Clinical trials have demonstrated that kilohertz-frequency transcutaneous spinal cord stimulation (TSCS) can be used to facilitate the recovery of sensory-motor function for patients with spinal cord injury, whereas the neural mechanism of TSCS is still undetermined so that the choice of stimulation parameters is largely dependent on the clinical experience. In this paper, a finite element model of transcutaneous spinal cord stimulation was used to calculate the electric field distribution of human spinal cord segments T ₁₂ to L ₂, whereas the activation thresholds of spinal fibers were determined by using a double-cable neuron model. Then the variation of activation thresholds was obtained by varying the carrier waveform, the interphase delay, the modulating frequency, and the modulating pulse width. Compared with the sinusoidal carrier, the usage of square carrier could significantly reduce the activation threshold of dorsal root (DR) fibers. Moreover, the variation of activation thresholds was no more than 1 V due to the varied modulating frequency and decreases with the increased modulating pulse width. For a square carrier at 10 kHz modulated by rectangular pulse with the frequency of 50 Hz and the pulse width of 1 ms, the lowest activation thresholds of DR fibers and dorsal column fibers were 27.6 V and 55.8 V, respectively. An interphase delay of 5 μs was able to reduce the activation thresholds of the DR fibers to 20.1 V. The simulation results can lay a theoretical foundation on the selection of TSCS parameters in clinical trials.
Humans ; Spinal Cord Stimulation/methods* ; Nerve Fibers/physiology* ; Finite Element Analysis ; Spinal Cord/physiology* ; Computer Simulation ; Spinal Cord Injuries/physiopathology* ; Lumbosacral Region ; Lumbar Vertebrae ; Transcutaneous Electric Nerve Stimulation/methods* ; Models, Neurological

In order to investigate the mechanical response of lumbar vertebrae during gait cycle in adolescents with idiopathic scoliosis (AIS), the present study was based on computed tomography (CT) data of AIS patients to construct model of the left support phase (ML) and model of the right support phase (MR), respectively. Firstly, material properties, boundary conditions and load loading were set to simulate the lumbar vertebra-pelvis model. Then, the difference of stress and displacement in the lumbar spine between ML and MR was compared based on the stress and displacement cloud map. The results showed that in ML, the lumbar stress was mostly distributed on the convex side, while in MR, it was mostly distributed on the concave side. The stress of the two types of stress mainly gathered near the vertebral arch plate, and the stress of the vertebral arch plate was transmitted to the vertebral body through the pedicle with the progress of gait. The average stress of the intervertebral tissue in MR was greater than that in ML, and the difference of stress on the convex and convex side was greater. The displacement of lumbar vertebrae in ML decreased gradually from L1 to L5. The opposite is true in MR. In conclusion, this study can accurately quantify the stress on the lumbar spine during gait, and may provide guidance for brace design and clinical decision making.
Humans ; Lumbar Vertebrae/diagnostic imaging* ; Scoliosis/diagnostic imaging* ; Adolescent ; Gait/physiology* ; Biomechanical Phenomena ; Tomography, X-Ray Computed ; Stress, Mechanical ; Female ; Male

The lumbar intervertebral disc exhibits a complex physiological structure with interactions between various segments, and its components are extremely complex. The material properties of different components in the lumbar intervertebral disc, especially the water content (undergoing dynamic change as influenced by age, degeneration, mechanical loading, and proteoglycan content) - critically determine its mechanical properties. When the lumbar intervertebral disc is under continuous pressure, water seeps out, and after the pressure is removed, water re-infiltrates. This dynamic fluid exchange process directly affects the mechanical properties of the lumbar intervertebral disc, while previous isotropic modeling methods have been unable to accurately reflect such solid-liquid phase behaviors. To explore the load-bearing mechanism of the lumbar intervertebral disc and establish a more realistic mechanical model of the lumbar intervertebral disc, this study developed a solid-liquid biphasic, fiber-reinforced finite element model. This model was used to simulate the four movements of the human lumbar spine in daily life, namely flexion, extension, axial rotation, and lateral bending. The fluid pressure, effective solid stress, and liquid pressure-bearing ratio of the annulus fibrosus and nucleus pulposus of different lumbar intervertebral discs were compared and analyzed under the movements. Under all the movements, the fluid pressure distribution was closer to the nucleus pulposus, while the effective solid stress distribution was more concentrated in the outer annulus fibrosus. In terms of fluid pressure, the maximum fluid pressure of the lumbar intervertebral disc during lateral bending was 1.95 MPa, significantly higher than the maximum fluid pressure under other movements. Meanwhile, the maximum effective solid stress of the lumbar intervertebral disc during flexion was 2.43 MPa, markedly higher than the maximum effective solid stress under other movements. Overall, the liquid pressure-bearing ratio under axial rotation was smaller than that under other movements. Based on the solid-liquid biphasic modeling method, this study more accurately revealed the dominant role of the liquid phase in the daily load-bearing process of the lumbar intervertebral disc and the solid-phase mechanical mechanism of the annulus fibrosus load-bearing, and more effectively predicted the solid-liquid phase co-load-bearing mechanism of the lumbar intervertebral disc in daily life.
Humans ; Finite Element Analysis ; Intervertebral Disc/physiology* ; Lumbar Vertebrae/physiology* ; Weight-Bearing/physiology* ; Biomechanical Phenomena ; Stress, Mechanical ; Computer Simulation ; Models, Biological

Lumbar disc (LD) herniation and aging are prevalent conditions that can result in substantial morbidity. This study aimed to clarify the mechanisms connecting the LD aging and herniation, particularly focusing on cellular senescence and molecular alterations in the nucleus pulposus (NP). We performed a detailed analysis of NP samples from a diverse cohort, including individuals of varying ages and those with diagnosed LD herniation. Our methodology combined histological assessments with single-nucleus RNA sequencing to identify phenotypic and molecular changes related to NP aging and herniation. We discovered that cellular senescence and a decrease in nucleus pulposus progenitor cells (NPPCs) are central to both processes. Additionally, we found an age-related increase in NFAT1 expression that promotes NPPC senescence and contributes to both aging and herniation of LD. This research offers fresh insights into LD aging and its associated pathologies, potentially guiding the development of new therapeutic strategies to target the root causes of LD herniation and aging.
Intervertebral Disc Displacement/metabolism* ; Humans ; Aging/pathology* ; Nucleus Pulposus/pathology* ; Male ; Female ; Transcriptome ; Middle Aged ; Lumbar Vertebrae/pathology* ; Adult ; Cellular Senescence ; Stem Cells/pathology* ; Aged ; Intervertebral Disc Degeneration/metabolism*

OBJECTIVE: To determine the prevalence of lumbar spondylolysis (LS) and the proportion of spondylolytic spondylolisthesis (SS) in China, and to evaluate the musculoskeletal status of patients with LS and SS. METHODS: Spine Computed Tomography (CT) images were collected from community populations aged 40 and above in a nationwide multi-center project. LS was diagnosed, and SS was graded by an experienced radiologist. Bone mineral density (BMD) and paraspinal muscle parameters were quantified based on CT images. RESULTS: One hundred and seventeen patients of a total of 3,317 individuals were diagnosed with LS, corresponding to a prevalence rate of 3.53%. 63 of the 1,214 males (5.18%) and 54 of the 2,103 females (2.57%) were diagnosed with LS. SS occurred in 64/121 vertebrae (52.89%). BMD was not associated with LS ( P = 0.341). The L5 extensor paraspinal muscle density was higher in the LS group than in the non-LS group. In the LS group, patients with SS had a smaller L5 paraspinal extensor muscle cross-sectional area than those without SS ( P = 0.003). CONCLUSION The prevalence of LS in Chinese adults was 3.53%, with prevalence rates of 5.18% in males and 2.57% in females. Patients with LS have higher muscle density, whereas those with SS have smaller muscle cross-sectional areas at the L5 level.
Humans ; Male ; Female ; Middle Aged ; China/epidemiology* ; Prevalence ; Adult ; Lumbar Vertebrae/diagnostic imaging* ; Spondylolysis/diagnostic imaging* ; Aged ; Bone Density ; Tomography, X-Ray Computed ; Aged, 80 and over ; Spondylolisthesis/epidemiology* ; East Asian People

OBJECTIVE: To investigate the short-term effectiveness of uni-portal non-coaxial spinal endoscopic surgery (UNSES) via crossing midline approach (CMA) in the treatment of free lumbar disc herniation (FLDH). METHODS: Between March 2024 and June 2024, 16 patients with FLDH were admitted and treated with UNSES via CMA. There were 9 males and 7 females with an average age of 55.1 years (range, 47-62 years). The disease duration was 8-30 months (mean, 15.6 months). The pathological segments was L _{3, 4} in 4 cases, L _{4, 5} in 5 cases, and L ₅, S ₁ in 7 cases. The preoperative pain visual analogue scale (VAS) score was 6.9±0.9 and the Oswestry disability index (ODI) was 57.22%±4.16%. The operation time, intraoperative bleeding volume, postoperative hospital stay, and incidence of complications were recorded. The spinal pain and functional status were evaluated by VAS score and ODI, and effectiveness was evaluated according to the modified MacNab criteria. CT and MRI were used to evaluate the effect of nerve decompression. RESULTS: All 16 patients underwent operation successfully without any complications. The operation time was 63-81 minutes (mean, 71.0 minutes). The intraoperative bleeding volume was 47.3-59.0 mL (mean, 55.0 mL). The length of hospital stay after operation was 3-4 days (mean, 3.5 days). All patients were followed up 1-3 months, with 15 cases followed up for 2 months and 14 cases for 3 months. The VAS score and ODI gradually decreased over time after operation, and there were significant differences between different time points ( P<0.05). At 3 months after operation, the effectiveness was rated as excellent in 12 cases and good in 2 cases according to the modified MacNab criteria, with an excellent and good rate of 100%. CT and MRI during follow-up showed a significant increase in the diameter and cross-sectional area of the spinal canal, indicating effective decompression of the canal. CONCLUSION When using UNSES to treat FLDH, choosing CMA for nerve decompression has the advantages of wide decompression range, large operating space, and freedom of operation. It can maximize the preservation of the articular process, avoid fracture and breakage of the isthmus, clearly display the exiting and traversing nerve root, and achieve good short-term effectiveness.
Humans ; Male ; Intervertebral Disc Displacement/diagnostic imaging* ; Middle Aged ; Female ; Lumbar Vertebrae/surgery* ; Endoscopy/methods* ; Treatment Outcome ; Operative Time ; Pain Measurement ; Length of Stay

OBJECTIVE: To investigate the short-term effectiveness of the anterior and middle columns in thoracolumbar tuberculosis reconstructed with whole autogenous spinous process-laminar bone through posterior approach. METHODS: The retrospective study included 78 patients with thoracolumbar tuberculosis who underwent posterior approach surgery and anterior and middle column bone graft reconstruction between January 2012 and May 2023. Based on the type of autogenous bone graft used, patients were divided into group A (whole autogenous spinous process-laminar bone graft, 38 cases) and group B (autogenous structural iliac bone graft, 40 cases). There was no significant difference of baseline data, such as age, gender, disease duration, involved segment of spinal tuberculosis, and preoperative erythrocyte sedimentation rate (ESR), C reactive protein (CRP), Oswestry disability index (ODI), visual analogue scale (VAS) score, the American Spinal Injury Association (ASIA) grade, segmental kyphotic angle, and intervertebral height between the two groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospital stays, ESR, CRP, VAS score, ODI, bone fusion time, ASIA grade for neurological status valuation, postoperative complications, change of segmental kyphotic angle, change of intervertebral height were recorded and compared between the two groups. RESULTS: The operation time in group A was significantly shorter than that in group B ( P<0.05); there was no significant difference in intraoperative blood loss, postoperative drainage, and hospital stays between the two groups ( P>0.05). All patients in the two groups were followed up 14-110 months (mean, 64.1 months); there was no significant difference in the follow-up time between the two groups ( P>0.05). The ESR, CRP, ODI, and VAS score at each time point after operation in both groups significantly improved when compared with those before operation, and further improved with the extension of time, the differences were significant ( P<0.05). There was no significant difference between the two groups ( P>0.05) except that the VAS score of group A was significantly better than that of group B at 3 days after operation ( P<0.05). There was no significant difference in fusion time between the two groups ( P>0.05). The neurological function of most patients improved after operation, and there was no significant difference in ASIA grade between the two groups at last follow-up ( P>0.05). There was no significant difference in segmental kyphosis angle and intervertebral height between the two groups at each time point ( P>0.05), and no significant difference in segmental kyphosis angle, intervertebral height correction and loss were found between the two groups ( P>0.05). In group A, there was 1 case of incision fat liquefaction and 1 case of incision infection; in group B, there was 1 case of deep venous thrombosis, 2 cases of pleural effusion, and 10 cases of pain in bone harvesting area; in both groups, there were 2 cases of gout caused by hyperuricemia. There was a significant difference in the incidence of pain in bone harvesting area between the two groups ( P<0.05), and there was no significant difference in the incidence of other complications between the two groups ( P>0.05). CONCLUSION Whole autogenous spinous process-laminar bone grafting is equivalent to structural iliac bone graft in reconstruction of the anterior and middle columns in thoracolumbar tuberculosis through posterior approach, effectively supporting the stability of the anterior and middle columns of the spine, while resulting in shorter operation time and less postoperative pain in bone harvesting area.
Humans ; Tuberculosis, Spinal/surgery* ; Thoracic Vertebrae/surgery* ; Lumbar Vertebrae/surgery* ; Bone Transplantation/methods* ; Retrospective Studies ; Male ; Female ; Treatment Outcome ; Plastic Surgery Procedures/methods* ; Adult ; Middle Aged ; Transplantation, Autologous ; Operative Time ; Ilium/transplantation*

OBJECTIVE: To investigate the effectiveness of digital three-dimensional (3D) assisted unilateral biportal endoscopy (UBE) in the treatment of highly isolated lumbar disc herniation (LDH) with translaminar approach. METHODS: The clinical data of 59 patients who met the selection criteria and underwent UBE treatment due to highly isolated LDH between January 2022 and December 2023 were retrospectively analyzed. Among them, 25 cases were treated with digital 3D assisted translaminar approach (observation group) and 34 cases were treated with interlaminar approach (control group). There was no significant difference in gender, age, disease duration, surgical segment, and preoperative visual analogue scale (VAS) score and Oswestry disability index (ODI) between the two groups ( P>0.05). The operation time, intraoperative blood loss, and lateral articular surface preservation rate were recorded and compared between the two groups. VAS score and ODI were used to evaluate the improvements of pain and function before operation and at 3 and 6 months after operation. The modified MacNab criteria was used to evaluate the effectiveness at last follow-up. RESULTS: One patient in the control group had dural tear, and the other patients had no nerve injury, infection, dural tear, or other related complications. There was no significant difference in operation time and intraoperative blood loss between the two groups ( P>0.05). Patients in both groups were followed up 6-13 months, with an average of 8.3 months. The lateral articular surface preservation rate in the observation group was significantly higher than that in the control group ( P<0.05). Three patients in the observation group and 2 patients in the control group had calf muscle venous thrombosis, which was cured after anticoagulant treatment with rivaroxaban and delayed exercise time. There was no recurrence or second operation during the follow-up period. The VAS score and ODI of the two groups at 3 and 6 months after operation significantly improved when compared with those before operation ( P<0.05). There was no significant difference between the two groups at each time point after operation ( P>0.05). At last follow-up, the effectiveness was evaluated according to the modified MacNab criteria, and there was no significant difference in the evaluation grade and excellent and good rate between the two groups ( P>0.05). CONCLUTION UBE via translaminar approach is safe and effective for the treatment of highly isolated LDH, which is beneficial to protect the facet joint, maintain spinal stability, and reduce soft tissue injury. With the assistance of digital 3D technique, preoperative planning can be performed accurately.
Humans ; Intervertebral Disc Displacement/diagnostic imaging* ; Lumbar Vertebrae/diagnostic imaging* ; Male ; Retrospective Studies ; Female ; Endoscopy/methods* ; Treatment Outcome ; Middle Aged ; Adult ; Imaging, Three-Dimensional ; Operative Time ; Pain Measurement

OBJECTIVE: To summarize the advances in MRI-based bone quality scoring systems and their clinical applications. METHODS: A comprehensive literature review was conducted on recent studies related to the MRI-based bone quality scoring system, focusing on measurement methods, influencing factors, and clinical significance. RESULTS: Osteoporosis has a high incidence in China, significantly impacting patients' quality of life and the postoperative outcomes of related orthopedic surgeries. Early identification of osteoporosis holds important clinical significance. In recent years, both domestic and international research has enriched the MRI-based bone quality scoring systems, which includes vertebral bone quality scoring, endplate bone quality scoring, and pedicle bone quality scoring. Compared to the "gold standard" of bone density measurement, dual-energy X-ray absorptiometry, the bone quality scoring systems demonstrate good efficacy in identifying abnormal bone mass and predicting postoperative complications, while being less influenced by degenerative changes in the lumbar spine, indicating its important clinical application value. CONCLUSION The MRI-based bone quality scoring systems have good value in clinical applications. However, current studies are mostly retrospective cohort and case-control studies, which carry a risk of bias. The clinical application value needs further clarification through meta-analysis and large-scale prospective studies.
Humans ; Magnetic Resonance Imaging/methods* ; Bone Density ; Osteoporosis/diagnosis* ; Absorptiometry, Photon ; Bone and Bones/diagnostic imaging* ; Lumbar Vertebrae/diagnostic imaging* ; Quality of Life ; Postoperative Complications

OBJECTIVE: To explore decompression strategies for lateral lumbar spinal stenosis under unilateral biportal endoscopy (UBE) assistance. METHODS: A clinical data of 86 patients with lateral lumbar stenosis treated with UBE-assisted intervertebral decompression between September 2022 and December 2023 was retrospectively analyzed. There were 42 males and 44 females with an average age of 63.6 years (range, 45-79 years). The disease duration ranged from 6 to 14 months (mean, 8.5 months). Surgical levels included L _{2, 3} in 3 cases, L _{3, 4} in 26 cases, L _{4, 5} in 42 cases, and L ₅, S ₁ in 15 cases. According to Lee's grading system, there were 21 cases of grade 1, 37 cases of grade 2, and 28 cases of grade 3 for lumbar spinal stenosis. Based on the location of stenosis and clinical symptoms, the 33 cases underwent interlaminar approach, 7 cases underwent interlaminar approach with auxiliary third incision, 26 cases underwent contralateral inclinatory approach, and 20 cases underwent paraspinal approach; then, the corresponding decompression procedures were performed. Visual analogue scale (VAS) score was used to evaluate lower back/leg pain before operation and at 1 and 3 months after operation, while Oswestry disability index (ODI) was used to evaluate spinal function. At 3 months after operation, the effectiveness was evaluated using the modified MacNab evaluation criteria. The spinal stenosis and decompression were evaluated based on Lee's grading system using lumbar MRI before operation and at 3 months after operation. RESULTS: All procedures were successfully completed with mean operation time of 95.1 minutes (range, 57-166 minutes). Dural tears occurred in 2 cases treated with interlaminar approach with auxiliary third incision. All incisions healed by first intention. All patients were followed up 3-10 months (mean, 5.9 months). The clinical symptoms of the patients relieved to varying degrees. The VAS scores and ODI of lower back and leg pain at 1 and 3 months after operation significantly improved compared to preoperative levels ( P<0.05), and the indicators at 3 months significantly improved than that at 1 month ( P<0.05). According to the modified MacNab evaluation criteria, the effectiveness at 3 months after operation was rated as excellent in 52 cases, good in 21 cases, and poor in 13 cases, with an excellent and good rate of 84.9%. No lumbar instability was detected on flexion-extension X-ray films during follow-up. The Lee's grading of lateral lumbar stenosis at 2 days after operation showed significant improvement compared to preoperative grading ( P<0.05). CONCLUSION For lateral lumbar spinal stenosis, UBE-assisted decompression of the spinal canal requires the selection of interlaminar approach, interlaminar approach with auxiliary third incision, contralateral inclinatory approach, and paraspinal approach based on preoperative imaging findings and clinical symptoms to achieve better effectiveness.
Humans ; Spinal Stenosis/diagnostic imaging* ; Female ; Male ; Middle Aged ; Decompression, Surgical/methods* ; Aged ; Lumbar Vertebrae/surgery* ; Endoscopy/methods* ; Retrospective Studies ; Treatment Outcome