An Innovative Stepwise C-Means Clustering Approach for Classification of Adolescent Idiopathic Scoliosis

Abstract

Objective: Existing 3D classification systems for scoliosis primarily guide surgical treatment, with limited application in conservative management. This study aims to establish a preliminary 3D classification system for moderate adolescent idiopathic scoliosis patients in China, providing a theoretical foundation for the standardization and automation of conservative treatment plans.

Methods: Data from 404 adolescent idiopathic scoliosis patients who did not undergo surgery were retrospectively collected from 2022 to 2025. EOS imaging technology was used to perform 3D reconstruction for each patient. The parameters included the 3D centroid coordinates of the vertebrae and vertebral angular displacement. A total of 102 features were extracted per model, and dimensionality reduction yielded 30 final features by the Stacked Autoencoder method. Fuzzy C-means clustering with two classification approaches is used: direct clustering and iterative clustering. Iterative clustering was performed based on coronal plane parameters for initial classification, followed by further clustering. Direct classification involved immediate clustering without further subdivision.

Results: Clustering identified 8 distinct 2D curve types, which were further subdivided into 13 3D subtypes. A comparison of the 13 clusters from direct classification with those obtained from iterative clustering was made using Euclidean and Mahalanobis distances between cluster centers and clinical data. The difference in similarity was higher for direct classification, indicating greater variability.

Conclusion: EOS imaging technology combined with Fuzzy C-Means iterative clustering enables a preliminary 3D classification of AIS by capturing more detailed and individualized morphological features. Compared to direct clustering, the iterative method not only improves geometric interpretability but also enhances classification accuracy by better identifying subtle variations in spinal curvature. It further improves specificity, particularly in distinguishing sagittal and axial plane deformities, which are often overlooked in 2D systems. This enhanced resolution provides a stronger basis for developing personalized conservative treatment plans, such as brace design and rehabilitation strategy. Although the proposed method shows promise, further clinical validation is needed to confirm its effectiveness in guiding conservative treatment decisions.

Keywords

3D classification / adolescent idiopathic scoliosis / conservative treatment / fuzzy C-means clustering / spine

References

[1] W. Wei, T. Zhang, Z. Huang, and J. Yang, “Finite Element Analysis in Brace Treatment on Adolescent Idiopathic Scoliosis,” Medical & Biological Engineering & Computing 60 (2022): 907-920, https://doi.org/10.1007/s11517-022-02524-0.

[2] K. Menon, “Classification Systems in Adolescent Idiopathic Scoliosis Revisited: Is a Three-Dimensional Classification Needed?,” Indian Spine Journal 3 (2020): 143-150, https://doi.org/10.4103/isj.isj_74_19.

[3] H. A. King, J. H. Moe, D. S. Bradford, and R. B. Winter, “The Selection of Fusion Levels in Thoracic Idiopathic Scoliosis,” Journal of Bone and Joint Surgery. American Volume 65, no. 9 (1983): 1302-1313, https://doi.org/10.2106/00004623-198365090-00012.

[4] L. G. Lenke, R. R. Betz, J. Harms, et al., “Adolescent Idiopathic Scoliosis,” Journal of Bone and Joint Surgery. American Volume 83A (2001): 1169-1181, https://doi.org/10.2106/00004623-200108000-00006.

[5] G. X. Qiu, “PUMC Classification and Fusion Level Selection for Adolescent Idiopathic Scoliosis,” Chinese Journal of Surgery 45 (2007): 505-509, https://doi.org/10.3760/j.issn:0529-5815.2007.08.001.

[6] M. Rigo and M. Jelacic, “Brace Technology Thematic Series: The 3D Rigo Cheneau-Type Brace,” Scoliosis Spinal Disord 12 (2017): 1-10, https://doi.org/10.1186/s13013-017-0114-2.

[7] H.-R. Weiss, “The Method of Katharina Schroth - History, Principles and Current Development,” Scoliosis 6 (2011): 1-46, https://doi.org/10.1186/1748-7161-6-17.

[8] Z. Cai, Z. Zhu, and Y. Qiu, “Research Progress in Spontaneous Lumbar Curve Correction After Selective Thoracic Fusion in Lenke 1 and 2 Adolescent Idiopathic Scoliosis,” Chinese Journal Spine Spinal Cord 33 (2023): 270-273.

[9] Y. Li, J. Li, K. D. K. Luk, C. Zhang, J. Sun, and G. Wang, “Relationship Between Fusion Mass Shift and Postoperative Distal Adding-On in Lenke 1 Adolescent Idiopathic Scoliosis After Selective Thoracic Fusion,” Asian Spine Journal 17 (2023): 1117-1124, https://doi.org/10.31616/asj.2022.0466.

[10] H. Labelle, C.-E. Aubin, R. Jackson, L. Lenke, P. Newton, and S. Parent, “Seeing the Spine in 3D: How Will It Change What We Do?,” Journal of Pediatric Orthopedics 31 (2011): S37-S45, https://doi.org/10.1097/BPO.0b013e3181fd8801.

[11] S. Donzelli, S. Poma, L. Balzarini, et al., “State of the Art of Current 3-D Scoliosis Classifications: A Systematic Review From a Clinical Perspective,” Journal of Neuroengineering and Rehabilitation 12 (2015): 91, https://doi.org/10.1186/s12984-015-0083-8.

[12] J. Shen, S. Parent, J. Wu, et al., “Towards a New 3D Classification for Adolescent Idiopathic Scoliosis,” Spine Deform 8 (2020): 387-396, https://doi.org/10.1007/s43390-020-00051-2.

[13] L. Duong, F. Cheriet, and H. Labelle, “Three-Dimensional Classification of Spinal Deformities Using Fuzzy Clustering,” Spine 31 (2006): 923-930, https://doi.org/10.1097/01.brs.0000209312.62384.c1.

[14] Q. Fan, J. Yang, L. Sha, and J. Yang, “Factors That Influence In-Brace Derotation Effects in Patients With Adolescent Idiopathic Scoliosis: A Study Based on EOS Imaging System,” Journal of Orthopaedic Surgery and Research 19 (2024): 293, https://doi.org/10.1186/s13018-024-04789-7.

[15] F. R. Labrom, M. T. Izatt, G. N. Askin, R. D. Labrom, A. P. Claus, and J. P. Little, “Segmental Deformity Markers Offer Novel Indicators of Deformity Progression Risk in Deformity-Matched Adolescent Idiopathic Scoliosis Patients,” Spine Deform 12 (2024): 1647-1655, https://doi.org/10.1007/s43390-024-00927-7.

[16] S. Pasha, S. Shah, B. Yaszay, P. Newton, and Harms Study Group, “Discovering the Association Between the Pre- and Post-Operative 3D Spinal Curve Patterns in Adolescent Idiopathic Scoliosis,” Spine Deform 9 (2021): 1053-1062, https://doi.org/10.1007/s43390-020-00276-1.

[17] T. Arginteanu, D. DeTurck, and S. Pasha, “Global 3D Parameter of the Spine: Application of Calugareanu-White-Fuller Theorem in Classification of Pediatric Spinal Deformity,” Medical & Biological Engineering & Computing 58 (2020): 2963-2969, https://doi.org/10.1007/s11517-020-02259-w.

[18] S. Pasha, V. Ho-Fung, M. Eker, S. Nossov, and M. Francavilla, “Three-Dimensional Classification of the Lenke 1 Adolescent Idiopathic Scoliosis Using Coronal and Lateral Spinal Radiographs,” BMC Musculoskeletal Disorders 21 (2020): 824, https://doi.org/10.1186/s12891-020-03798-x.

[19] S. Pasha, S. Tom, Z. Xiaowei, et al., “Application of Low-Dose Stereoradiography in In Vivo Vertebral Morphologic Measurements: Comparison With Computed Tomography,” Journal of Pediatric Orthopedics 39, no. 9 (2019): 487-494, https://doi.org/10.1097/BPO.0000000000001043.

[20] D. G. Birhiray, S. V. Chilukuri, C. C. Witsken, et al., “Machine Learning Identifies Clusters of the Normal Adolescent Spine Based on Sagittal Balance,” Spine Deform 13 (2025): 89-99, https://doi.org/10.1007/s43390-024-00952-6.

[21] R. M. Thompson, E. W. Hubbard, C. H. Jo, D. Virostek, and L. A. Karol, “Brace Success Is Related to Curve Type in Patients With Adolescent Idiopathic Scoliosis,” Journal of Bone and Joint Surgery 99 (2017): 923-928, https://doi.org/10.2106/jbjs.16.01050.

[22] S. Pasha, P. Hassanzadeh, M. Ecker, and V. Ho, “A Hierarchical Classification of Adolescent Idiopathic Scoliosis: Identifying the Distinguishing Features in 3D Spinal Deformities,” PLoS One 14, no. 3 (2019): 0213406, https://doi.org/10.1371/journal.pone.0213406.

[23] S. Kadoury and H. Labelle, “Classification of Three-Dimensional Thoracic Deformities in Adolescent Idiopathic Scoliosis From a Multivariate Analysis,” European Spine Journal 21 (2012): 40-49, https://doi.org/10.1007/s00586-011-2004-2.

[24] W. Thong, S. Parent, J. Wu, C. E. Aubin, H. Labelle, and S. Kadoury, “Three-Dimensional Morphology Study of Surgical Adolescent Idiopathic Scoliosis Patient From Encoded Geometric Models,” European Spine Journal 25 (2016): 3104-3113, https://doi.org/10.1007/s00586-016-4426-3.

[25] S. Pasha and J. Flynn, “Data-Driven Classification of the 3D Spinal Curve in Adolescent Idiopathic Scoliosis With an Applications in Surgical Outcome Prediction,” Scientific Reports 8, no. 1 (2018): 16296, https://doi.org/10.1038/s41598-018-34261-6.

[26] A. P. Sangole, C. E. Aubin, H. Labelle, et al., “Three-Dimensional Classification of Thoracic Scoliotic Curves,” Spine 34 (2009): 91-99, https://doi.org/10.1097/BRS.0b013e3181877bbb.

[27] K. G. Dhal, A. Das, S. Ray, K. Sarkar, and J. Gálvez, “An Analytical Review on Rough Set Based Image Clustering,” Archives of Computational Methods in Engineering 29 (2022): 1643-1672, https://doi.org/10.1007/s11831-021-09629-z.

[28] J. C. Bernard, E. Berthonnaud, J. Deceuninck, L. Journoud-Rozand, G. Notin, and E. Chaleat-Valayer, “Three-Dimensional Reconstructions of Lenke 1A Curves,” Scoliosis Spinal Disord 13 (2018): 1-7, https://doi.org/10.1186/s13013-017-0149-4.

[29] W. Q. Wei, L. Cheng, Y. T. Dong, et al., “2D and 3D Classification Systems for Adolescent Idiopathic Scoliosis: Clinical Implications and Technological Advances,” Orthopaedic Surgery 0 (2025): 1-223, https://doi.org/10.1111/os.14362.

[30] E. Garcia-Cano, F. Arambula Cosio, L. Duong, et al., “Dynamic Ensemble Selection of Learner-Descriptor Classifiers to Assess Curve Types in Adolescent Idiopathic Scoliosis,” Medical & Biological Engineering & Computing 56 (2018): 2221-2231, https://doi.org/10.1007/s11517-018-1853-9.

[31] S. Pasha, J. Shen, and S. Kadoury, “True 3D Parameters of the Spinal Deformity in Adolescent Idiopathic Scoliosis,” Spine Deform 9 (2021): 703-710, https://doi.org/10.1007/s43390-020-00254-7.

RIGHTS & PERMISSIONS

2025 The Author(s). Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.