Finite element modeling of anatomical constitutional types of the lumbar spine and pelvis (Roussouly) for study of the biomechanical aspects

Introduction Sagittal morphotypes graded by Roussouly are characterized by specific biomechanics of the spinopelvic alignment (SPA) that can be investigated using the finite element (FE) modeling.     
The objective was to design three-dimensional realistic models simulating anatomical and constitutional types LPA and evaluate deformity and strength of the models under compression.
Materal and methods Lateral standing spondylograms of the skull, pelvis and upper third of the femur were produced for volunteers (n = 169) who agreed to participate in the study. Radiographs were interpreted with  Surgimap 2.3.2.1.) and computed tomography (CT) of the SPA was performed for individuals (n = 5) with average sagittal parameters for each of the five Roussouly morphotypes (I, II, III, IIIA, IV). The CT findings were used to simulate (SolidWorks) five parametric finite element models of normal morphotypes of SPA and examine the deformity and strength.
Results The highest von Mises stresses under compression were measured in the bodies and intervertebral discs (IVD) ThX–LI (2.961 MPa), posterior supporting structures LIV–SI (2.515 Mpa) with type I model; vertebral bodies and IVD of the thoracic and lumbar spine, mainly at the ThXII–LI (3.082 MPa) and LIV– LV (3.120 Mpa) levels with type II model; anterior aspects of the bodies and IVD ThXI–LII, posterior thirds of the bodies, pedicles and facet joints LI–SI (1.720 Mpa) with type III model; the bodies and intervertebral discs of the ThIX–LII vertebrae (1.811 MPa), posterior supporting structures of the LI–SI vertebrae (1.650 Mpa) with type IIIA model; in the spinous processes and articular portion of the arches of the LI–SI vertebrae (3.232 MPa) with type IV model.
Discussion The lateral configuration of the SPA has a key effect on the segmental distribution of gravitational force and determines the specificity of the sagittal biomechanics of the spine, its resistance to dynamic loads and tendency to various degenerative pathologies.
Conclusion Types III and IIIA were the most biomechanically balanced types, hypolordotic form (types  I and II) was associated with overloaded anterior vertebral structures including intervertebral disc protrusion (IDP) and overloaded posterior supporting structures in case of hyperlordosis (type IV).

1. Diebo BG, Varghese JJ, Lafage R, et al. Sagittal alignment of the spine: What do you need to know? Clin Neurol Neurosurg. 2015;139:295‑301. doi: 10.1016/j.clineuro.2015.10.024.

2. Le Huec JC, Saddiki R, Franke J, et al. Equilibrium of the human body and the gravity line: the basics. Eur Spine J. 2011;20(Suppl 5):558-563. doi: 10.1007/s00586-011-1939-7.

3. Hasegawa K, Okamoto M, Hatsushikano S, et al. Standing sagittal alignment of the whole axial skeleton with reference to the gravity line in humans. J Anat. 2017;230(5):619-630. doi: 10.1111/joa.12586.

4. Duval-Beaupère G, Schmidt C, Cosson P. A Barycentremetric study of the sagittal shape of spine and pelvis: the conditions required for an economic standing position. Ann Biomed Eng. 1992;20(4):451-62. doi: 10.1007/BF02368136.

5. Berthonnaud E, Dimnet J, Roussouly P, Labelle H. Analysis of the sagittal balance of the spine and pelvis using shape and orientation parameters. J Spinal Disord Tech. 2005;18(1):40-47. doi: 10.1097/01.bsd.0000117542.88865.77.

6. Roussouly P, Gollogly S, Berthonnaud E, Dimnet J. Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position. Spine (Phila Pa 1976). 2005;30(3):346-53. doi: 10.1097/01.brs.0000152379.54463.65.

7. Roussouly P, Pinheiro-Franco JL. Biomechanical analysis of the spino-pelvic organization and adaptation in pathology. Eur Spine J. 2011;20 Suppl 5(Suppl 5):609-18. doi: 10.1007/s00586-011-1928-x.

8. Naoum S, Vasiliadis AV, Koutserimpas C, et al. Finite Element Method for the Evaluation of the Human Spine: A Literature Overview. J Funct Biomater. 2021;12(3):43. doi: 10.3390/jfb12030043.

9. Kossovich LYu, Kharlamov AV, Lysunkina YuV, Shul’ga AE. Mathematical modeling and prediction of the effectiveness of surgical treatment in surgery of the spine and pelvic complex. J Samara State Tech Univ Ser Phys Math Sci. 2019;23(4):744-755. doi: https://doi.org/10.14498/vsgtu1702.

10. Zhang S, Bai T, Zhang X, et al. Application of Finite Element Analysis in Biomechanical Research of Degenerative Diseases of Lumbar Spine. JBM. 2022;(10):21-33. doi: 10.4236/jbm.2022.103004.

11. Kudo N, Yamada Y, Xiang X, et al. Concept of mathematical modeling of lumbar and thoracic spine based on elastic beam theory. JBSE. 2022;17(2):21-00331. doi: 10.1299/jbse.21-00331.

12. Sciortino V, Pasta S, Ingrassia T, Cerniglia D. On the Finite Element Modeling of the Lumbar Spine: A Schematic Review. Appl Sci. 2023;13(2):958. doi:10.3390/app13020958.

13. Cho PG, Yoon SJ, Shin DA, Chang MC. Finite Element Analysis of Stress Distribution and Range of Motion in Discogenic Back Pain. Neurospine. 2024;21(2):536-543. doi: 10.14245/ns.2347216.608.

14. Kolmakova TV, Rikun YuA. Study of deformation behavior of the intervertebral disc with the slope of cervical spine segment. Bulletin of the Buryat State University: Mathematics, informatics. 2017;(2):54-60. (In Russ.)

15. Grigoriev AI, Volozhin AI, Stupakov GP. Mineral metabolism in humans under conditions of altered gravity. In: Problems of space biology. Moscow: Nauka Publ.; 1994. 994;74:192-212. (In Russ.)

16. Berezovsky VA, Kolotilov NN. Biophysical characteristics of human tissues: reference book. Kiev: Nauk. Dumka; 1990:224. (In Russ.)

17. Chumachenko EN, Logashina IV. Calculation of the stress-strain state of the spinal motor segment under loads. Aerospace and Environmental Medicine. 2014;48(5):51-57. (In Russ.)

18. Tan SH, Teo EC, Chua HC. Quantitative three-dimensional anatomy of cervical, thoracic and lumbar vertebrae of Chinese Singaporeans. Eur Spine J. 2004;13(2):137-146. doi: 10.1007/s00586-003-0586-z.

19. Berry JL, Moran JM, Berg WS, Steffee AD. A morphometric study of human lumbar and selected thoracic vertebrae. Spine (Phila Pa 1976). 1987;12(4):362-367. doi: 10.1097/00007632-198705000-00010.

20. Laouissat F, Sebaaly A, Gehrchen M, Roussouly P. Classification of normal sagittal spine alignment: refounding the Roussouly classification. Eur Spine J. 2018;27(8):2002-2011. doi: 10.1007/s00586-017-5111-x.

21. Abelin-Genevois K. Sagittal balance of the spine. Orthop Traumatol Surg Res. 2021;107(1S):102769. doi: 10.1016/j.otsr.2020.102769.

22. Galbusera F, Brayda-Bruno M, Costa F, Wilke HJ. Numerical evaluation of the correlation between the normal variation in the sagittal alignment of the lumbar spine and the spinal loads. J Orthop Res. 2014;32(4):537-544. doi: 10.1002/jor.22569.

23. Wang W, Pei B, Wu S, et al. Biomechanical responses of human lumbar spine and pelvis according to the Roussouly classification. PLoS One. 2022;17(7):e0266954. doi: 10.1371/journal.pone.0266954.

24. Bassani T, Casaroli G, Galbusera F. Dependence of lumbar loads on spinopelvic sagittal alignment: An evaluation based on musculoskeletal modeling. PLoS One. 2019;14(3):e0207997. doi: 10.1371/journal.pone.0207997.

25. Remus R, Selkmann S, Lipphaus A, et al. Muscle-driven forward dynamic active hybrid model of the lumbosacral spine: combined FEM and multibody simulation. Front Bioeng Biotechnol. 2023;11:1223007. doi: 10.3389/fbioe.2023.1223007.

26. Cosgun Z, Dagistan E, Dagistan Y. Effects of sagittal balance differences on spondylolisthesis. Acta Ortop Bras. 2019;27(2):120-123. doi: 10.1590/1413-785220192702205665.

27. Yüksel S, Özmen E, Barış A, et al. Publication Trends in the Pelvic Parameter Related Literature between 1992 and 2022 : A Bibliometric Review. J Korean Neurosurg Soc. 2024;67(1):50-59. doi: 10.3340/jkns.2023.0047.

28. Müller A, Rockenfeller R, Damm N, et al. Load Distribution in the Lumbar Spine During Modeled Compression Depends on Lordosis. Front Bioeng Biotechnol. 2021;9:661258. doi: 10.3389/fbioe.2021.661258.

29. Naserkhaki S, Jaremko JL, El-Rich M. Effects of inter-individual lumbar spine geometry variation on loadsharing: Geometrically personalized Finite Element study. J Biomech. 2016;49(13):2909-2917. doi: 10.1016/j.jbiomech.2016.06.032.

30. Filardi V, Simona P, Cacciola G, et al. Finite element analysis of sagittal balance in different morphotype: Forces and resulting strain in pelvis and spine. J Orthop. 2017;14(2):268-275. doi: 10.1016/j.jor.2017.03.007.