Pull-out strength of pedicle hooks with fixation screws: influence of screw length and angulation

The pull-out force of thoracic spinal pedicle hooks secured by long fixation screws engaging the posterior portion of the vertebral endplate was measured. The perfomance of these hooks was compared with that of hooks using a shorter screw and different screw orientation such that the vertebral endplates were not perforated. The longer and differently angulated screws, engaging the endplate, significantly enhanced the fixation potential of the hooks.     

A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation

Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine.     

非影像监视下行脊柱侧凸胸椎椎弓根螺钉置入的临床应用

目的:探讨脊柱侧凸胸椎椎弓根螺钉非影像监视下徒手置入的方法及可行性。方法:57例脊柱侧凸患者行后路椎弓根螺钉系统矫形手术,徒手法置入胸椎椎弓根螺钉。术后常规拍摄脊柱全长X线片,随机选取10例患者行CT扫描观察,了解螺钉置入的准确性。结果:共置入胸椎椎弓根螺钉362枚。术后X线片观察到10枚螺钉偏外,4枚螺钉偏下,其中2枚螺钉引起轻微肋间神经痛,3周后完全缓解。CT观察47枚螺钉有2枚螺钉导致椎弓根内壁膨胀内移,没有相应神经症状。主弯Cobb角术前平均60.4°(32°～121°),术后平均18.3°(1°～70°),平均矫正率71.9%(38.1%～98.0%)。结论:徒手法置入脊柱侧凸胸椎椎弓根螺钉是可行的。     

椎弓根螺钉把持椎弓根皮质骨对其固定强度的影响

目的：了解椎弓根螺钉把持椎弓根皮质骨对椎弓根螺钉固定强度的影响。方法：将成年羊腰椎椎弓根48个依据椎弓根皮质骨内径和椎弓根螺钉直径（6．25mm）的相对关系分为三组：A组，螺钉直径小于椎弓根皮质骨内径：B组．螺钉直径超出椎弓根皮质骨内径0.01～0．50mm；C组，螺钉直径超出椎弓根皮质骨内径0.51～1．00mm。每组再根据进钉深度与椎弓根长度（平均约8mm）的相对关系分为Ⅰ（进钉深度为16mm）、Ⅱ（进钉深度为8mm）两组。将椎弓根螺钉置入椎弓根中，观察钉道结构、膨胀情况，测量椎弓根螺钉最大轴向拔出力。结果：椎弓根螺钉置入后，椎弓根发生不同程度膨胀；椎弓根螺纹能够切入皮质骨中；C Ⅰ组最大轴向拔出力比A Ⅰ组和B Ⅰ组大（P〈0．05），C Ⅱ组最大轴向拔出力比A Ⅱ组和B Ⅱ组大（P〈0．05），B Ⅱ组比A Ⅱ组大（P〈0.05）。结论：椎弓根螺钉把持椎弓根皮质骨能够增加椎弓根螺钉的固定强度；且椎弓根螺钉把持椎弓根皮质骨量越大，固定强度越大。     

胸椎骨折导航中点注册、面注册对手术精确度的影响比较

目的 比较点注册和面注册两种不同注册方式对胸椎骨折椎弓根钉导航置入的精确性、手术时间的影响.方法 采用导航技术对24例胸椎骨折行椎弓根钉(148枚)内固定,根据注册方式的不同分为“点注册组”和“面注册组”,分析导航记录图像与术后CT螺钉置入准确性,比较两组注册时间.结果 (1)注册时间:点注册组平均( 292±45)s,面注册组平均(245±32)s,两组比较差异无统计学意义(P＞0.05);(2)准确率:点注册组CT扫描显示椎弓根钉准确率为88.16％,面注册组为95.83％,两组差异有统计学意义(P＜0.05);(3)匹配误差:点注册组(1.10±0.23) mm,面注册组(0.80±0.11) mm,差异有统计学意义(P＜0.05).结论 在胸椎骨折椎弓根钉运用导航技术置入中,虽然点注册和面注册操作时间无差异,但面注册可提高术中定位的精确性.     

Anterior pedicle screw fixation for multilevel cervical corpectomy and spinal fusion

Summary   Background. Prevention of graft dislodgement in multilevel cervical corpectomy and fusion has been an unresolved problem. Anterior plate fixation has a significant failure rate. External support with a halo-vest is uncomfortable for patients. In the present study, we report a new surgical technique of anterior pedicle screw (APS) fixation for multilevel cervical corpectomy and spinal fusion, and describe the safety and utility of the system. Method. After cervical corpectomy, the pedicles on the right side were visualised under oblique fluoroscopy. Guide wires were inserted into the pedicles from the inner wall of the excavated vertebral body until they were hidden in the pedicles. After a fibula autograft was placed, the graft was penetrated in the reverse direction by the guide wires. After drilling and tapping, cannulated screws were inserted into the pedicles through the grafted fibula along the guide wires. Findings. In 9 patients with cervical myelopathy, the surgery was accomplished with a fibula autograft using APS fixation. A total of 22 APSs were inserted, and 21 screws were placed precisely in the pedicles. There were no neurovascular complications. Patients were allowed to ambulate without a halo-vest on the second day after the surgery. Post-operatively, no dislodgement of the grated fibula occurred, and all patients improved neurologically. Conclusions. The insertion of APSs is feasible and safe. APS fixation enables us to obtain rigid fixation anteriorly, and we propose that APS fixation is an attractive option for multilevel cervical corpectomy and fusion. Correspondence: Masashi Yamazaki, MD, PhD, Spine Section, Department of Orthopaedic Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8677, Japan.     

Complexity of the thoracic spine pedicle anatomy

Transpedicular screw fixation provides rigid stabilization of the thoracolumbar spine. For accurate insertion of screws into the pedicles and to avoid pedicle cortex perforations, more precise knowledge of the anatomy of the pedicles is necessary. This study was designed to visualize graphically the surface anatomy and internal architecture of the pedicles of the thoracic spine. Fifteen vertebrae distributed equally among the upper, middle, and lower thoracic regions were used. For the purpose of mapping surface anatomy, each pedicle was cleaned, spraypainted white, and marked with more than 100 fine points. Using an optoelectronic digitizer, three-dimensional coordinates of the marked points and three additonal points, representing a coordiate system, were digitized. A solid modeling computer program was used to create three-dimensional surface images of the pedicle. To obtain cross-sectional information, each pedicle was sectioned with a thin diamond-blade saw to obtain four slices, 1 mm in thcikness and 0.5 mm apart. The pedicle slices were X-rayed and projected onto a digitizer. The internal and external contours were digitized and converted into graphs by a computer. The pedicles exhibited significant variability in their shape and orientation, not only from region to region within the thoracic spine, but also within the same region and even within the same pedicle. These variations are extremely significant in light of current techniques utilized in transpedicular screw fixation in the thoracic spine. Information documenting the three-dimensional complexity of pedicle anatomy should be valuable for surgeons and investigators interested in spinal instrumentation.     

胸椎椎弓根螺钉固定矫治青少年脊柱侧凸

目的 :探讨青少年胸椎椎弓根螺钉的固定方法及注意事项。方法 :测量 2 0例正常青少年胸椎椎弓根影像学参数 ,并在此基础上采用自行设计的胸椎椎弓根螺钉固定器械 (Scofix器械 ) ,对 32例青少年脊柱侧凸进行了矫正治疗。结果 :正常青少年T4椎弓根横径最小 ( 3 9± 0 6 6mm) ,胸椎椎弓根中点均位于横突根部上缘与中点之间 ,椎弓根与矢状面夹角在T11、T12为负角 ,T10以上为正角 ,T1最大 ( 35 8°± 0 84°)。 2 7例患者术后平均随访 11个月 ,特发性和先天性侧凸的矫正率分别为 5 7 8%和 46 4% ,无严重并发症。结论 :根据测量结果 ,如选择好进钉点、方向及深度 ,Scofix器械对青少年脊柱侧凸的矫正可获得更好的稳定性和固定强度     

寰椎后路单或双层皮质骨螺钉固定强度的生物力学评价

目的:测量单层皮质骨和双层皮质骨寰椎侧块螺钉固定与寰椎椎弓根螺钉固定的强度,为临床选择寰椎后路螺钉固定的方式提供生物力学依据。方法:利用12例新鲜的寰椎和第三颈椎标本,进行单层皮质骨和双层皮质骨的椎弓根螺钉或侧块螺钉固定,测试并比较其螺钉拔出强度。结果:双层皮质骨寰椎椎弓根螺钉固定的拔出力最大,为1757.0±318.7N;单层皮质骨寰椎椎弓根螺钉固定(1192.5±172.6N)与双层皮质骨寰椎侧块螺钉固定(1243.8±350.0N)及单层皮质骨C3椎弓根螺钉固定(1121.6±224.6N)的拔出力之间均无明显差异。结论:应用寰椎侧块螺钉固定时宜选用双层皮质骨螺钉固定,而寰椎椎弓根螺钉固定选用单层皮质骨螺钉即可。     

胸椎椎弓根螺钉植入位置的分区及临床意义

目的 探讨术后CT扫描对胸椎椎弓根螺钉位置分区及其临床意义。方法对64例共450枚胸椎椎弓根螺钉固定患者的临床资料进行统计分析。所有患者术后均采用手术节段椎弓根CT扫描,根据椎弓根螺钉在CT片显示的位置及可能引起的危险将其分为A、B、C三个区：A区,螺钉位置正常（椎弓根螺钉位于椎弓根中央,未穿透椎弓根和椎体,深度合适）。B区,螺钉引起椎弓根部分皮质破裂或穿透椎体前方或侧方,但没有引起严重的神经或血管损害。同时,将椎弓根螺钉偏向椎弓根外侧或上方、内侧或下方、穿透椎体前方或侧方分别划分为B1、B2、B3三个部分。C区,椎弓根螺钉位置严重偏差,直接威胁脊髓、神经根或大血管。平均随访时间25．8个月。比较胸椎不同位置使用椎弓根螺钉固定时椎弓根螺钉的准确位置及术后可能因为椎弓根螺钉位置偏差引起的并发症。结果A区共367枚（81．6％）,B区78枚（17．3％）,其中B,区40枚（8．8％）、B2区23枚（5．1％）、B3区15枚（3．4％）,C区5枚（1．1％）。从结果看T3-6节段最容易发生椎弓根螺钉的位置错误。结论根据CT扫描影像结果对椎弓根螺钉位置进行分区,有助于准确判断椎弓根螺钉的位置,预防并发症的发生。     

带有BMP中空侧孔新型椎弓根钉作用特点的实验研究

目的 探讨带有MBP中空侧孔新型椎弓根钉的作用特点,明确其在腰椎骨折模型中内固定的效果.方法 比较两种不同椎弓根钉的生物力学测试,包括轴向最大拔出力,垂直压缩刚度及极限压缩强度.采用X线摄片及CT观察伤椎内固定后的大体形态,比较两组中伤椎前缘高度及椎管正中矢状径(MD)的差异.结果 新型椎弓根钉组其平均轴向最大拔出力明显高于普通型组,差异有统计学意义(P＜0.05);两种椎弓根钉行椎弓根钉固定后即刻状态的整体刚度差异无统计学意义(P＞0.05),极限抗压强度差异有统计学意义(P＜0.05).普通型与新型椎弓根钉相比较,其平均前缘高度及伤椎平均MD值差异均有统计学意义(P＜0.05).结论 新型椎弓根钉内固定的稳定性明显优于普通型椎弓根钉,值得推广应用.     

寰椎椎弓根螺钉联合经寰枢关节螺钉内固定稳定性的生物力学研究

目的:评估寰椎椎弓根螺钉联合经寰枢关节螺钉固定技术的力学稳定性.方法:选取成人颈椎新鲜标本6具,解剖剔除肌肉制备上颈椎完整模型(完整组),用生物力学测试及计算机视觉分析软件测量在1.5Nm力矩下前屈后伸、左右侧弯和左右旋转时C 1-C2的活动度(ROM);破坏寰椎前弓和侧块制备不稳模型(失稳组),再次测量相同力矩下各运...     

Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep

Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. Thirteen sheep were operated on with destabilising laminectomies at two levels, L2-L3 and L4-L5. Two instrumentations with four pedicle screws in each were used for stabilisation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomised fashion. Four sheep were examined immediately after the application of the screws, three sheep at 6 weeks and four sheep at 12 weeks. Two sheep were euthanised early due to complications. The pull-out resistance was recorded in two HA-coated and two standard screws in each animal. The maximum pull-out resistance was higher for the HA-coated screws at 0 weeks (P< 0.02) and at 12 weeks (P<0.01) when compared to the uncoated screws, while there was no significant difference between the groups at 6 weeks. We believe that the higher pull-out resistance for HA-coated screws at 0 weeks was mainly caused by differences in surface roughness, while the difference at 12 weeks was due to a favourable bone reaction around the HA-coated screws. At 12 weeks, the average stiffness was significantly higher for the HA-coated screws, while there was no significant differences in stiffness between the two screw types at 0 and 6 weeks. Energy to failure was significantly higher for coated screws when compared to the uncoated screws at all three time points. HA coating improves fixation of loaded pedicle screws, with increased pull-out resistance and reduced risk of loosening.     

可注射硫酸钙在椎弓根螺钉固定中的生物力学研究

目的:探讨可注射硫酸钙在椎弓根螺钉固定中的作用。方法:取16个新鲜猪腰椎标本,随机分为两组,每组8个。第1组在双侧椎弓根丝锥攻丝,一侧钉道内填充可注射硫酸钙MIIGX3(minimally invasive injectable graftX3)(1A组),另一侧作为自身对照(1B组),拧入椎弓根钉后1h行拔出实验。第2组同样双侧攻丝,一侧填充MIIGX3(2A组),另一侧自身对照(2B组),拧入椎弓根钉后24h行拔出实验。比较填充MIIGX3与不填充以及填充1h与填充24h的最大轴向拔出力有无差别。结果:1A组最大轴向拔出力为1837.5±251.7N,1B组为1003.8±85.0N,2A组为1895.0±252.5N,2B组为1027.5±97.8N。对4组数据作析因设计的方差分析,填充MIIGX3与不填充比较,即1A组与1B和2A组与2B组比较,存在显著性差异(P<0.001);填充1h与填充24h比较,即1Avs2A,无显著性差异(P>0.05)。结论:MIIGX3对椎弓根钉的固定有明显的增强作用,且填充1h与填充24h固定强度无差异。     

Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm² and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm² and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

经皮椎体成形术与椎弓根螺钉固定治疗骨质疏松性胸腰椎骨折的生物力学研究

目的比较经皮椎体成形术(PVP)和椎弓根螺钉内固定(PSF)治疗骨质疏松性胸腰椎骨折的生物力学强度,为临床应用和离床活动指导提供实验依据。方法18具冻存的新鲜尸体,应用双能X线骨密度仪(DEXA)测定脊柱的骨密度(BND),取胸腰段脊椎(T_(12)～L_2 12具,L_1 6具)随机分成三组：PVP组、PSF组(T_(12)L_2)和正常对照组(L_1),每组6具。PVP组和PFS组实验椎体均制成骨折模型,PVP组给予经双侧椎弓根注入低粘度的含显影剂骨水泥各2．5mL。PSF组于T_(12)、L_2椎弓根置入钉棒系统固定,测试并比较两组和对照组静态最大抗压强度及刚度。结果PVP组骨水泥分布面积皆大于50%,其平均最大抗压强度与刚度分别为(2645±478)N,(117±81)N/mm；PSF组平均最大抗压强度与刚度分别为(1862±620)N,(125±33)N/mm。两组比较平均最大抗压强度差异有显著性意义(P＜0．05),最大刚度差异无显著性意义(P＞0．05)。结论骨折椎体内注入骨水泥PMMA,其抗压强度优于椎弓根钉方法,对于轻度骨质疏松者尤为适用。PVP术后患者可早期(3～5d)下床活动,而PSF术后患者离床活动时间可适当延后。     

枢椎椎板螺钉与椎弓根螺钉抗拔出强度的比较

目的:比较枢椎椎板螺钉与枢椎椎弓根螺钉的抗拔出强度,为临床应用枢椎椎板螺钉固定提供生物力学依据。方法:在7具成年男性新鲜尸体枢椎标本上进行枢椎单皮质椎弓根螺钉和双皮质椎板螺钉固定,测试螺钉拔出力。结果:单皮质枢椎椎弓根螺钉的最大拔出力平均为875.3±403.2N,双皮质枢椎椎板螺钉的最大拔出力平均为679.5±308.2N;椎弓根螺钉的最大拔出力大于椎板螺钉,但二者之间无统计学差异。结论:枢椎椎板螺钉进行双皮质固定具有可靠的力学固定强度,可作为枢椎椎弓根螺钉的补充固定技术。     

高海拔地区应用伤椎置钉技术治疗脊柱爆裂骨折

目的:针对高海拔地区脊柱爆裂骨折的特点及当地医疗条件,探讨椎弓根螺钉短节段固定联合伤椎置钉技术治疗胸腰椎爆裂骨折的临床疗效。方法:自2018年8月至2021年12月,采用伤椎置钉技术治疗12例无神经症状的单椎体胸腰椎爆裂骨折患者,其中男7例,女5例;年龄29~54(42.50±7.95)岁;车祸伤6例,高坠伤4例,重物砸伤2例;T₁₁2例,T₁₂4例,L₁3例,L₂2例,L₃1例。手术首先在骨折上下椎置钉,并在伤椎置入椎弓根螺钉,安装连接棒,通过体位及撑开实现骨折椎体复位。应用视觉模拟评分(visual analogue scale,VAS)及日本骨科协会(Japanese Orthopaedic Association,JOA)评分评估患者疼痛及生活质量改变情况,通过X线测量受伤节段后凸矫正率及矫正丢失率。结果:所有患者手术顺利,术中无明显并发症,12例患者均获随访,时间9~27(17.75±5.79)个月。术后3 d,VAS与术前入院时相比差异有统计学意义(t=6.701,P=0.000);术后9个月JOA评分与术前入院时相比差异有统计学意义(t=5.085,P=0.000)。术后3 d,Cobb角为(4.42±1.16) °,与术前入院时的(25.67±5.71) °相比矫正率为(82±5)%;术后9个月Cobb角(5.08±1.24) °,矫正丢失率为(16±13)%。无内固定松动及断裂。结论:高原低气压低氧环境下,应保证手术效果的同时减少创伤,应用伤椎置钉技术能够有效恢复并维持伤椎高度,出血少,固定节段短,是治疗高海拔地区脊柱爆裂骨折的有效方法。     

新型微创椎弓根钉-板固定系统的生物力学测试

目的 :评估新型微创椎弓根钉-板内固定系统的生物力学强度。方法:根据美国材料测试协会(ASTM)标准构建单钉-棒测试组件,在万能材料试验机上分别对微创椎弓根钉-板、单向椎弓根钉-棒和万向椎弓根钉-棒组件进行生物力学强度测试。测试内容包括静态侧压测试和疲劳测试。在静态侧压测试中使用6套组件,记录组件屈服载荷、屈曲刚度以及失效模式。在疲劳测试中记录完成250万次循环负荷的最大应力数值。结果:微创椎弓根钉-板组件的屈服载荷和屈曲刚度显著低于单向椎弓根钉-棒组件(834.6±74.5N vs 1087.7±59.0N,218.1±22.4N vs 300.0±14.9N,P0.001)。微创椎弓根钉板组件的屈服载荷与万向椎弓根钉-棒组件比较无显著性差异(834.6±74.5N vs 762.8±88.6N,P=0.118);而钉-板组件的刚度显著低于万向钉-棒组件(218.1±22.4N/mm vs 389.5±37.2N/mm,P0.001)。单向椎弓根钉-棒组件的失败模式为连接棒发生塑性形变,万向椎弓根钉-棒组件为"球窝偶联"结构失效,微创椎弓根钉-板组件为钛板的塑性形变和钉-板连接部位失效。在250万次动态侧压疲劳测试中,单向椎弓根钉-棒组件、微创椎弓根钉-板组件和万向椎弓根钉-棒组件分别在450N、450N和350N循环载荷下完成测试。结论:新型微创椎弓根钉-板内固定系统可耐受250万次450N循环载荷作用,同时具有高屈服载荷和低屈曲刚度的特点。     

Early complications of spinal pedicle screw

The complications of 648 consecutively inserted Universal AO pedicle screws (140 in the thoracic spine and 508 in the lumbar spine) performed by one surgical team to treat 91 patients with spinal problems, were reviewed. The spinal pathology consisted of: scoliosis (34 patients), degenerative lower lumbar spinal disease (25 patients), neoplastic spinal disease (11 patients), thoracic kyphosis (8 patients), spinal fractures (7 patients), lumbo-sacral spondylolisthesis (3 patients), and osteomyelitis (3 patients). Intraoperative complications were: screw misplacement (n = 3), nerve root impingement (n = 1), cerebrospinal fluid leak (n = 2) and pedicle fracture (n = 2). Postoperative complications were; deep wound infection (n = 4), screw loosening (n = 2) and rod-screw disconnection (n = 1). The conclusion was that pedicle screw fixation has an acceptable complication rate and neurological injury during this procedure is unlikely.