Objective Lumbar disc herniation is among the most common and disabling spinal disorders, driven by the interplay of mechanical overload, structural failure, and cellular dysfunction. Despite advances in surgical interventions, achieving true biological repair of herniated discs remains a major clinical challenge. This review aims to critically examine the biomechanical landscape of disc herniation, focusing on how altered load transmission, tissue stiffness, and structural disruption influence cellular behavior and tissue regeneration. It further explores mechanobiological mechanisms governing repair and highlights emerging biomimetic models and technologies that integrate mechanical and biological insights to promote functional disc restoration.
Methods A comprehensive literature review was conducted using the Web of Science Core Collection, PubMed (National Library of Medicine), and ScienceDirect databases. The search was limited to peer-reviewed journal articles published in English and focused on studies related to lumbar disc herniation.
Results While decades of research have elucidated the biomechanical factors contributing to disc herniation, recent advances in mechanobiology have uncovered how mechanical cues influence cellular behavior, tissue repair, and degeneration. Evidence suggests that true disc regeneration cannot be achieved through biological replacement or mechanical stabilization alone; rather, it requires restoring functional biomechanics, specifically, the disc’s ability to sense, adapt to, and sustain physiological loading.
Conclusion Viewing disc herniation through a mechanobiological lens offers new opportunities to develop targeted therapies aimed at restoring both tissue integrity and load-bearing functionality, paving the way for more effective regenerative interventions.
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Integrating Structures and Biology: Cellular and Molecular Interactions with Functionally Graded Spinal Cage Designs Yuen Ho Cheng, Amy Libing Fu, Jessica Gaff, Gianluca Vadala, Amit Jain, Javad Tavakoli International Journal of Molecular Sciences.2026; 27(10): 4531. CrossRef
From mechanotransduction to manual therapy: advances in piezo/TRP channels and lumbar degeneration Zhennan Liu, Tianzhong Peng, Wenli Li, Manhua Zhu Frontiers in Physiology.2026;[Epub] CrossRef
Objective To evaluate the biomechanical characteristics of 2 anterior fixation techniques (clival plate fixation [CPF], transoral atlantoaxial reduction plate [TARP]) versus posterior occipitocervical fixation (POCF) for basilar invagination with atlantoaxial dislocation (BI-AAD), under varying atlantoaxial lateral mass cage heights (4–10 mm).
Methods Seven fresh cadaveric specimens (occiput to C3, Oc–C3) were tested in the following conditions: (1) intact state; (2) BI-AAD state; (3) BI-AAD+CPF; (4) BI-AAD+TARP fixation; (5) BI-AAD+POCF. A pure 1.5 N·m moment loads to specimens in flexion/extension, lateral bending and axial rotation. Range of motion (ROM) and neutral zone (NZ) values at Oc–C2 were calculated and compared.
Results ROM of the C1–2 segment under the intact and BI-AAD states were as follows: 9.3°±4.6° versus 21.3°±8.3° in flexion, 4.6°±1.9° versus 9.3°±3.8° in extension, 3.6°±2.2° versus 12.0°±6.5° in lateral bending, and 68.9°±14.4° versus 76.6°±6.6° in axial rotation, respectively. Compared with BI-AAD states, all internal fixation techniques significantly reduced the ROM of the Oc–C2 segment. TARP fixation exhibited larger ROM in flexion-extension. While in lateral bending and axial rotation, the ROM values for the anterior plate constructs were smaller than that of POCF, with a statistically significant difference observed between CPF and POCF. Cage height variations showed no significant impact on overall biomechanical stability.
Conclusion Anterior plate fixation techniques demonstrated superior resistance to lateral bending and rotational forces compared to posterior approaches, with clival plate fixation exhibiting optimal biomechanical stability for BI-AAD. Variations in cage height exhibited negligible impact on stability when internal fixation achieved adequate rigidity.
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Reducibility-Based Posterior Reduction and Fusion Strategies for Atlantoaxial Dislocation: A Clinical and Radiological Study Guipeng Zhao, Haotian Long, Dingyu Du, Dean Chou, Longyi Chen, Junting Hu, Hailong Feng, Qidong Liu, Jinping Liu Neurospine.2026; 23(2): 411. CrossRef
Objective Based on spinopelvic parameters and biomechanical principles, the pedicle-facet joint (PFJ) morphological characteristics of isthmic and degenerative spondylolisthesis were analyzed, and the mechanism of their onset and progression was discussed.
Methods This retrospective cross-sectional study included 194 patients with L5 spondylolysis or L5–S1 low-grade isthmic spondylolisthesis (IS group), 172 patients with L4–5 degenerative spondylolisthesis (DS group), and 366 patients with nonlumbar spondylolysis (NL group). The spinopelvic parameters and PFJ morphological parameters of the patients were measured, the differences in these parameters among and within the 3 groups were compared, and the correlations were analyzed.
Results Sacral slope (SS) and lumbar lordosis (LL) were the highest in the IS group, the second highest in the DS group, and the lowest in the NL group. Among the 3 groups, the L4 facet joint angle (FJA) was the largest in the IS group, the second largest in the NL group, and the smallest in the DS group. The L4 pedicle-facet joint angle (PFA) was the largest in the DS group, the second largest in the IS group, and the smallest in the NL group. Pearson correlation analysis showed that within each group, SS and LL were negatively correlated with FJA and positively correlated with PFA.
Conclusion This study found a correlation between the PFJ morphological characteristics of patients with lumbar spondylolisthesis and spinopelvic parameters, suggesting that the morphological characteristics of PFJs may be caused by varying stresses under different spinopelvic morphologies.
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Risk factors for recurrent lumbar disc herniation after percutaneous endoscopic lumbar discectomy: the role of spinopelvic parameters and facet joint degeneration Xiangdong Gong, Shiyong Wang, Rubin Yao, Lirong Ren, Shaobo Li, Baojia Yang, Jianrong He, Zhongjie Li, Feifei Liu, Yushan Ruan, Kaishun Yang, Ming zhang European Spine Journal.2026;[Epub] CrossRef
Clinical study on the 3D morphology and mechanical factors of lumbar facet joints in patients with degenerative lumbar spondylolisthesis Xiao Xiong, Yunsheng Wang, Da Shi, Tong Tong, Baoyue Zhang, Yilai Li, Linfeng Wang Bone & Joint Research.2026; 15(7): 880. CrossRef
Objective Interspinous spacer (ISS)-based and pedicle screw-rod dynamic fixator (PDF)-based topping-off devices have been applied in lumbar/lumbosacral fusion surgeries for preventing the development of proximal adjacent segment degeneration. However, little attention has been paid to sacroiliac joint (SIJ), which belongs to the adjacent joints. Accordingly, the objective of this study was to compare how these 2 topping-off devices affect the SIJ biomechanics.
Methods A validated, normal finite-element lumbopelvic model (L3–pelvis) was initially adjusted to simulate interbody fusion with rigid fixation at the L5–S1 level, and then the DIAM or BioFlex system was instrumented at the L4–5 level to establish the ISS-based or PDF-based topping-off model, respectively. All the developed models were loaded with moments of 4 physiological motions using hybrid loading protocol.
Results Compared with the rigid fusion model (without topping-off devices), range of motion and von-Mises stress at the SIJs were increased by 23.1%–64.1% and 23.6%–62.8%, respectively, for the ISS-based model and by 51.2%–126.7% and 50.4%–108.7%, respectively, for the PDF-based model.
Conclusion The obtained results suggest that the PDF-based topping-off device leads to higher increments in SIJ motion and stress than ISS-based topping-off device following lumbosacral fusion, implying topping-off technique could be linked to an increased risk of SIJ degeneration, especially when using PDF-based device.
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Biomechanical Effects of Osteoporosis on the Sacroiliac Joint After Lumbosacral Fusion Surgery Wei Fan, Chao Wang, Sheng-Nan Liu, Yu Zhang, Ming Zhang, Li-Xin Guo IRBM.2025; 46(2): 100877. CrossRef
Comparative efficacy of S2-alar-iliac versus iliac screw techniques in treating adult spinal deformity: a meta-analysis of postoperative outcomes and complications Amit Saraf, Sanjeev Kumar Jain, Sonika Sharma Asian Spine Journal.2025; 19(5): 847. CrossRef
Objective This study assessed biomechanical properties of pedicle screws enhanced or revised with 3 materials. We aimed to compare the efficacy of these materials in pedicle augmentation and revision.
Methods One hundred twenty human cadaveric vertebrae were utilized for in vitro testing. Vertebrae bone density was evaluated. Allograft bone particles (ABP), calcium phosphate cement (CPC), and demineralized bone matrix (DBM) were used to augment or revise pedicle screw. Post the implantation of pedicle screws, parameters such as insertional torque, pullout strength, cycles to failure and failure load were measured using specialized instruments.
Results ABP, CPC, and DBM significantly enhanced biomechanical properties of the screws. CPC augmentation showed superior properties compared to ABP or DBM. ABP-augmented screws had higher cycles to failure and failure loads than DBM-augmented screws, with no difference in pullout strength. CPC-revised screws exhibited similar strength to the original screws, while ABP-revised screws showed comparable cycles to failure and failure loads but lower pullout strength. DBM-revised screws did not match the original screws’ strength.
Conclusion ABP, CPC, and DBM effectively improve pedicle screw stability for pedicle augmentation. CPC demonstrated the highest efficacy, followed by ABP, while DBM was less effective. For pedicle revision, CPC is recommended as the primary choice, with ABP as an alternative. However, using DBM for pedicle revision is not recommended.
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Establishing and Validating Cervical and Lumbar Vertebral Bone Quality Thresholds for Predicting Mechanical Complications in Patients Undergoing Spinal Fusion: A Systematic Review and Meta-Analysis Omar Lubbad, Akram Hagos, Yahya El-Tahlawy, Laila Lubbad, Giuseppe Lambros Morassi, Nektarios K. Mazarakis Global Spine Journal.2026; 16(5): 2424. CrossRef
Objective To evaluate the biomechanical stability of anterior transarticular crossing screw (ATCS) and compare it with anterior transarticular screw (ATS) which may provide basic evidence for clinical application.
Methods Eight human fresh cadaveric specimens (occiput-C4) were tested with 5 conditions including the intact status, the injury status (type II odontoid fracture), the injury+ATS fixation status (traditional bilateral ATS fixation); the injury+unilateral ATCS fixation status; and the injury+bilateral ATCS fixation status. Specimens were applied to a pure moment of 1.5 Nm in flexion-extension, lateral bending, and axial rotation, respectively. The range of motions (ROMs) and the neutral zones (NZs) of C1 to C2 segment were calculated and compared between 5 status.
Results ATS and ATCS fixations significantly reduced the motions in all directions when compared with the intact and injury statues (p < 0.05). In flexion-extension, the ROMs of ATS, unilateral ATCS, and bilateral ATCS were 4.7° ± 2.5°, 4.1° ± 1.9°, and 3.2° ± 1.2°, respectively. Bilateral ATCS resulted in a significant decrease in ROM in flexion-extension when compared with ATS and unilateral ATCS (p = 0.035 and p = 0.023). In lateral bending and axial rotation, there was no significant difference in ROM between the 3 fixations (p > 0.05). Three fixations resulted in similar NZs in all directions (p > 0.05).
Conclusion ATCS is a biomechanically effective alternative or supplemental method for atlantoaxial instability.
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Objective Lumbar lateral interbody fusion (LLIF) allows placement of large interbody cages while preserving ligamentous structures important for stability. Multiple clinical and biomechanical studies have demonstrated the feasibility of stand-alone LLIF in single-level fusion. We sought to compare the stability of 4-level stand-alone LLIF utilizing wide (26 mm) cages with bilateral pedicle screw and rod fixation.
Methods Eight human cadaveric specimens of L1–5 were included. Specimens were attached to a universal testing machine (MTS 30/G). Flexion, extension, and lateral bending were attained by applying a 200 N load at a rate of 2 mm/sec. Axial rotation of ± 8° of the specimen was performed at 2°/sec. Three-dimensional specimen motion was recorded using an optical motion-tracking device. Specimens were tested in 4 conditions: (1) intact, (2) bilateral pedicle screws and rods, (3) 26-mm stand-alone LLIF, (4) 26-mm LLIF with bilateral pedicle screws and rods.
Results Compared to the stand-alone LLIF, bilateral pedicle screws and rods had 47% less range of motion in flexion-extension (p < 0.001), 21% less in lateral bending (p < 0.05), and 20% less in axial rotation (p = 0.1). The addition of bilateral posterior instrumentation to the stand-alone LLIF resulted in decreases of all 3 planes of motion: 61% in flexion-extension ( p < 0.001), 57% in lateral bending (p < 0.001), 22% in axial rotation (p = 0.002).
Conclusion Despite the biomechanical advantages associated with the lateral approach and 26 mm wide cages, stand-alone LLIF for 4-level fusion is not equivalent to pedicle screws and rods.
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Objective Lumbar cortical screw fixation (CSF), rather than pedicle screw fixation (PSF), has recently been attempted in lumbar interbody fusion. The purpose of our study was to evaluate the biomechanical stability of lumbar CSF using a finite element (FE) model.
Methods A 3-FE model, including the L1 to S1 levels, was designed to evaluate and compare the biomechanical stability of lumbar CSF and PSF in single-level lumbar interbody fusion at L4–5. Cortical or pedicle screws were inserted bilaterally, and posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) were modeled at L4–5, respectively. We compared the stability of CSF to that of PSF in these 2 different anatomic variations of PLIF, as well as in TLIF.
Results Lumbar CSF showed less stability than PSF in PLIF when the midline posterior ligaments were not preserved, but demonstrated similar stability when the ligaments were preserved. The range of motion (ROM) at the treated level in CSF was larger than that observed for PSF, in all PLIF and TLIF models. Furthermore, the ROM in the posterior ligament-sacrificing PLIF with CSF model was larger than the ROM in the posterior ligament-preserving PLIF with CSF or PSF model.
Conclusion Based on our FE analysis, the stability of CSF is comparable to that of PSF in PLIF and TLIF when the midline posterior ligaments are preserved.
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In surgical treatments of degenerative lumbar disc disease, arthrodesis is well known to be a gold standard; however various disadvantages related to elimination of the segmental motion and the procedures of fusion surgery have become a matter of concern. To this end, total disc replacement (TDR) was recently highlighted as one of alternative surgical modalities and being used widely.
However, although it has been almost 10 years since lumbar TDR was int- roduced and actively used in the clinic, its clinical usefulness is still in dispute. The authors review and put together the history, biomechanics, and currently available prostheses of lumbar TDR in the present study.
Some of the recent preliminary, mid-term and long-term clinical results of lumbar TDR in degenerative lumbar spine diseases are also reviewed. Lastly, we look out over the future prospect of lumbar TDR.
OBJECTIVE Total intervertebral disc replacement is designed to preserve motion and avoid limitations of fusion after removing local pathology. The authors report the results of a signle-center study to determine functional and radi- ologic outcomes associated with cervical total disc replacement versus those of cervical fusion. METHODS We retrospectively reviewed the charts and radiographs of patients who underwent a total intervertebral disc replacement(TDR) or a single-level anterior cervical fusion(ACDF) between January 1, 2004, and September 31, 2007. Clinical symptom was assessed using the Visual Analog Scale(VAS) of the neck and of the arm pain. Range of motion was determined by radiologic assessment of flexion-extension radiographs. Data were collected before surgery and at 6 weeks, 3, 6, 12, and 24 months after surgery.
RESULT: A total of 125 patients were identified with 63 having TDR(43 males and 20 females) and 62 having fusion(42 males and 20 females). The average age was 49.1 years(TDR) and 51.7 years(ACDF)(p=0.229). The mean neck pain VAS before surgery was 6.52(TDR) and 6.61(ACDF)(p=0.732). At 2-year follow-up, the average neck pain VAS for the TDR group was 1.59 and ACDF 1.85(p=0.168). The mean arm pain VAS before surgery was 6.37(TDR) and 6.60(ACDF)(p=0.335). At 2 years: 1.41(TDR) and 1.65(ACDF)(P = 0.148). More motion(an average of 9.00 degrees at 24 months) was retained after surgery in the TDR group than the fusion group at the treatment level.
There was no significant diffe- rence in motion at adjacent levels. CONCLUSION Total disc replacement maintained physiological segmental motion at the 2-year follow-up. The finding that there was no statistically significant difference between the groups in motion at adjacent levels must be verified on further studies.
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