Impact of lamina formation range on lumbar biomechanics in unilateral biportal endoscopic spine surgery: a finite element analysis for surgical optimization_Chinese Journal of Reparative and Reconstructive Surgery

Authors：

JI Shuo ^1,2 , MA Bingxu ³ ^{共同第一作者} , ZOU Yang ¹ , ZHANG Menglong ¹ , REN Mingyu ¹ , Li Huanyu ^1,4 , DUAN Keyou ^1,4 , XU Chen ^1,4 , ZHANG Changchun ^1,4 ,  YE Yuchen ^1,4 ,  ZHOU Pinghui ^1,4

1. Department of Orthopedics, the First Affiliated Hospital of Bengbu Medical University, Bengbu Anhui, 233004, P. R. China;
2. Department of Clinical Medicine, Bengbu Medical University, Bengbu Anhui, 233030, P. R. China;
3. Department of Orthopedics, the First People’s Hospital of Bengbu City, Bengbu Anhui, 233000, P. R. China;
4. Anhui Provincial Key Laboratory of Tissue Transplantation, Bengbu Medical University, Bengbu Anhui, 233030, P. R. China;

Corresponding?author：

YE Yuchen, Email: yeaheason@126.com; ZHOU Pinghui, Email: zphdoctor@126.com

Keywords：

Unilateral biportal endoscopy; lumbar biomechanics; laminoplasty; decompression surgery; finite element analysis

DOI：

10.7507/1002-1892.202511054

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Objective To explore the impact of different lamina formation ranges on the biomechanical stability of L₅, S₁ in spine surgery with unilateral biportal endoscopy (UBE), providing a theoretical basis for optimizing clinical surgical plans. Methods A complete lumbar finite element model (M0) was constructed based on CT data of L₃-S₁ from a healthy male volunteer. Four different UBE surgical models with varying lamina formation ranges (M1-M4) were simulated. M1 model involved initial laminectomy with essentially intact facets; M2 model involved minor facet resection (5-10 mm from the inferior facet joint surface); M3 model involved greater facet resection with partial laminectomy depth >10 mm; M4 model involved complete facet resection to simulate extreme decompression. Finite element analysis was performed to assess the range of motion (ROM), maximum displacement, and maximum von Mises stress of the vertebrae under different physiological activities (flexion, extension, left/right bending, and left/right rotation), as well as the maximum displacement and maximum von Mises stress of the intervertebral disc, and the maximum von Mises stress of right facet joints under left rotation and right bending. Results With increasing forming range, the ROM of the vertebrae in flexion showed a slight increase (0.32° higher in M4 model than in M0 model), and the maximum displacement generally increased in all motion states. For the intervertebral disc, the maximum von Mises stress and displacement increased mildly in flexion and left rotation, which were approximately 17% and 12% higher in M3 and M4 models than in M0 model, respectively. And the biomechanical parameters changed little among different models under extension, right rotation, and left bending. The von Mises stress of the right facet joint increased stepwise with forming range during left rotation (about 57% higher in M3 model than in M0 model) and was higher in all surgical models than in M0 model during right bending. Conclusion Expanding the lamina formation range in UBE spine surgery can lead to reduced stability in flexion and left rotation activities at L₅, S₁, increasing the mechanical load on the intervertebral disc and facet joints. Clinically, under the premise of achieving adequate decompression, prioritizing a forming range corresponding to the lower transverse width partition (25%-50%) may better balance decompression efficacy with biomechanical stability of the L₅, S₁ segment, thereby reducing the potential risk of long-term degeneration caused by excessive bony resection.

Citation： JI Shuo, MA Bingxu, ZOU Yang, ZHANG Menglong, REN Mingyu, Li Huanyu, DUAN Keyou, XU Chen, ZHANG Changchun, YE Yuchen, ZHOU Pinghui. Impact of lamina formation range on lumbar biomechanics in unilateral biportal endoscopic spine surgery: a finite element analysis for surgical optimization. Chinese Journal of Reparative and Reconstructive Surgery, 2026, 40(4): 616-622. doi: 10.7507/1002-1892.202511054 Copy

1.	Parker SL, Godil SS, Mendenhall SK, et al. Two-year comprehensive medical management of degenerative lumbar spine disease (lumbar spondylolisthesis, stenosis, or disc herniation): a value analysis of cost, pain, disability, and quality of life: clinical article. J Neurosurg Spine, 2014, 21(2): 143-149.
2.	Shi HX, Gao YJ, Wang SR. Electroacupuncture in non-surgical management of lumbar spinal stenosis: mechanistic potential in attenuating ligamentum flavum thickening via inflammatory factor modulation. Front Immunol, 2025, 16: 1644394. doi: 10.3389/fimmu.2025.1644394.
3.	高景華, 劉代遠, 李路廣, 等. 《腰椎管狹窄癥中西醫結合診療指南(2023年)》解讀. 中國中醫骨傷科雜志, 2025, 33(1): 84-87.
4.	Wu X, Pan H, Wang H, et al. Unilateral biportal endoscopic in spine surgery: a global bibliometric analysis of research trends and influences. Eur Spine J, 2025. doi: 10.1007/s00586-025-09002-9.
5.	Chu PL, Wang T, Zheng JL, et al. Global and current research trends of unilateral biportal endoscopy/biportal endoscopic spinal surgery in the treatment of lumbar degenerative diseases: a bibliometric and visualization study. Orthop Surg, 2022, 14(4): 635-643.
6.	Lee CW, Yoon KJ, Kim SW. Percutaneous endoscopic decompression in lumbar canal and lateral recess stenosis-the surgical learning curve. Neurospine, 2019, 16(1): 63-71.
7.	Park SM, Kim HJ, Kim GU, et al. Learning curve for lumbar decompressive laminectomy in biportal endoscopic spinal surgery using the cumulative summation test for learning curve. World Neurosurg, 2019, 122: e1007-e1013.
8.	Xu S, Wu H, Liu H, et al. Unilateral biportal endoscopic decompression for two-level adjacent lumbar spinal stenosis through a single sliding approach: technical report and early follow-up. J Orthop Surg Res, 2025, 20(1): 1067. doi: 10.1186/s13018-025-06480-x.
9.	Tan H, Liu Y, Li G, et al. Unilateral biportal endoscopic decompression for degenerative lumbar spinal stenosis under local anesthesia in elderly patients with medical comorbidities. Orthop Surg, 2025, 17(8): 2362-2370.
10.	Kim SK, Kang SS, Hong YH, et al. Clinical comparison of unilateral biportal endoscopic technique versus open microdiscectomy for single-level lumbar discectomy: a multicenter, retrospective analysis. J Orthop Surg Res, 2018, 13(1): 22. doi: 10.1186/s13018-018-0725-1.
11.	Min WK, Kim JE, Choi DJ, et al. Clinical and radiological outcomes between biportal endoscopic decompression and microscopic decompression in lumbar spinal stenosis. J Orthop Sci, 2020, 25(3): 371-378.
12.	Zheng B, Xu S, Guo C, et al. Efficacy and safety of unilateral biportal endoscopy versus other spine surgery: A systematic review and meta-analysis. Front Surg, 2022, 9: 911914. doi: 10.3389/fsurg.2022.911914.
13.	Pao JL. A review of unilateral biportal endoscopic decompression for degenerative lumbar canal stenosis. Int J Spine Surg, 2021, 15(suppl 3): S65-S71.
14.	Pranata R, Lim MA, Vania R, et al. Biportal endoscopic spinal surgery versus microscopic decompression for lumbar spinal stenosis: a systematic review and meta-analysis. World Neurosurg, 2020, 138: e450-e458.
15.	Ye Y, Jin S, Zou Y, et al. Biomechanical evaluation of lumbar spondylolysis repair with various fixation options: A finite element analysis. Front Bioeng Biotechnol. 2022, 10: 1024159. doi: 10.3389/fbioe.2022.1024159.
16.	Li J, Xu W, Zhang X, et al. Biomechanical role of osteoporosis affects the incidence of adjacent segment disease after percutaneous transforaminal endoscopic discectomy. J Orthop Surg Res, 2019, 14(1): 131. doi: 10.1186/s13018-019-1166-1.
17.	Song C, Chang H, Zhang D, et al. Biomechanical evaluation of oblique lumbar interbody fusion with various fixation options: a finite element analysis. Orthop Surg, 2021, 13(2): 517-529.
18.	Campbell JQ, Coombs DJ, Rao M, et al. Automated finite element meshing of the lumbar spine: Verification and validation with 18 specimen-specific models. J Biomech, 2016, 49(13): 2669-2676.
19.	Dreischarf M, Zander T, Shirazi-Adl A, et al. Comparison of eight published static finite element models of the intact lumbar spine: predictive power of models improves when combined together. J Biomech, 2014, 47(8): 1757-1766.
20.	Shim CS, Park SW, Lee SH, et al. Biomechanical evaluation of an interspinous stabilizing device, locker. Spine (Phila Pa 1976), 2008, 33(22): E820-E827.
21.	Yamamoto I, Panjabi MM, Crisco T, et al. Three-dimensional movements of the whole lumbar spine and lumbosacral joint. Spine (Phila Pa 1976), 1989, 14(11): 1256-1260.
22.	Lorio M, Kim C, Araghi A, et al. International society for the advancement of spine surgery policy 2019-surgical treatment of lumbar disc herniation with radiculopathy. Int J Spine Surg, 2020, 14(1): 1-17.
23.	Ren C, Qin R, Li Y, et al. Microendoscopic discectomy combined with annular suture versus percutaneous transforaminal endoscopic discectomy for lumbar disc herniation: a prospective observational study. Pain Physician. 2020, 23(6): E713-E721.
24.	程偉, 邵榮學, 朱承躍, 等. 單側雙通道內鏡下經對側入路治療腰椎間孔狹窄癥的臨床療效. 中國骨傷, 2024, 37(4): 331-337.
25.	Li K, Zhang Z, Ran J, et al. Unilateral endoscopic and unilateral biportal endoscopic surgery for lumbar spinal stenosis: a systematic review and meta-analysis. Front Surg, 2025, 12: 1585783. doi: 10.3389/fsurg.2025.1585783.
26.	Shi Z, Shi L, Chen X, et al. The biomechanical effect on the adjacent L₄/L₅ segment of S₁ superior facet arthroplasty: a finite element analysis for the male spine. J Orthop Surg Res, 2021, 16(1): 391. doi: 10.1186/s13018-021-02540-0.
27.	Yang JH, Lee KJ, Lee SY, et al. Relationship of the iliac crest height with subsidence after oblique lateral interbody fusion at L_4-5: A quantitative and categorical analysis. J Clin Med, 2024, 13(20): 6223. doi: 10.3390/jcm13206223.
28.	Jelec V, Turner R, Frani? M, et al. Facet orientation and tropism: association with accelerated degeneration of stabilizing structures in lower lumbar spine. Acta Clinica Croatica, 2016, 55(1): 117-124.
29.	Li W, Han J, Xin Q, et al. Finite element mechanical analysis of ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery. J Orthop Surg Res, 2023, 18(1): 979. doi: 10.1186/s13018-023-04476-z.
30.	Rahmani MS, Terai H, Akhgar J, et al. Anatomical analysis of human ligamentum flavum in the cervical spine: Special consideration to the attachments, coverage, and lateral extent. J Orthop Sci, 2017, 22(6): 994-1000.

1. Parker SL, Godil SS, Mendenhall SK, et al. Two-year comprehensive medical management of degenerative lumbar spine disease (lumbar spondylolisthesis, stenosis, or disc herniation): a value analysis of cost, pain, disability, and quality of life: clinical article. J Neurosurg Spine, 2014, 21(2): 143-149.
2. Shi HX, Gao YJ, Wang SR. Electroacupuncture in non-surgical management of lumbar spinal stenosis: mechanistic potential in attenuating ligamentum flavum thickening via inflammatory factor modulation. Front Immunol, 2025, 16: 1644394. doi: 10.3389/fimmu.2025.1644394.
3. 高景華, 劉代遠, 李路廣, 等. 《腰椎管狹窄癥中西醫結合診療指南(2023年)》解讀. 中國中醫骨傷科雜志, 2025, 33(1): 84-87.
4. Wu X, Pan H, Wang H, et al. Unilateral biportal endoscopic in spine surgery: a global bibliometric analysis of research trends and influences. Eur Spine J, 2025. doi: 10.1007/s00586-025-09002-9.
5. Chu PL, Wang T, Zheng JL, et al. Global and current research trends of unilateral biportal endoscopy/biportal endoscopic spinal surgery in the treatment of lumbar degenerative diseases: a bibliometric and visualization study. Orthop Surg, 2022, 14(4): 635-643.
6. Lee CW, Yoon KJ, Kim SW. Percutaneous endoscopic decompression in lumbar canal and lateral recess stenosis-the surgical learning curve. Neurospine, 2019, 16(1): 63-71.
7. Park SM, Kim HJ, Kim GU, et al. Learning curve for lumbar decompressive laminectomy in biportal endoscopic spinal surgery using the cumulative summation test for learning curve. World Neurosurg, 2019, 122: e1007-e1013.
8. Xu S, Wu H, Liu H, et al. Unilateral biportal endoscopic decompression for two-level adjacent lumbar spinal stenosis through a single sliding approach: technical report and early follow-up. J Orthop Surg Res, 2025, 20(1): 1067. doi: 10.1186/s13018-025-06480-x.
9. Tan H, Liu Y, Li G, et al. Unilateral biportal endoscopic decompression for degenerative lumbar spinal stenosis under local anesthesia in elderly patients with medical comorbidities. Orthop Surg, 2025, 17(8): 2362-2370.
10. Kim SK, Kang SS, Hong YH, et al. Clinical comparison of unilateral biportal endoscopic technique versus open microdiscectomy for single-level lumbar discectomy: a multicenter, retrospective analysis. J Orthop Surg Res, 2018, 13(1): 22. doi: 10.1186/s13018-018-0725-1.
11. Min WK, Kim JE, Choi DJ, et al. Clinical and radiological outcomes between biportal endoscopic decompression and microscopic decompression in lumbar spinal stenosis. J Orthop Sci, 2020, 25(3): 371-378.
12. Zheng B, Xu S, Guo C, et al. Efficacy and safety of unilateral biportal endoscopy versus other spine surgery: A systematic review and meta-analysis. Front Surg, 2022, 9: 911914. doi: 10.3389/fsurg.2022.911914.
13. Pao JL. A review of unilateral biportal endoscopic decompression for degenerative lumbar canal stenosis. Int J Spine Surg, 2021, 15(suppl 3): S65-S71.
14. Pranata R, Lim MA, Vania R, et al. Biportal endoscopic spinal surgery versus microscopic decompression for lumbar spinal stenosis: a systematic review and meta-analysis. World Neurosurg, 2020, 138: e450-e458.
15. Ye Y, Jin S, Zou Y, et al. Biomechanical evaluation of lumbar spondylolysis repair with various fixation options: A finite element analysis. Front Bioeng Biotechnol. 2022, 10: 1024159. doi: 10.3389/fbioe.2022.1024159.
16. Li J, Xu W, Zhang X, et al. Biomechanical role of osteoporosis affects the incidence of adjacent segment disease after percutaneous transforaminal endoscopic discectomy. J Orthop Surg Res, 2019, 14(1): 131. doi: 10.1186/s13018-019-1166-1.
17. Song C, Chang H, Zhang D, et al. Biomechanical evaluation of oblique lumbar interbody fusion with various fixation options: a finite element analysis. Orthop Surg, 2021, 13(2): 517-529.
18. Campbell JQ, Coombs DJ, Rao M, et al. Automated finite element meshing of the lumbar spine: Verification and validation with 18 specimen-specific models. J Biomech, 2016, 49(13): 2669-2676.
19. Dreischarf M, Zander T, Shirazi-Adl A, et al. Comparison of eight published static finite element models of the intact lumbar spine: predictive power of models improves when combined together. J Biomech, 2014, 47(8): 1757-1766.
20. Shim CS, Park SW, Lee SH, et al. Biomechanical evaluation of an interspinous stabilizing device, locker. Spine (Phila Pa 1976), 2008, 33(22): E820-E827.
21. Yamamoto I, Panjabi MM, Crisco T, et al. Three-dimensional movements of the whole lumbar spine and lumbosacral joint. Spine (Phila Pa 1976), 1989, 14(11): 1256-1260.
22. Lorio M, Kim C, Araghi A, et al. International society for the advancement of spine surgery policy 2019-surgical treatment of lumbar disc herniation with radiculopathy. Int J Spine Surg, 2020, 14(1): 1-17.
23. Ren C, Qin R, Li Y, et al. Microendoscopic discectomy combined with annular suture versus percutaneous transforaminal endoscopic discectomy for lumbar disc herniation: a prospective observational study. Pain Physician. 2020, 23(6): E713-E721.
24. 程偉, 邵榮學, 朱承躍, 等. 單側雙通道內鏡下經對側入路治療腰椎間孔狹窄癥的臨床療效. 中國骨傷, 2024, 37(4): 331-337.
25. Li K, Zhang Z, Ran J, et al. Unilateral endoscopic and unilateral biportal endoscopic surgery for lumbar spinal stenosis: a systematic review and meta-analysis. Front Surg, 2025, 12: 1585783. doi: 10.3389/fsurg.2025.1585783.
26. Shi Z, Shi L, Chen X, et al. The biomechanical effect on the adjacent L₄/L₅ segment of S₁ superior facet arthroplasty: a finite element analysis for the male spine. J Orthop Surg Res, 2021, 16(1): 391. doi: 10.1186/s13018-021-02540-0.
27. Yang JH, Lee KJ, Lee SY, et al. Relationship of the iliac crest height with subsidence after oblique lateral interbody fusion at L_4-5: A quantitative and categorical analysis. J Clin Med, 2024, 13(20): 6223. doi: 10.3390/jcm13206223.
28. Jelec V, Turner R, Frani? M, et al. Facet orientation and tropism: association with accelerated degeneration of stabilizing structures in lower lumbar spine. Acta Clinica Croatica, 2016, 55(1): 117-124.
29. Li W, Han J, Xin Q, et al. Finite element mechanical analysis of ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery. J Orthop Surg Res, 2023, 18(1): 979. doi: 10.1186/s13018-023-04476-z.
30. Rahmani MS, Terai H, Akhgar J, et al. Anatomical analysis of human ligamentum flavum in the cervical spine: Special consideration to the attachments, coverage, and lateral extent. J Orthop Sci, 2017, 22(6): 994-1000.

Chinese Journal of Reparative and Reconstructive Surgery

Impact of lamina formation range on lumbar biomechanics in unilateral biportal endoscopic spine surgery: a finite element analysis for surgical optimization

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