Objective To assess the possibility of placing the posterior pedicle screw on atlas. Methods Twenty human cadaver specimens were used to insert pedicle screws in atlas, through the posterior arch or the pedicle of C1 into the lateral mass. The screw entry point was on the posterior surface of C1 posterior arch and at the intersection of the vertical line through the center of C2 inferior articular process and the horizontal line at least 3 mm below the superior rim of the C1 lamina. The screw of 3.5 mm in diameter was placed in a direction of 10° medial angle and 5° upwardangle. After placement of C1 pedicle screw, the distance from C1 screw entry point to the mediallateral midpoint of C1 pedicle, the maximum length of screw trajectory and the actual screw trajectory angles were measured. The direction of screw penetrating through the cortical of C1 pedicle or lateral mass and the injuries to the vertebral artery and spinal cord were observed.Results Forty pedicle screws were placed on atlas, the mean distance from C1 screw entry point to the medial-lateral midpoint of C1 pedicle was (2.20±0.42)mm, the maximum length of screw trajectory averaged (30.51±1.59)mm, and the actual screw trajectory angle measured (9.7±0.67)° in a medial direction and (4.6±0.59) ° in a upward direction. Only 1 screw penetrated the upper cortical bone of the atlas pedicle because the upward angle was too large, and 8 screws were inserted so deep that the inferior cortical bone of the C1 lateral mass was penetrated. But no injuries to the vertebral artery and spinal cord wereobserved. Conclusion C1 posterior pedicle screw fixation is quite accessible and safe, but the su
ObjectiveTo explore the effectiveness of a new point contact pedicle navigation template (referred to as “new navigation template” for simplicity) in assisting screw implantation in scoliosis correction surgery. MethodsTwenty-five patients with scoliosis, who met the selection criteria between February 2020 and February 2023, were selected as the trial group. During the scoliosis correction surgery, the three-dimensional printed new navigation template was used to assist in screw implantation. Fifty patients who had undergone screw implantation with traditional free-hand implantation technique between February 2019 and February 2023 were matched according to the inclusion and exclusion criteria as the control group. There was no significant difference between the two groups (P>0.05) in terms of gender, age, disease duration, Cobb angle on the coronal plane of the main curve, Cobb angle at the Bending position of the main curve, the position of the apical vertebrae of the main curve, and the number of vertebrae with the pedicle diameter lower than 50%/75% of the national average, and the number of patients whose apical vertebrae rotation exceeded 40°. The number of fused vertebrae, the number of pedicle screws, the time of pedicle screw implantation, implant bleeding, fluoroscopy frequency, and manual diversion frequency were compared between the two groups. The occurrence of implant complications was observed. Based on the X-ray films at 2 weeks after operation, the pedicle screw grading was recorded, the accuracy of the implant and the main curvature correction rate were calculated. ResultsBoth groups successfully completed the surgeries. Among them, the trial group implanted 267 screws and fused 177 vertebrae; the control group implanted 523 screws and fused 358 vertebrae. There was no significant difference between the two groups (P>0.05) in terms of the number of fused vertebrae, the number of pedicle screws, the pedicle screw grading and accuracy, and the main curvature correction rate. However, the time of pedicle screw implantation, implant bleeding, fluoroscopy frequency, and manual diversion frequency were significantly lower in trial group than in control group (P<0.05). There was no complications related to screws implantation during or after operation in the two groups. ConclusionThe new navigation template is suitable for all kinds of deformed vertebral lamina and articular process, which not only improves the accuracy of screw implantation, but also reduces the difficulty of operation, shortens the operation time, and reduces intraoperative bleeding.
Objective To assess the outcomes of pedicle subtration osteotomy and short-segment pedicle screw internal fixation in kyphosisdeformity. Methods From June 2001 to November 2003, 16 cases of kyphosis deformity were treated with pedicle subtration osteotomy and short-segment pedicle screw internal fixation, including 11 males and 5 females and aging 24-51 years. The kyphosis deformity was caused by ankylosing spondylitis in 12 cases, old lumbothoracic fracturedislocation in 2 cases, and vertebral dysplasia in 2 cases. The disease course was 7-25 years with an average of 12.8years. The whole spine radiographs were taken pre-and postoperatively. The sagittal balance was assessed by measuring thoracic kyphosis angle, lumbar lordosis angle, acrohorizontal angle and distance between posterosuperior point of S1and the vertical line. The clinical outcomes were assessed by Bridwell-Dewald scale for spinal disorders. Results The mean follow-up period was25.6 months. The mean bleeding was 1 100 ml. Satisfactory bone graft healing was achieved at final follow-up. Complications were paralytic intestinal obstruction in 1 case, dura laceration in 1 case, and temporary lower limb paralysis in 2 cases. Final follow-up radiograph showed an increase in lumbar lordosis angle from 9.6±16.4° to 42.6±14.3°(P＜0.05), whereas thoracic kyphosis angle remained relative stable. The distance between posterosuperior point of S1 and the vertical line was decreased from 97.5±45.6 mm to 10.7±9.6 mm(P＜0.05). Satisfactory clinical outcome was achieved by evaluating the changes of pain, social and working status. Conclusion Pedicle subtraction osteotomy and short-segment pedicle screw internal fixation is effective for correction of kyphosis deformity.
Objective To explore the feasibilities, methods, outcomes and indications of atlas pedicle screw system fixation and fusion for the treatment of upper cervical diseases. Methods From October 2004 to January 2006, 17 patients with upper cervical diseases were treated with atlas pedicle screw system fixation and fusion. There were 13 males and 4 females, ageing 19 to 52 years. Of 17 cases, there were 14 cases of atlantoaxial dislocation(including 3 cases of congenital odontoid disconnection，4 cases of old odontoid fracture，2 cases of new odontoid fracture(typeⅡC), 3 cases of rupture of the transverse ligament, and 2 cases of atlas fracture； 2 cases of tumor of C2; 1case of giant neurilemoma of C2,3 with instability after the resection oftumors. JOA score before operation was 8.3±3.0. Results The mean operative time and bleeding amount were 2.7 hours (2.1-3.4 hours) and 490 ml (300-750 ml) respectively. No injuries to the vertebral artery and spinal cord were observed. The medial-superior cortex of lateral mass was penetrated by 1 C1 screw approximately 3 mmwithout affecting occipito-atlantal motions. All patients were followed up 3-18 months. The clinical symptoms were improved in some extents and the screws were verified to be in a proper position, no breakage or loosening of screw and rob occurred. All patients achieved a solid bone fusion after 3-6 months. JOA score 3 months after operation was14.6±2.2. JOA improvement rates were 73%-91%(mean 82%). Conclusion The atlas pedicle screw system fixation and fusion is feasible for the treatment of upper cervical diseases and has betteroutcomes, wider indications if conducted properly.
目的:探讨后路寰枢椎椎弓根螺钉内固定的术前计划方案,明确其手术指导意义。方法:选取经CT评估寰枢椎椎弓根螺钉置入可行的,并拟选择该手术治疗的上颈椎不稳患者15例,容积再现重建(VR)寰枢椎椎弓表面影像,了解个体椎弓后方表面解剖形态与骨性解剖标志。同时按寰枢椎椎弓根理想的钉道走行,多平面重建(MPR)个体椎弓根断面影像。术前根据这些解剖影像设计手术暴露路经、理想的进钉点与钉道轨迹。术中按该术前计划手术暴露,找到理想的进钉点并钻孔置椎弓根螺钉。将术中观察到的C1后弓及C2椎弓表面解剖,与术前CT重建影像对比。术后CT复查,评价螺钉置入情况。结果:15例术中观察到的C1后弓及C2椎弓表面解剖特征与术前CT容积再现的影像一致。参照寰枢椎椎弓CT影像解剖制定术前计划方案,术中按其逐一操作,手术简单、直观,无重要血管神经损伤,置钉准确。结论:根据CT容积再现与多平面重建的寰枢椎解剖影像,制定后路寰枢椎椎弓根螺钉内固定术前计划方案,指导手术安全、可靠。
目的:探讨后路椎弓根螺钉固定在地震伤胸腰椎骨折中的应用及优点。方法:对19例胸腰椎骨折的地震伤患者行后路椎弓根螺钉内固定术。结果:本组病例的手术时间70～115分钟,平均出血量约280mL,两例病员术中出血超过400mL进行输血,复位椎体前缘高度由术前平均57.5%恢复到术后平均93.6%,后突角由术前平均21°矫正到术后平均3°,术后3～7天转往外地继续治疗,Frankel分级平均提高0.4。结论:后路椎弓根螺钉固定具有省时、节约医疗资源、提高救治效率、减轻患者痛苦的优点,尤其适用于大批伤病员的紧急救治。
Objective To ascertain whether augmentation pedicle screw fixation with polymethylmethacrylate (PMMA) can enhance the stability of unstable thoracolumbar burst fractures of osteoporotic spine. Methods Six fresh frozen female osteoporotic spines (T10-L5) were harvested and an anterior and posterior columnunstable model of L1 was made. Each specimen was fixated with plate and the stability test were performed by flexion, extension, axial rotation and lateral bending. The test of fatigue was done with MTS 858.The tests were repeated after screws were augmented with PMMA. To compare the biomechanical stability of 6 different conditions:○anormal specimens(control), ○bdefectmodel fixed with plate, not augmented and not fatigued, ○cafter fatigued, not augmented, ○dscrews augmented with PMMA, not fatigued, ○e after augmented and fatigued. ResultsIn ○b,○d and ○e conditions, the ranges of motion(ROM) were 6.23±1.56，4.49±1.00，4.46±1.83 inflexion and 6.60±1.80，4.41±0.82，4.46±1.83 in extension. There was no significant difference (Pgt;0.05), they were significantly smaller than those in ○a and ○c conditions (8.75±1.88，1.47±2.25 and 8.92±2.97，12.24±3.08) (Plt;0.01).Conclusion The results demonstrated that augmentation pedicle screws fixation with PMMA can increase the stability of osteoporotic spine.
Objective To evaluate the biomechanical stability of a newly-designed Y type pedicle screw (YPS) in osteoporotic synthetic bone. Methods The osteoporotic synthetic bone were randomly divided into 3 groups (n=20). A pilot hole, 3.0 mm in diameter and 30.0 mm in deep, was prepared in these bones with the same method. The YPS, expansive pedicle screw (EPS), and bone cement-injectable cannulated pedicle screw (CICPS) were inserted into these synthetic bone through the pilot hole prepared. X-ray film examination was performed after 12 hours; the biomechanical stability of YPS, EPS, and CICPS groups was tested by the universal testing machine (E10000). The test items included the maximum axial pullout force, the maximum running torque, and the maximum periodical anti-bending. Results X-ray examination showed that in YPS group, the main screw and the core pin were wrapped around the polyurethane material, the core pin was formed from the lower 1/3 of the main screw and formed an angle of 15° with the main screw, and the lowest point of the inserted middle core pin was positioned at the same level with the main screw; in EPS group, the tip of EPS expanded markedly and formed a claw-like structure; in CICPS group, the bone cement was mainly distributed in the front of the screw and was dispersed in the trabecular bone to form a stable screw-bone cement-trabecular complex. The maximum axial pullout force of YPS, EPS, and CICPS groups was (98.43±8.26), (77.41±11.41), and (186.43±23.23) N, respectively; the maximum running torque was (1.42±0.33), (0.96±0.37), and (2.27±0.39) N/m, respectively; and the maximum periodical anti-bending was (67.49±3.02), (66.03±2.88), and (143.48±4.73) N, respectively. The above indexes in CICPS group were significantly higher than those in YPS group and EPS group (P<0.05); the maximum axial pullout force and the maximum running torque in YPS group were significantly higher than those in EPS group (P<0.05), but there was no significant difference in the maximum periodical anti-bending between YPS group and EPS group (P>0.05). Conclusion Compared with EPS, YPS can effectively enhance the maximum axial pullout force and maximum rotation force in the module, which provides a new idea for the design of screws and the choice of different fixation methods under the condition of osteoporosis.
目的 探讨经伤椎椎弓根螺钉内固定治疗胸腰椎骨折的临床疗效。 方法 2008年5月－2010年12月，选择38例胸腰椎骨折患者，采用椎弓根螺钉固定伤椎及相邻上下椎体。其中男28例，女10例；年龄21～65岁，平均36.5岁。骨折部位：胸8 1例，胸9 2例，胸10 4例，胸11 8例，胸12 7例，腰1 10例，腰2 4例，腰3 2例。受伤至手术时间3～7 d，平均4.5 d。对患者手术前后椎体高度、矢状面后凸Cobb角、神经功能Frankel分级变化等指标进行测量并随访。 结果 术后患者切口均Ⅰ期愈合。38例获随访12～18个月，平均15个月。骨折均获得骨性融合，无钉棒断裂、无死亡或神经损伤加重患者。术后神经功能Frankel分级较术前有明显改善（P＜0.05）。术后X线片复查示伤椎高度恢复达90%以上，外形正常；CT复查示椎管内有效矢状径恢复满意，椎管前方无明显骨性压迫，伤椎椎体骨愈合良好。术后1、12个月时伤椎前、后缘高度及后凸Cobb角均较术前显著改善（P＜0.05）；术后12个月随访椎体高度无丢失。 结论 经伤椎椎弓根钉复位、减压、内固定治疗胸腰椎骨折具有创伤小、固定节段少、脊柱稳定性好、能有效矫正及预防脊柱后凸畸形等优点。
目的:研究枢椎椎弓根关节突复合体的解剖结构特征,探讨该解剖概念的临床意义。方法:观察80具枢椎干骨标本椎弓根关节突部位的解剖结构特征。并随机抽取其中20具标本,在椎弓骨背侧表面做枢椎经椎弓根螺钉固定及经关节(C1-2)螺钉固定钉道投影画线,另2具标本按两种螺钉内固定方式设置直径3.5 mm钉道,并螺旋CT扫描多平面重建(MPR)钉道断面影像,了解两种钉道与椎弓根关节突结构的解剖关系。回顾性分析25例外伤致枢椎椎弓根关节突部位骨折的CT资料,包括其中12例枢椎螺钉内固定术后CT,研究该部位骨折特点及钉道所在的断面解剖。结果:枢椎解剖学上,无严格定义下完整的椎弓根。而枢椎椎弓根关节突作为复合体,具有解剖结构上整体性特征,其周围界线清楚。外伤致枢椎椎弓根关节突复合体骨折可分为椎弓根上关节突骨折、关节突间部骨折及单纯上关节突骨折。枢椎经椎弓根螺钉固定及经关节(C1-2)螺钉内固定的钉道均通过椎弓峡部中心,但起点不同,走向不同。结论:枢椎椎弓根关节突复合体作为临床解剖概念,具有解剖结构的完整性。明确该解剖概念及各构件对该区域骨折分类与螺钉内固定手术具有指导作用。