Dorsale operative Korrektur der idiopathischen Skoliose

Posterior correction and fusion of scoliosis with multisegmental instrumentation systems was developed by Cotrel-Dubousset in the 1980s. Initially correction and instrumentation was performed using hooks only. Later pedicle screws were implemented first for the lumbar and then for the thoracic spine. Nowadays instrumentation based on pedicle screws only is well established for posterior scoliosis surgery. Biomechanical studies demonstrated higher pull-out forces for pedicle than for hook constructs. In clinical studies several authors reported better Cobb angle correction of the primary and the secondary curves and less loss of correction in pedicle screw versus hook instrumentations. Furthermore, pedicle screw instrumentation allows fewer segments to be fused, especially caudally, and thus saving mobile segments. In most of these publications there were no differences in operation time, blood loss and complication rates. In summary, there is better curve correction without an increased risk using multisegmental pedicle screw instrumentation in modern posterior scoliosis surgery.     

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.     

Treatment of idiopathic scoliosis with CD-instrumentation: lumbar pedicle screws versus laminar hooks in 66 patients

We studied whether the pedicle screw is better than laminar hooks for fixation of the lumbar spine in the treatment of idiopathic scoliosis. 66 consecutive patients with idiopathic scoliosis (King I and II) were studied retrospectively. Group S included 33 patients (25 females) treated with pedicle screws. Their mean age at operation was 17 (13-54) years. Group H included 33 patients (30 females) treated exclusively with hooks. Their mean age at operation was 16 (1140) years. The preoperative mean angles of the thoracic curve in group S was 66 (42.115) degrees, and in group H 65 (42-121) degrees. The lumbar curve averaged 46 (20-85) degrees in group H and 53 (33-86) degrees in group S. All patients were fused only posteriorly with Cotrel-Dubousset instrumentation and an autogenic bone graft. The mean follow-up time was 4 (2-7) years. Mean correction of the thoracic curve was 45% in group S and 50% in group H. The lumbar curve was corrected by 50% in group S and 51% in group H. Loss of correction of the thoracic curve occurred in 5% in group S and 6% in group H and of the lumbar curve in 3% in group S and 10% in group H (p = 0.04). Group S better maintained the correction of the lateral tilt of the uninstrumented segment adjacent to the fusion (p = 0.04). Derotation, according to Perdriolle, in the distal segment adjacent to the fusion was 6% in group S and 2% in group H. We found no difference between correction of the thoracic and lumbar curves using pedicle screws and laminar hooks in the lumbar spine. Pedicle screws better maintained the correction of the lumbar curve and the lateral tilt in the distal segment adjacent to fusion.     

全椎弓根螺钉与钩钉联合系统对脊柱侧凸的矫形效果比较

目的比较全椎弓根螺钉与钩钉联合系统对特发性脊柱侧凸的后路矫形效果。方法对40例特发性脊柱侧凸患者进行回顾性对照研究,其中全节段椎弓根螺钉组20例,钩钉联合器械组20例。对两组的手术效果、手术时间和失血量等进行对照分析。结果平均冠状面矫形率：全节段椎弓根螺钉组82．4％,钩钉联合器械组71．8％（P〈0．01）;术后1—3年平均冠状面矫形率：全节段椎弓根螺钉组77．O％,钩钉联合器械组62．5％（P〈0．01）;平均顶椎旋转矫正率：全节段椎弓根螺钉组63％,钩钉联合器械组32％（P〈0．01）。而矢状面矫形效果、下固定椎倾斜度改善率、躯干偏移、手术时间、失血量方面,两组无明显差别（P〉0．05）。所有病例均未出现脊髓、神经根损伤等严重并发症。结论全椎弓根螺钉较钩钉联合系统具有更好的矫形效果,胸椎椎弓根螺钉置入安全可靠。     

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.     

Treatment of idiopathic scoliosis with CD-instrumentation: Lumbar pedicle screws versus laminar hooks in 66 patients

We studied whether the pedicle screw is better than laminar hooks for fixation of the lumbar spine in the treatment of idiopathic scoliosis. 66 consecutive patients with idiopathic scoliosis (King I and II) were studied retrospectively. Group S included 33 patients (25 females) treated with pedicle screws. Their mean age at operation was 17 (13-54) years. Group H included 33 patients (30 females) treated exclusively with hooks. Their mean age at operation was 16 (11-40) years. The preoperative mean angles of the thoracic curve in group S was 66 (42-115)°, and in group H 65 (42-121)°. The lumbar curve averaged 46 (20-85)° in group H and 53 (33-86)° in group S. All patients were fused only posteriorly with Cotrel-Dubousset instrumentation and an autogenic bone graft. The mean follow-up time was 4 (2-7) years. Mean correction of the thoracic curve was 45% in group S and 50% in group H. The lumbar curve was corrected by 50% in group S and 51% in group H. Loss of correction of the thoracic curve occurred in 5% in group S and 6% in group H and of the lumbar curve in 3% in group S and 10% in group H (p = 0.04). Group S better maintained the correction of the lateral tilt of the uninstrumented segment adjacent to the fusion (p = 0.04). Derotation, according to Perdriolle, in the distal segment adjacent to the fusion was 6% in group S and 2% in group H. We found no difference between correction of the thoracic and lumbar curves using pedicle screws and laminar hooks in the lumbar spine. Pedicle screws better maintained the correction of the lumbar curve and the lateral tilt in the distal segment adjacent to fusion.     

Treatment of idiopathic scoliosis with CD-instrumentation: Lumbar pedicle screws versus laminar hooks in 66 patients

We studied whether the pedicle screw is better than laminar hooks for fixation of the lumbar spine in the treatment of idiopathic scoliosis.

66 consecutive patients with idiopathic scoliosis (King I and II) were studied retrospectively. Group S included 33 patients (25 females) treated with pedicle screws. Their mean age at operation was 17 (13-54) years. Group H included 33 patients (30 females) treated exclusively with hooks. Their mean age at operation was 16 (11-40) years. The preoperative mean angles of the thoracic curve in group S was 66 (42-115)°, and in group H 65 (42-121)°. The lumbar curve averaged 46 (20-85)° in group H and 53 (33-86)° in group S. All patients were fused only posteriorly with Cotrel-Dubousset instrumentation and an autogenic bone graft. The mean follow-up time was 4 (2-7) years.

Mean correction of the thoracic curve was 45% in group S and 50% in group H. The lumbar curve was corrected by 50% in group S and 51% in group H. Loss of correction of the thoracic curve occurred in 5% in group S and 6% in group H and of the lumbar curve in 3% in group S and 10% in group H (p = 0.04). Group S better maintained the correction of the lateral tilt of the uninstrumented segment adjacent to the fusion (p = 0.04). Derotation, according to Perdriolle, in the distal segment adjacent to the fusion was 6% in group S and 2% in group H.

We found no difference between correction of the thoracic and lumbar curves using pedicle screws and laminar hooks in the lumbar spine. Pedicle screws better maintained the correction of the lumbar curve and the lateral tilt in the distal segment adjacent to fusion.     

椎板钩和椎弓根钉系统治疗脊柱侧凸病例对照研究

目的 探讨脊柱椎弓根钉系统治疗脊柱侧凸是否安全．是否可以矫正出更好的曲线，是否能达到更短节段的融合。方法 50例特发性脊柱侧凸患者中15例采用椎板钩系统手术(椎板钩组)，25例采用上胸段椎板钩、下胸段和腰段椎弓根钉联合术式或者完全川椎弓根钉系统手术(椎弓根钉组)比较两组矫正曲线、融合长度以及并发症发生率。结果 随访1～8年，曲线校正：椎弓根钉组达50．1％，明显好于椎板钩组的41.1％。矢状面畸形的矫正：两组没有区别融合长度：椎弓根钉组较椎板钩组平均少0．6个锥体。结论 椎弓根钉组在矫正侧凸的角度等方面明显好于椎板钩组。     

Segmental pedicle screw instrumentation in idiopathic thoracolumbar and lumbar scoliosis

The role of posterior correction and fusion in thoracolumbar and lumbar scoliosis as well as pedicle screw instrumentation in scoliosis surgery are matters of debate. Our hypothesis was that in lumbar and thoracolumbar scoliosis, segmental pedicle screw instrumentation is safe and enables a good frontal and sagittal plane correction with a fusion length comparable to anterior instrumentation. In a prospective clinical trial, 12 consecutive patients with idiopathic thoracolumbar or lumbar scolioses of between 40° and 60° Cobb angle underwent segmental pedicle screw instrumentation. Minimum follow-up was 4 years (range 48– 60 months). Fusion length was defined according to the rules for Zielke instrumentation, normally ranging between the end vertebrae of the major curve. Radiometric analysis included coronal and sagittal plane correction. Additionally, the accuracy of pedicle screw placement was measured by use of postoperative computed tomographic scans. Major curve correction averaged 64.6%, with a loss of correction of 3°. The tilt angle was corrected by 67.0%, the compensatory thoracic curve corrected spontaneously according to the flexibility on the preoperative bending films, and led to a satisfactory frontal balance in all cases. Average fusion length was the same as that of the major curve. Pathological thoracolumbar kyphosis was completely corrected in all but one case. One patient required surgical revision with extension of the fusion to the midthoracic spine due to a painful junctional kyphosis. Eighty-five of 104 screws were graded “within the pedicle”, 10 screws had penetrated laterally, 5 screws bilaterally and 4 screws medially. No neurological complications were noted. In conclusion, despite the limited number of patients, this study shows that segmental pedicle screw instrumentation is a safe and effective procedure in the surgical correction of both frontal and sagittal plane deformity in thoracolumbar and lumbar scoliosis of less than 60°, with a short fusion length, comparable to anterior fusion techniques, and minimal loss of correction. Received: 23 September 1999 Revised: 20 January 2000 Accepted: 26 January 2000     

Surgical treatment of adolescent idiopathic scoliosis: a comparative study of two segmental instrumentation systems

This study compares two different surgical techniques and instrumentation types in the treatment of adolescent idiopathic scoliosis. The charts and radiographs of 116 patients with adolescent idiopathic scoliosis treated by posterior spine fusion with Isola or Cotrel-Dubousset instrumentation were reviewed. Patients were separated into two equivalent groups matched for age, sex, curve type, and curve magnitude. All patients had a minimum of 2 years follow-up. The instrumentation in group 1 consisted of hooks, wires, and pedicle screws. That used in group 2 was limited to hooks and rods. The Mann-Whitney, Wilcoxin, and the paired Student t tests for matched pairs were used for statistical analysis. Patients in group 1 had increased curve correction (66% vs. 52%), apical vertebral translation (63% vs. 30%), and correction of the end vertebral tilt angle (11 degrees vs. 3 degrees) (p < 0.001). The percentage of coronal curve correction in curves larger than 65 degrees also was greater in group 1 (59% vs. 40%). Physiologic sagittal alignment was obtained in 80% of the patients in group 1 and 25% in group 2. No major complication or pseudoarthrosis occurred in either group. This study supports improved correction of curve magnitude, apical translation, and end vertebral tilt angle with the use of multiple anchor types compared with the correction achieved with standard hook-and-rod constructs.     

全椎弓根螺钉与钉钩混合系统治疗青少年特发性脊柱侧凸的疗效分析

目的 通过临床病例回顾,对后路全椎弓根螺钉系统和钉钩混合系统治疗青少年特发性脊柱侧凸的疗效进行对比分析研究.方法 从2000年至2004年进行手术治疗的青少年特发性脊柱侧凸患者中选取60例配对分为两组(A、B两组,各30例),A组采用后路钉钩混合系统固定,B组采用后路全椎弓根螺钉系统固定,配对患者年龄相似、融合节段相仿、Lenke分型相近.通过比较手术前后影像学改变、手术时间、术中出血等,对两种手术方法的疗效进行对比分析研究.结果 A组患者术前冠状面主弯Cobb角平均为61°,术后为25°,平均矫正率为59%;B组患者术前冠状面主弯Cobb角平均为60°,术后为18°,平均矫止率为70%.两组患者主弯矫正率差异有统计学意义(P=0.002),随访2年两组间主弯矫正率差异仍有统计学意义(A、B两组分别为49%、67%,P<0.001).矢状面上,与术前相比,术后2年A组的胸椎后凸角平均减少了1°,而B组则减少了6°,差异有统计学意义(P=0.026).随访结果 提示,两组在下端椎远端融合椎体数、平均失血量方面差异均无统计学意义.两组患者术后均未出现神经系统并发症.结论 全椎弓根螺钉系统较钉钩混合系统能提供更好的主弯矫止率,而在最下端固定椎体的选择、术中失血量方面,两种内固定系统未见明显差异.     

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。     

青少年特发性脊柱侧凸椎弓根螺钉的误置模式及危险因素

目的 评估青少年特发性脊柱侧凸(AIS)椎弓根螺钉不良置入的模式并分析其原因.方法 收集从2008年7月至9月行后路椎弓根螺钉固定的70例AIS患者的临床资料,其中男性12例,女性58例;年龄12～19岁,平均(14.5±2.7)岁;术前Cobb角40°～125°,平均62.0°±18.2°.术中根据解剖标志徒手置入椎弓根螺钉,所有患者术后均行CT检查.在PACS系统上通过PacsClient软件测量螺钉穿破椎弓根内、外壁以及椎体前缘的距离.定义穿破任一壁超过2 mm为不良置钉.不良置钉中穿破内壁超过4 mm或钉尖使主动脉变形定义为高危置钉.对数据进行统计学分析,探讨不良置钉的危险因素.结果 共置入椎弓根螺钉1030枚,胸椎773枚,腰椎257枚.不良置钉108枚(10.5%),其中穿破外壁35枚,穿破内壁56枚,穿破椎体前缘33枚(其中有16枚既穿破了椎体前缘又穿破了外壁).高危置钉16枚(1.6%).顶椎、顶椎近端第5节段和顶椎远端第4节段的不良置钉率高于其他节段,其中顶椎左侧和顶椎近端第5节段右侧不良置钉率均高于对侧.顶椎区高危置钉率最高,达4.8%.Cobb角>90°组不良置钉率高于Cobb角40°～90°组,椎体旋转Ⅲ～Ⅳ度组不良置钉率高于椎体旋转0～Ⅱ度组.结论 AIS不良置钉集中在顶椎、顶椎近端第5节段和顶椎远端第4节段3个区域,高危置钉多发生在顶椎区,危险因素包括Cobb角大小、旋转程度以及与顶椎的距离.     

Difficult thoracic pedicle screw placement in adolescent idiopathic scoliosis

STUDY DESIGN: Retrospective radiographic and clinical consecutive case series. OBJECTIVE: The objective of this study was to identify patients treated with posterior spinal fusion and pedicle screw instrumentation for adolescent idiopathic scoliosis (AIS) in whom it was not possible to place a planned pedicle screw, and describe the possible difficulties in screw placement. SUMMARY OF BACKGROUND DATA: Despite the knowledge of anatomic characteristics of upper thoracic spine pedicles and considerable experience in thoracic pedicle screw placement, inserting pedicle screws in some patients with AIS may be difficult. METHODS: We reviewed 96 patients with AIS in whom the intent was to use an all-screw construct in 2004. Placement of the pedicle screws was usually by the freehand method, with intraoperative fluoroscopy used as needed. If a screw could not be safely placed after multiple attempts, a down-going supralaminar or transverse process hook was placed. Medical records were reviewed and radiographs were measured by one of the authors. RESULTS: We identified 17 cases (18%) in which a hook had been placed. All cases had a major thoracic curve (Lenke 1, 2, and 3) and the single hook had always been placed at the most cephalad level of the construct on the patient's right side. The most common levels for hook placement were T3 and T4; these pedicles were noted to be sclerotic, narrow, and have a moderate amount of rotation on the preoperative posterior-anterior and side bending radiographs. CONCLUSIONS: Care should be exercised during pedicle screw instrumentation in the apical region of the proximal thoracic curve, whether structural or nonstructural, especially in the concavity. The preoperative radiographs may give helpful clues to intraoperative challenges of pedicle screw insertion at the uppermost level of instrumentation. Hook fixation was satisfactory in this scenario.     

Selective ventral derotation spondylodesis in idiopathic thoracic scoliosis: a prospective study

AIM: Radiometric curve analysis of instrumented primary and spontaneous secondary curve correction after anterior correction and fusion of idiopathic thoracic scoliosis. METHOD: Sixty-four patients with idiopathic thoracic scoliosis were prospectively evaluated. All patients were operated either with the Zielke-VDS or with a primary stable double rod instrumentation with selective fusion of the thoracic curve from end-to end-vertebra. Follow-up averaged 29 months (24 - 52 months). RESULTS: The Cobb angle of the primary curve averaged 63.2 degrees preoperatively and was corrected to 21.4 degrees postoperatively with an average loss of correction of 5.3 degrees (58 % final curve correction). Apical thoracic vertebral rotation was corrected by 48 %. The secondary lumbar curve measured 38.2 degrees preoperatively (72 % correction on the bending films) and was spontaneously corrected by 57 % to 16.4 degrees without significant loss of correction in the final follow-up. Apical vertebral rotation averaged 11.3 degrees in the lumbar curve and was corrected spontaneously by 24 % to 8.6 degrees without significant loss of correction. Lumbar apex vertebra deviation showed no significant reduction. There was no case of lumbar curve decompensation in either frontal or sagittal plane. Implant related complications were observed in 7 patients (rod breakage), but no pseudarthrosis occurred. There were no neurological complications noted. CONCLUSION: Selective anterior correction and fusion in idiopathic thoracic scoliosis enables a satisfactory correction of both primary and lumbar secondary curves. The advantage of selective anterior correction and fusion of thoracic scoliosis is the short fusion length, better derotation and satisfactory correction of the secondary lumbar curve. The disadvantages of single threaded rod techniques in terms of lack of primary stability and a kyphogenic effect have been eliminated by the development of a primary stable, small size double rod instrumentation.     

New means in spinal pedicle hook fixation

Summary Pedicle hooks which are used as an anchorage for posterior spinal instrumentation may be subjected to considerable three-dimensional forces. In order to achieve stronger attachment to the implantation site, hooks using screws for additional fixation have been developed. The failure loads and mechanisms of three such devices have been experimentally determined on human thoracic vertebrae: the Universal Spine System (USS) pedicle hook with one screw, a prototype pedicle hook with two screws and the Cotrel-Dubousset (CD) pedicle hook with screw. The USS hooks use 3.2-mm self-tapping fixation screws which pass into the pedicle, whereas the CD hook is stabilised with a 3-mm set screw pressing against the superior part of the facet joint. A clinically established 5-mm pedicle screw was tested for comparison. A matched pair experimental design was implemented to evauluate these implants in constrained (series I) and rotationally unconstrained (series II) posterior pull-out tests. In the constrained tests the pedicle screw was the strongest implant, with an average pull-out force of 1650 N (SD 623 N). The prototype hook was comparable, with an average failure load of 1530 N (SD 414 N). The average pull-out force of the USS hook with one screw was 910 N (SD 243 N), not significantly different to the CD hook's average failure load of 740 N (SD 189 N). The result of the unconstrained tests were similar, with the prototype hook being the strongest device (average 1617 N, SD 652 N). However, in this series the difference in failure load between the USS hook with one screw and the CD hook was significant. Average failure loads of 792 N (SD 184 N) for the USS hook and 464 N (SD 279 N) for the CD hook were measured. A pedicular fracture in the plane of the fixation screw was the most common failure mode for USS hooks. The hooks usually did not move from their site of implantation, suggesting that they may be well-suited for the socalled segmental spinal correction technique as used in scoliosis surgery. In contrast, the CD hook disengaged by translating caudally from its site of implantation in all cases, suggesting a mechanical instability. The differences in observed hook failure modes may be a function of the type and number of additional fixation screws used. These results suggest that additional screw fixation allows stable attachment of pedicle hooks to their implantation site. Hooks using additional fixation screws passing obliquely into the pedicle apparently provide the most rigid attachment. The second fixation screw of the prototype hook almost doubles the fixation strength. Thus, the prototype hook might be considered as an alternative to the pepdicle screw, especially in the upper thoracic region.     

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.     

Hybrid instrumentation for correction of adolescent idiopathic scoliosis

New technology and instrumentation techniques are continually entering the spine field, leaving the scoliosis surgeon with a wide variety of options for the treatment of adolescent idiopathic scoliosis. All-screw constructs are currently the most popular. However, they remain controversial because of possible complications, and also because they have been associated with a decrease in thoracic kyphosis, not observed with hybrid instrumentation. The aim of the present study was to evaluate a hybrid construct: hooks and wires proximally, but pedicle screws distally. Forty-three patients with a minimum 2-year follow-up were included. The mean preoperative Cobb angle of the major curve was 60.85 degrees +/- 21 degrees. At the final evaluation it was reduced to 28.44 degrees +/- 11.9 degrees (mean correction 53.3%, p < 0.0001). The mean translation of the apical vertebra was corrected from -19.13 +/- 49 mm to -9.42 +/- 28.9 mm. The average thoracic kyphosis improved from 24 degrees +/- 14.3 degrees preoperatively to 30.7 degrees +/- 7.1 degrees, representing a mean correction of 28%. Kyphosis at the T10-L2 level was within normal values in all patients at the final evaluation. Complications included one superficial infection, one implant removal due to late onset wound infection, and 2 revisions to extend the fusion more distally. In other words, operative treatment with hybrid instrumentation yielded satisfactory results, with less risk of neurological damage. An excellent outcome in all planes could be safely achieved and maintained for a minimum of 2 years. CONCLUSION: why use an expensive all-screw construct, knowing that a hybrid construct is kyphosis sparing, cheaper, safer and more resistant to pull-out?     

Anterior dual rod instrumentation in idiopathic thoracic scoliosis

For anterior correction and instrumentation of thoracic curves single rod techniques are widely used. Disadvantages of this technique include screw pullouts, rod fractures and limited control of kyphosis. This is a prospective study of 23 consecutive patients with idiopathic thoracic scoliosis treated with a new anterior dual rod system. Aim of the study was to evaluate the safety and efficacy of this new technique in the surgical treatment of idiopathic thoracic scoliosis. To the best knowledge of the authors, this is the largest series on dual rod dual screw instrumentation over the entire fusion length in thoracic scoliosis. Twenty-three patients with an average age of 15 years were surgically treated with a new anterior dual rod system through a standard open double thoracotomy approach. Average clinical and radiological follow-up was 28 months (24–46 months). Fusion was carried out mostly from end-to-end vertebra. The primary curve was corrected from 66.6° to 28.3° (57.5% correction) with an average loss of correction of 2.0° at Cobb levels and of 1.3° at fusion levels. Spontaneous correction of the secondary lumbar curve averaged 43.2% (preoperative Cobb angle 41.2°). The apical vertebral rotation was corrected by 41.1% with a consecutive correction of the rib hump of clinically 66.7%. The thoracic kyphosis measured 29.2° preoperatively and 33.6° at follow-up. In seven patients with a preoperative hyperkyphosis of on average 47.3° thoracic kyphosis was corrected to 41.0°. This new instrumentation enables an entire dual rod instrumentation over the whole thoracic fusion length. It offers primary stability without the need of postoperative bracing. Dual screw dual rod instrumentation offers the advantages of a high screw pullout resistance, an increased overall stability and satisfactory sagittal plane control.     

Indications of proximal thoracic curve fusion in thoracic adolescent idiopathic scoliosis: recognition and treatment of double thoracic curve pattern in adolescent idiopathic scoliosis treated with segmental instrumentation

STUDY DESIGN: A retrospective study. OBJECTIVES: To determine the indications of fusing the proximal thoracic curve when treating idiopathic thoracic scoliosis with segmental instrumentation. SUMMARY OF BACKGROUND DATA: Failure to recognize a significant proximal thoracic curve often results in postoperative shoulder asymmetry due to relative overcorrection of the lower thoracic curve. With segmental instrumentation that enhances the correction of the instrumented curve, the double thoracic curve pattern that needs fusion of both the proximal and the distal thoracic curves should be redefined. METHODS: Forty patients with thoracic adolescent idiopathic scoliosis with a right lower thoracic curve of more than 40 degrees and a left proximal thoracic curve of more than 25 degrees treated by segmental pedicle screw instrumentation were analyzed after a minimum follow-up of 2 years. RESULTS: Of the 40 patients, 18 were treated by fusion of both the proximal and the distal curves, whereas 22 were treated by fusion of the distal curve only. The postoperative shoulder height difference (SHD, in millimeters) was 0.9 x preoperative SHD + 5.3 for the fusion of both curves and 0.6 x preoperative SHD + 12 for the distal curve fusion (linear regression), showing that proximal thoracic curve fusion improved the SHD when the left shoulder was level with or higher than the right. CONCLUSIONS: Idiopathic thoracic scoliosis with a proximal thoracic curve of more than 25 degrees and level or elevated left shoulder should be considered a double thoracic curve pattern and should be treated by fusing both the proximal and the distal curves when using segmental instrumentation.