X-Ray assessment of the effect of pedicle screw on vertebra and spinal canal growth in children before the age of 7 years

Purpose

To determine the reliability of pedicle screws placed in children younger than 7 years of age, and to evaluate the effect of pedicle screw insertion on further growth of the vertebra and spinal canal.

Methods

A retrospective study of 35 consecutive patients through Jan 2003–Dec 2010 for congenital scoliosis in <7 years children was performed at one spine center. Patients undergoing pedicle screw instrumentation of at least two levels, which had been followed-up for at least 24 months were included. Measurements were performed in instrumented and adjacent non-instrumented levels. The effect of pedicle screw insertion on further growth was evaluated.

Results

The average age at surgery was 4.4 year (53 months, range, 23–84 months). 190 segments in 35 patients met the inclusion criteria. 77 segments had no screws and 113 had at least one screw. There was a significant difference between the pre-operative and final follow-up values of the measurement of spinal canal and vertebral body parameters (P < 0.001). No significant difference existed between growth rates of vertebral bodies and the sagittal diameters of spinal canal with or without screws. The growth rates of vertebral bodies in lumbar spine were higher than in thoracic spine in both instrumented and adjacent groups.

Conclusion

Pedicle screw instrumentation does not cause a retardation effect on the development of vertebral bodies and the spinal canal in children at an early age. It is a safe and reliable procedure to achieve a stable fixation.     

The effect of pedicle screw insertion at a young age on pedicle and canal development

STUDY DESIGN.: A longitudinal case study. OBJECTIVE.: To determine whether pedicle screws placed in an immature spine exert effect on the continued growth of the vertebral body. SUMMARY OF BACKGROUND DATA.: Pedicle screws have revolutionized surgical treatment of spinal deformities by allowing a mode of secure fixation that provides consistently better correction rates in adults and adolescents. In the young child, however, the trajectory of pedicle screws takes them through an open physis: the neurocentral cartilage. There exists little information regarding the possible effect of pedicle screws inserted at a young age on further development of the spine and the spinal canal. METHODS.: Patients undergoing pedicle screw instrumentation of at least 2 levels before the age of 5 years (60 mo) for the first time for any diagnosis and who had been followed for at least 24 months were included. Measurements were performed in instrumented and adjacent noninstrumented levels without visible deformity in pre- and postoperative cross-sectional images and compared using statistical methods. RESULTS.: Ninety segments in 15 patients met the inclusion criteria (average age at instrumentation 46.3 mo [range, 29-60 mo]). Forty segments had no screws and 50 had at least 1 screw. Pedicle length and vertebral body diameter had significantly increased in both groups, whereas spinal canal parameters did not change significantly. No significant difference was observed between the growth rates in levels with or without screws in pedicle length, vertebral body diameter, or spinal canal parameters (anterior-posterior and interpedicular diameters, and area). CONCLUSION.: Pedicle screw instrumentation performed before the age of 5 years does not cause a negative effect on the growth of pedicles, the transverse plane of the vertebral body, or the spinal canal. It can be safely performed in the treatment of deformity in this age group.     

Accuracy of upper thoracic pedicle screw placement using three-dimensional image guidance

Background contextPedicle screw malposition rates using conventional techniques have been reported to occur with a frequency of 6% to 41%. The upper thoracic spine (T1–T3) is a challenging area for pedicle screw placement secondary to the small size of the pedicles, the inability to visualize this area with lateral fluoroscopy, and significant consequences for malpositioned screws. We describe our experience placing 150 pedicle screws in the T1–T3 levels using three-dimensional (3D) image guidance.PurposeThe aim of this study was to assess the accuracy of 3D image guidance for placing pedicle screws in the first three thoracic vertebrae.Study designThe accuracy of pedicle screw placement in the first three thoracic vertebrae was evaluated using postoperative thin-section computed tomography (CT) scans of the cervicothoracic region.Patient sampleThirty-four patients who underwent cervicothoracic fusion were included.Outcome measuresRadiological investigation with CT scans was performed during the postoperative period.MethodsThirty-four consecutive patients underwent cervicothoracic instrumentation and fusion for a total of 150 pedicle screws placed in the first three thoracic vertebrae. All screws were placed using 3D image guidance. Medical records and postoperative imaging of the cervicothoracic junction for each patient were retrospectively reviewed. An independent radiologist reviewed the placement of the pedicle screws and assessed for pedicle breach. All cortical violations were reported as Grade 1, 0 to 2 mm; Grade 2, 2 to 4 mm; and Grade 3, greater than 4 mm.ResultsOverall, 140 (93.3%) out of 150 screws were contained solely in the desired pedicle. All 10 pedicle violations were Grade 1. The direction of pedicle violation included three medial, four inferior, two superior, and one minor anterolateral vertebral body. No complication occurred as a result of screw placement or the use of image guidance.ConclusionsUpper thoracic pedicle screw placement is technically demanding as a result of variable pedicle anatomy and difficulty with two-dimensional visualization. This study demonstrates the accuracy and reliability of 3D image guidance when placing pedicle screws in this region. Advantages of this technology in our practice include safe and accurate placement of spinal instrumentation with little to no radiation exposure to the surgeon and operating room staff.     

钉棒及钩棒系统治疗胸腰椎多节段脊柱骨折

目的评价钉棒及钩棒系统治疗胸腰椎多节段脊柱骨折的临床疗效。方法23例多节段胸腰椎骨折患者，后路切开复位，选择性椎管减压．钉棒或钩棒系统内固定及后外侧植骨融合进行手术治疗。其中相邻多节段型13例，非相邻多节段型8例，混合型2例。结果全组病例平均随访14个月，未发现内固定物松动、断离，无继发性脊柱后凸畸形加重。椎体高度由术前平均48．4％恢复至术后平均92．4%。2例完全性及11例不完全性脊髓损伤者．脊髓神经功能获改善。结论在椎管进行充分减压的基础上．钉棒及钩棒系统能有效复位椎体骨折，重建脊柱稳定性，是多节段胸腰椎不稳定性骨折合并脊髓神经损伤后路手术的理想选择。     

椎弓根螺钉在颈胸段骨折脱位中的临床运用

目的：评价椎弓根螺钉技术在颈胸段骨折脱位（C6-T2）中的运用价值。方法：2001年5月至2008年1月运用椎弓根螺钉植入技术治疗颈胸段骨折脱位患者26例,男17,女9例;年龄20-75岁,平均48．5岁。采用单纯后路椎弓根螺钉技术17例,后路椎弓根螺钉技术结合前路减压钢板内固定9例。术后3d运用CT平扫及重建片观察评价植入颈胸段椎弓根螺钉的准确性、螺钉植入相关并发症;随访观察患者颈胸段术后植骨融合情况;统计患者术前与术后6个月JOA评分及ASIA分级改善情况,综合评价患者脊髓及神经功能改善情况。结果：所有患者获得随访,随访时间3～74个月,平均36．5个月。4例完全性瘫痪患者术后6个月内死亡。共计植入椎弓根螺钉104枚,其中颈椎椎弓根74螺钉枚（其中：C516枚,C616枚,C742枚）,胸椎椎弓根螺钉30枚（其中：T1 22枚,T28枚）,所有椎弓根螺钉在术中均成功植入,无脊髓、神经根及椎动脉损伤。术后CT提示颈椎椎弓根螺钉11枚（14．9％）穿破椎弓根,其中7枚（9．5％）穿破外侧皮质,1枚（1．4％）穿破椎弓根上侧皮质,3枚（4．1％）穿破椎弓根下侧皮质。胸椎椎弓根螺钉中,3枚（10％）穿破胸椎椎弓根,其中2枚（6．7％）穿出椎弓根外侧缘,1枚（3．3％）穿破内侧缘（〈2mm）,但无临床症状。术后随访1枚C,椎弓根螺钉断裂,但患者无明显临床症状,其余无螺钉松动及断钉情况出现。所有患者固定良好,并均达到骨性融合。术后6个月患者平均JOA评分由术前（7．5±2．0）分恢复到（14．5±2．3）分,差异有统计学意义（t=6．34,P〈0．05）。ASIA分级情况,除3例完全性瘫痪患者脊髓功能术后无明显改善外,余患者术后脊髓神经功能均有不同程度恢复。结论：椎弓根螺钉在颈胸段骨折脱位治疗中安全、可靠。术者应熟练掌握颈胸段后?     

The ventral lamina and superior facet rule: a morphometric analysis for an ideal thoracic pedicle screw starting point

Background contextWith the increasing popularity of thoracic pedicle screws, the freehand technique has been espoused to be safe and effective. However, there is currently no objective, definable landmark to assist with freehand insertion of pedicle screws in the thoracic spine. With our own increasing surgical experience, we have noted a reproducible and unique anatomic structure known as the ventral lamina.PurposeWe set out to define the morphologic relationship of the ventral lamina to the superior articular facet (SAF) and pedicle, and describe an optimal medial-lateral pedicle screw starting point in the thoracic spine.Study designWe conducted an in vitro fresh-frozen human cadaveric study.MethodsOne hundred fifteen thoracic spine vertebral levels were evaluated. After the vertebral body was removed, Kirschner wires were inserted retrograde along the four boundaries of the pedicle. Using digital calipers, we measured width of the SAF and pedicle at the isthmus, and from the borders of the SAF to the boundaries of the pedicle. We calculated the morphologic relationship of the ventral lamina and the center of the pedicle (COP) to the SAF.ResultsTwo hundred twenty-nine pedicles were measured, with one pedicle excluded because of fracture of the SAF during disarticulation. The ventral lamina was clearly identifiable at all levels, forming the roof of the spinal canal and confluent with the medial pedicle wall (MPW). The mean distance from the SAF midline to the MPW was 1.36±1.23 mm medial. The MPW was lateral to SAF midline in 34 pedicles (14.85%) and, on average, was a distance of 0.52±0.51 mm lateral. The mean distance from the SAF midline to the COP was 2.17±1.38 mm lateral. The COP was medial to SAF midline in only 11 pedicles (4.80%).ConclusionsThe ventral lamina is an anatomically reproducible structure located consistently medial to the SAF midline (85%). We also found the COP consistently lateral to the SAF midline (95%). Based on these morphologic findings, the medial-lateral starting point for thoracic pedicle screws should be 2 to 3 mm lateral to the SAF midline (superior facet rule), allowing screw placement in the COP and avoiding penetration into the spinal canal.     

枢椎椎板螺钉在上颈椎后路固定术中的应用

目的探讨枢椎椎板螺钉固定术应用于上颈椎后路融合内固定术中的可行性。方法回顾性分析本院2012年1月—2014年12月在上颈椎后路融合固定术中采用枢椎椎板螺钉固定的19例患者资料,术中根据枢椎椎弓根是否存在缺如、细小等情况,选择置入双侧枢椎椎板螺钉或单侧枢椎椎板螺钉并对侧椎弓根螺钉,联合枕骨板螺钉和/或寰椎侧块螺钉。15例上颈椎畸形患者均有不同程度脊髓功能损害表现,日本骨科学会(JOA)评分为5~15分,平均11.5分。4例外伤性寰枢椎骨折患者有后颈部疼痛及活动障碍,疼痛视觉模拟量表(VAS)评分为2~7分,平均4.5分。术后复查患者影像学资料,观察内固定位置及植骨融合情况。结果所有手术顺利完成,未发生椎动脉、脊髓等损伤。术后复查CT,显示所有枢椎椎板螺钉位置良好,均未突破内侧皮质骨。随访时X线、CT示螺钉位置良好,无松动及断钉。所有患者术后12个月植骨均融合,上颈椎畸形患者神经功能均有不同程度改善,JOA评分为13~17分,平均15.3分。外伤性寰枢椎骨折患者颈部疼痛及活动障碍明显改善,VAS评分为0~2分,平均1.0分。结论枢椎椎板螺钉固定在上颈椎后路固定手术中方法简单安全、效果良好,对于无法行枢椎椎弓根螺钉固定的患者,枢椎椎板螺钉固定是一种安全有效的替代方法。     

徒手置钉技术在脊柱畸形矫正中的准确性与安全性研究

目的 探究徒手置钉技术在脊柱畸形矫正中的准确性与安全性.方法 回顾性分析本院2012年4月-2012年8月所有因脊柱畸形而接受脊柱后路三维矫形椎弓根内固定手术的36名病例.所有病例术中仅采用徒手置钉技术,均不使用C形臂X线机透视或导航系统等计算机辅助设备,较严重病例或重度后凸需要截骨者使用神经电生理监测.术后行脊柱全长正侧位X线片及CT扫描,通过影像归档和通信系统（picture archiving and communication systems,PACS）查看影像资料,记录皮质穿破的类型及距离.术后密切观察有无血管及神经源性并发症直至出院.结果 36名患者置入螺钉总数为550枚.其中210枚螺钉发生误置,总发生率为38.18%（210/550）.内侧皮质穿破（medial cortical perforation,MCP）的发生率为5.27%（29/550）;外侧皮质穿破（lateral cortical perforation,LCP）的发生率为27.09%（149/550）;椎体前壁穿破（anterior cortical perforation,ACP）的发生率为6.55%（36/550）;上终板穿破（endplate perforation,EPP）的发生率为0.55%（3/550）;椎间孔穿破（foramen perforation,FP）的发生率为0.91%（5/550）.上、中、下胸椎及腰椎的MCP发生率分别为3.39%（2/59）、3.90%（51/128）、5.81%（10/172）、6.28%（12/191）,LCP发生率分别为44.07%（26/59）、50.78%（65/128）、25.00%（43/172）、7.85%（15/191）.MCP在胸椎及腰椎的发生率相近,分别为4.7%（17/359）、6.3%（12/191）,差异无统计义意义（P＞0.05）,而胸椎较腰椎更易发生LCP,发生率分别为 37.3%（134/359）、7.9%（15/191）,差异有统计学意义（P＜0.01）.所有病例术后均无神经、血管及内脏相关并发症出现.结论 徒手置钉技术在脊柱畸形矫正中的应用是安全的,可以避免使用术中透视、计算机导航等带来的不利影响.LCP是最常见的穿破类型,在胸椎的发生率比在腰椎高,因而在胸椎使用计算机图像系统等协助置钉可能更有应用价值.     

Accuracy of pedicle screw placement for upper and middle thoracic pathologies without coronal plane spinal deformity using conventional methods

There is a growing interest in the implantation of pedicle screws into the middle and upper thoracic spine. However, usage of the technique is still under debate for these levels because the pedicles in these regions are small and exhibit a high degree of inter- and intraspecimen variability. Twenty-four consecutive patients treated for upper and middle thoracic pathologies by pedicle screw instrumentation under biplanar or uniplanar fluoroscopy were evaluated retrospectively. The rate of screw misplacement on postoperative computerized tomography and complications caused by misplaced screws were determined. In 24 cases, a total of 113 upper-middle thoracic pedicle screws were inserted. Fifty-one of them were inserted between T2 and T5 with guidance of biplanar fluoroscopy, and 62 were inserted between T6 and T8 with uniplanar fluoroscopy. The rate of misplacement was 20.3% for 113 screws (27.4% for T2 to T5 screws, and 14.5% for 62 T6 to T8 screws). Four screws were incorrectly inserted which could have clinical significance (3.5%), and 1 of them required revision. The difference between the upper and middle thoracic screws was not statistically significant (P=0.089). Screw insertion with laminectomy did not cause significant difference in both upper and middle thoracic regions. Only 2 complications were seen because of screw insertion. Pedicle screw insertion with guidance of fluoroscopy may be a reliable and safe method for upper and middle thoracic pathologies.     

Abstracts Presented at Aps Forty-Fifth Annual Conference Paper Abstracts

Abstract

Background: Image guidance provides additional anatomic information to the surgeon, which may allowmore accurate insertion of spinal implants. Imprecise placement of anterior thoracic screws places the spinalcord and paraspinal structures at risk for injury. Image guidance may afford a safety benefit to patients whenanterior thoracic screws are required in the setting of spinal stabilization after trauma.

Objectives: To compare the accuracy of anterior thoracic screw placement using standard fluoroscopy,computer-assisted fluoroscopic image guidance, lso-C3D image guidance, and electromagnetic fluoroscopicimage guidance.

Study Design: A surgical simulation study in human cadaver spine specimens.

Methods: After an open thoracotomy approach, anterior thoracic screws were placed by experienced spinesurgeons using 4 different image-guided techniques in 4 human cadaver thoracic spines. Screws were placedin the 9th, 1Oth, and 11th thoracic vertebrae of each specimen. The specimens were then examined with thincutcomputed tomography (CT) scans, and with sagittal and coronal reconstructions. Measurements includedthe distance of the screw from the spinal canal, the angle of the screw path in relation to a perpendicular toa line that bisects the spinous process, and the angle of screw divergence from the superior endplate.

Results: There was no evidence of sp inal canal penetrance with any of the image-guided techniques usedto place anterior thoracic vertebral body screws. Screws inserted with standard fluoroscopy tended to aimanterolaterally by 18°. The image-guidance systems allowed more accurateplacement of anterior thoracicscrews in the transverse plane compared with standard fluoroscopy. There was no statistically significantdifference in coronal plane screw angulation (angle of divergence with the superior endplate) between anyof the imaging methods.

Conclusions: Spinal image-guidance systems may allow spine surgeons to place anteriorthoracic screws moreprecisely, particularly in the axial plane. The improved accuracy of spinal implant insertion could ultimately provide a benefit to patient safety, especially in the setting of malaligned vertebral bodies after trauma.     

Accuracy and safety of free-hand pedicle screw fixation in age less than 10 years

Background:

Pedicle screws are being used commonly in the treatment of various spinal disorders. However, use of pedicle screws in the pediatric population is not routinely recommended because of the risk of complications. The present study was to evaluate the safety of pedicle screws placed in children aged less than 10 years with spinal deformities and to determine the accuracy and complication (early and late) of pedicle screw placement using the postoperative computed tomography (CT) scans.

Materials and Methods:

Thirty one patients (11 males and 20 females) who underwent 261 pedicle screw fixations (177 in thoracic vertebrae and 84 in lumbar vertebrae) for a variety of pediatric spinal deformities at a single institution were included in the study. The average age of patients was 7 years and 10 months. These patients underwent postoperative CT scan which was assessed by two independent observers (spine surgeons) not involved in the treatment.

Results:

Breach rate was 5.4% (14/261 screws) for all pedicles. Of the 177 screws placed in the thoracic spine, 13 (7.3%) had breached the pedicle, that is 92.7% of the screws were accurately placed within pedicles. Seven screws (4%) had breached the medial pedicle wall, 4 screws (2.3%) had breached the lateral pedicle wall and 2 screws (1.1%) had breached the superior or inferior pedicle wall respectively. Of the 84 screws placed in the lumbar spine, 83 (98.8%) screws were accurately placed within the pedicle. Only 1 screw (1.2%) was found to be laterally displaced. In addition, the breach rate was found to be 4.2% (11/261 screws) with respect to the vertebral bodies. No neurological, vascular or visceral complications were encountered.

Conclusions:

The accuracy of pedicle screw placement in pedicles and vertebral bodies were 94.6% and 95.8% respectively and there was no complication related to screw placement noted until the last followup. These results suggest that free-hand pedicle screw fixation can be safely used in patients younger than 10 years to treat a variety of spinal disorders.     

Facet joint violation after open and percutaneous posterior instrumentation: a comparative study

Purpose

Posterior instrumentation is the state-of-the-art surgical treatment for fractures of the thoracic and lumbar spine. Options for pedicle screw placement comprise open or minimally invasive techniques. Open instrumentation causes large approach related muscle detachment, which minimally invasive techniques aim to reduce. However, concerns of accurate pedicle screw placement are still a matter of debate. Beside neurological complications due to pedicle screw malplacement, also affection of the facet joints and thus motion dependent pain is known as a complication. The aim of this study was to assess accuracy of pedicle screw placement concerning facet joint violation (FJV) after open- and minimally invasive posterior instrumentation.

Methods

A retrospective data analysis of postoperative computer tomographic scans of 219 patients (1124 pedicle screws) was conducted. A total of 116 patients underwent open screw insertion (634 screws) and 103 patients underwent minimally invasive, percutaneous screw insertion (490 screws).

Results

In the lumbar spine (segments L3, L4, L5), there were significantly more and higher grade (open = 0.55 vs. percutaneous = 1.2; p = 0.001) FJV’s after percutaneously compared to openly inserted screws. In the thoracic spine, no significant difference concerning rate and grade of FJV was found (p > 0.56).

Conclusion

FJV is more likely to occur in percutaneously placed pedicle screws. Additionally, higher grade FJV’s occur after percutaneous instrumentation. However, in the thoracic spine we didn’t find a significant difference between open and percutaneous technique. Our results suggest a precise consideration concerning surgical technique according to the fractured vertebrae in the light of the individual anatomic structures in the preop CT.

     

Complications of pedicle screw fixation in reconstructive surgery of the cervical spine

STUDY DESIGN: Retrospective evaluation of complications in 180 consecutive patients with cervical disorders who had been treated by using pedicle screw fixation systems. OBJECTIVES: To determine the risks associated with pedicle screw fixation in the cervical spine and to emphasize the importance of preoperative planning and surgical techniques in reducing the risks of this procedure. SUMMARY OF BACKGROUND DATA: Generally, pedicle screw fixation in the cervical spine has been considered too risky for the neurovascular structures. There have been several reports describing the complications of lateral mass screw-plate fixation. However, no studies have examined in detail the complications associated with cervical pedicle screw fixation. METHODS: One hundred eighty patients who underwent cervical reconstructive surgery using cervical pedicle screw fixation were reviewed to clarify the complications associated with the pedicle screw fixation procedure. Cervical disorders were spinal injuries in 70 patients and nontraumatic lesions in 110 patients. Seven hundred twelve screws were inserted into the cervical pedicles, and the locations of 669 screws were radiologically evaluated. RESULTS: Injury of the vertebral artery occurred in one patient. The bleeding was stopped by bone wax, and no neurologic complication developed after surgery. On computed tomographic (CT) scan, 45 screws (6.7%) were found to penetrate the pedicle, and 2 of 45 screws caused radiculopathy. Besides these three neurovascular complications directly attributed to screw insertion, radiculopathy caused by iatrogenic foraminal stenosis from excessive reduction of the translational deformity was observed in one patient. CONCLUSIONS: The incidence of the clinically significant complications caused by pedicle screw insertion was low. Complications associated with cervical pedicle screw fixation can be minimized by sufficient preoperative imaging studies of the pedicles and strict control of screw insertion. Pedicle screw fixation is a useful procedure for reconstruction of the cervical spine in various kinds of disorders and can be performed safely.     

三维平板透视引导上颈椎椎弓根螺钉置入准确性及疗效分析

目的 评价在三维平板透视系统引导下应用上颈椎椎弓根螺钉内固定加植骨融合技术治疗上颈椎骨折的安全性和临床疗效。方法 回顾性分析自2012-06-2013-10我科收治的11例上颈椎骨折脱位病例,均在术中三维平板透视系统引导下采用上颈椎椎弓根螺钉短节段内固定加植骨融合技术进行手术治疗。结果 术后所有患者的颈椎稳定性均得到即刻恢复,44枚螺钉均在位良好,未发生脊髓及椎动脉损伤等任何与置钉相关的并发症,无螺钉断裂、松动。结论 在三维平板透视系统引导下经上颈椎椎弓根螺钉内固定加植骨融合技术治疗上颈椎骨折脱位,螺钉置入准确性高,有效防止置钉并发症,力学稳定性好,植骨融合率高,是上颈椎骨折后路固定术中理想的手术方式之一。     

The use of pedicle-screw internal fixation for the operative treatment of spinal disorders

Pedicle screws have dramatically improved the outcomes of spinal reconstruction requiring spinal fusion. Short-segment surgical treatments based on the use of pedicle screws for the treatment of neoplastic, developmental, congenital, traumatic, and degenerative conditions have been proved to be practical, safe, and effective. The Funnel Technique provides a straightforward, direct, and inexpensive way to very safely apply pedicle screws in the cervical, thoracic, or lumbar spine. Carefully applied pedicle-screw fixation does not produce severe or frequent complications. Pedicle-screw fixation can be effectively and safely used wherever a vertebral pedicle can accommodate a pedicle screw--that is, in the cervical, thoracic, or lumbar spine. Training in pedicle-screw application should be standard in orthopaedic training programs since pedicle-screw fixation represents the so-called gold standard of spinal internal fixation.     

上胸椎椎弓根螺钉固定并发症的探讨

目的分析上胸椎椎弓根螺钉固定的并发症,总结其手术技巧和经验。方法回顾性分析2009年4月至2012年4月采用T1~4椎弓根螺钉技术治疗的各类上胸椎损伤68例(共384枚螺钉),上胸椎骨折/脱位45例,均行Ⅰ期后路切开复位内固定术;结核合并后凸畸形23例,均行前路病灶清除植骨融合内固定术+后路矫形术。所有患者结合术中胸椎椎弓根四壁探查、术后手术节段椎体X线片、CT扫描,观察螺钉在椎弓根内的位置、角度及与椎弓根壁的关系和距离。结果椎弓根壁损伤54枚(14.06%),其中外侧壁损伤39枚(10.16%),包括Ⅰ级损伤27枚(7.03%),Ⅱ级损伤12枚(3.12%);内侧壁损伤15枚,均为Ⅰ级损伤。无1枚螺钉损伤上下壁,无1枚螺钉同时损伤超过2个壁,无术中置钉失败,螺钉松动位移2枚,创伤患者Frankel分级无加重,非创伤患者脊髓功能JOA评分由术前的5.9分提高至术后的11.5分,未发现植骨不融合、假关节形成或节段不稳表现。结论上胸椎椎弓根螺钉固定的并发症发生率低,是相对安全的操作方法。术前详细分析影像学资料、熟悉局部解剖特点、掌握合理的置钉技术,可有效避免并发症的发生。     

枢椎棘突螺钉与椎弓根螺钉的解剖学比较

目的：比较枢椎棘突螺钉和椎弓根螺钉的技术难度和相关解剖学参数,探讨枢椎棘突螺钉固定的可行性和安全性。方法：自2010年2月至7月,选取10具颈椎标本,男5具,女5具,年龄45～76岁,平均60.5岁。将标本俯卧,颈部置于中立位。从C1-C3剔除颈部后侧所有的软组织,以清楚地暴露枢椎侧块和峡部。枢椎椎体左右侧任意选择进行棘突螺钉和椎弓根螺钉固定,各10枚螺钉,置入直径为4.0mm的皮质骨螺钉。枢椎棘突螺钉以枢椎棘突螺钉的进钉点选择为棘突的基底部、棘突和椎板的交界处,进钉角度水平置钉,螺钉由对侧棘突基底部穿出,形成双层皮质固定;枢椎椎弓根螺钉进钉点为枢椎下关节突根部中点,钉道方向与矢状面夹角15°～20°,与横断面夹角约30°。螺钉置入后,使用多层螺旋CT扫描机对标本进行扫描重建。测量螺钉在骨内的实际深度,记录椎弓根螺钉和棘突螺钉置钉失败、穿破椎弓根、进入椎管或置入横突孔的螺钉数目。结果：枢椎棘突螺钉和椎弓根螺钉的置入均无明显的技术困难。棘突螺钉未见螺钉置入椎管和劈裂棘突,但椎弓根螺钉有1枚螺钉突出椎弓根外侧皮质,侵犯横突孔。枢椎棘突螺钉的平均钉道长度为（21.4±1.4）mm,稍短于枢椎椎弓根螺钉的（23.7±1.0）mm,但两者间差异无统计学意义（t=-4.387,P〉0.05）。结论：枢椎棘突基底部具有螺钉固定的可行性,枢椎棘突螺钉较椎弓根螺钉固定相对安全、简单。     

青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性评价

目的：探讨青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性，以减少相关手术并发症。方法：32例青少年脊柱侧凸患者术前均对畸形脊柱进行标准俯卧位CT加密扫描，测量进钉点至椎体前缘的深度、进针角度、椎弓根直径和椎体的旋转角度，根据测得数据确定椎弓根螺钉置入的深度和方向，置入螺钉后再行脊柱全长X线片及CT扫描评价置钉的准确性和安全性。结果：32例共置入226枚胸椎椎弓根螺钉，术后CT加密和X线片观察到205枚螺钉（90．7％）完全在椎弓根皮质骨内。10例21枚螺钉（9.3％）发生错置，7枚螺钉（3．1％）偏外，5枚螺钉（2．2％）偏前外侧（其中2枚螺钉靠近节段血管），4枚螺钉（1．8％）偏下，4枚螺钉（1．8％）直径过大导致椎弓根内壁膨胀内移，1枚螺钉（0．4％）误入椎管导致完全性脊髓损伤。T1～T4错置12枚（18．2％），T5～T12错置9枚（6．1％）；凸侧椎根螺钉置入的准确率为93．8％，凹侧为83．1％。结论：脊柱畸形患者术前应常规采用标准俯卧位CT加密扫描，根据扫描图像测得的相关数据可为术中准确置入椎弓根螺钉提供重要参考依据。在青少年脊柱侧凸患者胸椎椎弓根螺钉置入有一定的误置率，螺钉发生错置多见于上胸椎和凹侧．术中应高度重视。     

Evaluation of the value of pedicle screws for cervicothoracic fracture‐dislocation

Objective: To explore the value of pedicle screw implantation for fracture‐dislocation injuries of the cervicothoracic junction (C₆–T₂). Methods: Pedicle screws were implanted into 26 patients (17 male and 9 female) with cervicothoracic fracture‐dislocations from May 2001 to January 2008. Computed tomography (CT) scan was used to evaluate the accuracy of placement of the pedicle screws three days after surgery. Complications and state of neurological recovery were also recorded after the procedures. Results: One hundred and four pedicle screws were implanted successfully in our group. Seventy‐four pedicle screws were inserted into cervical vertebrae, 16 at C₅, 16 at C₆, and 42 at C₇, while thirty were implanted in the upper thoracic vertebrae, 22 at T₁ and 8 at T₂. Injury to the spinal cord, nerve roots or vertebral artery did not occur during surgery. Eleven screws (14.9%) perforated pedicles in the cervical spine. Three screws (10%) perforated the pedicle wall in the upper thoracic spine. Fusion was achieved in all cases and no failure of internal fixation was found, except for one screw which broke at C₅. Neurological improvement was found in all patients according to the American Spinal Injury Association (ASIA) score except for eight who suffered from complete paralysis. The Japanese Orthopaedic Association (JOA) score increased from 7.5 ± 2.0 to 14.5 ± 2.3 (t= 6.34, P < 0.05). Conclusion: Implantation of pedicle screws is a safe and reliable method for treating fracture‐dislocation injuries at the cervicothoracic junction.     

椎弓根螺钉对幼犬腰椎发育的影响

目的通过动物实验观察椎弓根螺钉置入对腰椎形态发育的影响。方法取16只2月龄幼犬，随机分为三组。A组为空白对照组（3只），自L1-7做后路切开显露，暴露目标椎的椎板部分，仅造成对目标椎椎板的软组织剥离损伤。B组为对照组（5只），暴露目标椎椎板后，将螺钉穿过椎弓根，造成对目标椎椎弓根及神经弓中心软骨的隧道破坏后再将螺钉取出，螺钉不留置。C组为实验组（8只），暴露目标椎椎板后，将螺钉穿过椎弓根，造成对目标椎椎弓根及神经弓中心软骨的隧道破坏后不取出，螺钉留置于目标椎椎弓根内。实验的目标椎设计为L2、L4、L6，目标椎的上下两个相邻椎体的相应测量指标的平均值设计为其自身对照。CT测量术后当日及术后3个月的腰椎形态学指标，通过配对t检验比较各组目标椎在不同时期的形态学指标测量值与其自身对照值的差异情况，从而判断椎弓根螺钉的置入对脊椎形态发育的影响效果。结果C组目标椎的椎管面积、横径、纵径、椎弓根长度与相邻脊椎平均值比较差异有统计学意义（P〈0．05），而A组、B组与相邻脊椎平均值比较差异无统计学意义（P〉0．05）。各组椎体横径、纵径、高度与相邻脊椎平均值比较差异无统计学意义（P〉0．05）。结论椎弓根螺钉固定可影响幼犬腰椎椎管及椎弓的发育，可能导致医原性椎管狭窄而对于椎体发育无明确影响。仅破坏神经弓中心软骨联合而不留置螺钉对腰椎发育无明显的影响。