Upper Lumbar Disc Herniation (ULDH) is a rare form of lumbar disc herniation, but its symptoms are more severe due to the conus medullaris and the tight spinal canal. Surgical intervention for these fragments is also considered demanding once they demonstrate high-grade downward migration into the "hidden zone" medial to the pedicle. Obstructions due to bone or dangers of damaging nerve tissue by retraction are common limitations of the classical minimally invasive methods. We report on the case of a 69-year-old man with an extreme down-migrated L1-L2 disc herniation (Lee classification Zone 4). The patient had severe left thigh pain and numbness and was unable to walk, with preoperative VAS and ODI scores of 7/10 and 74, respectively. A modified posterior transpedicular approach utilizing Unilateral Biportal Endoscopy (UBE) was successfully conducted. The use of the medial cortical wall of the pedicle as a natural navigational "Cortical Guidance" guides a direct path to the ventral pathology through minimal bone removal and results in true "Zero-Retraction" of the neural structures. Herniated fragments were totally resected postoperatively and the discectomy patient showed significant symptomatic improvement with VAS and ODI scores reduced to 1/10 and 12, respectively. At the 6-month follow-up, the patient had complete neurological recovery. The modified posterior transpedicular UBE technique is a safe, simple, and effective approach for the treatment of highly migrated ULDH and enables extensive decompression with maximal preservation of spinal stability.

ObjectiveTo evaluate the clinical efficacy of bilateral channel minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the management of lumbar degenerative diseases.MethodsA retrospective analysis was conducted of 68 patients diagnosed with lumbar degenerative diseases who underwent surgical intervention at Ningbo No.6 Hospital between April 2021 and February 2022. The patients were categorized into a traditional TLIF group (38 cases) and a bilateral channel MIS-TLIF group (30 cases). Comparative assessments were performed between the two groups in terms of surgical outcomes.ResultsAll surgical procedures were successfully performed and postoperative follow-up was maintained for (12.7 ± 1.7 months). Statistically significant differences were observed in operation time, intraoperative fluoroscopy frequency, intraoperative blood loss, postoperative drainage volume, and length of hospital stay between two groups. The VAS scores and ODI of the two groups measured at 7 days postoperatively and at the final follow-up were significantly lower than the preoperative values, with statistically significant differences. The fusion rates were 89.5% in the traditional group and 93.3% in the bilateral channel MIS-TLIF group, with no statistically significant differences.ConclusionBilateral channel MIS-TLIF is a feasible surgical procedure and it can reduce the surgical duration and radiation exposure associated with intraoperative fluoroscopy.

Background: Finegoldia magna is a common Gram-positive anaerobic coccus that forms part of the normal flora of the skin, oral cavity, and gastrointestinal tract. However, in certain clinical settings, such as disruption of the mucocutaneous barrier or immunosuppression, it can act as an opportunistic pathogen, accounting for approximately 5-12% of anaerobic infections, and may cause a variety of conditions, including skin and soft tissue infections, bone and joint infections, breast abscesses, and diabetic foot infections. Here, we present the first reported case of deep lumbar spine infection caused by Finegoldia magna due to improper acupuncture combined with cupping therapy. Case Presentation: We report the case of a 58-year-old patient with lumbar disk herniation who developed F. magna infection of the lumbar disk following acupuncture with wet cupping therapy. Post-debridement treatment with piperacillin-tazobactam lowered C-reactive protein levels. However, during follow-up, the patient reported persistent pain, and C-reactive protein levels increased again. Changing the antibiotic regimen to oral amoxicillin-clavulanate potassium combined with moxifloxacin improved and stabilized the symptoms. Conclusion: Our findings highlight the need for thorough cleaning and disinfection of tools and the patient's skin during acupuncture treatment. Moreover, as debridement of lumbar spine infections may yield false-positive results regarding antibiotic efficacy, we recommend at least 2 months of follow-up after debridement, as well as prompt adjustment of the antibiotic regimen based on patient symptoms to prevent infection recurrence.

OBJECTIVE:To compare the biomechanical properties of four internal fixation methods in a lower cervical spine injury model using the finite element method. METHODS:Cervical CT data of a 28-year-old healthy adult male were utilized to establish a finite element model of the normal cervical spine and a lower cervical spine three-column injury model. Four internal fixation methods were then applied to the three-column injury model, resulting in four groups:Group A, anterior cervical locked-plate(ACLP) fixation system model(anterior approach);Group B, posterior cervical pedicle screw fixation model (posterior approach);Group C, combined anterior and posterior cervical pedicle screw fixation model; Group D, Novel composite anterior cervical internal fixation model. A 75 N axial compressive load and a 1.0 N·m pure moment were applied to the upper surface of the cervical spine model to simulate flexion, extension, rotation, and lateral bending movements. The intervertebral range of motion(ROM) and stress distribution of the internal fixators under different motion conditions were compared across all models. RESULTS:Compared with the normal model, the reductions in overall intervertebral ROM for each group under flexion, extension, rotation, and lateral bending were as follows:Group A, 24.04°, 23.12°, 6.24°, and 9.06°;Group B, 24.42°, 24.34°, 6.48°, and 9.20°;Group C, 25.43°, 25.29°, 7.17°, and 9.57°;Group D, 24.75°, 25.5°, 6.71°, and 9.12°. The peak stress values of the internal fixators in each group were:Group A, 53.9 MPa, 79.9 MPa, 61.4 MPa, and 80.3 MPa;Group B, 218.3 MPa, 105.4 MPa, 206.6 MPa, and 186.8 MPa;Group C, 40.8 MPa, 97.2 MPa, 47.1 MPa, and 39.4 MPa;Group D, 93.0 MPa, 144.0 MPa, 64.8 MPa, and 106.3 MPa. CONCLUSION:The biomechanical properties of the novel composite anterior cervical internal fixation method are similar to those of the combined anterior-posterior fixation method, and superior to both the anterior cervical ACLP plate-screw fixation and posterior cervical pedicle screw fixation methods.

OBJECTIVE:To establish a two-segment vertebrectomy model using the finite element method, and to measure and compare the biomechanical properties of the lower cervical anterior transpedicular root screw (ATPRS) plate system, lower cervical anterior pedicle screw (ATPS) plate system, and lower cervical anterior cervical locked-plate (ACLP) system on this model. METHODS:CT data of the cervical spine (C0-T1) from a 34-year-old healthy adult male volunteer were collected. A nonlinear complete model of the lower cervical spine (C3-C7) was established using Mimics 10.01 software, based on which the ATPRS fixation model, ATPS fixation model, and ACLP fixation model were constructed respectively. An axial pressure of 75 N and a pure couple moment of 1.5 N·m were applied to C3 to make the model perform flexion-extension, left-right lateral bending, and left-right rotation movements. The range of motion (ROM) and stress distribution of each model under different working conditions were compared. RESULTS:The ROM of the C4-C7 segments in the ACLP group, ATPS group, and ATPRS group was reduced to 0.65° (-95.2%), 0.58° (-95.7%), and 0.62° (-95.4%) respectively compared with the intact model during flexion-extension movement;during lateral bending movement, it was reduced to 0.58° (-95.2%), 0.51°(-95.8%), and 0.60° (-95.1%) respectively;during rotation movement, it was reduced to 1.17° (-89.6%), 1.26° (-88.8%), and 1.27°(-88.7%) respectively. In terms of the stress on the titanium mesh graft, the ATPS group and ATPRS group had the maximum load during extension and the minimum load during flexion. Compared with the ACLP group, the stress on the titanium mesh graft in ATPS and ATPRS decreased by (-33.7%) and (-15.8%) in flexion, (-29.4%) and (-13.2%) in extension, (-26.2%) and (-23.4%) in lateral bending, and (-18.8%) and (-5.4%) in rotation, respectively. In terms of bone-screw interface stress, the peak bone stress near the C7 screw in the ACLP group, ATPS group, and ATPRS group increased by 49.2%, 45.0%, and 47.6% respectively compared with the peak bone stress near the C4 screw during extension. However, during flexion and lateral bending, there was no significant difference in the peak bone stress near the C4 and C7 screws. During rotation, the difference between the peak bone stress near the C4 screw and that near the C7 screw showed that in the ACLP group, left rotation (37.6%) was similar to right rotation (36.7%), while in the ATPS group and ATPRS group, left rotation was lower than right rotation. CONCLUSION:Compared with the ACLP group, the ATPS group and ATPRS group have greater fixation stiffness and more stable fixation. However, in rotational movement, due to the uneven distribution of fixation stiffness, the stress distribution during torsion is uneven, but it is still better than the ACLP group. This indicates that ATPRS, like ATPS, has good primary stability, providing favorable conditions for bone graft fusion.

STUDY DESIGN:This study was to compare the biomechanical properties of 4 internal fixation methods on the lower cervical injury model by finite element method. OBJECTIVE:Using the finite element method to study the biomechanical characteristics of the novel composite anterior cervical spine fixation technique-combining anterior transpedicular screw fixation with a zero-track internal fixation. SUMMARY OF BACKGROUND INFO:Several studies have demonstrated lower cervical 3-column injury is not effective treated by anterior cervical surgery. To the best of our knowledge, few studies has examined the effectiveness of enhanced anterior cervical surgery alone. METHODS:CT data of a healthy 28-year-old male adult were selected to create finite element models of a 3-column injury model of the lower cervical spine. Four internal fixation methods were applied to the lower cervical spine injury model: anterior cervical locking plate model (group A), posterior transpedicular screw fixation model (group B), anterior+posterior transpedicular screw fixation model (group C), and the novel composite anterior cervical spine fixation model (group D). These models were subjected to 75 N axial force and 1.0 Nm to induce various movements. Comparing the range of motion (ROM), vertebral displacement, and stress distribution of the different models under various conditions. RESULTS:Compared with the normal model, in flexion, extension, rotation, and lateral bending, the overall intervertebral mobility of group D demonstrated less ROM, but a slightly larger than group C. In flexion, rotation, and lateral bending, the peak stresses for group D were less than group B. In flexion and extension, the vertebral displacements of C3-6 in group D showed less displacement, but a slightly larger than group C. CONCLUSIONS:The biomechanical characteristics of the new composite anterior cervical fixation method are favorable. LEVEL OF EVIDENCE:Level III.

OBJECTIVE:To investigate the feasibility of mimics software in analyzing a new type of complex anterior cervical fixation -- anterior transpedicular screw fixation+zero notch internal fixation.METHODS:From January 2021 to September 2022, 50 normal pedestrians who underwent cervical spine CT scanning were selected for C1-C7 segment scanning, including 27 males and 23 females, aged from 25 to 65 years old with an average of (46.0 ± 9.0) years old. The dicom format is exported and engraved into the CD, and use the mimics software to perform 3D reconstruction of each segment. A simulated screw is placed on the image according to the critical value of zero notch screw (head and tail angle 44°, internal angle 29°). The position of zero notch screw in each segment is observed to determine the feasibility of anterior transpedicular screw fixation plus zero notch internal fixation.RESULTS:For the upper zero notch screws the three-dimensional images of the cervical spine across all 50 subjects within the C3-C7 segments demonstrated safe position, with no instances of intersection with ATPS. For the lower zero notch screw, in C3-C4 and C4-C5, 4 out of 50 subjects are in the safe position in the three-dimensional images of cervical vertebrae, and 46 cases could achieve secure screw placement when the maximum caudal angle is(32.3±1.9) ° and (36.1±2.2) °, respectively. In C5-C6 and C6-C7 segments, no lower zero notch screws intersected with ATPS, and all screws are in safe positions.CONCLUSION:Lower cervical anterior pedicle screw fixation plus zero notch internal fixation can achieve successful nail placement through the selected entry point and position.

Background: The cervical anterior transpedicular screw (ATPS) fixation technology can provide adequate stability for cervical three-column injuries. However, its high risk of screw insertion and technical complexity have restricted its widespread clinical application. As an improvement over the ATPS technology, the cervical anterior transpedicular root screw (ATPRS) technology has been introduced to reduce the risk associated with screw insertion. This study aims to use finite element analysis (FEA) to investigate the biomechanical characteristics of a cervical spine model after using the novel ATPRS intervertebral fusion system, providing insights into its application and potential refinement.Methods: A finite element (FE) model of the C3-C7 lower cervical spine was established and validated. After two-level (C4-C6) anterior cervical discectomy and fusion (ACDF) surgery, FE models were constructed for the anterior cervical locked-plate (ACLP) internal fixation, the ATPS internal fixation, and the novel ATPRS intervertebral fusion system. These models were subjected to 75N axial force and 1.0 Nm to induce various movements. The range of motion (ROM) of the surgical segments (C4-C6), maximum stress on the internal fixation systems, and maximum stress on the adjacent intervertebral discs were tested and recorded.Results: All three internal fixation methods effectively reduced the ROM of the surgical segments. The ATPRS model demonstrated the smallest ROM during flexion, extension, and rotation, but a slightly larger ROM during lateral bending. Additionally, the maximum bone-screw interface stresses for the ATPRS model during flexion, extension, lateral bending, and axial rotation were 32.69, 64.24, 44.07, 35.89 MPa, which were lower than those of the ACLP and ATPS models. Similarly, the maximum stresses on the adjacent intervertebral discs in the ATPRS model during flexion, extension, lateral bending, and axial rotation consistently remained lower than those in the ACLP and ATPS models. However, the maximum stresses on the cage and the upper endplate of the ATPRS model were generally higher.Conclusion: Although the novel ATPRS intervertebral fusion system generally had greater endplate stress than ACLP and ATPS, it can better stabilize cervical three-column injuries and might reduce the occurrence of adjacent segment degeneration (ASD). Furthermore, further studies and improvements are necessary for the ATPRS intervertebral fusion system.

Purpose To compare the biomechanical properties of anterior transpedicular root screw (ATPRS), anterior transpedicular screw (ATPS) and anterior cervical locked-plate (ACLP) in the lower cervical spine by finite element method. Methods We collect CT data of the cervical spine from a healthy 34-year-old adult male volunteer. Use Mimics 10.01 software to build a nonlinear complete model of the lower cervical spine. The model was subjected to 75N axial force and 1.0 N·M to induce various movements. The range of motion (ROM) and stress distribution of each model under different working conditions were compared. Results Compared with the intact model, the ROM in the ACLP, ATPS and ATPRS groups decreased to 0.65, 0.58 and 0.62 during flexion and extension. In terms of titanium mesh graft stress, the ATPS and ATPRS groups had the largest load during extension and the smallest load during flexion. In terms of bone-screw interface stress, the peak stress around screw C7 was higher than that around screw C4 during extension in ACLP, ATPS and ATPRS groups, respectively. Conclusion Biomechanical characteristics of anterior transpedicular root screw system are favorable.

我国人口老龄化不断加剧,老年骨质疏松性椎体压缩性骨折（osteoporotic vertebral compression fractures,OVCFs）发病率也在上升,其主要临床表现是腰背部疼痛及活动障碍,严重影响老年人生活质量 [1] 。经皮椎体成形术（percutaneous vertebroplasty,PVP）和经皮椎体后凸成形术（percutaneous kyphoplasty,PKP）是治疗OVCFs患者的常用方法,其主要特点是微创、有效、简便,能迅速改善腰背部疼痛,提高患者生活质量 [2] 。

Objective:To explore the best screw path and safe screw path angle range of anterior transpedicular screws in the lower cervical spine based on 3D CT imaging by screw axial fluoroscopy.Methods:Fifty cervical CT data integral from volunteers from June 2019 to July 2020 were selected from Ningbo No. 6 Hospital and were confirmed to have no obvious defect. Among the cases, 24 were males and 26 were females aged 22-52 (31.9±5.4) years. The original data of CT scanning were imported into Mimics software in DICOM format for 3D reconstruction. On the coronal and sagittal images of the reconstructed 3D CT images, the leading edge of the C 3-7 vertebral body was divided into four parts. The MEDcap module was used for simulated screw placement in the right pedicle, and the best screw path was obtained by screw axial fluoroscopy. The best screw insertion area, the angle between the horizontal screw and the posterior edge of the vertebral body, and the angle between the sagittal screw and the anterior edge of the vertebral body were recorded. Then, the head of the screw was moved to obtain the maximum head inclination, tail inclination, inward inclination, and outward inclination of the safety screw path. The angles formed by the best screw path with the maximum head inclination, tail inclination, inward inclination, and outward inclination safety screw path were denoted respectively. The data of males and females were compared by independent sample t-test. Results:In 50 patiens, the best screw entry area in sagittal plane was zone 2 at C 3-5 (72%[36/50], 68%[34/50], 78%[39/50], respectively), zone 3 at C 6-7 (70%[35/50], 76%[38/50], respectively), and the best screw entry area in horizontal plane was zone 3 at C 3-5 (90%[45/50], 82%[41/50], 88%[44/50], respectively), zone 2 at C 6-7 (80%[40/50], 84%[42/50], respectively). The best angles for screw insertion in the sagittal and horizontal positions were 78.3°-69.9° and 46.7°-50.1° for males and 76.1°-64.9° and 44.7°-48.7° for females, respectively. The sagittal and horizontal angles between men and women had significant differences (all P values<0.001). The maximum safe angles of head inclination, tail inclination, inward inclination, and outward inclination were 8.7°-14.2°, 8.9°-13.1°, 5.4°-8.5°, and 5.3°-8.4° for males and 7.5°-13.4°, 8.4°-12.8°, 4.8°-8.0°, and 4.7°-7.8° for females, respectively. The difference was statistically significant (all P values<0.05). Conclusion:The optimal screw path and safe screw path angle of ATPS in lower cervical are obtained by screw axial fluoroscopy combined with CT three-dimensioal software to simulate screw placement and measurement, which provides imaging anatomical data support for the safety of screw placement.

Objective:To evaluate the pull-out strength on the osteoporotic vertebral body for anterior transpedicular root screw in cervical spine.Methods:9 wet specimens of normal adult osteoporotic cervical spine (C3-C7) were selected, including 5 males and 4 females. The anterior transpedicular root screw (ATPRS) , anterior transpedicular screw (ATPS) or vertebral body screw (VBS) was randomly placed on both sides of each specimen. All was divided into three groups (ATPRS vs ATPS, ATPRS vs VBS and ATPS vs VBS) with three specimens in each group. After all specimens were scanned by thin-layer CT, DICOM format data was imported into Mimics software for 3D reconstruction, then the guidance drill template of ATPS was designed and quickly printed by 3D printer. ATPS was placed under the guidance drill template, ATPRS and VBS were placed by hand. Finally, the specimens were placed on the biomechanical experimental machine, and the pull-out strength of each group of screw was tested.Results:The average maximum pull-out strength of ATPRS was (287.94±76.78) N, ATPS was (462.23±174.35) N, and VBS was (169.20±89.07) N. There was statistical difference between ATPRs and VBS, ATPRS and VBS and ATPS and VBS for pull-out strength (all P<0.05) . Conclusions:The pull-out strength of the ATPRS was better than VBS, which can provide the biomechanical support for clinical application.

患者,女,63 岁,5 年前出现双下肢酸痛乏力,腹部有束带感,初始以腰椎疾病进行腰椎MRI检查未见明显异常,症状逐渐加重,进一步行胸椎MRI检查提示T4～6 平面椎管内占位,考虑脊膜瘤可能. 2019 年9 月3 日至宁波市第六医院就诊,胸椎MRI检查(见图1)显示:T4～5平面脊髓向前方移位疝出、成角、变细,背侧蛛网膜下腔增宽,呈C字形.

Abstract Objective This study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system. Methods A total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior–posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results. Results The screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92–6.08 mm) and female (2.32–5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73–66.76°), lower screw (48.05–65.35°); female group upper screw (49.15–65.66°) and lower screw (49.42–63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06–39.56°), lower screw (29.12–36.95°); female group upper screw (30.97–38.92°) and lower screw (27.29–37.20°). The anterior–posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). Conclusions Through the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

Abstract Objective: Exploring the safe range of anterior transpedicular screw (ATPS) in the lower cervical spine. Methods: Fifty healthy adult cervical spine CT imaging data were selected from our institution for this study. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Then, using the intersection of the pedicle axis and the anterior wall of the vertebral body as the screw entry point, a 3.5 mm simulated screw was inserted. The simulated screw was rotated and moved with the intersection acting as its center. On the horizontal view, the included angle (α) between the simulated screw axis and the mid-sagittal plane, the width of the pedicle, and the distance between the transverse point and the mid-sagittal plane at the anterior vertebral body wall were measured from C3 to C7; On the sagittal view, the included angle (β) between the simulated screw axis and the plane of the anterior vertebral body wall, the height of pedicle, and the distance between the sagittal intersection point and the upper endplate were measured C3 to C7. Results: No matter in the transverse or sagittal planes, C7 had the largest average safety range, while C3 was the smallest. The average safety range of screw placement on the transverse plane increased from C3 to C7, ranging from 5.25°to 9.43°, of which C7 was the largest (9.43°) and C3 was the smallest (5.25°). The average safety range of screw placement on the sagittal plane showed a trend of first increasing, then decreasing, and then increasing, ranging from 12.57° to 14.70°, of which C7 was the largest (14.70°), and C3 was the smallest (12.57°). There was no statistical difference between the left and right pedicles of the same cervical level (P>0.05). Conclusions: When the entry point was determined, there was a certain safety range for ATPS in the lower cervical spine. Those are helpful for the clinical application of ATPS technology. However, the individual anatomy of the cervical spine is relatively different, and sufficient preoperative preparations should still be made to ensure the safety and accuracy of screw placement.

Multilevel cervical corpectomy has raised the concern among surgeons that reconstruction with the anterior cervical screw plate system (ACSPS) alone may fail eventually. As an alternative, the anterior cervical transpedicular screw (ACTPS) has been adopted in clinical practice. We used the finite element analysis to investigate whether ACTPS is a more reasonable choice, in comparison with ACSPS, after a 2-level corpectomy in the subaxial cervical spine. These 2 types of implantation models with the applied 75 N axial pressure and 1 N • m pure moment of the couple were evaluated. Compared with the intact model, the range of motion (ROM) at the operative segments (C4–C7) decreased by 97.5% in flexion-extension, 91.3% in axial rotation, and 99.3% in lateral bending in the ACTPS model, whereas it decreased by 95.1%, 73.4%, 96.9% in the ACSPS model respectively. The ROM at the adjacent segment (C3/4) in the ACTPS model decreased in all motions, while that of the ACSPS model increased in axial rotation and flexion-extension compared with the intact model. Compared to the ACSPS model, whose stress concentrated on the interface between the screws and the titanium plate, the stress of the ACTPS model was well-distributed. There was also a significant difference between the maximum stress value of the 2 models. ACTPS and ACSPS are biomechanically favorable. The stability in reducing ROM of ACTPS may be better and the risk of failure for internal fixator is relatively low compared with ACSPS fixation except for under lateral bending in reconstruction the stability of the subaxial cervical spine after 2-level corpectomy.

Objective:To study the optimum entry point and trajectory for anterior transpedicular root screw (ATPRS) placement into the lower cervical spine (LCS), so as to provide a basis for clinical application.Methods:A retrospective analysis of cervical CT images of patients who underwent cervical CT examination in the Spinal Surgery of Ningbo No. 6 Hospital from January 2020 to August 2021 was conducted. The data were obtained and modeled. On the coronal plane, the vertebral body (VB) between the anterior midline of cervical vertebral segments C3-7 and the left P line (by drawing the line parallel to the anterior midline of the VB at the intersection of the anterior edge of the Luschka's joint and the upper endplate) was equally divided into 9 zones (a-i). The ideal entry point and path of cervical ATPRS were designed and recorded. Additionally, 7 cadaveric specimens were selected, and the screw placement parameters were regenerated according to the above methods for screw placement.Results:Zone i of each segment, with the longest screw length, was the best area for screw placement. In all patients, the horizontal angles of vertebrae C3-7 in zones a, d, and g, zones b, e, and h, and zones c, f, and i showed a gradually decreasing trend. The sagittal angle range of C3-7 in all patients showed a gradually increasing trend in zones a-c, d-f, and g-i. The distance from the anterior midline of C3-7 to the P line increased in all patients, and the distance was longer in males than in females, with statistical significance. Pedicle screws were successfully inserted in all the 7 cadaveric specimens.Conclusions:ATPRS placement can be used for LCS internal fixation, and the precise screw placement parameters can be simulated by the software, which provides theoretical basis for its future clinical application.

•The stress distribution of the atlantoaxial intraarticular cages with fixation was indicated.•Intraarticular cages with fixation could restore stability to the atlantoaxial junction.•The addition of the intraarticular cages to could reduce the maximum Von Mises stress.

OBJECTIVE:To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C3-C7) in order to provide a finite element modeling method for anterior cervical reconstruction.METHODS:The CT data of the cervical segment (C1-T1) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C3-C7) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C5 and C6 vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3 in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups.RESULTS:There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C3-C7) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C3,4 segment was increased slightly.CONCLUSION:The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.