徒手胸椎椎弓根螺钉置入技术治疗青少年特发性脊柱侧凸的安全性评价

目的 评价徒手胸椎椎弓根螺钉置入技术治疗青少年特发性脊柱侧凸的安全性。方法从2002年7月～2004年6月对38例青少年特发性脊柱侧凸患者，徒手应用胸椎椎弓根螺钉进行后路矫形内固定，所有患者术中进行神经电生理监测及X线透视确认，术后进行X线成像、CAT扫描评估螺钉位置，并对其中35例进行随访，从而评价本技术的安全性。结果共置入胸椎椎弓根螺钉326个，每一水平置入的螺钉数如下：T1,n=2；T2，n=10;T3，n=19；T4，n=27；L，n=28；T6，n=24；T7，n=23；TB，n=25；T9，n=29；T10,n=34；T11,n=48；T12，n=57。通过胸椎CT扫描评价326枚置入畸形胸椎的螺钉位置。共有19枚螺钉（5．8％）有中等程度的皮质穿破，即螺钉的中线在椎弓根壁皮质之外，其中6枚螺钉（1．8％）穿破椎弓根内侧壁。对35例患者进行术后跟踪随访，平均随访时间2年，未发现任何与置入的胸椎椎弓根螺钉（全部326枚螺钉）相关的神经、血管或内脏并发症。结论遵循严格步骤，逐步置入胸椎椎弓根螺钉的徒手技术在治疗青少年特发性脊柱侧凸中具有可靠的安全性。     

O形臂导航辅助、C形臂辅助与常规徒手置入胸腰椎椎弓根螺钉准确性的定量比较

目的 比较O形臂导航辅助、C形臂辅助与常规徒手置入胸腰椎椎弓根螺钉的准确性。方法回顾性分析2015年2月-2018年12月应用椎弓根螺钉系统辅助融合治疗的129例胸腰椎置钉患者术后CT资料,其中胸腰段以下脊柱骨折41例,退行性疾病88例。常规开放手术直视下徒手置钉(徒手组)42例,C形臂辅助下经皮置钉(C形臂组)46例,开放手术O形臂导航辅助下置钉(O形臂组)41例。从螺钉长度、横断面进钉角度、矢状位进钉角度、椎弓根内侧壁、椎弓根上下壁、椎弓根外侧壁6个方面,采用10分制定量评估椎弓根螺钉置钉准确性,记录得分情况并进行组间比较。结果共置钉712枚。徒手组置钉准确性评分为7.79±0.93,满分比例为7.7%(16/208);C形臂组评分为9.13±0.59,满分比例为51.0%(101/198);O形臂组评分为9.27±0.65,满分比例为62.1%(190/306)。C形臂组和O形臂组置钉准确性评分差异无统计学意义(P > 0.05),但均高于徒手组,差异有统计学意义(P < 0.05)。结论 C形臂辅助经皮置钉和O形臂导航辅助置钉的准确性优于传统徒手置钉,C形臂辅助经皮置钉与O形臂导航辅助置钉准确性相当。     

快速成型个体化导航模板辅助胸椎椎弓根螺钉置入可行性研究

[目的]通过尸体标本实验的方法探讨个体化导航模板辅助胸椎椎弓根螺钉置入的准确性及可行性.[方法]对6具胸椎尸体标本进行CT扫描,根据CT扫描资料,利用逆向工程原理及快速成型技术设计制造出个体化导航模板,利用个体化导航模板在尸体标本上辅助置入胸椎椎弓根螺钉,所有螺钉的置入由同一位具有腰椎椎弓根螺钉置钉经验但无胸椎椎弓根螺钉置钉经验的骨科医师进行操作,随后采用大体解剖的方法肉眼观察置钉的准确性;并根据螺钉是否穿破椎弓根、穿出距离及穿破方向进行分级.[结果]共设计制作了72个个体化导航模板辅助置入胸椎椎弓根螺钉144枚,132枚(91.7%)螺钉完全在椎弓根内;12(8.3%)枚螺钉穿破椎弓根,其中2枚螺钉穿破椎弓根内侧壁(穿破距离分别为0.6、0.8 mm),10枚螺钉穿破椎弓根外侧壁(9枚螺钉穿出距离<2 mm,1枚螺钉穿出距离为2.5 mm);没有椎弓根上方、下方及椎体前方穿破的螺钉.所有穿破椎弓根壁的螺钉均在安全可接受的范围内.[结论]快速成型个体化导航模板辅助胸椎椎弓根螺钉置入准确率高,对术者无特别的经验要求,手术操作简单、安全,可避免术中放射性损伤,为胸椎椎弓根螺钉的置入提供了一种新的可行方法,尤其适用于初学者.     

胸椎椎弓根螺钉置入位置的CT评价

目的:探讨胸椎椎弓根螺钉置入的准确性和安全性。方法:对37例胸椎椎弓根螺钉内固定患者术后行CT断层扫描,观察螺钉在椎弓根内的位置,记录螺钉穿透骨壁的位置、数目和距离。结果:37例患者共置入405枚胸椎椎弓根螺钉,124枚螺钉(30.61%)穿透骨壁,其中76枚(18.77%)穿透椎弓根外侧壁,32枚(7.90%)穿透椎弓根内侧壁,16枚(3.95%)穿透椎体前壁。66枚(16.30%)穿透距离<2mm,37枚(9.14%)穿透距离在2mm~4mm之间,21枚(5.9%)穿透距离>4mm。结论:胸椎椎弓根螺钉骨壁穿透率较高,应严格按照胸椎椎弓根螺钉置入方法,仔细操作,避免出现因螺钉置入不当造成神经、血管或内脏损伤等并发症。     

Accuracy and safety of pedicle screw placement in neuromuscular scoliosis with free-hand technique

It is a retrospective analytic study of 1,009 transpedicular screws (689 thoracic and 320 lumbosacral), inserted with free-hand technique in neuromuscular scoliosis using postoperative CT scan. The aim of paper was to determine the accuracy and safety of transpedicular screw placement with free-hand technique in neuromuscular scoliosis and to compare the accuracy at different levels in such population. All studies regarding accuracy and safety of pedicle screw in scoliosis represent idiopathic scoliosis using various techniques such as free-hand, navigation, image intensifier, etc., for screw insertion. Anatomies of vertebrae and pedicle are distorted in scoliosis, hence accurate and safe placement of pedicle screw is prerequisite for surgery. Between 2004 and 2006, 37 consecutive patients, average age 20 years (9–44 years), of neuromuscular scoliosis were operated with posterior pedicle screw fixation using free-hand technique. Accuracy of pedicle screws was studied on postoperative CT scan. Placement up to 2 mm medial side and 4 mm lateral side was considered within-safe zone. Of the 1,009 screws, 273 screws were displaced medially, laterally or on the anterior side showing that 73% screws (68% in thoracic and 82.5% in lumbar spine) were accurately placed within pedicle. Considering the safe zone, 93.3% (942/1009, 92.4% in thoracic and 95.3% in lumbar spine) of the screws were within the safe zone. Comparing accuracy according to severity of curve, accuracy was 75% in group 1 (curve <90°) and 69% in group 2 (curve >90°) with a safety of 94.8 and 91.2%, respectively (P = 0.35). Comparing the accuracy at different thoracic levels, it showed 67, 64 and 72% accuracy in upper, middle and lower thoracic levels with safety of 96.6, 89.2 and 93.1%, respectively, exhibiting no statistical significant difference (P = 0.17). Pedicle screw placement in neuromuscular scoliosis with free-hand technique is accurate and safe as other conditions.     

Thoracic pedicle screw instrumentation using the "Funnel Technique": part 2. Clinical experience

This study is a retrospective review of the clinical results of patients treated with thoracic pedicle screws using the "funnel technique." The objective is to report the clinical results of patients treated with thoracic pedicle screws using the funnel technique for screw placement. A total of 115 patients treated with the use of at least one thoracic pedicle screw were retrospectively identified. All patients were treated at a single medical center, under the senior author's supervision. Twenty-five different residents were responsible for placing 50-60% of these screws, and five different fellows and the senior author placed the remainder. The accuracy of screw placement and the complications related to the use of thoracic pedicle screws were analyzed by assessing intraoperative and postoperative charts and radiographs. There were 115 patients (age range 9-82 years) with the average follow-up period of 17 months. The total number of screws used was 348; the screw diameter ranged from 4.0 to 7.75 mm. There were no vascular or pulmonary complications. There was no iatrogenic neurologic injury, except for one patient who developed a transient anterior thigh numbness from intraoperative positioning. In fracture patients, 35% (10 of 28) had documented neurologic improvement postoperatively. There were no obviously misplaced pedicle screws on detailed review of intraoperative and postoperative radiographs. No screws had to be electively removed for complications related to misplacement. There were four broken screws, one broken rod, two loose screws, and three connector disengagements. Two patients had deep infections and four patients had pseudarthrosis requiring additional surgery. The clinical results proved that thoracic pedicle screws can be safely placed with the funnel technique.     

Learning curve of thoracic pedicle screw placement using the free-hand technique in scoliosis: how many screws needed for an apprentice?

Purpose

The purpose of this study is to evaluate the learning curve of thoracic pedicle screw (TPS) placement of an inexperienced apprentice in scoliosis with the free-hand technique.

Methods

The patients with scoliosis who underwent TPS inserted with the free-hand technique by the apprentice under the direction of a chief surgeon were included in this study. The TPS placement by the apprentice was evaluated by examining the assessed position in chronological subgroups of 30 screws. The TPS position was assessed on the postoperative computed tomography (CT) scan images using Zdichavsky grading evaluation system and pedicle breach. The rates of good and dangerous screw placement and the rates of pedicle breaches in each apprentice subgroup were compared with those in the chief surgeon group.

Results

Thirty-eight patients with 311 TPS were retrospectively analyzed in our study. Of all screws, 154 pedicle screws were inserted by the apprentice, and were divided chronologically into five subgroups. The rates of dangerous placement performed by the apprentice in the first two subgroups were 26.7 and 23.3%, respectively, and were significantly higher than 9.1% by the chief surgeon (P < 0.05). Meanwhile, the breach rate was 46.6% in subgroup 1 and 50.0% in subgroup 2, and was significantly higher than 29.3% in chief surgeon (P < 0.05). Furthermore, after the first 60 TPS placements, the assessed rates in apprentice reached to a stable level, and no significant difference could be found among the subgroups (subgroup 3, 4 and 5) and the chief surgeon group (P > 0.05).

Conclusions

For an apprentice, an experience of at least 60 screw placements under the direction of an experienced surgeon is needed for inserting the TPS in scoliosis using the free-hand technique independently.     

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.     

Inserting pedicle screws in the upper thoracic spine without the use of fluoroscopy or image guidance. Is it safe?

Several studies have looked at accuracy of thoracic pedicle screw placement using fluoroscopy, image guidance, and anatomical landmarks. To our knowledge the upper thoracic spine (T1–T6) has not been specifically studied in the context of screw insertion and placement accuracy without the use of either image guidance or fluoroscopy. Our objective was to study the accuracy of upper thoracic screw placement without the use of fluoroscopy or image guidance, and report on implant related complications. A single surgeon inserted 60 screws in 13 consecutive non-scoliotic spine patients. These were the first 60 screws placed in the high thoracic spine in our institution. The most common diagnosis in our patient population was trauma. All screws were inserted using a modified Roy-Camille technique. Post-operative axial computed tomography (CT) images were obtained for each patient and analyzed by an independent senior radiologist for placement accuracy. Implant related complications were prospectively noted. No pedicle screw misplacement was found in 61.5% of the patients. In the remaining 38.5% of patients some misplacements were noted. Fifty-three screws out of the total 60 implanted were placed correctly within all the pedicle margins. The overall pedicle screw placement accuracy was 88.3% using our modified Roy-Camille technique. Five medial and two lateral violations were noted in the seven misplaced screws. One of the seven misplaced screws was considered to be questionable in terms of pedicle perforation. No implant related complications were noted. We found that inserting pedicle screws in the upper thoracic spine based solely on anatomical landmarks was safe with an accuracy comparable to that of published studies using image-guided navigation at the thoracic level.     

Accuracy of thoracic pedicle screw placement in scoliosis using the ideal pedicle entry point during the freehand technique

Previously, we described the ideal pedicle entry point (IPEP) for the thoracic spine at the base of the superior facet at the junction of the lateral one third and medial two thirds with the freehand technique on cadavers. Here we measured the accuracy of thoracic pedicle screw placement (Chung et al. Int Orthop 2008) on post-operative computed tomography (CT) scans in 43 scoliosis patients who underwent operation with the freehand technique taking the same entry point. Of the 854 inserted screws, 268 (31.3%) were displaced; 88 (10.3%) and 180 (21.0%) screws were displaced medially and laterally, respectively. With regard to the safe zone, 795 screws were within the safe zone representing an accuracy rate of 93%; 448 and 406 thoracic screws inserted in adolescent idiopathic and neuromuscular scoliosis showed an accuracy of 89.9 and 94%, respectively (p = 0.6475). The accuracy rate of screws inserted in the upper, middle and lower thoracic pedicles were 94.2, 91.6 and 93.7%, respectively (p = 0.2411). The results indicate that IPEP should be considered by surgeons during thoracic pedicle screw instrumentation.     

CT accuracy of percutaneous versus open pedicle screw techniques: a series of 1609 screws

Introduction

Traditional open exposure for posterior instrumentation requires significant soft tissue mobilization and causes significant blood loss and increased recovery time. Mal-placed screws can injure nerve roots, the spinal cord, viscera, vasculature and the cardiopulmonary system. Placement of pedicle screws using a minimally invasive technique can decrease bleeding risk, damage to soft tissues, and post-operative pain. The purpose of this study is to compare the radiographic accuracy of open free-hand versus percutaneous technique for pedicle screw placement.

Methods

Consecutive patients undergoing thoracolumbar surgery from September 2006 to October 2011 with post-operative CT imaging were included in this study. Three-dimensional screw positioning within the pedicle and the vertebral body was assessed on CT. The magnitude and location of violations were measured and recorded. Facet breaches at the cephalad and caudad ends of the construct were documented and graded.

Results

Two-hundred and twenty-three patients met the inclusion criteria for a total of 1609 pedicle screws. Seven-hundred and twenty-four screws were placed using a standard open free-hand technique and 885 were placed percutaneously. There was a significant difference in overall pedicle breach rates: 7.5 % for open and 4.7 % for percutaneous techniques. The magnitude of breach was greater for the percutaneous technique compared to the open technique: 5.4 versus 3.7 mm, respectively. The difference in vertebral body breaches was also significant: 11.3 % for open and 3.6 % for percutaneous. The rates of facet breach did not significantly differ.

Discussion and conclusion

This is the largest series comparing the accuracy of percutaneous to open pedicle screw placement. The rates of pedicle, vertebral body, and facets breaches in the percutaneous group were similar to the rates in the open technique group as well as rates reported in the literature. This demonstrates that the percutaneous technique described here is an accurate alternative to standard open free-hand technique.

     

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.     

Thoracic pedicle screw insertion in scoliosis using posteroanterior C-arm rotation method

OBJECTIVE: Previous researches have emphasized the importance and difficulties in accurate thoracic pedicle screw insertion in scoliosis patients. However, there has been no report on accuracy of the insertion using posteroanterior C-arm fluoroscopy rotated to allow en face visualization of the pedicle in humans. This study aimed to evaluate the accuracy of the thoracic pedicle screw insertion technique using a C-arm fluoroscopy rotation method for the treatment of scoliosis. METHODS: Between October 1997 and September 2005, 33 scoliosis patients who underwent surgical treatment with a total of 410 screws were analyzed. Eleven were male, 22 female and the mean age was 13.4 years. The mean preoperative Cobb angle was 59.7 degrees. Screws were inserted using the C-arm rotation method; screw positions were evaluated with postoperative computed tomography scans. RESULTS: The mean preoperative Cobb angle of 59.7 degrees was corrected to 18.9 degrees (range, 3 to 45 degrees) in the coronal plane (mean correction rate 68%). Postoperative computed tomography scans demonstrated 48 screws penetrated the medial (9 screws) or lateral (39 screws) pedicle cortex with a mean distance of 3.1 and 3.6 mm, respectively. No screws penetrated the inferior or superior cortex in the sagittal plane. CONCLUSIONS: Thoracic pedicle screw insertion in scoliosis patients using the posteroanterior C-arm rotation method allows en face visualization of both pedicles by rotating the C-arm to compensate for the rotational deformity, making it a practical, simple and safe method.     

Safety and efficacy of pedicle screw placement for adult spinal deformity with a pedicle-probing conventional anatomic technique

A prospective study of 50 adults treated with fusion, realignment, and segmental spinal instrumentation for spinal deformity was conducted to assess the safety, accuracy, and efficacy of the free-hand pedicle screw placement technique. Postoperative computed tomographic scans were performed to evaluate the placement of 282 screws and were correlated with patients' clinical outcomes. Five screws were placed at T12, 26 at L1, 39 at L2, 48 at L3, 73 at L4, 35 at L5, and 50 at S1. Nine screws (3%) were misplaced and included three screws (1.06%) that violated the medial wall with no clinical sequelae or revision surgery needed. There were no neurologic deficits related to screw placement. The free-hand technique is a safe and cost-effective method for pedicular screw placement during surgery for adult spine deformities.     

The accuracy of pedicle screw placement in the thoracic spine using the "Funnel Technique": part 1. A cadaveric study

A cadaveric study using the "funnel technique" to probe thoracic pedicles was conducted. The results (location, level, and perforation rate) of three spine surgeons of varying experience were compared. The objectives were to evaluate the reliability and accuracy of the funnel technique for the placement of thoracic pedicle screws and to describe the technique. Nine fresh cadavers (216 thoracic pedicles) were used for pedicle screw placement using the funnel technique. The study was conducted by three spine surgeons with a significantly different level of experience in thoracic pedicle screw placement (72 thoracic pedicles each). Critical and noncritical perforations were recorded. The perforation rate was 6% (13 of 216 pedicles). Of this, only 0.4% (1 of 216) was a critical perforation (a contact with T8 nerve root). The junior spine surgeon who had no previous experience with thoracic pedicle screw placement had a 12.5% (9 of 72) perforation rate, the surgeon very familiar with the technique had a 5.5% (4 of 72) perforation rate, and the senior author who originated this technique had a 1.4% (1 of 70) perforation rate. All perforations made by the junior spine surgeon occurred in his first 24 pedicles; none occurred in his last 48 pedicles. The reliability of the funnel technique in placement of thoracic pedicle screws was proven in our cadaveric study. It provided even an entry-level surgeon with a safe way to identify and place thoracic pedicle screws. The funnel technique is a simple, safe, and cost-effective alternative to any other currently recommended techniques for pedicle screw placement.     

Freehand technique for C2 pedicle and pars screw placement: is it safe?

Background Context

During placement of C2 pedicle and pars screws, intraoperative fluoroscopy is used so that neurovascular complications can be avoided, and screws can be placed in the proper position. However, this method is time consuming and increases radiation exposure. Furthermore, it does not guarantee a completely safe and accurate screw placement.

三维重建技术在上胸椎和颈椎椎弓根螺钉植入的临床应用

目的通过应用三维重建技术辅助椎弓根螺钉的植入,评价其在上胸椎和颈椎置钉中的准确性和安全性。方法 2013年1月至2013年11月,对12例需要行上胸椎、颈椎椎弓根螺钉植入手术的患者术前通过Mimics三维重建图像设计进钉通道并获取相关参数,术中辅助植入上胸椎、颈椎椎弓根螺钉共50枚,术后CT扫描评价螺钉位置,记录有无与螺钉植入的相关并发症。结果通过Mimics三维重建植入的50枚椎弓根螺钉,47枚完全在椎弓根内,3枚穿破椎弓根壁,椎弓根穿破率为6%,植钉准确率为94%,所有穿破椎弓根壁的螺钉的穿出距离均小于2 mm,螺钉位置可接受率为100%。无一例出现螺钉植入有关的神经、血管损伤等并发症。结论 Mimics三维重建技术辅助上胸椎、颈椎椎弓根螺钉植入的置钉准确性高、安全,且明显缩短手术时间。     

Accuracy and safety of thoracic pedicle screw placement in spinal deformities

OBJECTIVES: To determine the safety of pedicle screw fixation in thoracic spine deformity correction. METHODS: One hundred twelve pedicle screws were surgically placed in 25 patients with degenerative, posttraumatic, and Scheuermann kyphosis and idiopathic and neuromuscular scoliosis. Screw position was evaluated using intraoperative and postoperative radiographs and thin-slice computed tomography. RESULTS: Of the total 112 thoracic pedicle screws that were inserted, 98 screws (87.5%) were fully contained within the cortical boundaries of the pedicle. When comparing proximal screws (T1-T8) with distal screws (T9-T12) and convex placed screws with concave ones, a statistically significant difference in screw placement was evident (P < 0.05). More misplaced screws were seen proximally and on the concave side. Of the 14 malpositioned screws, 2 (1.8%) demonstrated aortic abutment. There were no neurologic deficits, vascular injuries, or mechanical failures recorded. CONCLUSIONS: Placement of thoracic pedicle screws is both feasible and safe.     

应用椎板开窗法置入胸椎椎弓根螺钉的精确性和安全性评估

目的 分析应用椎板开窗法行胸椎椎弓根螺钉置入治疗重度脊柱侧后凸患者的精确性和安全性. 方法 1996年6月至2007年12月,应用椎板开窗法行胸椎椎弓根螺钉置入治疗23例重度脊柱侧后凸患者(A组),其中男性9例,女性14例;年龄13～23岁,平均17.8岁;术前主胸弯冠状面Cobb角平均97.3°,平均后凸角67.4°.作为对照,同期应用非开放法置钉治疗重度脊柱侧后凸患者22例(B组),其中男性7例,女性15例;年龄14～21岁,平均17.2岁;术前主胸弯冠状面Cobb角平均为96.6°,平均后凸角62.1°.两组患者术后均行CT扫描,统计螺钉置入并发症,对螺钉穿透椎弓根皮质骨的CT扫描图像进行联机测量并统计分析.结果 A组和B组各置入胸椎椎弓根螺钉209和201枚,术中发生椎弓根骨折5例和16例,发生硬膜撕裂4例和7例,螺钉错置18枚和45枚.B组螺钉错置率高于A组,差异具有统计学意义(P<0.05).A组上、中胸椎与下胸椎之间、凸侧与凹侧之间,螺钉错置率差异均具有统计学意义(P<0.05).两组均无脊髓及大血管损伤. A和B组经平均3.2年、3.4年随访,术后冠状面和矢状面平均矫正度未见明显丢失.结论 重度脊柱侧后凸胸椎椎弓根螺钉置入技术难度较高,应用椎板开窗法可有效增加螺钉置入精确性和安全性.     

Accuracy of computed tomography in assessing thoracic pedicle screw malposition

OBJECTIVE: Transpedicular instrumentation of the thoracic spine is potentially dangerous because of the close proximity of vital structures and the morphologic variability seen. Computed tomography has become the gold standard in evaluating the position of thoracic pedicle screws in vivo. Unfortunately, despite its common use, the accuracy of computed tomography has not been adequately investigated. The objective of this work was to evaluate the accuracy of computed tomography in evaluating the position of thoracic pedicle screws. METHODS: One hundred ninety-four thoracic pedicles in nine cadaveric specimens were instrumented and evaluated postoperatively with computed tomography and open dissection. Computed tomography films were assessed by three blinded observers who noted the position of each pedicle screw on two separate occasions. These data were subsequently compared with the open dissection data. RESULTS: Computed tomography was found to be 76 +/- 16% sensitive and 75 +/- 13% specific when compared with open dissection. Overall accuracy was 76 +/- 8%. Intraobserver accuracy was 79 +/- 5% in assessing thoracic pedicle screws by computed tomography. Fair to moderate degree of agreement was demonstrated for both interobserver and intraobserver data using kappa values. CONCLUSIONS: Computed tomography was found to be relatively insensitive in assessing thoracic pedicle screw position. In the face of postoperative complications, surgical exploration and hardware removal may still be necessary despite negative computed tomography.