经骨折椎椎弓根直接复位固定治疗胸腰椎爆裂性骨折

目的探讨胸腰椎爆裂性骨折经骨折椎椎弓根直接复位固定的可行性及原理。方法2001年6月～2005年11月手术治疗胸腰椎单节段爆裂性骨折患者24例,男16例,女8例；平均年龄32．5岁。骨折部位：T_(11) 2例,T_(12) 9例,L_1 11例,L_2 2例。按ASIA脊髓神经功能障碍分级标准：A级1例,B级2例,C级5例,D级3例,E级13例。按椎管阻塞面积分为4度：Ⅰ度3例,Ⅱ度9例,Ⅲ度10例,Ⅳ度2例。手术方法：骨折椎及相邻的上、下椎体经椎弓根置入螺钉后,按固定区的正常矢状面形态将棒预弯；旋转预弯棒,利用中间螺钉作为支点,将骨折椎向前推顶,纠正伤椎后突畸形及水平移位；上、下椎弓根钉撑开,行后外侧植骨。结果所有患者获得3～34个月(平均21个月)随访,伤椎高度恢复至正常的93．6%,水平移位恢复至正常的0．6%,矢状面Cobb角由术前26．5°恢复至术后的3．1°。椎管面积由术前的44．6%增加至术后的92．1%。骨折椎体愈合满意,不完全神经损伤手术后脊髓神经功能有1～2级的恢复。无神经损伤及加重等并发症。结论经骨折椎椎弓根螺钉固定是安全可靠的方法；对骨折直接复位和固定可提高复位质量,改善固定强度及应力分布。     

后路多节段固定结合经椎弓根椎间融合治疗胸腰椎爆裂性骨折

[目的]用多节段椎弓根螺钉或椎弓根螺钉加钩棒系统后路固定,结合经椎弓根椎间融合治疗胸腰椎爆裂性骨折的临床疗效.[方法]对25例Denis分类Type B型胸腰椎爆裂性骨折实施了后路椎弓根钉系统固定术.受伤至手术间隔时间平均7 d,平均年龄38.6岁.平均随访时间28个月.采用多节段椎弓根螺钉或椎弓根螺钉加钩棒系统的后路固定法.植骨采用经椎弓根切除椎间盘椎体间植骨的方法.[结果]局部后弯从术前的Cobb角平均15.5°改善到4.7°.术后平均28个月随访时为9.4°,平均损失4.7°.[结论]多节段椎弓根螺钉或椎弓根螺钉加钩棒系统,经椎弓根椎体间植骨,加强前柱的支持性是治疗胸腰椎爆裂性骨折的有效方法.     

TSRH器械在特发性脊柱侧凸中的应用

[目的]观察TSRH三维矫形系统矫正特发性脊柱侧凸冠状面、矢状面和轴状面的疗效,评价应用钉棒系统和钉钩棒系统随访时的效果。[方法]分析采用TSRH系统治疗特发性脊柱侧凸79例,男48例,女31例,平均15.5岁。全部应用椎弓根螺钉系统56例,胸椎应用椎弓根钩或椎板钩,腰椎应用椎弓根螺钉23例。对照分析2组的矫正效果。[结果]术后冠状位矫正为18~31°,矫正率为56%~87%,平均为68%,矢状位矫正为21~33°,平均25°,旋转矫正Ⅰ度。身高平均增高3 cm。63例平均随访2.5 a,2组冠状面和矢状面的矫正率以及冠状面矫正度的丢失有明显的差异。[结论]TSRH矫形系统治疗脊柱侧凸可得到满意的治疗效果,应用椎弓根螺钉效果更佳。     

经骨折椎椎弓根直接复位固定治疗胸腰椎爆裂性骨折

目的探讨胸膜椎爆裂性骨折经骨折椎椎弓根复位固定的可行性。方法2001年6月-2005年11月本院手术治疗了胸膜椎单节段爆裂性骨折患者24例,男16例,女8例;平均年龄为32．5岁。骨折部位：T11 2例,T12 9例,L1 11例,L2 2例。按ASIA脊髓神经功能障碍分级标准：A级1例,B级2例,C级5例,D级3例和E级13例。椎管阻塞面积分为Ⅳ度：阻塞Ⅰ度3例,Ⅱ度9例,Ⅲ度10例,Ⅳ度2例。手术方法：骨折椎及相邻的上、下椎体经椎弓根置钉后,上、下椎弓根钉撑开;按固定区的正常矢状面形态将棒预弯,旋转预弯棒,利用中间螺钉作为支点,将骨折椎向前推顶,纠正伤椎后凸畸形及水平移位。结果伤椎高度恢复至正常的93．6％,水平移位恢复至正常的0．6％,矢状面Cobb角术后恢复至3．1°,椎管面积术后增加至正常的92．1％。骨折椎体愈合满意,不完全神经损伤患者手术后脊髓神经功能有1～2级的恢复。无神经损伤加重等并发症。结论经骨折椎椎弓根螺钉固定对骨折直接复位和固定可提高复位质量,改善固定强度及应力分布,是治疗胸膜椎爆裂性骨折安全可靠的方法。     

术前CT引导胸腰椎椎弓根螺钉置入改良技术

目的:探讨总结以术前CT扫描椎弓根轴心来获得螺钉置入解剖参数引导胸腰段椎弓根螺钉置入的改良方法。方法:使用改良置钉技术对56例脊柱损伤患者置入胸腰椎弓根螺钉242枚,其中男32例,女24例;年龄21～69岁,平均43岁。以术前CT扫描确定椎弓根轴心线,轴心线附近的解剖标志为参照确定螺钉入点,内聚E角、螺钉长度、直径均可在CT椎弓根轴心片上读出,而矢状F角可由X线侧位片上读出或观察脊突线得出。结果:242枚螺钉术后均拍摄椎弓根CT片复查,238枚螺钉完全置入椎弓根内,仅4枚有穿破椎弓根皮质,失误率1.65%,但穿破较小,均无神经根症状。结论:术前CT扫描椎弓根引导胸腰椎椎弓根螺钉的置入是一个较好的改良方法,能有效降低不良置钉率。     

经椎弓根椎体内植骨治疗胸腰椎爆裂骨折

目的探讨经椎弓根椎体内植骨治疗胸腰椎爆裂骨折的临床疗效。方法治疗组新鲜爆裂骨折16例,男11例,女5例;年龄19~59岁,平均43岁;经椎弓根椎体内植骨,结合短节段椎弓根螺钉系统固定治疗。对照组胸腰椎新鲜爆裂骨折36例,男25例,女11例;年龄21~63岁,平均41岁;单纯用短节段椎弓根螺钉系统固定治疗。两组均于术前、术后及术后1年行X线检查,测量矢状面指数和椎体前缘压缩百分比,并对结果行统计学分析。结果治疗组在纠正局部后凸(矢状面指数),恢复椎体前缘高度(椎体前缘压缩百分比)方面均优于对照组。结论短节段椎弓根螺钉固定和经椎弓根椎体内植骨治疗胸腰椎骨折,可重建前、中柱的稳定性,有效防止纠正度的丢失。     

椎弓根螺钉内固定间接减压治疗胸腰椎骨折疗效观察

目的探讨经椎弓根螺钉内固定间接减压治疗胸腰椎骨折的疗效。方法32例胸腰椎骨折患者中，17例以4枚椎弓根螺钉固定伤椎上下相邻椎体，15例以6枚椎弓根螺钉固定含伤椎及相邻上下椎体，对患者术前术后的椎体高度、矢状径Cobb角、椎管矢状径占有率、神经功能Frankel分级变化等指标进行测量并随访。结果所有患者获4～42个月随访，伤椎平均高度由术前（43．2±1．8）％恢复至（91±2．0）％，矢状面Cobb角由术前（24．2±3．0）°恢复至（5±1．0）°，椎管内矢状径占有率由（60．2±8．7）％增到（85．5±12．8）％。神经损伤术后Frankel分级：A级2例无恢复；B级2例恢复至E级1例，1例无恢复；C级5例恢复至D级1例，E级4例；D级10例恢复至E级9例，1例无恢复。无死亡或神经损伤加重病例。1例螺钉松动，1例螺钉断裂。结论用椎弓根钉复位、内固定、间接减压治疗胸腰椎骨折具有创伤小、出血少、手术时间短、脊柱稳定性好、有效矫正及预防脊柱后凸畸形、手术并发症低等优点。     

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.     

改良“Krag”置钉固定方式对胸腰段单椎体骨折复位程度的影响

目的:探讨U型椎弓根钉棒系统单节段改良"Krag"置钉固定方式对胸腰段单椎体骨折复位程度的影响.方法:对具备手术适应证的43例胸腰段单椎体骨折患者采用单节段经椎弓根改良"Krag"置钉固定结合椎间植骨融合治疗,术前、术后1周摄X线片,测量椎体成角、上下终板成角、椎体前缘高度与正常高度的比值,了解术前椎体压缩程度及术后骨折复化情况.把-5°≤上下终板成角≤5°视为骨折理想复位;上下终板成角<-5°为骨折过伸复位:上下终板成角>5°为骨折过屈复位.对于复位理想及不理想者,测量术前椎体压缩程度、矢状面螺钉角度(α,伤椎的矢状面螺钉角度;β,邻椎的矢状面螺钉角度)及连接棒预弯曲度(γ)等,并对两组测量结果进行对比分析.结果:术后37例(86%)骨折复位理想,6例(14%)骨折复位不够理想.两组术前椎体成角、上下终板成角及伤椎前缘高度与正常高度的比值无显著性差异(P>0.05),但术后1周差异有显著性(P<0.05).矢状面螺钉角度(α、β)与连接棒预弯曲度(γ)的关系与骨折复位程度明显相关,-5°≤(α+β)-γ≤5°时骨折理想复位;α+β-γ<-5°时骨折过伸复位;α+β-γ>5°时骨折过屈复位.结论:改良"Krag"置钉固定方式中置入椎弓根螺钉椎体矢状面倾斜角度与连接棒预弯曲度的大小关系是决定骨折复位程度理想与否的关键.     

不同材料矫形棒在青少年特发性脊柱侧凸矢状面重建中作用的有限元研究

目的探讨不同材料、不同预弯弧度矫形棒在青少年特发性脊柱侧凸(AIS)矢状面重建中的作用。方法建立从T_1到骨盆的AIS非线性有限元仿真模型。在建立的有限元模型上进行模拟手术,分别设定矫形棒的属性为钛合金和钴铬合金,比较2种材料在28°预弯弧度时对矢状面重建的效果以及螺钉拔出应力的差异。进一步探讨当预弯弧度为40°时,钛合金棒对矢状面重建的影响。结果建立了完整的AIS仿真三维有限元模型,模型包括691 271个单元。其中实体单元、壳单元以及仿真单元计数分别为667 459、62 838和575。在28°预弯弧度下,钴铬合金比钛合金能够更好地矫正AIS矢状面后凸,但是钴铬棒组螺钉拔出应力显著增加。当预弯弧度为40°时,钛合金棒对矢状面后凸矫正效果显著优于预弯弧度为28°时,同时螺钉拔出应力显著增加。结论采用强度较大的钴铬合金棒及适当加大矫形棒预弯弧度有助于矢状面力线的恢复,但也会导致螺钉拔出应力增加。     

2- to 4-year outcome of dorsal double rod instrumentation spondylodesis in idiopathic scoliosis]

INTRODUCTION: In order to evaluate the results of posterior correction and fusion using the Münster Posterior Doublerod-System (MPDS) 48 patients with idiopathic scoliosis were studied prospectively. METHODS: All patients underwent clinical examination and radiological analysis of the frontal and sagittal plane preoperatively, postoperatively and at follow-up (2-4 years). Pedicle screws were used at the lumbar and thoracolumbar spine exclusively. RESULTS: The preoperative average Cobb angle was 61.4 degrees with an average flexibility of 36.8% to 38.8 degrees. The average postoperative Cobb angle was 24.8 degrees (59.6%) with an average loss of correction of 2.6 degrees Cobb angle (3.6%). Due to the use of thoracolumbar and lumbar pedicle screws instrumented fusion could be stopped at the lower endvertebra in 71%. Patients in whom only pedicle screws had been used improved correction of frontal plane could be shown compared to combined instrumentations with hooks and screws. CONCLUSION: The posterior instrumentation guarantees primary stability with good results of correction and allows brace free treatment postoperatively. The postoperative correction compared to the results at follow-up proves the stability of the instrumentation largely. The results of mainly pedicle screw based instrumentations verify that an improved correction can be achieved. In most cases fusion levels end at the lower end vertebra and therefore are shorter compared to instrumentation's based on hooks only.     

Pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine

While the biomechanical properties of pedicle screws have proven to be superior in the lumbar spine, little is known concerning pullout strength of pedicle screws in comparison to hooks in the thoracic spine. In vitro biomechanical pullout testing was performed to evaluate the axial pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine with regard to surgical correction techniques in scoliosis. Nine human cadaveric thoracic spines were harvested and disarticulated. To simulate a typical posterior segmental scoliosis instrumentation, standard pedicle hooks were used between T4 and T8 and supralaminar hooks between T9 and T12 and tested against pedicle screws. The pedicle screws were loaded strictly longitudinal to their axis; the hooks were loaded perpendicular to the intended rod direction. In total, 90 pullout tests were performed. Average pullout strength of the pedicle screws was significantly higher than in the hook group (T4-T8: 531 N versus 321 N, T9-T12: 807 N versus 600 N, p < 0.05). Both screw diameter and the bone mineral density (BMD) had significant influence on the pullout strength in the screw group. For scoliosis correction, pedicle screws might be beneficial, especially for rigid thoracic curves, since they are significantly more resistant to axial pullout than both pedicle and laminar hooks.     

下胸椎和腰椎椎弓根形态学测量及其临床意义

对15具T_9—L_5段尸体脊椎标本的推弓根进行了实体及X线片形态学测量.测量内容包括:椎弓根高、椎弓根宽、椎弓根后缘皮质与前缘皮质的距离及椎弓根轴线与矢状面夹角.结果提示:临床应用椎弓根螺钉固定时,应选择合适的螺钉,选准进钉点,并注意进钉方向及深度.     

Biomechanical analysis of a novel hook-screw technique for C1-2 stabilization

The Food and Drug Administration has not cleared the following medical devices for the use described in this study. The following medical devices are being discussed for an off-label use: cervical lateral mass screws. Object As an alternative for cases in which the anatomy and spatial relationship between C-2 and a vertebral artery precludes insertion of C-2 pedicle/pars or C1-2 transarticular screws, a technique that includes opposing laminar hooks (claw) at C-2 combined with C-1 lateral mass screws may be used. The biomechanical stability of this alternate technique was compared with that of a standard screw-rod technique in vitro. Methods Flexibility tests were performed in 7 specimens (occiput to C-3) in the following 6 different conditions: 1) intact; 2) after creating instability and attaching a posterior cable/graft at C1-2; 3) after removing the graft and attaching a construct comprising C-1 lateral mass screws and C-2 laminar claws; 4) after reattaching the posterior cable-graft at C1-2 (posterior hardware still in place); 5) after removing the posterior cable-graft and laminar hooks and placing C-2 pedicle screws interconnected to C-1 lateral mass screws via rod; and 6) after reattaching the posterior cable-graft at C1-2 (screw-rod construct still in place). Results All types of stabilization significantly reduced the range of motion, lax zone, and stiff zone compared with the intact condition. There was no significant biomechanical difference in terms of range of motion or lax zone between the screw-rod construct and the screw-claw-rod construct in any direction of loading. Conclusions The screw-claw-rod technique restricts motion much like the standard Harms technique, making it an acceptable alternative technique when aberrant arterial anatomy precludes the placement of C-2 pars/pedicle screws or C1-2 transarticular screws.     

Biomechanical comparison of two-level cervical locking posterior screw/rod and hook/rod techniques.

BACKGROUND CONTEXT: Locking posterior instrumentation in the cervical spine can be attached using 1) pedicle screws, 2) lateral mass screws, or 3) laminar hooks. This order of options is in order of decreasing technical difficulty and decreasing depth of fixation, and is thought to be in order of decreasing stability. PURPOSE: We sought to determine whether substantially different biomechanical stability can be achieved in a two-level construct using pedicle screws, lateral mass screws, or laminar hooks. Secondarily, we sought to quantify the differential and additional stability provided by an anterior plate. STUDY DESIGN: In vitro biomechanical flexibility experiment comparing three different posterior constructs for stabilizing the cervical spine after three-column injury. METHODS: Twenty-one human cadaveric cervical spines were divided into three groups. Group 1 received lateral mass screws at C5 and C6 and pedicle screws at C7; Group 2 received lateral mass screws at C5 and C6 and laminar hooks at C7; Group 3 received pedicle screws at C5, C6, and C7. Specimens were nondestructively tested intact, after a three-column two-level injury, after posterior C5-C7 rod fixation, after two-level discectomy and anterior plating, and after removing posterior fixation. Angular motion was recorded during flexion, extension, lateral bending, and axial rotation. Posterior hardware was subsequently failed by dorsal loading. RESULTS: Laminar hooks performed well in resisting flexion and extension but were less effective in resisting lateral bending and axial rotation, allowing greater range of motion (ROM) than screw constructs and allowing a significantly greater percentage of the two-level ROM to occur across the hook level than the screw level (p<.03). Adding an anterior plate significantly improved stability in all three groups. With combined hardware, Group 3 resisted axial rotation significantly worse than the other groups. Posterior instrumentation resisted lateral bending significantly better than anterior plating in all groups (p<.04) and resisted flexion and axial rotation significantly better than anterior plating in most cases. Standard deviation of the ROM was greater with anterior than with posterior fixation. There was no significant difference among groups in resistance to failure (p=.74). CONCLUSIONS: Individual pedicle screws are known to outperform lateral mass screws in terms of pullout resistance, but they offered no apparent advantage in terms of construct stability or failure of whole constructs. Larger standard deviations in anterior fixation imply more variability in the quality of fixation. In most loading modes, laminar hooks provided similar stability to lateral mass screws or pedicle screws; caudal laminar hooks are therefore an acceptable alternative posteriorly. Posterior two-level fixation is less variable and slightly more stable than anterior fixation. Combined instrumentation is significantly more stable than either anterior or posterior alone.     

In situ contouring technique in the treatment of thoracolumbar fractures

Burst fractures typically occur at T12 or L1 and create a sagittal deformity by a compression mechanism. This posttraumatic kyphosis is evaluated preoperatively by measuring the sagittal index of Farcy. Posterior instrumentation using in situ contouring is based on a bilateral insertion of rods which take the shape of the spine first. The rods are placed in a perpendicular position to monoaxial pedicular screws and then bent in situ, which makes the spine follow the movements of the rods. This principle makes it possible to correct the posttraumatic kyphosis at the level of the fractured vertebra and the overlying disk, which will open progressively using a ligamentotaxis mechanism. An additional anterior approach is indicated if the sagittal correction through the disk represents less than 50% compared to the total correction (in otherwords, if the correction of the traumatic deformity is obtained more in the disk than in the bone (>50%), an additional anterior approach is performed: more through the disk than the vertebral body (>50%)). This reliable technique meets the requirements of sagittal posttraumatic kyphosis correction, and provides a solid construct which avoids bracing.

     

The effect of Harrington rod contouring on lumbar lordosis

The effect of Harrington rod sagittal plane contouring, or lack of it, on total lumbar, segmental lumbar, and lumbosacral lordosis was studied retrospectively in a series of 36 patients operated on for idiopathic scoliosis. Regardless of contouring, there was a decrease in total lumbar lordosis and lordosis above L4, with an increase in lordosis below L5. Although not statistically significant, patients with contoured rods had less loss of segmental (L1-4) lordosis and less increase in segmental lumbosacral lordosis (L4-S1) than the noncontoured group. Although helpful, additional steps beyond concave rod contouring appear to be necessary to consistently preserve lumbar lordosis.     

The effect of kyphosis on the mechanical strength of a long-segment posterior construct using a synthetic model

STUDY DESIGN: This experimental study used synthetic spine models to compare the effect of the angle of kyphosis, rod diameter, and hook number on the biomechanical stiffness of a long-segment posterior spinal construct. OBJECTIVE: To examine the biomechanical effects of incremental kyphosis on variously instrumented long-segment posterior spinal constructs. SUMMARY OF BACKGROUND DATA: Euler's formula for loading of curved long columns would suggest that kyphosis has a profound impact on the biomechanical behavior of long-segment posterior spinal constructs. The effects of sagittal contour on the mechanical properties of long-segment posterior spinal constructs have not been well documented. METHODS: Kyphotic and straight synthetic spine models were used to test long-segment posterior instrumentation constructs biomechanically while varying rod diameter and the number of hook sites. The synthetic spines, composed of polypropylene vertebral blocks and isoprene elastomer intervertebral spacers, were fabricated with either 0 degrees, 27 degrees, or 53 degrees of sagittal contour. The models were instrumented with 5.5- or 6.35-mm titanium rods, and with either 8 or 12 hooks. The models were loaded from 0 to 300 N in a cyclical ramp fashion using an MTS 858 Bionix testing device testing device. Construct stiffness (force and displacement) during axial compression was determined. RESULTS: Straight model: Changing the hook number from 8 to 12 caused a 32% increase in construct stiffness with the 5.5-mm rod. Changing the rod diameter from 5.5 to 6.35 mm caused a 36% increase in construct stiffness with the 8-hook pattern. Changing both the rods and hooks caused the stiffness to increase 44%. 27 degrees Model: Changing the hook number from 8 to 12 caused a 20% increase in construct stiffness with the 6.5-mm rod. Changing the rod diameter from 5.5 to 6.35 mm caused a 29% increase in construct stiffness with the 12-hook pattern. Changing both the rods and hooks caused the construct stiffness to increase 26%. 53 degrees Model: Changing the hook number from 8 to 12 caused a 14% increase in construct stiffness with the 6.35-mm rod. Changing the rod diameter from 5.5 to 6.35 mm caused a 17% (P<0.0005) increase in construct stiffness with the 12-hookpattern. Changing both rods and hooks caused the stiffness to increase 21%. Summary data on angular kyphosis: Using the same rod diameter and the same number of hooks, and progressing from a straight alignment to 27 degrees of sagittal contour decreased construct stiffness 32%. Going from straight alignment to 53 degrees decreased the stiffness 59.6%. All reported values were statistically significant (P < 0.0005). CONCLUSIONS: The biomechanical stiffness of the straight spine was sensitive to both an increase in hook fixation sites and an increase in rod diameter. The kyphotic spines, however, were more sensitive to variations in rod diameter. Although with increasing kyphosis, the optimum instrumentation strategy will maximize both rod diameter and the number of hook sites, instrumented kyphotic spines remain biomechanically "disadvantaged" as compared with nonkyphotic instrumented spines.     

Correlative analysis of the results of surgical treatment of thoracolumbar injuries with long Texas Scottish rite hospital construct: is the use of pedicle screws versus hooks advantageous in the lumbar spine?

This is a prospective, randomized study to compare the efficacy of two similar "long-segment" Texas Scottish Rite Hospital instrumentations with the use of hooks in the thoracic spine and pedicle screws versus laminar hook claw in the lumbar spine for thoracolumbar A3, B, and C injuries. Forty consecutive patients with such thoracolumbar fractures (T11-L1) associated with spinal canal encroachment underwent early operative postural reduction and stabilization. The patients were randomly sampled into two groups: Twenty patients received hooks in "claw configuration" in both the thoracic and the lumbar spine (group A), and 20 patients received hooks in the thoracic vertebrae and pedicle screws in the lumbar vertebrae (group B). Pre- and postoperative plain roentgenograms and computed tomography scans were used to evaluate any changes in Gardner post-traumatic kyphotic deformity, anterior and posterior vertebral body height at the fracture level, and spinal canal clearance (SCC). All patients were followed for an average period of 52 months (range 42-71 months). The correction of anterior vertebral body height was significantly more (P < 0.01) in the spines of group B (33%) than in group A (16%), with a subsequent 11% loss of correction at the latest evaluation in group A and no loss of correction in group B. There were no significant differences in the changes of posterior vertebral body height and Gardner angle between the two groups. The SCC was significantly more (P < 0.05) immediately postoperatively in the spine of group B (32%) than in group A (19%). In the latest evaluation, there was a 9% loss of the immediately postoperatively achieved SCC in group A, while SCC was furthermore increased at 10.5% in group B. All patients with incomplete neurologic lesions in groups A and B were postoperatively improved at 1.1 and 1.7 levels, respectively. There were two hook dislodgements in the thoracic spine, one in each group, while there was no screw failure in group B. There was neither pseudarthrosis nor neurologic deterioration following surgery. Visual Analog Pain Scale and Short Form-36 scores were equally improved and did not differ between the two groups. The use of pedicle screws in the lumbar spine to stabilize the lowermost end of a long rigid construct applied for A3, B, and C thoracolumbar injuries was advantageous when compared with that using hook claws in the lumbar spine because the constructs with screws restored and maintained the fractured anterior vertebral body height better than the hooks without subsequent loss of correction and safeguarded postoperatively a continuous SCC at the injury level.     

Correction of adolescent idiopathic scoliosis using thoracic pedicle screw fixation versus hook constructs

This retrospective study was undertaken to determine the effectiveness and cost of thoracic pedicle screws versus laminar and pedicle hooks in patients undergoing surgical correction of adolescent idiopathic scoliosis (AIS). Immediate preoperative and 6-week postoperative radiographs were examined in 25 consecutive cases of children with AIS who were divided into two groups, those with thoracic pedicle screw constructs and those with thoracic hook constructs. Endpoints collected included radiographic measures, complications, surgical time, implant cost, and quality-of-life measures. Ten children underwent spinal fusion using thoracic pedicle screw fixation and 15 underwent thoracic constructs composed of hooks. Similar sex and age distribution were noted in both groups, and among the 20 girls and 5 boys the average age was 14.5. The mean preoperative Cobb angle was 53.5 degrees for the screw group and 52.5 degrees for the hook group. Correction averaged 70.2% for the screw group and 68.1% for the hook group. There were no significant differences between the two patient groups in terms of percentage of or absolute curve change after surgery. The apical vertebral translation, end vertebral tilt angle, and coronal balance did not differ significantly between the two patient groups. Comparison of operative time and quality of life revealed no significant differences. Screw constructs were significantly more expensive than hook constructs. The correction obtained from thoracic pedicle screw fixation is comparable to traditional hook constructs in AIS. Surgery using either construct effectively corrects AIS.