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

Extracellular vesicles (EVs), defined as cell-secreted nanoscale vesicles that carry bioactive molecules, have emerged as a promising therapeutic strategy in tumor and tissue regeneration. Their potential in repairing intervertebral disc degeneration (IDD) through multidimensional regulatory mechanisms is a rapidly advancing field of research. This paper provided an overview of the mechanisms of EVs in IDD repair, thoroughly reviewed recent literature on EVs for IDD, domestically and internationally, and summarized their therapeutic mechanisms. In IDD repair, EVs could act through different mechanisms at the molecular, cellular, and tissue levels. At the molecular level, EVs could treat IDD by inhibiting inflammatory reactions, suppressing oxidative stress, and regulating the synthesis and decomposition of extracellular matrix. At the cellular level, EVs could treat IDD by inhibiting cellular pyroptosis, ferroptosis, and apoptosis and promoting cell proliferation and differentiation. At the tissue level, EVs could treat IDD by inhibiting neovascularization. EVs have a strong potential for clinical application in the treatment of IDD and deserve more profound study.
Extracellular Vesicles/physiology* ; Humans ; Intervertebral Disc Degeneration/therapy* ; Apoptosis ; Cell Proliferation ; Oxidative Stress ; Cell Differentiation ; Extracellular Matrix/metabolism* ; Animals ; Pyroptosis

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

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 evaluate the safety and effectiveness of anterior cervical discectomy and fusion (ACDF) by using zero-profile anchored cage (ZAC) in treatment of consecutive three-level cervical spondylosis, by comparing with plate-cage construct (PCC). METHODS: A clinical data of 65 patients with cervical spondylosis admitted between January 2020 and December 2022 and met the selection criteria was retrospectively analyzed. During consecutive three-level ACDF, 35 patients were fixed with ZAC (ZAC group) and 30 patients with PCC (PCC group). There was no significant difference in baseline data between the two groups ( P>0.05), including gender, age, body mass index, surgical segment, preoperative Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), visual analogue scale (VAS) score, prevertebral soft tissue thickness (PSTT), cervical lordosis, and surgical segmental angle. The operation time, intraoperative blood loss, hospital stay, clinical indicators (JOA score, NDI, VAS score), and radiological indicators (cervical lordosis, surgical segmental angle, implant subsidence, surgical segment fusion, and adjacent segment degeneration), and the postoperative complications [swelling of the neck (PSTT), dysphagia] were recorded and compared between the two groups. RESULTS: Patients in both groups were followed up 24-39 months. There was no significant difference in follow-up duration between the two groups ( P>0.05). The operation time and intraoperative blood loss were lower in ZAC group than in PCC group, and the length of hospital stay was longer, but there was no significant difference ( P>0.05). At each time point after operation, both groups showed significant improvements in JOA score, VAS score, and NDI compared with preoperative scores ( P<0.05), but there was no significant difference between the two groups at each time point after operation ( P>0.05). Both groups showed an increase in PSTT at 3 days and 3, 6 months after operation compared to preoperative levels ( P<0.05), but returned to preoperative levels at last follow-up ( P>0.05). The PSTT at 3 days and 3 months after operation were significantly lower in ZAC group than in PCC group ( P<0.05), and there was no significant difference between the two groups at 6 months and at last follow-up ( P>0.05). The incidences of dysphagia at 3 days and 3 months were significantly lower in ZAC group than in PCC group ( P<0.05), while no significant difference was observed at 6 months and last follow-up between the two groups ( P>0.05). There was no postoperative complication in both groups including hoarseness, esophageal injury, cough, or hematoma. Both groups showed improvement in cervical lordosis and surgical segmental angle compared to preoperative levels, with a trend of loss during follow-up. The cervical lordosis loss and surgical segmental angle loss were significantly more in the ZAC group than in PCC group ( P<0.05). The incidence of implante subsidence was significantly higher in ZAC group than in PCC group ( P<0.05). There was no significant difference between the ZAC group and PCC group in the incidences of surgical segment fusion and adjacent segment degeneration ( P>0.05). CONCLUSION In consecutive three-level ACDF, both ZAC and PCC can achieve satisfactory effectiveness. The former can reduce the incidence of postoperative dysphagia, while the latter can better maintain cervical curvature and reduce the incidence of implant subsidence.
Humans ; Spondylosis/surgery* ; Cervical Vertebrae/surgery* ; Spinal Fusion/instrumentation* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Diskectomy/instrumentation* ; Bone Plates ; Treatment Outcome ; Adult ; Aged ; Internal Fixators ; Operative Time ; 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 explore the anatomical parameters of the cervical uncinate process "inflection point" through cervical CT angiography (CTA) and MRI measurements, offering a reliable and safe anatomical landmark for anterior cervical decompression surgery. METHODS: A retrospective analysis was conducted on the cervical CTA and MRI imaging data of normal adults who met the selection criteria between January 2020 and January 2024. The CTA dataset included 326 cases, with 200 males and 126 females, aged 22-55 years (mean, 46.7 years). The MRI dataset included 300 cases, with 200 males and 100 females, aged 18-55 years (mean, 43.7 years). Based on the CTA data, three-dimensional models of C ₃-C ₇ were constructed, and the following measurements were obtained from the superior view: uncinate process "inflection point" to vertebral artery distance (UIVD), uncinate process tip to vertebral artery distance (UTVD), uncinate process "inflection point" to "inflection point" distance (UID), uncinate process long-axis to sagittal angle (ULSA), and uncinate process "inflection point" to transverse foramen-sagittal angle (UITSA). From the anterior view, the anterior uncinate process to sagittal angle (AUSA) was measured. From the posterior view, the posterior uncinate process to sagittal angle (PUSA) was measured. Based on the MRI data, uncinate process "inflection point" to dural sac distance (UIDD) and dural sac width (DSW) were measured. The trends in measurement parameters of C ₃-C ₇ were observed, and the differences in measurement parameters between genders and between the left and right sides of the same segment were compared, as well as the difference in UID and DSW within the same segment was compared. RESULTS: The measurement parameters from C ₃ to C ₇ in the CTA data showed a general increasing trend, with no significant difference between the left and right sides within the same segment ( P>0.05). The UIVD, UTVD, and UID were greater in males than in females, with significant differences observed in the UIVD and UTVD at C ₃ and C ₆ and UID at C ₃, C ₆, and C ₇ ( P<0.05). The MRI measured DSW showed a general increasing trend from C ₃ to C ₇, and the DSW at C ₆ was greater in females than in males, with a significant difference ( P<0.05). The UIDD showed a gradual decreasing trend, with the smallest value at C ₆. There was no significant difference between males and females or between the left and right sides within the same segment ( P>0.05). The UID was greater than the DSW at C ₃-C ₇, and the differences were significant ( P<0.05). CONCLUSION The uncinate process "inflection point" is a constant anatomical structure located at the anteromedial aspect of the uncinate process tip and laterally to the dural sac. It maintains a certain safe distance from the vertebral artery. As a decompression landmark in anterior cervical spine surgery, it not only ensures surgical safety but also guarantees complete decompression.
Humans ; Adult ; Male ; Female ; Middle Aged ; Retrospective Studies ; Cervical Vertebrae/surgery* ; Magnetic Resonance Imaging ; Decompression, Surgical/methods* ; Young Adult ; Adolescent ; Computed Tomography Angiography ; Imaging, Three-Dimensional ; Vertebral Artery/anatomy & histology* ; Anatomic Landmarks/diagnostic imaging*

OBJECTIVE: To investigate correlation between preoperative C ₂ slope (C2S) and effectiveness at 2 years after short-segment anterior cervical discectomy and fusion (ACDF), with the aim of providing reliable indicators for predicting effectiveness. METHODS: One hundred and eighteen patients with cervical spondylotic myelopathy, who received short-segment ACDF between January 2018 and December 2022 and met the selection criteria, were enrolled in the study. There were 46 males and 72 females, aged from 26 to 80 years, with a mean age of 53.6 years. The operative duration was (127.6±33.46) minutes and the intraoperative blood loss was (34.75±30.40) mL. All patients were followed up 2 years. The pre- and post-operative Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) score, and visual analogue scale (VAS) score for pain were recorded. Based on the anteroposterior and lateral cervical X-ray films, the sagittal parameters of the cervical spine were measured [C ₂-C ₇ Cobb angle, C ₀-C ₂ Cobb angle, T ₁ slope, C2S, sagittal segmental angle (SSA) of the surgical segment, and average surgical disc height (ASDH) of the surgical segment]. Statistical analyses were performed to assess the differences in these indicators between pre- and post-operation, as well as the correlations between the preoperative C2S and the JOA score, NDI, and VAS score at 2 years after operation. The patients were allocated into group A (C2S >11.73°) and group B (C2S≤ 11.73°) according to the median value of the preoperative C2S (11.73°). The JOA score, NDI, and VAS score before operation and at 2 years after operation, as well as the differences between pre- and post-operative values (change values), were compared between the two groups. RESULTS: The T ₁ slope, C ₂-C ₇ Cobb angle, C ₀-C ₂ Cobb angle, SSA, and ASDH at immediate after operation and JOA score, NDI, and VAS score at 2 years after operation significantly improved in 118 patients when compared with preoperative ones ( P<0.05). Pearson correlation analysis showed that preoperative C2S was not correlated with JOA score and NDI at 2 years after operation ( P>0.05), but negatively correlated with VAS score ( P<0.05). There were 59 patients with preoperative C2S>11.73° (group A) and 59 with C2S≤11.73° (group B). There was no significant difference in preoperative JOA score, NDI, and VAS score between the two groups ( P>0.05). There were significant differences in VAS score at 2 year after operation and the change value between the two groups ( P<0.05); there was no significant difference in the JOA score and NDI ( P>0.05). CONCLUSION Patients with cervical spondylotic myelopathy and a higher preoperative C2S exhibited superior long-term pain relief and effectiveness following short-segment ACDF.
Humans ; Male ; Spinal Fusion/methods* ; Female ; Middle Aged ; Cervical Vertebrae/diagnostic imaging* ; Diskectomy/methods* ; Aged ; Adult ; Treatment Outcome ; Aged, 80 and over ; Spondylosis/diagnostic imaging* ; Pain Measurement ; Preoperative Period ; Follow-Up Studies

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