经椎间孔椎体间植骨治疗胸腰椎C型旋转骨折脱位

目的 探讨后路经椎间孔椎体间融合治疗胸腰椎C型旋转骨折脱位的可行性及疗效.方法 2009年3月～2010年8月收治胸腰椎AO分型C型旋转骨折脱位患者10例,均为青年男性,伤椎累及T10～L3.AO分类C1型7例,C3型3例,神经功能按美国脊髓损伤学会（American Spinal Injury Association,ASIA）分级全部为A级.均行后路椎弓根螺钉内固定结合经椎间孔椎体间植骨融合手术治疗,术后随访神经功能恢复和植骨愈合.结果 10例患者手术时间平均130 min,术中出血平均 520 mL.术后X线片显示脊柱复位良好,植骨位置良好.随访12个月椎间植骨均获得骨性融合,4例ASIA分级A级恢复到B级,6例无恢复.结论 后路切开复位减压椎弓根螺钉内固定结合经椎间孔椎体间融合能从单一入路能同时完成胸腰椎C型旋转骨折脱位的减压、复位、固定和融合的治疗.     

一期后路保留部分关节突开窗病灶清除短节段椎弓根螺钉内固定治疗腰骶椎结核

目的探讨一期后路保留部分关节突开窗、病灶清除、植骨融合、短节段椎弓根螺钉内固定治疗腰骶椎结核的可行性及疗效。方法 2010年1月-2014年12月对符合选择标准的32例腰骶椎(L4~S1)脊柱结核患者,采用一期后路保留部分关节突开窗、病灶清除、植骨融合、短节段椎弓根螺钉内固定治疗。男20例,女12例;年龄17~62岁,平均43岁。病程12~48个月,平均18个月。病灶累及节段:L5、S1 19例,L4、5 13例。临床效果采用Oswestry功能障碍指数(ODI)及影像学指标(手术前后腰骶角矫正情况及术后X线片骨融合Bridwell分级和CT骨融合标准)评价。结果患者均顺利完成手术,手术时间平均180 min,术中出血量平均400 m L。32例均获随访,随访时间12~67个月,平均15.6个月。末次随访时患者结核中毒症状均消失,无内固定物松动、断裂发生;7例神经症状患者神经功能均恢复正常,美国脊柱损伤协会(ASIA)分级由术前C级2例、D组5例均恢复至E级。术后1年及末次随访时ODI评分均较术前显著改善(P0.05),术后1年及末次随访间比较差异无统计学意义(P0.05)。术后7 d、1年及末次随访时腰骶角均较术前显著增加(P0.05),术后各时间点间比较差异无统计学意义(P0.05)。术后植骨融合时间为9~24个月,平均12个月。术后1年和末次随访时X线片Bridwill骨融合率分别为87.50%(28/32)和93.75%(30/32),CT总融合率分别为87.50%(28/32)和90.63%(29/32),两个时间点间植骨融合情况比较差异有统计学意义(P0.05)。4例出现耐药,经调整抗结核方案1年后3例呈BridwillⅢ级融合,1例呈Ⅳ级融合。结论一期后路保留部分关节突开窗能有效清除病灶,椎体及附件间植骨、短节段椎弓根螺钉内固定能维持术后脊柱可靠的稳定性并获得较满意的植骨融合率,是治疗腰骶椎结核的有效方法。     

胸腰段骨折后正中单切口360°椎管减压椎体间植骨内固定术的临床观察

目的：探讨后正中单切口360。椎管减压椎体间植骨后路椎弓根螺钉内固定术治疗严重胸腰段骨折伴脊髓压迫症的安全性及有效性。方法：自2009年1月至2010年3月,从收治的108例胸腰椎骨折病例中选取硬膜前后方均有骨性压迫的胸腰段骨折5例患者,男2例,女3例;年龄23-72岁;损伤部位：T12 2例,L,2例,k1例。采用后正中单切口经椎弓根入路360°椎管减压椎体间植骨后路椎弓根螺钉内固定术治疗。记录手术时间、术中出血量、术后24hVAS评分及吗啡用量、手术前后神经功能Frankel／ASIA分级。结果：所有病例获得随访,时间12～18个月,平均14．6个月。手术时间3．1~6．2h;术中出血量1000～2300ml;术后24hVAS评分为1～4分;术后24h吗啡用量为28．8—30．8mg。Frankel／ASIA等级：术前B级1例,C级2例,D级1例,E级1例;术后E级4例,1例从B级提高到D级。结论：后正中单切口360°椎管减压椎间植骨椎弓根螺钉内固定术治疗胸腰段严重骨折是安全、有效的,术后疼痛较轻、并发症较少。     

微创椎弓根螺钉内固定联合前路病灶清除植骨治疗胸腰椎结核

[目的]探讨微创椎弓根螺钉内固定联合前路病灶清除植骨对胸腰椎结核的治疗效果。[方法]随访2012年1月~2015年1月在本科行微创椎弓根螺钉内固定联合前路病灶清除植骨治疗的胸腰椎结核手术患者资料24例,其中男14例,女10例,年龄21~65岁,平均45岁,胸椎结核7例,胸腰段结核11例,腰椎结核6例,术前至少1周抗结核治疗,术后标准疗程抗结核治疗,随访手术前后VAS评分、ASIA神经功能分级、影像学资料及结核愈合情况。[结果]24例患者切口均一期愈合,围手术期无重大并发症,随访时间24~60个月,无结核复发病例。VAS评分术前4~7分,平均5.6分,末次随访1~3分,平均1.9分,ASIA神经功能分级术前C级3例,D级5例,E级16级;术后D级2例,E级22例。后凸畸形均得到显著改善,术后6个月随访植骨均融合,无内固定并发症,后凸矫正角度无明显丢失。[结论]微创椎弓根螺钉内固定联合前路病灶清除植骨治疗胸腰椎结核,创伤较传统前后路联合手术小,有利于彻底病灶清除及植骨融合,能有效矫正后凸矫形,适用于前中柱破坏较多而后柱完整、无需后方减压,且一般情况相对良好的患者。     

一期后路病灶清除植骨融合内固定治疗腰骶椎结核

目的探讨一期后路病灶清除植骨融合内固定治疗腰骶椎结核的临床疗效。方法对15例腰骶椎结核患者采用一期后路病灶清除、植骨融合、腰椎椎弓根钉和骶骨椎弓根钉或侧翼钉内固定治疗。结果手术时间平均为170.5 min±24.2 min,术中出血量平均为980.3 ml±168.6 ml。无硬脊膜和大血管损伤,无窦道形成等。患者均获随访,时间12~39个月,均获得骨性融合,无内固定松脱。按骨结核治愈标准评价:患者全部治愈,无结核复发迹象。11例术前下肢肌力不同程度减退,末次随访时除1例趾伸肌力由Ⅲ级恢复至Ⅳ级外,其余全部恢复至Ⅴ级;11例术前小腿或足皮肤痛触觉减退,末次随访时除2例部分恢复外,其余全部恢复正常;术前膝、踝反射减弱或消失9例,末次随访时2例部分恢复,其余全部恢复正常;术前6例直腿抬高试验60°内阳性,术后全部恢复正常。结论在正规抗结核治疗基础上,一期行后路病灶清除植骨融合内固定治疗腰骶椎结核是一种安全有效的手术方式。     

强直性脊柱炎胸腰椎骨折的损伤特点和治疗

目的分析强直性脊柱炎胸腰椎骨折的损伤特点,探讨治疗方法。方法强直性脊柱炎胸腰椎骨折11例,保守治疗1例(L1压缩性骨折者);手术治疗10例,其中前路手术减压内固定3例,后路椎弓根螺钉系统复位内固定、植骨7例。结果切口无感染,无脑脊液漏。1例T12L1骨折行后路椎弓根螺钉系统复位内固定并植骨术(未行椎管探查或减压),麻醉苏醒后发现脊髓神经症状由术前的C级加重为B级;1例L3～5骨折伴马尾神经损伤行前路手术后第2天出现内固定松动、骨折椎再次移位,脊髓神经症状加重,再次行前路内固定取出和后路长节段椎弓根螺钉系统固定植骨术。患者均获得随访,时间10个月～5年,平均(32±4.8)个月,手术患者中8例植骨于6个月获得融合,2例不能明确是否融合。后期未出现内固定松动或断裂现象。脊髓神经损伤者除1例A级无改变、1例C级加重为B级(末次随访时为C级)、1例D级加重为A级外,其余3例有Ⅰ～Ⅱ级的恢复。9例无腰背痛,2例遗留轻度腰背部酸痛。结论强直性脊柱炎胸腰椎骨折患者宜行后路椎弓根螺钉固定、植骨治疗。     

伤椎置钉单节段固定植骨融合治疗胸腰段脊柱骨折

目的总结伤椎椎弓根螺钉单节段固定植骨融合在胸腰段脊柱骨折中的治疗效果。方法回顾2006年4月至2009年11月我科治疗的31例胸腰段脊柱骨折患者,其中男21例,女10例,年龄22～49岁,平均34．7岁。对其在伤椎及上位椎行短节段椎弓根螺钉内固定,椎间植骨或置椎间融合器。结果本组随访6～24个月,术后2周可下床锻炼,术后伤椎高度及脊柱Cobb角均有较大的恢复。结论伤椎椎弓根螺钉单节段固定植骨融合治疗胸腰段脊柱骨折创伤小,能较大程度的恢复骨折椎的高度及脊柱Cobb角,为脊柱生物力学重建和功能恢复提供了一个坚强而稳固的基础。     

经椎间孔椎体间植骨融合结合伤椎椎弓根螺钉内固定治疗严重胸腰椎骨折

目的 探讨经椎间孔椎体间植骨融合结合伤椎椎弓根螺钉内固定治疗严重胸腰椎骨折的临床疗效.方法 对15例严重胸腰椎骨折患者经椎间孔椎体间植骨、伤椎椎弓根螺钉内固定治疗,术后进行临床和影像学随访.结果 15例均获得随访,时间6～12个月.患者骨折椎体高度均明显恢复,伤椎椎体高度比:术前为49.2%±15.7%,术后3 d及3个月分别为99.2%±4.5%、91.1%±5.8%,与术前比较差异均有统计学意义(P＜0.05).Cobb角:术前为32.3°±9.6°,术后3 d和术后3个月分别为3.5°±3.4°、3.9°±3.7°,与术前比较差异均有统计学意义(P＜0.05).神经功能按ASIA分级,除5例A级患者无恢复外,其余较术前均有1级或1级以上的恢复.结论 经椎间孔椎体间植骨融合结合伤椎椎弓根螺钉内固定是治疗严重胸腰椎骨折的良好方法.     

前后路一期病灶清除植骨内固定治疗腰骶脊柱结核

目的探讨采用前后路一期病灶清除植骨内固定治疗腰骶脊柱结核的临床效果。方法采用后路椎弓根内固定加前路病灶清除植骨治疗腰骶椎结核10例，术后抗痨治疗。结果切口均一期愈合，无窦道形成。随访1-4年，植骨块均在4—6个月融合，无植骨块松动移位发生，所有患者腰痛、下肢麻痛症状消失。结论采用后路椎弓根内固定加前路病灶清除植骨是治疗腰骶椎结核的一种稳定可靠的手术方法。     

新型扩张器辅助伤椎内植骨结合椎弓根内固定治疗胸腰段爆裂性骨折

目的 探讨采用新型椎体扩张器经椎弓根椎体内自体骨植骨结合椎弓根内固定治疗胸腰段爆裂性骨折的近期疗效.方法 2007年8月至2008年3月共收治胸腰段爆裂性骨折16例,根据AO分型:A2型10例.A3型6例.按ASIA脊髓神经功能障碍分级标准:A级2例,B级2例,C级2例,D级3例,E级7例.采用自行设计的新型椎体扩张器经伤椎椎弓根椎体内自体骨植骨,椎管减压(或不减压),相邻节段椎弓根内固定. 结果 伤椎椎体前缘高度由术前(18.3±2.5)mm恢复到术后(25.1±2.8)mm,Cobb角由术前36.33°±2.14°恢复到术后2.77°±0.41°(术后1周),差异均有统计学意义(P<0.01).伤椎经扩张器扩张后平均椎体内植骨量(10.53±3.62)cm3 椎体扩张器下伤椎椎体内植骨未引起神经、血管损伤等术中和术后并发症,术后随访6个月,椎体内植骨融合良好,伤椎前缘高度丢失和Cobb角与术后1周相比无明显变化,不完全性神经损伤术后脊髓神经功能有1～2级的恢复. 结论 采用新型椎体扩张器经伤椎椎弓根椎体内自体骨植骨治疗胸腰段爆裂性骨折可有效恢复伤椎椎体高度,重建前中柱的稳定性,防止术后由于椎体高度丢失所导致的并发症;椎体扩张器具有良好的临床运用价值.     

Three-dimensional image-guided placement of S2 alar screws to adjunct or salvage lumbosacral fixation

Background ContextAchieving fusion across the lumbosacral junction is challenging because of the unfavorable biomechanics associated with ending a fusion at this level. Bicortical placement of S1 pedicle screws can increase the construct stability at the lumbosacral junction; however, construct failure and pseudoarthrosis can still result. Iliac screws have been shown to increase the stiffness of lumbosacral constructs, but disadvantages include difficulty in connecting the iliac screw to adjacent sacral screws, painful screw loosening or prominence requiring removal, and the inability to place the screws in some patients with previous iliac crest autograft harvest.PurposeThe purpose of the study is to describe a technique of S2 alar screw placement using three-dimensional image guidance.Study Design/SettingThe study design is a retrospective analysis.Patient SampleTwenty patients undergoing lumbosacral fusion had 32 screws placed using this technique.Outcome MeasuresAn independent radiologist graded screw placement and lumbosacral fusion on thin-cut postoperative computed tomographic (CT) scans.MethodsImage guidance in this study was accomplished with the Medtronic Stealth Station Treon (Medtronic Inc., Littleton, MA, USA) used in conjunction with the O-ARM (Medtronic Inc.). Indications for placement of S2 alar screws included the following: to adjunct S1 pedicle screws in multilevel fusion cases; as an adjunct or alternative to S1 pedicle screws in pseudoarthrosis revision cases in which the S1 screws had loosened; as an alternative to S1 pedicle screws in cases where medial trajectory of an S1 pedicle screw was difficult to obtain because of a low-set lumbosacral junction; and a combination of the above. The entry point of the screw was typically chosen lateral and superior to the S2 dorsal foramen with the trajectory directed anterior, inferior, and lateral. Attempt was made to place the screw with the tip purchasing, but not penetrating through, the triangular area of cortical bone that can be found at the anterior, inferior, and lateral boundary of the sacral ala. An independent radiologist graded the placement of the screws on the intraoperative CT scan obtained with the O-ARM or on postoperative CT scans. Lumbosacral fusion was assessed on postoperative CT scans obtained at follow-up.ResultsNo complications occurred in this study as a result of S2 alar screw placement or image guidance. Five screws did penetrate the anterior cortex of the sacrum, with no clinical consequence. At the time of abstract submission, 16 patients were able to have follow-up CT scans, 15 of which were graded as solid fusion at the lumbosacral junction by the grading radiologist.ConclusionsThree-dimensional image guidance allows for safe placement of large S2 sacral alar screws that can provide additional biomechanical stability to lumbosacral constructs or serve as an alternate point of sacral fixation when S1 pedicle screws cannot be salvaged or placed in a medial trajectory.     

Location of the first and second sacral nerve roots in relation to pedicle screw placement

Dissection and measurements of the first 2 sacral nerve roots with regard to the commonly used entrance points for S1 and S2 pedicle screw placement were performed to determine the location of the first 2 sacral nerve roots in relation to the pedicle screw entrance points in the upper 2 sacral vertebrae. The sacral nerve roots, dural sac, and pedicles were exposed after laminectomy. The mean distance from the reference point to the adjacent nerve roots superiorly and inferiorly at the S2 pedicle level was smaller than those at the S1 pedicle level. The medial angle of the sacral nerve roots progressively decreased from L5 to S3. The nerve root passing through the next foramen formed an immediate medial relation to the sacral pedicle rather than the dural sac. Pedicle screw placement in the first 2 sacral vertebral pedicles has been recommended for lumbosacral fusion and internal fixation of sacral fractures. No anatomic study is available regarding the location of the sacral nerve roots relative to the entrance points of sacral pedicle screw placement. Violation of the sacral canal and foramina by a sacral pedicle screw may injure the sacral nerve roots, especially at the level of the S2 pedicle.     

单枚cage单侧椎弓根螺钉内固定术治疗退行性腰椎不稳

目的:探讨后路单枚cage单侧椎弓根钉内固定术治疗退行性腰椎不稳的临床效果.方法:采用后路椎弓根钉及椎间融合器治疗需行内固定融合手术的退行性腰椎不稳患者(均有腰痛及一侧下肢疼痛)51例,男32例,女19例,年龄41～72岁.单节段47例,其中L3/4 1例,L4/5 25例,L5/S1 21例;双节段4例,其中L3/4和L4/5 1例,L4/5和L5/S1 3例.手术方法均采用单侧显露症状侧椎板及关节突,单侧置入椎弓根钉,经椎间孔入路(TLIF手术)切除椎间盘及软骨终板,植骨后放入单枚cage.根据日本JOA评分法评估术后疗效,结果:手术时间单节段平均100min,双节段平均150min.术中出血90～430ml,其中单节段平均140ml,双节段24Oml.术前JOA评分平均11分,术后1年时平均25分.优38例(74.51%),良10例(19.61%),可2例(3.92%),差1例(1.96%),优良率为94.12%.经1～2.5年随访,所有患者椎体间融合良好,未发现断钉及cage移位.结论:单侧椎弓根钉及cage内固定术,手术方法简单,出血少、手术时间短,对脊柱结构破坏少,是治疗退行性腰椎不稳可供选择的较好方法.     

The radiologic anatomy of the lumbar and lumbosacral pedicles

STUDY DESIGN: An anatomic and radiologic study of lumbar and lumbosacral pedicle anatomy. OBJECTIVES: To define the radiologic anatomy of the lumbar and first sacral pedicle in the coaxial projection. SUMMARY OF BACKGROUND DATA: Fluoroscopic assistance for pedicle screw placement requires radiologic landmarks. The radiologic landmarks have previously been assumed. Detailed study of the correlation between anatomy and radiology is required. METHODS: Lumbar vertebrae and sacra were marked with radiopaque material to demonstrate the pedicle cortical borders. The vertebrae were then imaged in the coaxial projection to determine the correlation between the pedicle cortex and the radiologic image. Pedicle dimensions were recorded. RESULTS: Pedicle dimensions were consistent with known measurements, yet the long axis of the L4 and L5 pedicle ellipse was oblique to the vertical. Consequently, the minor diameter of the pedicle ellipse was considerably less than the measured pedicle width at L5. The radiologic pedicle image was consistently within the true pedicle cortex, by up to 3 mm, and probably represents the inner cortical border of the pedicle. The S1 pedicle has reliable anatomic landmarks, yet only the medial and superior borders were visualized. CONCLUSIONS: The radiologic pedicle image in the lumbar and lumbosacral spine is a reliable guide to the true bony cortex of the pedicle. At S1 the pedicle image is less well correlated with the cortical borders of the pedicle, yet other reliable anatomic landmarks exist.     

Pitfalls of pedicle screw fixation in the sacrum. A cadaver model.

Five male cadavers were used to evaluate anatomically structures at risk using sacral pedicle screw fixation. Risk was defined as the likelihood of penetration by K-wires placed through the pedicles and cortices at the S1, S2, and S3 levels. A scale based on the distance from the wire to the vital structure was developed to quantify risk. Instrument insertion techniques were classified as direct and lateral. The direct technique at S1 placed the left common iliac vein and the sympathetic chain at high risk. The sympathetic chain was also at high risk at the S2 and S3 levels. The lateral technique placed the lumbosacral trunk at high risk at the S1 level, as well as the S1 nerve root with screw placement at the S2 level. Anterior cortical penetration during sacral pedicle screw fixation places anatomic structures at variable risk depending on the technique used.     

S1 screw bending moment with posterior spinal instrumentation across the lumbosacral junction after unilateral iliac crest harvest

STUDY DESIGN: A biomechanical study comparing fixation across the lumbosacral junction. OBJECTIVES: To determine which long posterior construct across the lumbosacral junction produces the least bending moment on the S1 screw when only one ilium is available for fixation. SUMMARY OF BACKGROUND DATA: Recent in vitro studies have demonstrated the benefit of anterior support and fixation into the ilium when instrumenting a long posterior construct across the lumbosacral junction. METHODS: Four L2-sacrum constructs were tested on six synthetic models of the lumbar spine and pelvis simulating that the right ilium had been harvested. Construct 1: L2-S1 bilateral screws. Construct 2: L2-S1 + left iliac bolt. Construct 3: L2-S1 + left iliac bolt + right S2 screw. Construct 4: L2-S1 + bilateral S2 screws. The four constructs were then retested with an anterior L5-S1 strut. A flexion-extension moment was applied across each construct, and the moment at the left and right S1 pedicle screw was measured with internal strain gauges. RESULTS: Iliac bolt fixation was found to significantly decrease the flexion-extension moment on the ipsilateral S1 screw by 70% and the contralateral screw by 26%. An anterior L5-S1 strut significantly decreased the S1 screw flexion-extension moment by 33%. Anterior support at L5-S1 provided no statistical decrease in the flexion-extension moment when bilateral posterior fixation beyond S1 was present with either a unilateral iliac bolt and contralateral S2 screw, or bilateral S2 screws. CONCLUSIONS: There is a significant decrease in the flexion-extension moment on the S1 screw when extending long posterior constructs to either the ilium or S2 sacral screw. There is no biomechanical advantage of the iliac bolt over the S2 screw in decreasing the moment on the S1 screw in flexion and extension. Adding anterior support to long posterior constructs significantly decreases the moment on the S1 screw. Adding distal posterior fixation to either the ilium or S2 decreases the moment on S1 screws more than adding anterior support. Further, adding anterior support when bilateral distal fixation past S1 is already present does not significantly decrease the moment on the S1 screws in flexion and extension.     

Determination of a neurologic safe zone for bicortical S1 pedicle screw placement

BACKGROUND CONTEXTLumbosacral fixation is commonly used for the management of lumbosacral instability. As the sacrum mainly consists of cancellous bone, bicortical fixation, in which the pedicle screw penetrates the anterior sacral cortex, can help increase the strength of fixation. However, this method carries a risk to the L5 nerves which lie anterior to the sacrum at this level.PURPOSEThe goal of this study is to determine a safe zone for the placement of S1 pedicle screws to decrease the likelihood of L5 nerve injury.STUDY DESIGNRetrospective imaging review.PATIENT SAMPLEThis study evaluated imaging data of patients who underwent lumbar spine magnetic resonance imaging (MRI) at our institute between September 1, 2020 and September 1, 2021.OUTCOME MEASUREST1-weighted axial MRIs were measured at the level of S1 pedicle screw placement. The space medial and lateral to the L5 nerve root on the anterior sacrum were measured and defined as safe zones. Additionally, the nerve width and sacral lengths were measured at this level.METHODSThe distribution of the measurements were evaluated to determine a medial and lateral safe zone, as well as the average nerve width at the level of S1 pedicle screw placement. Correlation analysis was performed to determine a relationship between safe zone sizes and sacral size.RESULTSA total of 400 MRIs were analyzed. The average medial safe zone measured was 32.8 mm (95% CI: 32.2–33.4) with no nerves lying within 22.3 mm of the midline sacrum. The average lateral safe zone measured was 17.7 mm (95% CI: 17.1–18.2), with no nerves within 5.3 mm of the lateral border of the sacrum. The average nerve root width was 6.2 mm (95% CI: 6.13–6.34). An increased sacral length was associated with a larger medial (p<.001) and lateral (p<.001) safe zone.CONCLUSIONSOur study revealed lateral and medial safe zones for the placement of S1 pedicle screws to avoid iatrogenic nerve injury in a retrospective cohort of 400 patients. There were no L5 nerve roots found within 22.3 mm of the sacrum's mid-axis or within 5.3 mm of the sacrum's anterolateral border. These defined safe zones can be used during pedicle screw planning and placement to decrease the risk of injury to the L5 nerve root.     

胸腰段钉棒系统内固定术后断钉原因分析

目的分析椎弓根螺钉术后断钉的原因。方法分析45例胸腰段骨折患者术后10例发生断钉的骨折类型、术中操作、产品设计、螺钉负荷、椎弓根螺钉置入情况、术后活动情况以及术后预防措施。结果 10例术后断钉患者中,术后1个月复查时发现断钉2例,术后4~6个月复查时发现断钉7例,术后30个月复查时发现断钉1例。T11断钉1例,T12断钉4例,L1断钉3例,L2断钉2例。未减压24例(其中含Chance骨折3例)中断钉4例,减压未植骨5例中断钉3例;减压植骨16例(其中含骨折脱位型4例)中断钉3例。45例中椎弓根螺钉预留骨界面过长4例中断钉3例。结论骨折类型与植骨、术中操作、撑开后螺钉负荷过大、术后活动不当、内固定取出过迟为螺钉断裂的主要原因。     

Stepwise methodology for plain radiographic assessment of pedicle screw placement: a comparison with computed tomography

OBJECTIVE: The objective of this study is to evaluate the effectiveness of a specific methodology for plain radiographic assessment of lumbar pedicle screw position. PURPOSE: To evaluate the effectiveness of using orthogonal plain radiographs and a systematic method of interpretation, developed by the senior author, in assessing the placement of lumbar and lumbosacral pedicle screws. STUDY DESIGN: This was an adult cadaver study of the accuracy of using plain radiographs or computed tomography to assess pedicle screw position. Plain radiographs were performed and compared with computed tomography (CT) scans. Gross anatomic dissections were performed to directly confirm screw position. Variables, including screw material, radiographic view, and screw dimensions, were assessed for their effect on the ability of physicians to determine pedicle screw position. Multiple readers were included in the study, including 1 spine Fellow, 3 experienced orthopedic spine surgeons, and 1 neuroradiologist. METHODS: Five adult cadaveric spines were instrumented with titanium pedicle screws from L1 to S1. Screws were placed outside the confines of the pedicle in all 4 quadrants or within the pedicle using a Latin-Square design. Each cadaver was imaged with orthogonal radiographs and high-resolution CT scans. The spines were then reimaged after the instrumentation was replaced with stainless steel screws placed in the identical position. Finally, each spine was dissected to assess the exact position of the screws. Images were read in a blinded fashion by 1 spine fellow, 2 staff surgeons, and a staff radiologist. The results were compared with the known screw positions at dissection. RESULTS: In total, 120 pedicle screws were placed, 44 (38%) outside the confines of the pedicle. Sensitivity, defined as the percent of the misplaced screws that were correctly identified, was similar across the 3 diagnostic tests, but markedly improved when all CT formats were considered together. Similarly, specificity, defined as the percent of screws correctly read as being placed within the pedicle, was independent of radiographic examination. Sensitivity of the radiographic technique was 70.1% and specificity was 83.0%, whereas sensitivity for CT scans was 84.7% and specificity was 89.7%.There was an observed association with anatomic level, with a consistently less accuracy in detecting screw position at L1 with plain x-ray (P=0.001). Additionally, correct position of stainless steel screws was more difficult to detect as compared with titanium (P=0.033) using either x-rays or CT. Other variables examined, such as screw length and screw diameter, did not have an effect on the ability to read the positioning. CONCLUSIONS: CT scans, often considered the "gold standard" for clinical assessment of pedicle screw placement, have limitations when validated with gross anatomical dissection. The described systematic method for evaluating pedicle screw placement using orthogonal plain radiographs attained accuracy comparable to high-resolution CT scans.     

An anatomic study on the placement of the second sacral screw and its clinical applications

Background

The fixation of lumbosacral and sacral pelvis can be performed on the ilium and the Second Sacrum Vertebrae (S2). Although several studies on the anatomical and biomechanical features of S2 screw fixation have been published, little clinical application has been reported, especially combination of anatomical investigation and clinical study. This study was performed to design and optimize the method of pedicle screw placement for S2.

Materials and methods

Fifteen adult dry sacrum specimens were prepared and truncated from the S1–S2 and S2–S3 vertebral fusion remnants, and the morphology of the S2 vertebral body was observed from this section. The intersection of the horizontal line through the lowest point of the inferior edge of the first posterior sacral foramen and the lateral sacral crest was the entry point (Point X). The screws were inserted anterolaterally or anteromedially at Point X in 10 cadavers, with all of the screws penetrating the sacrum. Finally, the S2 sacral screw fixation technique was applied to a total of 13 patients with lumbosacral lesions, and the clinical outcome was evaluated at a minimum follow-up of 1 year.

Results

Two S2 sacral screw placement methods were developed, i.e., the anterolateral and anteromedial insertions. Seven patients had complete preoperative, postoperative, and follow-up data. In all cases, the bilateral S2 screws were placed in good position and the fixation was firm. There was no surgical wound infection or internal fixation loosening. All the patients achieved partial bone graft healing, which was verified by computed tomography.

Conclusions

The intersection of the horizontal line through the lowest point of the inferior edge of the first posterior sacral foramen and the lateral sacral crest can be used as the entry point for S2 sacral screw fixation. The S2 pedicle screw fixation shows good clinical effectiveness and safety for stable reconstruction of lumbosacral lesions.