a gait laboratory. The kinematic and ground reaction force data were measured for both concave-side and convex-side limb cycles, and used to calculate the IA and RCIA, the jerk index of IA, and the temporal-spatial parameters. Correlations between the Cobb angle, IA and RCIA were quantified using Pearson’s correlation coefficients (r).

Results

The patients showed less smooth COM-COP motion with increased jerk index of IA in the sagittal plane during single limb support (SLS) of the concave-limb (p = 0.05) and in the frontal plane during double limb support (DLS) (p < 0.05). The patients also showed significantly increased posterior RCIA on both the concave and convex side during initial (p = 0.04, p = 0.03) and terminal (p = 0.04, p = 0.03) DLS when compared to healthy controls. In the frontal plane, the patients walking on the concave-side limb showed decreased IA over SLS (p = 0.01), and at contralateral toe-off (p<0.01) and contralateral heel-strike (p = 0.02), but increased mean IA magnitude over terminal DLS (p = 0.01). The frontal IA at contralateral toe-off and SLS for AIS-A showed a moderate to strong correlation with Cobb angles (r = -0.46 and -0.61), and the sagittal RCIA over the initial DLS for AIS-A also showed a significant, strong correlation with Cobb angles (r = -0.50).

Conclusions

The patients with Lenke 1 thoracic scoliosis in the current study showed altered and jerkier COM-COP control during level walking when compared to healthy controls. During DLS, the patients increased the posterior RCIA in the sagittal plane with increased IA jerk index in the frontal plane for both the concave- and the convex-side limb, indicating their difficulty in maintaining a smooth transfer of the body weight. During SLS of the concave-side limb, the patients adopted a conservative COM-COP control strategy, as indicated by a decreased IA in the frontal plane, but showed a jerky COM-COP control in the sagittal plane. The COM-COP control of the patients was associated with the severity of the spinal deformity. The current results suggest that this patient group should be monitored for signs of an increased risk of loss of balance during weight transfer on the concave-side limb.

Defining criteria for optimal lumbar curve correction following the selective thoracic fusion surgery in Lenke 1 adolescent idiopathic scoliosis: developing a decision tree

OBJECTIVE

The aim of this study was to identify the range of optimal versus suboptimal rates of spontaneous lumbar Cobb correction (SLCC%) and the factors predicting such outcomes in a cohort of Lenke 1 adolescent idiopathic scoliosis (AIS) after posterior spinal fusion surgery.

METHODS

Seventy-one consecutive Lenke1 B and C AIS patients with a fusion level to L1 and higher with two-year follow-up were included. Thoracic kyphosis (T1-T4 and T4-T12 TK), lumbar lordosis (L1-S1 LL), thoracic and lumbar Cobb angles, thoracic and lumbar apical vertebral rotations and translations (AVR and AVT), pelvic incidence, sacral slope, and sagittal and frontal balances were measured at preoperative, early postoperative, and two-year follow-up. The SLCC% was calculated between preoperative and two-year follow-up. A clustering analysis determined the subgroups of patients with significantly higher and lower (optimal versus suboptimal) rate of SLCC% in the cohort at two-year follow-up. The cutoff values of the preoperative and early postoperative radiographic parameters that significantly predicted the optimal and suboptimal SLCC% were determined using a decision tree.

RESULTS

The averages of the optimal versus suboptimal range of SLCC% in the cohort were 72% [55%, 105%] versus 39% [- 7%, 42%]. Preoperative and early postoperative spinal parameters predicted the optimal versus suboptimal SLCC% with an accuracy of 82%, 95%CI [0.73-0.94]. Preoperative AVT_Lumbar < 10 mm was a predictor of optimal SLCC%. In patients with a preoperative AVT_Lumbar > 10 mm, early postoperative T4-T12 TK < 24° (but not less than 17°) accompanied by - 5° < AVR_Thoracic < 5° were the main predictors of optimal SLCC% in our cohort.

CONCLUSION

Quantitative clustering of the SLCC% into optimal and suboptimal groups allowed identifying the cutoff values of preoperative (AVT_Lumbar) and early postoperative (T4-T12 TK and AVR_Thoracic) spinal parameters that can predict the optimal range of SLCC% at two-year postoperative in our cohort of Lenke 1 AIS.

LEVEL OF EVIDENCE

IV.

Bone Remodeling and Disc Morphology in the Distal Unfused Spine After Spinal Fusion in Adolescent Idiopathic Scoliosis

BACKGROUND

Morphologic changes in the vertebral body in adolescent idiopathic scoliosis (AIS) have been associated with curve development and progression. Yet, after an AIS spinal surgery, the impact of the global and local spinal realignment on the vertebral body and intervertebral disc morphologic changes, particularly in the distal unfused spine, have not been determined.

QUESTIONS/PURPOSES

To determine the changes in the unfused lumbar vertebrae and disc morphology two years after spinal fusion in AIS patients undergoing selective thoracic fusion (STF).

PATIENTS AND METHODS

A total of 58 patients with Lenke type 1 AIS who underwent STF with a minimum two-year follow-up and 20 nonscoliotic adolescents were included. Biplanar stereoradiography of the spine at preoperative, early postoperative, and two-year follow-up were used to generate 3D models of the spine. Lumbar spine vertebral and intervertebral heights (anterior, posterior, left, and right) and the degree of wedging in the frontal and sagittal plane were calculated in the local coordinate system of the vertebral bodies. The morphology of vertebrae and discs were compared between the pre- and postoperative visits of AIS patients and nonscoliotic controls.

RESULTS

Lumbar lordosis was not statistically different between the pre- and post-operative AIS and controls, p > .05. The contribution of the lumbar vertebral bodies and discs' sagittal wedging to the total L1-L5 lordosis were 20% and 80%, respectively, for nonscoliotic controls and 61% and 39%, respectively, for AIS patients at two-year follow-up. The decrease in the anterior and left heights of the disc between the preoperative and two-year follow-up was significant, p < .05.

CONCLUSION

Patients undergoing STF for Lenke 1 AIS are able to achieve normal lumbar lordosis after surgery but seem to regain their sagittal alignment by morphologic changes in the disc more so than the vertebral body. A larger contribution of the vertebral sagittal wedging to the total lumbar lordosis at two years post STF was observed when these variables were compared to the nonscoliotic adolescents.

LEVEL OF EVIDENCE

Level IV.

A hierarchical classification of adolescent idiopathic scoliosis: Identifying the distinguishing features in 3D spinal deformities

This study aimed to identify the differentiating parameters of the spinal curves’ 2D projections through a hierarchical classification of the 3D spinal curve in adolescent idiopathic scoliosis (AIS). A total number of 103 right thoracic left lumbar pre-operative AIS patients were included retrospectively and consecutively. A total number of 20 non-scoliotic adolescents were included as the control group. All patients had biplanar X-rays and 3D reconstructions of the spine. The 3D spinal curve was calculated by interpolating the center of vertebrae and was isotropically normalized. A hierarchical classification of the normalized spinal curves was developed to group the patients based on the similarity of their 3D spinal curve. The spinal curves’ 2D projections and clinical spinal measurements in the three anatomical planes were then statistically compared between these groups and between the scoliotic subtypes and the non-scoliotic controls. A total of 5 patient groups of right thoracic left lumbar AIS patients were identified. The characteristics of the posterior-anterior and sagittal views of the spines were: Type 1: Normal sagittal profile and S shape axial view. T1 is leveled or tilted to the right in the posterior view. Type 2: Hypokyphotic and a V shape axial view. T1 is tilted to the left in the posterior view. Type 3: Hypokyphotic (only T5-T10) and frontal imbalance, S shape axial view. T1 is leveled or tilted to the right, and 3 frontal curves. Type 4: Flat sagittal profile (T1-L2), slight frontal imbalance with a V shape axial view, T1 tilted to the left. Type 5: flat sagittal profile and forward trunk shift with a proximal kyphosis and S shape axial view. T1 is leveled or tilted to the right. In conclusion, a hierarchical classification of the 3D scoliotic spine allowed identifying various distinguishing features of the spinal curves in patients with a right thoracic curve in an orderly fashion. The subtypes’ characteristics resulting from this 3D classification can be identified from the pairs of the frontal and sagittal spinal curves i.e. X-rays in right thoracic AIS patients.

Adult spinal deformity surgical decision-making score : Part 1: development and validation of a scoring system to guide the selection of treatment modalities for patients below 40 years with adult spinal deformity

PURPOSE

We aimed to develop and internally validate a simple scoring system: the adult spinal deformity (ASD) surgical decision-making (ASD-SDM) score, which is specific to the decision-making process for ASD patients aged below 40 years.

METHODS

A multicentre prospective ASD database was retrospectively reviewed. The scoring system was developed using data from a derivation cohort and was internally validated in a validation cohort. The accuracy of the ASD-SDM score was assessed using the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 316 patients were randomly divided into derivation (253 patients, 80%) and validation (63 patients, 20%) cohorts. A 10-point scoring system was created from four variables: self-image score in the Scoliosis Research Society-22 score, coronal Cobb angle, pelvic incidence minus lumbar lordosis mismatch, and relative spinopelvic alignment, and the surgical indication was graded into low (score 0-4), moderate (score 5-7), and high (score 8-10) surgical indication groups. In the validation cohort, the AUC for selecting surgical management according to the ASD-SDM score was 0.789 (SE 0.057, P < 0.001, 95% CI 0.655-0.880). The percentage of patients treated surgically were 21.1%, 55.0%, and 80.0% in the low, moderate, and high surgical indication groups, respectively.

CONCLUSIONS

The ASD-SDM score, to the best of our knowledge, is the first algorithm to guide the decision-making process for the ASD population and could be one of the indices for aiding the selection of treatment for ASD. These slides can be retrieved under Electronic Supplementary Material.

Data-driven Classification of the 3D Spinal Curve in Adolescent Idiopathic Scoliosis with an Applications in Surgical Outcome Prediction

Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) deformity of the spinal column. For progressive deformities in AIS, the spinal fusion surgery aims to correct and stabilize the deformity; however, common surgical planning approaches based on the 2D X-rays and subjective surgical decision-making have been challenged by poor clinical outcomes. As the suboptimal surgical outcomes can significantly impact the cost, risk of revision surgery, and long-term rehabilitation of adolescent patients, objective patient-specific models that predict the outcome of different treatment scenarios are in high demand. 3D classification of the spinal curvature and identifying the key surgical parameters influencing the outcomes are required for such models. Here, we show that K-means clustering of the isotropically scaled 3D spinal curves provides an effective, data-driven method for classification of patients. We further propose, and evaluate in 67 right thoracic AIS patients, that by knowing the patients’ pre-operative and early post-operation clusters and the vertebral levels which were instrumented during the surgery, the two-year outcome cluster can be determined. This framework, once applied to a larger heterogeneous patient dataset, can further isolate the key surgeon-modifiable parameters and eventually lead to a patient-specific predictive model based on a limited number of factors determinable prior to surgery.