Comparative analysis of pedicle screw and hook instrumentation in posterior correction and fusion of idiopathic thoracic scoliosis

Posterior correction and fusion with segmental hook instrumentation represent the gold standard in the surgical treatment of progressive idiopathic thoracic scoliosis. However, there is a debate over whether pedicle screws are safe in scoliosis surgery and whether their usage might enable a better curve correction and a shorter fusion length. The details of curve correction, fusion length and complication rate of 99 patients with idiopathic thoracic scoliosis treated with either hook or pedicle screw instrumentation were analyzed. Forty-nine patients had been operated with the Cotrel-Dubousset system using hooks exclusively ("hook group"). Fifty patients had been operated with either a combination of pedicle screws in the lumbar and lower thoracic and hooks in the upper thoracic spine or exclusive pedicle screw instrumentation using the Münster Posterior Double Rod System ("screw group"). The preoperative Cobb angle averaged 61.3 degrees (range 40 degrees-84 degrees ) in the hook group and 62.5 degrees (range 43 degrees-94 degrees ) in the screw group. Average primary curve correction was 51.7% in the hook group and 55.8% in the screw group ( P>0.05). However, at follow-up (2-12 years later) primary curve correction was significantly greater ( P=0.001) in the screw group (at 50.1%) compared to the hook group (at 41.1%). Secondary lumbar curve correction was significantly greater ( P=0.04) in the screw group (54.9%) compared to the hook group (46.9%). Correction of the apical vertebral rotation according to Perdriolle was minimal in both groups. Apical vertebral translation was corrected by 42.0% in the hook group and 55.6% in the screw group ( P=0.008). Correction of the tilt of the lowest instrumented vertebra averaged 48.1% in the hook group and 66.2% in the screw group ( P=0.0004). There were no differences concerning correction of the sagittal plane deformity between the two groups. Fusion length was, on average, 0.6 segments shorter in the screw group compared to the hook group ( P=0.03). With pedicle screws, the lowest instrumented vertebra was usually one below the lower end vertebra, whereas in the hook group it was between one and two vertebrae below the lower end vertebra. Both operative time and intraoperative blood loss were significantly higher in the hook group ( P<0.0001). One pedicle screw at T5 was exchanged due to the direct proximity to the aorta. There were no neurologic complications related to pedicle screw instrumentation. Pedicle screw instrumentation alone or in combination with proximal hook instrumentation offers a significantly better primary and secondary curve correction in idiopathic thoracic scoliosis and enables a significantly shorter fusion length.     

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.     

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.     

Short posterior fusion for patients with thoracolumbar idiopathic scoliosis.

Fifteen percent of all scolioses are idiopathic thoracolumbar and are characterized by significant imbalance in the frontal plane. A large curve of more than 40 degrees creates a trunk shift and under these circumstances an active correction is necessary. It is this imbalance that is the cause of increasing muscular fatigue. Arthritic changes may appear later which also are responsible for pain. The aim of a surgical procedure is to stop the progression of scoliosis, to obtain the reequilibrium of the spine in a frontal and a sagittal plane, and to correct the deformity. During the 1960s Dwyer6 developed his anterior instrumentation mainly for thoracolumbar and lumbar curves. In 1980 Hall developed the concept of a short anterior fusion with overcorrection for patients with thoracolumbar curves. In the present study 10 patients are presented who were operated on for thoracolumbar adolescent idiopathic scoliosis using short posterior fusion instrumented by segmental convex transpedicle screw fixation and concave hook stabilization. With a mean followup of 49 months, the results show that frontal and sagittal balances are restored. In the present study all patients achieved frontal and sagittal balances at the last followup. The angular correction achieved by surgery always is more effective than what is visualized in radiographs of the patient in the bending position obtained before surgery. The correction of the major curve in the frontal plane improved from a mean angle of 47 degrees preoperatively to 14 degrees postoperatively and to 17 degrees at the last followup. In all cases, mobile discs in the lower lumbar area are open. The posterior short fusion has the same power of correction as the anterior fusion with the advantage of an easier surgical approach and a better control of the lordosis. This paper will describe the operative indications, the choices of instrumented levels, and the medium term followup results.     

Simultaneous translation on two rods is an effective method for correction of hypokyphosis in AIS: radiographic results of 24 hypokyphotic thoracic scoliosis with 2 years minimum follow-up

Recent publications confirm that moderate correction of thoracic hypokyphosis can be achieved by posterior instrumentation with hooks or pedicle screws. Twenty-four prospective and consecutive thoracic adolescent scoliosis patients with hypokyphosis (<20°) were operated on by posterior spinal fusion (PSF) with a specific method of reduction: Simultaneous translation on two rods (ST2R), performed by the same surgeon using stable anchorages such as screws or self-stabilizing claws. Radiographic parameters were measured preoperatively, at 1 month, 1 year and at 2 years minimum follow-up. In the coronal plane, the average main curve was significantly reduced from 51° to 17° and maintained at last follow-up, corresponding to an average correction of 67%. In the sagittal plane, the average kyphosis angle was significantly improved from 9° to 30° postoperatively and to 32° at last follow-up, corresponding to a mean gain of 23°. The 24 patients reported normal kyphosis at last follow-up (≥20°). Reduction of scoliosis by ST2R is an effective method that gives coronal correction equivalent to all screw constructs and allows restoration of normal thoracic kyphosis.     

Can the caudal extent of fusion in the surgical treatment of scoliosis in Duchenne muscular dystrophy be stopped at lumbar 5?

Instrumentation and fusion to the sacrum/pelvis has been a mainstay in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD) and is recommended to correct pelvic obliquity. The caudal extent of instrumentation and fusion in the surgical treatment of scoliosis in DMD has remained a matter of considerable debate, and there have been few studies on the use of segmental pedicle screw instrumentation for this pathology. From 2004 to 2007, a total of 28 patients with DMD underwent segmental pedicle screw instrumentation and fusion only to L5. Assessment was performed clinically and with radiologic measurements. All patients had a curve with the apex at L2 or higher preoperatively. Preoperative coronal curve averaged 74°, with a postoperative mean of 14°, and 17° at the last follow-up. The pelvic obliquity improved from 17° preoperatively to 6° postoperatively, and 6° at the last follow-up. Good sagittal plane alignment was recreated after surgery and maintained long term. In 23 patients with a preoperative L5 tilt of less than 15°, the pelvic obliquity was effectively corrected to less than 10° and maintained by adequately addressing spinal deformity, while five patients with a preoperative L5 tilt of more than 15° had a postoperative pelvic obliquity of more than 15°. Segmental pedicle screw instrumentation and fusion to L5 was effective and safe in patients with DMD scoliosis with a minimal L5 tilt (<15°) and a curve with the apex at L2 or higher, both initially and long term, obviating the need for fixation to the sacrum/pelvis. Segmental pedicle screw instrumentation and fusion to L5 was safe and effective in patients with DMD scoliosis with stable L5/S1 articulation as evidenced by a minimal L5 tilt of less than 15°, even though pelvic obliquity was significant. There was no major complication. With rigid segmental pedicle screw instrumentation, the caudal extent of fusion in the treatment of DMD scoliosis should be determined by the degree of L5 tilt. This method in appropriate patients can be a viable alternative to instrumentation and fusion to the sacrum/pelvis in the surgical treatment of DMD scoliosis.     

内固定方式对青少年特发性脊柱侧凸选择性胸椎融合矢状面重建的影响

目的 探讨胸弯型青少年特发性脊柱侧凸患者行后路选择性胸椎融合术时采用不同内固定方式对胸椎矢状面形态及远端腰椎代偿模式的影响.方法 行胸弯后路矫形内同定术且有2年以上(2～3年)完整随访资料的lenke 1、2型青少年特发性脊柱侧凸患者51例,按内固定方式分为A组(全钩组)、B组(钩钉混合组)和C组(全钉组).测量术前及术后随访的胸弯Cobb角、腰弯Cobb角、胸椎后凸角、腰椎前凸角、远端交界性后凸、胸腰段交界性后凸及C7铅垂线偏离S1后上缘的距离.结果 三组患者主弯矫正率均大于60%,继发弯也获得较满意的自发性矫正.三组患者术前及随访中腰椎前凸角、C7铅垂线偏离S1后上缘的距离均保持正常.随访2年时,A组远端交界性后凸、胸椎后凸角、胸腰段交界性后凸分别达3.6°、23.0°、6.4°,其中远端交界性后凸与术前比较差异有统计学意义(P<0.05).B组和C组各项指标与术前比较差异均无统计学意义.结论 全钩型同定可以获得良好的冠状面矫形,且在随访中能保持腰椎前凸和欠状面平衡.但钩的固定不如椎弓根螺钉牢固,全钩型固定患者胸椎后凸角有增大趋势,胸腰椎交界区有失代偿的可能.     

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.     

Posterior pedicle screws combined with shortening and release techniques for lumbar and thoracolumbar adolescent idiopathic scoliosis

Objective: To prospectively evaluate the clinical and radiographic effects of posterior surgery with wide posterior shortening release and segmental pedicle screws techniques in a consecutive group of patients with thoracolumbar /lumbar adolescent idiopathic scoliosis. Methods: Between April 2002 and July 2005, 114 patients (86 women and 28 men) were enrolled in this study. There were 72 Lenke type 5, 32 Lenke type 6, and 10 Lenke type 3C curves. Radiographic parameters such as coronal plane Cobb angle; lordosis angle; lowest instrumented vertebrae (LIV) angulation; and the distances from the central sacral vertical line (CSVL) to the LIV, to the apical vertebra and to the C7 plumb line, were analyzed. Complication rates were also recorded during follow‐up. Results: The average coronal correction was from 61° to 13° (78.6%). In the sagittal plane, lumbar lordosis was normalized from 36° with a wide range (23°–67°) to 42° with a normal range (34°–55°). The LIV had 79% correction of coronal angulations. The center sacral line to LIV was improved from 2.3 cm to 0.5 cm, apex to center sacral line from 5.0 cm to 1.6 cm, and CSVL from 2.7 cm to 0.8 cm. A total of 1460 pedicle screws were placed safely, average 9.6 levels (5–14) were fused. The patients were followed up for an average of 30 months (range, 12–50). There was excellent maintenance of correction at final follow‐up. Conclusion: Wide posterior release and segmental pedicle screw instrumentation has excellent radiographic and clinical results with minimal complications.     

Segmental pedicle screws instrumentation and fusion to L5 for spinal deformity secondary to Duchenne muscular dystrophy: results with a minimum of 2 years follow-up

Background

Traditional treatment recommendations in the surgical treatment of scoliosis in Duchenne muscular dystrophy have included instrumentation and fusion to the sacrum/pelvis to correct pelvic obliquity and to restore the sitting balance of the trunk. However, caudal extent of instrumentation and fusion has remained a matter of considerable debate. This study was performed to determine the efficacy and safety of stopping segmental pedicle screw constructs at L5 in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD), with mild pelvic obliquity (<15°).

Materials and methods

From May 2005 to June 2007, a total of 22 consecutive patients underwent posterior spinal fusion and segmental pedicle screw instrumentation only to L5 for scoliosis secondary to DMD. A minimum 2-year follow-up was required for inclusion in this study. Assessment was performed clinically and with radiologic measurements. Radiologic measurements included the Cobb angles of the curves in the coronal plane, thoracic kyphosis and lumbar lordosis in the sagittal plane, and pelvic obliquity. The operating time, blood loss, and complications were evaluated.

Results

Twenty patients, aged 11–17, were enrolled. The average follow-up period was 35 months. Preoperative coronal curves averaged 70° (range: 51–85°), with a postoperative mean of 15° (range: 8–25°) and 17° (range: 9–27°) at the last follow-up. Pelvic obliquity improved from 13° (range: 7–15°) preoperatively to 5° (range: 3–8°) postoperatively and 6° (range: 3–9°) at the last follow-up. Good sagittal plane alignment was recreated and maintained. No loss of correction of scoliosis and pelvic obliquity was noted. The mean operating time was 271 min (range: 232–308 min). The mean intraoperative blood loss was 890 ml (range: 660–1260 ml). The mean total blood loss was 2100 ml (range: 1250–2880 ml).There was no major complication.

Conclusion

Segmental pedicle screw instrumentation and fusion to L5 is effective and safe in patients with scoliosis secondary to DMD without significant pelvic obliquity initially and long term, obviating the need for fixation to the sacrum/pelvis. There was no major complication.     

术中CT在后路全椎弓根螺钉治疗重度脊柱侧凸中的初步应用

目的:探讨术中CT在重度脊柱侧凸患者后路全椎弓根螺钉手术中的应用价值和临床疗效.方法:回顾性分析了2009年6月至201 1年6月行全椎弓根螺钉后路治疗的32例重度脊柱侧凸患者,其中男12例,女20例;年龄10～38岁,平均16.8岁;其中19例合并后凸.在术中椎弓根钉置钉完成后应用术中CT扫描多平面重建图像评估螺钉位置并分级,计算在上胸椎(T1-T4),中胸椎(T5-T8),下胸椎(T9-T12)和腰椎的螺钉评级结果及螺钉数目(比率),评估为2级和3级的螺钉为误置螺钉.计算术中应用CT次数.测量患者手术前后冠状面Cobb角及合并后凸病例手术前后矢状面后凸Cobb角,计算侧凸及后凸矫正率.结果:32例患者共置入胸腰椎螺钉686枚,其中胸椎螺钉544枚,腰椎螺钉142枚,其中14例患者行截骨手术.经术中CT评估分级,在上胸椎、中胸椎、下胸椎和腰椎的误置螺钉率分别是5.6％,11.1％,6.7％和4.3％,在胸腰椎总计是7.3％,误置螺钉在术中进行了修正.术中平均应用CT 2.6次(2～4次).术前侧凸Cobb角平均95°(78°～123°),术后侧凸Cobb角平均为34°(19°～53°),矫正率为64％;合并后凸病例术前后凸Cobb角69°(46°～82°),术后后凸Cobb角平均为32°(22°～45°),矫正率为54％.术后有4例患者脑脊液漏,未发现神经血管损伤病例及手术伤口感染病例.所有病例获得随访,时间12～26个月,平均18个月.未发现断钉、断棒、假关节形成等并发症发生.结论:在重度脊柱侧凸全椎弓根螺钉后路手术中应用术中CT可及时发现误置螺钉并进行修正,避免了因螺钉误置导致的二次手术,保障了手术安全,手术效果良好.     

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.     

Long-term three-dimensional changes of the spine after posterior spinal instrumentation and fusion in adolescent idiopathic scoliosis

This is a prospective study comparing the short- and long-term three-dimensional (3D) changes in shape, length and balance of the spine after spinal instrumentation and fusion in a group of adolescents with idiopathic scoliosis. The objective of the study was to evaluate the stability over time of the postoperative changes of the spine after instrumentation with multi rod, hook and screw instrumentation systems. Thirty adolescents (average age: 14.5 ± 1.6 years) undergoing surgery by a posterior approach had computerized 3D reconstructions of the spine done at an average of 3 days preoperatively (stage I), and 2 months (stage II) and 2,5 years (stage III) after surgery, using a digital multi-planar radiographic technique. Stages I, II and III were compared using various geometrical parameters of spinal length, curve severity, and orientation. Significant improvement of curve magnitude between stages I and II was documented in the frontal plane for thoracic and lumbar curves, as well as in the orientation of the plane of maximum deformity, which was significantly shifted towards the sagittal plane in thoracic curves. However, there was a significant loss of this correction between stages II and III. Slight changes were noted in apical vertebral rotation, in thoracic kyphosis and in lumbar lordosis. Spinal length and height were significantly increased at stage II, but at long-term follow-up spinal length continued to increase while spinal height remained similar. These results indicate that although a significant 3D correction can be obtained after posterior instrumentation and fusion, a significant loss of correction and an increase in spinal length occur in the years following surgery, suggesting that a crankshaft phenomenon may be an important factor altering the long-term 3D correction after posterior instrumentation of the spine for idiopathic scoliosis. Received: 3 March 1998 Revised: 22 August 1998 Accepted: 15 September 1998     

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。     

采用关键椎置钉及选择性融合治疗Lenke6型AIS可行性的有限元分析

[目的]通过有限元模型矫形手术模拟的方法探讨关键椎置钉技术的可行性及矫形效果,分析Lenke 6型脊柱侧凸是否适合采用选择性融合策略.[方法]通过CT图像建立1例Lenke 6型特发性脊柱侧凸三维有限元模型,并验证其有效性后,利用后路CD矫形手术模拟技术,分别模拟全节段椎弓根钉技术矫形工况、关键椎置钉技术矫形工况、胸腰弯选择性融合工况等.测量各种工况完成后双弯Cobb角度、计算矫形率,分析各种工况的矫形效果.[结果]全节段椎弓根钉技术(非选择性融合):胸腰弯矫形率47.8％,主胸弯矫形率43.9％;关键椎置钉技术:胸腰弯矫形率44.2％,主胸弯矫形率19.1％;胸腰弯选择性融合:胸腰弯矫形率43.5％,主胸弯矫形率14.3％.[结论]全节段椎弓根钉技术因矫形力施加点更多,矫形效果较关键椎置钉技术更佳;Lenke 6型脊柱侧凸采用选择性融合策略应慎重,非选择性融合策略能明显矫正双弯,纠正脊柱序列,更适合该类型病例.     

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.     

Is anterior release necessary in severe scoliosis treated by posterior segmental pedicle screw fixation?

With the advent of segmental pedicle screw fixation that enables more powerful corrective forces, it is postulated that an additional anterior procedure may be unnecessary even in severe deformities. The purpose of this paper is to evaluate the results of a posterior procedure alone using segmental pedicle screw fixation in severe scoliotic curves over 70°. Thirty-five scoliosis patients treated by pedicle screw fixation and rod derotation were retrospectively analyzed after a minimum follow-up of 2 years (range 2–10.4). The mean age of patients was 15.3 years (range 9.8–34.2). Diagnoses were idiopathic scoliosis in 29, neuromuscular scoliosis in 3 and scoliosis associated with Marfan syndrome in 3. Scoliosis consisted of single thoracic curve in 18, double thoracic in 5 and double major in 12. Twenty-five patients showed a major thoracic curve greater than 70° (range 70–100), and different ten patients showed a major lumbar curve greater than 70° (range 70–105), pre-operatively. The deformity angle, lowest instrumented vertebral tilt (LIVT) and spinal balance were measured. Pre-operatively there were nine patients with coronal decompensation. The pre-operative thoracic curve of 80 ± 9° with the flexibility of 45 ± 11% (45 ± 11° in side-bending film) was corrected to 27 ± 10° at the most recent follow-up, showing a correction of 66% (53°) and loss of correction of 3.0% (3.7°). The pre-operative lumbar curve of 79 ± 12° with the flexibility of 62 ± 14% (30 ± 11° in side-bending film) was corrected to 33 ± 14° at the most recent follow-up [59% (46°) curve correction, 3.5% (3.0°) loss of curve correction]. The pre-operative LIVT of 30 ± 8° was corrected to 11 ± 6°, showing a correction of 62% (19°). Residual coronal decompensation was observed in three patients postoperatively. Pre-operative thoracic kyphosis of 27° (range 0–82) improved postoperatively to 31° (range 14–53). In conclusion, posterior segmental pedicle screw fixation without anterior release in severe scoliosis had satisfactory deformity correction without significant loss of curve correction. In this series a posterior procedure alone obviated the need for the anterior release and avoided complications related anterior surgery.     

The effect of Luque segmental sublaminar instrumentation on the rib hump in idiopathic scoliosis

The change in back shape after Luque segmental sublaminar instrumentation was assessed in the frontal, sagittal, and transverse planes in 61 patients with adolescent idiopathic scoliosis using the Integrated Shape Investigation System (ISIS) and standard radiographic techniques. Luque instrumentation was found to be an effective method of correcting thoracic and thoracolumbar curves in the frontal plane with a 59% and 63% respective reduction in the size of the preoperative Cobb angle. Despite the frontal plane correction, however, the ISIS scan showed that of the 40 single thoracic curves, the rib hump was reduced in only 6 patients, was unchanged in 27 patients, and was worsened slightly in 7 patients. By contrast, thoracolumbar and lumbar curves were corrected in all three planes with a significant cosmetic improvement.     

Segmental analysis of the sagittal plane alignment of the normal thoracic and lumbar spines and thoracolumbar junction

Recent advances in spinal instrumentation have brought about a new emphasis on the three-dimensional spinal deformity of scoliosis and especially on the restoration of normal sagittal plane contours. Normal alignment in the coronal and transverse planes is easily defined; however, normal sagittal plane alignment is not so simple. This retrospective study was undertaken to increase the understanding of the normal alignment of the spine in the sagittal plane, with a special emphasis on the thoracolumbar junction. Measurements were made from the lateral radiographs of 102 subjects with clinically and radiographically normal spines. Cobb measurements of the thoracic kyphosis (T3-T12), the thoracolumbar junction (T10-T12 and T12-L2), and the lumbar lordosis (L1-L5) were determined. The spices of the thoracic kyphosis and lumbar lordosis also were determined. Using a computerized digitalizing table, the segmental angulation was determined at each level from T1-2 to L5-S1. In conclusion, there is a wide range of normal sagittal alignment of the thoracic and lumbar spines. When using composite measurements of the combined frontal and sagittal plane deformity of scoliosis, this wide range of sagittal variance should be taken into consideration. Using norms established here for segmental alignment, areas of hypokyphosis and hypolordosis commonly seen in scoliosis can be more objectively evaluated. The thoracolumbar junction is for all practical purposes straight; lumbar lordosis usually starts at L1-2 and gradually increases at each level caudally to the sacrum.