低龄儿童脊柱侧凸矫正术中椎弓根螺钉置入的精确性和安全性评估

目的:评估10岁及以下脊柱侧凸患儿侧凸矫正术中椎弓根螺钉置入的精确性及安全性,并分析其相关影响因素。方法:回顾性分析2008年2月~2008年7月我院收治的行后路椎弓根螺钉固定的10岁及以下脊柱侧凸41例患儿的临床资料,所有患者术前、术后均行CT检查,男26例,女15例,年龄2~10岁,平均5.4岁。先天性脊柱侧凸36例,特发性脊柱侧凸2例,神经肌肉源性脊柱侧凸2例,先天性软骨发育不全伴脊柱侧凸1例。术中根据解剖标志徒手置入椎弓根螺钉。在PACS系统上通过Pacs Client软件测量螺钉尖距椎弓根内壁、外壁、上壁、下壁以及椎体前缘的距离。若左侧椎弓根螺钉穿破椎弓根外壁或椎体前缘,测量钉尖与主动脉的距离。根据椎弓根螺钉所在位置(节段、凹凸侧、脊椎发育是否异常)分析其破壁率差别。不良置钉定义为椎弓根螺钉穿破椎弓根内、外壁或椎体前缘的距离超过2mm,和椎弓根螺钉进入椎间孔或穿破终板进入椎间盘。结果:本组病例共置入242枚椎弓根螺钉,胸椎128枚,腰椎114枚,平均每例患者置入5.8枚螺钉。螺钉完全在椎弓根内208枚,占86.0%。破壁34枚(占14.0%),其中不良置钉18枚(占7.4%),18枚中有5枚穿破外壁,8枚穿破内壁,5枚穿破椎体前缘。形态异常椎和凹侧的椎弓根螺钉的破壁率较高(分别为24.1%和17.9%)。术中一枚螺钉拔出,未出现其他螺钉置入相关并发症。穿破椎体前缘螺钉距离主动脉距离平均2.3mm。结论:10岁及以下儿童椎弓根螺钉的徒手置入有较高的精确性和安全性,但在发育不良椎体及凹侧置钉时应谨慎。     

顶椎置钉与否对Lenke 1型青少年特发性脊柱侧凸矫形效果的影响

目的:探讨顶椎置钉与否对Lenke 1型青少年特发性脊柱侧凸(AIS)患者矫形效果的影响。方法:回顾性分析从2009年6月～2010年1月采用全椎弓根螺钉后路矫形内固定融合术治疗的69例Lenke 1型AIS患者,年龄12～20岁,平均15.0岁,主弯Cobb角50°～70°,平均53.7°。根据顶椎置钉与否分为:顶椎凸凹侧均未置入螺钉组(A组,35例)和至少一侧置入螺钉固定组(B组,34例)。记录两组患者术前年龄、性别、主弯Cobb角、柔韧度、顶椎旋转度和固定节段数、置入物密度、术后Cobb角、主弯Cobb角矫正率、顶椎去旋转率等指标并进行两组间的比较分析。B组病例在CT图像上统计顶椎不良置钉率。结果:两组患者年龄、性别比、术前主弯Cobb角、柔韧度和顶椎旋转度等资料均无统计学差异(P>0.05)。所有病例矫形术后均未发生冠状面与矢状面的失代偿。随访24～30个月,平均27.7个月,两组患者无内固定松动及断钉断棒,植骨融合牢固,均未出现明显的矫正丢失。A、B两组置入物密度分别为63.4%、65.3%,平均固定节段数分别为11.3和11.6,主弯Cobb角矫正率分别为73.9%和72.6%。两组在置入物密度、内固定节段数和主弯Cobb角矫正率方面均无统计学差异(P>0.05)。术后顶椎去旋转率A组为18.4%,显著低于B组的34.8%(P<0.05)。B组顶椎置入的41枚螺钉中,有5枚为不良置钉(12.2%)。结论:对于Cobb角在50°～70°非严重的Lenke 1型青少年特发性脊柱侧凸,顶椎置钉尽管并不能显著提高侧凸矫正率,但可以明显矫正顶椎旋转,因此,在注意置钉安全性的前提下,应尽量在顶椎置入椎弓根螺钉。     

成人腰椎侧凸椎弓根螺钉误置模式

目的探讨成人腰椎侧凸椎弓根螺钉误置模式并分析其危险因素。方法选取2010年8月至2011年6月行后路全椎弓根螺钉固定的成人腰椎侧凸患者49例,男14例,女35例;年龄30～65岁,平均39．2±13．8岁。术中根据解剖标志徒手置入椎弓根螺钉,术后行CT检查。破壁螺钉按测量螺钉穿破椎弓根内、外侧壁及椎体前缘的距离分为4级：1级≤2mm,2级2．1—4．0mm,3级4．1～6．0mm,4级≥6．1mm。不良置钉为穿透任一壁距离超过2mm者,高危置钉为穿破内侧壁超过4mm或穿破外侧壁顶尖使主动脉变形者。比较不同分组螺钉破壁率的差异。结果49例共置入353枚螺钉,平均每例7．2枚。螺钉完全在椎弓根内且无椎体前缘穿破316枚（占89．5％）。破壁螺钉37枚（占10．5％）,根据破壁距离分级：1级25枚,2级8枚,3级1枚,4级3枚。不良置钉12枚（占3．4％）,其中穿破内、外侧壁及椎体前缘超过2mm分别为3枚、6枚、3枚。无高危置钉。螺钉破壁率：年龄〉50岁组为9．9％与年龄≤50岁组为10．9％无显著性差异（P=0．860）;顶椎（apicalvertebra,AV）高于AV上下各节段;凹侧为15．6％明显高于凸侧为5．9％（P=0．005）;Cobb角〉60°组为20．2％显著高于Cobb角≤60。组为6．1％（P〈0．001）。椎体旋转3—4度组为16．5％明显高于椎体旋转0～2度组为6．5％（P=0．012）。患者术中及术后均未出现神经并发症。结论成人腰椎侧凸椎弓根螺钉置人具有较高的精确性,破壁螺钉及不良置钉主要位于AV及凹侧,危险因素包括较大Cobb角、严重椎体旋转以及凹侧置钉。     

改良微创胸椎椎弓根钉置钉技术的应用研究

目的观察改良微创胸椎椎弓根钉置钉技术治疗胸椎压缩骨折的疗效,并探讨其临床应用的可行性。方法回顾性分析自2011-01—2013-12采用改良微创椎弓根钉置钉技术治疗的30例胸椎压缩骨折。取小切口,从最长肌及多裂肌之间进入,分离肌间隙后,显露出相关节段的下关节突及横突,选择下关节突外缘延长线与横突中轴线交界点为进针点,置入螺钉后透视证实螺钉位置。结果本组共置入螺钉180枚,按Mobbs-Raley分级标准评定螺钉置入的准确性:0级155枚,1级17枚,2级6枚,3级2枚,安全置钉率95.6%。2枚3级者(L4、L5各1枚)出现神经受压症状,行术后翻修。30例均获得随访12~26个月,平均15.6个月。术后1个月Cobb角、伤椎椎体前缘高度较术前明显改善,差异有统计学意义(P0.05);术后1年Cobb角、伤椎椎体前缘高度维持良好,与术后1个月比较差异无统计学意义(P0.05)。结论采用改良微创胸椎椎弓根钉置钉技术治疗胸椎骨折具有创伤小、操作便捷、辐射损伤小、置钉准确率高的优点,并且能够很好地恢复Cobb角及伤椎椎体前缘高度,后期并发症的发生率低。     

低骨量胸腰段椎体骨折椎弓根螺钉置入深度的作用

[目的]探讨低骨量胸腰段椎体骨折患者椎弓根螺钉置入深度对临床效果的影响。[方法]回顾性分析本院2012年1月～2016年12月行椎弓根螺钉复位固定治疗胸腰段骨折伴低骨量患者109例。依据术后CT显示椎弓钉置入深度将患者分为3组,椎弓根螺钉穿破椎体前缘皮质为双皮质组,椎弓根螺钉未穿破椎体前缘,但紧邻前缘皮质为皮质下组,椎弓根螺钉位于椎体中央或前1/3处为椎体内组。测量并记录术后Cobb角和伤椎前缘高度,计算术后矫正率与末次随访时矫正丢失率,三组间进行比较。[结果]109例患者中,符合双皮质组25例,皮质下组38例,椎体内组48例。术前三组间Cobb角和伤椎前缘高度的差异均无统计学意义(P0.05)。术后双皮质组和皮质下组在Cobb角矫正值和伤椎前缘高度矫正率方面均显著高于椎体内组,差异均具有统计学意义(P0.05),而双皮质组和皮质下组间的差异均无统计学意义(P0.05)。末次随访时双皮质组和皮质下组的Cobb角丢失值和伤椎前缘高度矫正丢失率均显著低于椎体内组,差异均具有统计学意义(P0.05),而前两组间差异无统计学意义(P0.05)。末次随访时,三组均有螺钉松动出现,双皮质组1例,皮质下组2例,椎体内组10例,差异有统计学意义(P0.05)。三组患者均未出现断钉或断棒。[结论]低骨量胸腰段椎体骨折行椎弓根螺钉固定时,应尽可能双皮质或皮质下置钉,以增加固定系统的稳定性与把持力。     

MSCT钉道设计在胸腰椎骨折伤椎置钉术中的应用

目的探讨多层螺旋CT(MSCT)设计钉道在胸腰椎骨折伤椎置钉术中的应用价值。方法回顾性分析自2014-01—2015-12行后路短节段椎弓根钉内固定联合伤椎置钉的102例胸腰椎骨折,52例采用MSCT设计钉道置入伤椎椎弓根钉(观察组),50例采用传统Weinstein法置入伤椎椎弓根钉(对照组)。结果观察组52例中伤椎共置入102枚椎弓根钉,其中2例伤椎单侧置钉;8枚螺钉穿破伤椎椎弓根皮质,其中2枚穿破内侧皮质,4枚穿破外侧皮质,1枚穿破上皮质,1枚穿破下皮质,置钉准确率为92.2%。对照组50例中伤椎共置入96枚椎弓根钉,其中4例伤椎单侧置钉;23枚螺钉穿破伤椎椎弓根皮质,其中6枚穿破椎弓根内侧皮质,9枚穿破外侧皮质,5枚穿破上皮质,3枚穿破下皮质,置钉准确率为76.0%。观察组置钉准确率明显高于对照组,差异有统计学意义(P 0.05)。结论采用MSCT三维重建技术设计钉道能够有效提高胸腰椎骨折伤椎置钉的准确率。     

下颈椎椎板和侧块作为椎弓根置钉角度参考标志的可靠性

【摘要】 目的：探讨下颈椎椎板和侧块作为椎弓根置钉角度参考标志的可靠性。方法：完整成人颈椎骨性标本10具,男、女各5具,模拟施行下颈椎椎弓根置钉手术;术前对C3~C7进行螺旋CT扫描多平面重建,确定椎弓根进钉轴,并以椎板和侧块作为椎弓根内倾角和上倾角的参考标志,测量椎弓根进钉轴与同侧椎板的夹角（PL角）及与侧块后表面的夹角（PLM角）,术中以相同参考标志和置钉角度置入椎弓根螺钉。术后复查CT并评估椎弓根螺钉置钉的准确率：0级,螺钉完全位于椎弓根内;1级,穿破椎弓根的部分<螺钉直径的25%;2级,螺钉直径的25%~50%穿破椎弓根;3级,螺钉直径>50%穿破椎弓根;2级和3级螺钉为误置。对颈椎标本各节段椎弓根螺钉位置的分级与椎弓根的宽度与高度进行相关性分析。2011年10月~2012年12月,用同样方法对6例患者进行下颈椎椎弓根螺钉置钉手术,评估置钉准确率和并发症情况。结果：10具颈椎标本的下颈椎椎弓根的PL角,C3、C4>C5、C6>C7;PLM角,C3、C4相似文献   

术中三维影像脊柱导航引导半椎体切除及椎弓根螺钉置入矫治儿童先天性脊柱侧后凸畸形

目的:探讨术中实时三维影像脊柱导航引导下后路椎弓根螺钉置入及半椎体切除矫治儿童先天性脊柱侧后凸畸形的临床疗效。方法:自2010年5月~2013年4月,对18例儿童先天性半椎体脊柱侧后凸畸形患者进行术中实时三维影像脊柱导航引导下进行脊柱矫形手术。其中,男7例,女11例,年龄7.6±2.9岁。术中在实时三维影像脊柱导航引导下经后路置入椎弓根螺钉并切除半椎体后进行矫形。术后通过CT评价椎弓根螺钉位置及半椎体切除情况,术前、术后摄脊柱正侧位X线片,评价矫形效果。结果:手术时间216±55min,术中出血量732±378ml。18例患者共置入椎弓根螺钉127枚(4~12枚/例)。术后CT证实124枚椎弓根螺钉位置准确,置钉准确率97.6%;1枚椎弓根螺钉穿破椎弓根内侧皮质,2枚椎弓根螺钉穿破椎弓根外侧皮质。1例出现椎弓根螺钉切割,1例出现血气胸,置入胸腔闭式引流。无神经损伤并发症病例,无螺钉误置而引起的并发症。术后CT证实18例患者半椎体均完整切除。18例中有16例获得随访,随访时间18.5±8.0个月。16例术前测量冠状面节段性侧凸Cobb角44.5°±11.4°,术后为9.3°±4.7°,末次随访时为9.7°±5.0°,矫正率为(78.2±7.8)%。节段性后凸Cobb角术前测量为32.2°±7.3°,术后为7.2°±3.5°,末次随访节时为7.7°±3.9°,矫正率为(76±9.4)%。侧凸及后凸矫正与术前相比均有统计学意义(P0.01)。末次随访时16例患者均获得骨性融合。结论:术中实时三维影像脊柱导航引导经后路矫治先天性脊柱侧后凸畸形半椎体切除完整,置入椎弓根螺钉准确率高,安全性高,畸形矫正效果满意。     

选择性增加伤椎单侧置钉内固定治疗胸腰段椎体骨折

目的探讨选择性增加经伤椎椎弓根置钉短节段钉棒内固定治疗胸腰段椎体骨折的临床效果。方法选择22例胸腰段椎体骨折,采用增加经伤椎椎弓根置钉短节段钉棒内固定,观察患者术前、术后伤椎前缘高度、脊柱Cobb角、神经恢复情况。结果术后伤椎前缘高度、脊柱Cobb角较术前明显恢复(P<0.01),无断钉、断棒。结论选择性增加经伤椎椎弓根置钉短节段钉棒内固定治疗胸腰椎严重骨折,术中伤椎复位满意、术后固定牢固、脊柱稳定性好,有利于伤椎骨折愈合和患者早期功能锻炼与康复。     

伤椎置入不同类型椎弓根螺钉治疗胸腰椎骨折的随机对照研究

目的通过对单一节段胸腰椎骨折患者的伤椎置入不同类型椎弓根螺钉的治疗效果的对比,来探讨伤椎椎弓根螺钉合理的选择方案。方法纳入符合标准的胸腰段单一椎体新鲜骨折患者共100例,随机分为两组,每组50例。A组术中采用伤椎置入等长单轴螺钉,B组术中于伤椎置入较短(30～35mm)万向螺钉。比较两组的伤椎前缘高度比率、伤椎前缘高度恢复率、伤椎前缘高度丢失率、伤椎后凸Cobb’s角、后凸Cobb’s角矫正度、后凸Cobb’s角丢失度,以及断钉断棒、ASD等手术相关不良事件。结果与术前比较,术后两组病例的伤椎椎体前缘高度比率及后凸Cobb’s角均有明显改善(P0.05);与术后相比,在末次随访两组的伤椎前缘高度及后凸Cobb’s角均稍有丢失,但丢失不明显(P0.05)。A组伤椎前缘高度及Cobb’s角较B组恢复更明显(P0.05)。B组伤椎前缘高度丢失率及后凸Cobb’s角丢失度要稍优于A组,但两组之间并无显著差异(P0.05)。A组中观测到2例患者出现断钉,1例患者发生ASD,而B组病例中均未见不良事件,但两组手术相关不良事件比较无统计学差异(P0.05)。结论对单一节段胸腰椎骨折患者的伤椎置入等长单轴螺钉或者较短(30～35mm)万向螺钉均可有效复位伤椎并维持脊柱稳定性,使用等长单轴螺钉在术后即刻复位效果上更有优势,但两者在复位效果的维持上并无显著差异。选择伤椎置入较短万向螺钉对于减少术后内固定失败、ASD等不良事件的发生有一定优势。     

In vivo accuracy of thoracic pedicle screws.

STUDY DESIGN: A retrospective observational study of 279 transpedicular thoracic screws using postoperative computed tomography (CT). OBJECTIVE: To determine the accuracy of transpedicular thoracic screws. SUMMARY OF BACKGROUND DATA: Previous studies have reported the importance of properly placed transpedicular thoracic screws. To our knowledge, the in vivo accuracy of pedicle screw placement throughout the entire thoracic spine by CT is unknown. METHODS: The accuracy of thoracic screw placement within the pedicle and vertebral body and the resultant transverse screw angle (TSA) were assessed by postoperative CT. Cortical perforations of the pedicle were graded in 2-mm increments. Screws were regionally grouped for analysis. RESULTS: Forty consecutive patients underwent instrumented posterior spinal fusion using 279 titanium thoracic pedicle screws of various diameters (4.5-6.5 mm). The regional distribution of the screws was 39 screws at T1-T4, 77 screws at T5-T8, and 163 screws at T9-T12. Fifty-seven percent of screws were totally confined within the pedicle. Although medial perforation of the pedicle wall occurred in 14% of screws, in <1% there was >2 mm of canal intrusion. Lateral pedicular perforation occurred in 68% of perforating screws and was significantly more common than medial perforation (P < 0.0005). Seventeen screws penetrated the anterior vertebral cortex by an average of 1.7 mm. Screws inserted between T1 and T4 had a decreased incidence of full containment within the pedicle (P < 0.0005) and vertebral body (P = 0.039) compared with T9-T12. The mean TSA for screws localized within the pedicle was 14.6 degrees and was significantly different from screws with either medial (mean 18.0 degrees ) or lateral (mean 11.5 degrees ) pedicle perforation (P < 0.0005). Anterior vertebral penetration was associated with a smaller mean TSA of 10.1 degrees (P = 0.01) and with lateral pedicle perforation (P < 0.0005). There were no neurologic or vascular complications. CONCLUSIONS: Ninety-nine percent of screws were fully contained or were inserted with either < or =2 mm of medial cortical perforation or an acceptable lateral breech using the "in-out-in" technique. Anterior cortical penetration occurred significantly more often with lateral pedicle perforation and with a smaller mean TSA. The incidence of fully contained screws was directly correlated with the region of instrumented thoracic spine.     

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 thoracic pedicle screw placement in adolescent idiopathic scoliosis

Pedicle screw fixation is a challenging procedure in thoracic spine, as inadvertently misplaced screws have high risk of complications. The accuracy of pedicle screws is typically defined as the screws axis being fully contained within the cortices of the pedicle. One hundred and eighty-five thoracic pedicle screws in 19 patients that were drawn from a total of 1.797 screws in 148 scoliosis patients being suspicious of medial and lateral malpositioning were investigated, retrospectively. Screw containment and the rate of misplacement were determined by postoperative axial CT sections. Medial screw malposition was measured between medial pedicle wall and medial margin of the pedicle screw. The distance between lateral margin of the pedicle screw and lateral vertebral corpus was measured in lateral malpositions. A screw that violated medially greater than 2 mm, while lateral violation greater than 6 mm was rated as an “unacceptable screw”. The malpositions were medial in 20 (10.8%) and lateral in 34 (18.3%) screws. Medially, nine screws were rated as acceptable. Of the 29 acceptable lateral misplacement, 13 showed significant risk; five to aorta, six to pleura, one to azygos vein and one to trachea. The acceptability of medial pedicle breach may change in each level with different canal width and a different amount of cord shift. In lateral acceptable malpositions, the aorta is always at a risk by concave-sided screws. This CT-based study demonstrated that T4–T9 concave segments have a smaller safe zone with respect to both cord-aorta injury in medial and lateral malpositions. In these segments, screws should be accurate and screw malposition is to be unacceptable.     

Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study

Background:

The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD), diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws.

Materials and Methods:

Sixty fresh human cadaveric vertebrae (D10–L2) were harvested. Dual-energy X-ray absorptiometry (DEXA) scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm) were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a) standard pedicle screw (no cortical perforation); b) screw with medial cortical perforation; and c) screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine.

Results:

Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra (P = 0.105), but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD (P = 0.901).

Conclusion:

The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different.     

Pedicle screw fixation of the C7 vertebra using an anteroposterior fluoroscopic imaging technique

Cervical pedicle screws have been reported to be biomechanically superior to lateral mass screws. However, placement of these implants is a technical challenge. The purpose of this investigation was to use an anatomic and a clinical study to evaluate a technique for placement of the pedicle screws in the C7 vertebra using fluoroscopic imaging in only the anteroposterior (A/P) plane. Ten adult cadaver C7 vertebrae were used to record the pedicle width, inclination and a suitable entry point for placement of pedicle screws. A prospective study of 28 patients undergoing posterior instrumentation of the cervical spine with C7 pedicle screw placement was also performed. A total of 55 C7 pedicle screws were placed using imaging only in the A/P plane with screw trajectory values obtained by the anatomic study. Radiographs and CT scans were performed post-operatively. The average posterior pedicle diameter of C7 vertebra was 9.5 ± 1.2 mm in this study. The average middle pedicle diameter was 7.1 mm and the average anterior pedicle diameter was 9.2 mm. The average transverse pedicle angle was 26.8 on the right and 27.3 on the left. CT scans were obtained on 20 of 28 patients which showed two asymptomatic cortical wall perforations. One screw penetrated the lateral wall of the pedicle and another displayed an anterior vertebral penetration. There were no medial wall perforations. The preliminary results suggest that this technique is safe and suitable for pedicle screw placement in the C7 vertebra.     

新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉

目的探讨新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉的准确性。方法对需要行颈椎后路椎弓根内固定治疗的22例下颈椎患者术前行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,采用Mimics 16.0和Imageware 12.0软件,制作颈椎三维模型,并设计出个体化的新型单椎单侧椎弓根导向模板,辅助颈椎椎弓根置钉。术后复查颈椎CT评价椎弓根螺钉的位置,按照Lee et al的评定方法将螺钉在椎弓根内的位置分为4级:0级,螺钉完全位于椎弓根内;1级,穿破椎弓根的部分螺钉直径的25%;2级,螺钉直径的25%~50%穿破椎弓根;3级,穿破椎弓根的部分螺钉直径的50%。0级和1级认为置钉满意,2级和3级认为螺钉误置。结果 22例均获得随访,时间6~36个月。22例患者共置入椎弓根螺钉113枚,改为侧块螺钉固定3枚。术后复查CT提示椎弓根螺钉位置107枚为0级,4枚为1级,2枚为2级。仅2例发生误置,置钉准确率达98.2%。其中1级和2级共6枚椎弓根螺钉均穿破椎弓根外侧壁,无椎弓根内侧壁及上、下壁穿破情况。对螺钉穿破外侧壁的患者行椎动脉MRA检查,未见椎动脉损伤。患者均未出现螺钉误置导致的脊髓、神经损伤并发症。结论新型单椎单侧椎弓根导向模板辅助下颈椎椎弓根个体化置钉准确性高,相关并发症少,为下颈椎椎弓根的置入提供了一种新的方法。     

Accuracy of fluoroscopically-assisted pedicle screw placement: analysis of 1,218 screws in 198 patients

Background contextWe retrospectively analyzed a total of 1,218 pedicle screws for accuracy, with postoperative computed tomography (CT), in 198 patients who were operated on between March 2004 and September 2012.PurposeTo determine the incidence of screw misplacement in patients who received a transpedicular screw fixation, with intraoperative fluoroscopy in the lateral and lateral with anteroposterior (AP) positions. The results are compared between the two groups.Study designRetrospective comparative study of accuracy of pedicle screw placement in thoracic and lumbar spine.Patient sampleThe sample consists of 198 consecutive patients who underwent transpedicular screw fixation.Outcome measuresAccuracy of screw placement was evaluated by postoperative CT scan. Misplacement was defined in cases where more than 25% of the screw size was residing outside the pedicle.MethodsThe indications for hardware placement, radiologic studies, patient demographics, and reoperation rates were recorded. Five hundred twenty-eight screws (Group A, n=81) were inserted into the vertebral body with the assistance of lateral fluoroscopy only, whereas 690 screws (Group B, n=117) were inserted with the assistance of lateral fluoroscopy, and the final positions of the screws were checked with AP fluoroscopy.ResultsA total of 1,218 screws were analyzed, with 962 screws placed at the lumbosacral region and 256 screws at the thoracic region. According to the postoperative CT scan, 27 screws (2.2%) were identified as breaching the pedicle. Nineteen of them (3.6%) were in Group A, whereas 8 (1.16%) were in Group B. The rate of pedicle breaches was significantly different between Group A and B (p=.0052). In Group A, the lateral violation of the pedicle was seen in 10 screws (1.9%), whereas medial violation was seen in 9 screws (1.7%). In Group B, the lateral violation of the pedicle was seen in six screws (0.87%), whereas medial violation was seen in two screws (0.29%). The medial and lateral penetration of screws were significantly different between Groups A and B (p<.05). A pedicle breach occurred in 21 patients, and 15 of them underwent a revision surgery to correct the misplaced screw. Of these patients, 11 (13.6%) were in Group A, and 4 (3.4%) were in Group B (p=.0335).ConclusionsIn this study, we evaluated and clarified the diagnostic value of intraoperative fluoroscopy in both the lateral and AP imaging that have not yet been evaluated in any comparative study. We concluded that the intraoperative use of fluoroscopy, especially in the AP position, significantly decreases the risk of screw misplacement and the results are comparable with other advanced techniques.     

Radiological and clinical outcome of screw placement in adolescent idiopathic scoliosis: evaluation with low-dose computed tomography

Posterior corrective surgery using “all pedicle screw construct” carries risk of neurovascular complications. The study aims were to assess the screw placement in patients with adolescent idiopathic scoliosis using CT with low-radiation dose, and to evaluate the clinical outcome in patients with misplaced pedicle screws. CTs of 49 consecutive patients (873 screws, 79% thoracic) were retrospectively evaluated by two independent radiologists. A new grading system was developed to distinguish between lateral, medial and anterior cortical perforations, endplate perforation and foraminal perforation. The grading system is based on whether the cortical violation is partial or total rather than on mm-basis. The overall rate of screw misplacement was 17% (n = 149): 8% were laterally placed and 6.1% were medially placed. The rates of anterior cortical, endplate and foraminal perforation were 1.5, 0.9, and 0.5%, respectively. Lateral cortical perforation was more frequent in the thoracic spine (P = 0.005), whereas other types of misplacement including medial cortical perforation were more frequent on the left and the concave side of scoliotic curves (P = 0.002 and 0.003). No neurovascular complications were reported. The association between the occurrence of screw misplacement and the Cobb angle was statistically significant (P = 0.037). Misplacements exceeding half screw diameter should be classified as unacceptable. Low-dose CT implies exposing these young individuals to a significantly lower radiation dose than do other protocols used in daily clinical practice. We recommend using low-dose CT and the grading system proposed here in the postoperative assessment of screw placement.     

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.