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.     

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.     

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.     

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.     

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.     

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.     

全椎弓根螺钉与钉钩联合系统治疗青少年Chiari畸形伴胸椎侧凸的疗效比较

 目的 评估青少年Chiari畸形伴胸椎侧凸不同内固定模式的选择对手术疗效的影响。 方法 回顾性分析2001年3月至2011年3月期间,接受后路胸椎融合术的75例Chiari畸形伴脊柱侧凸患者的病历资料,根据内固定方式分为全椎弓根螺钉组(44例)和钉钩联合组(31例)。分别测量术前、术后以及末次随访时的影像学指标：冠状面侧凸Cobb角、侧凸柔韧性、顶椎偏移、顶椎旋转及躯干偏移;矢状面胸椎后凸角、腰椎前凸角、躯干偏移及近端与远端交界区Cobb角。比较两组术前、术后及末次随访时上述影像学指标的改变。根据术前不同程度胸椎后凸进一步分组,比较两种内固定模式的手术疗效。结果 全椎弓根螺钉组术后胸弯平均矫正率为60.2％,明显著高于钉钩联合组(51.3％,t=2.372,P=0.023)。末次随访时全椎弓根螺钉组及钉钩联合组胸弯矫正丢失率分别为0.3％及1.7％(t=-0.468,P >0.05)。术后腰弯平均矫正率在全椎弓根螺钉组为61.7％,明显优于钉钩联合组51.1％(t=2.431,P=0.020)。术前全椎弓根螺钉组与钉钩联合组的胸弯顶椎偏移分别平均为25.0 mm和24.1 mm,术后减小至6.9 mm和7.4 mm,两组术后的胸弯顶椎偏移均获得明显改善。术前胸椎后凸>40°的病例中,全椎弓根螺钉组末次随访时矢状面近端交界区Cobb角为10.0°,高于钉钩联合组(4.5°,t=-2.031,P=0.052)。而且全椎弓根螺钉组近端交界性后凸发生率(20% )高于钉钩联合组(9%)。结论 对继发于青少年Chiari畸形的胸椎侧凸行后路内固定矫形,全椎弓根螺钉具有更好的畸形矫正率,但是,与钉钩联合固定相比,术前胸椎过度后凸的患者在胸椎全椎弓根螺钉固定术后远期发生近端交界性后凸的风险增高。     

Thoracic scoliosis fusion in adolescent and adult idiopathic scoliosis using posterior translational corrective techniques (Isola): is maximum correction of the thoracic curve detrimental to the unfused lumbar curve?

BACKGROUND CONTEXT: Postoperative coronal decompensation in selective thoracic fusion was reported with derotation maneuvers when using the Cotrel-Dubousset (CD) system. Isola instrumentation is a multiple anchor system that corrects spine deformity with segmental vertebral translation to a predetermined contoured longitudinal member. PURPOSE: To evaluate the efficacy of translational corrective techniques using Isola instrumentation in thoracic fusion for adolescent and adult idiopathic scoliosis patients. STUDY DESIGN/SETTING: This is a retrospective review of adolescent and adult patients with idiopathic scoliosis who underwent posterior thoracic fusion using translational corrective techniques with Isola instrumentation. PATIENT SAMPLE: Twenty-two patients (14 adolescents with idiopathic scoliosis, 8 adults with scoliosis) who underwent posterior thoracic fusion using translational corrective techniques were evaluated. OUTCOME MEASURES: The charts, radiographs and self-assessment questionnaire were reviewed. METHODS: Comparative analysis was done between patients who had Lenke Type A curves (Group 1) and Lenke Type B or C curves (Group 2) for both adolescent and adult scoliosis groups. RESULTS: The mean follow-up was 54 months (range, 33 to 80 months). The mean preoperative Cobb angle of thoracic and lumbar curves in all 22 patients was 48 degrees (range, 34 to 64 degrees) and 31 degrees (range, 20 to 46 degrees), respectively. Postoperative measurements were 16 degrees (range, 0 to 28 degrees) for thoracic and 13 degrees (range, 2 to 25 degrees) for lumbar (67% thoracic and 60% lumbar correction) in Group 1, and 19 degrees (range, 1 to 33 degrees) for thoracic and 12 degrees (1 to 21 degrees) for lumbar at latest follow-up (61% thoracic and 61% lumbar correction) in Group 2. There was no difference in the final correction of the lumbar curves between Groups 1 (64%) and 2 (58%), although the Cobb angle in Group 2 was larger. Radiographic coronal decompensation occurred in only one patient in Group 2, who remained asymptomatic and required no further treatment. Clinical outcome assessment showed 100% satisfaction (n=15), 92% relief of symptoms (n=13) and 92% improvement of activities in both groups. CONCLUSIONS: Fusion of the major thoracic curve using translational corrective technique (Isola) in patients with idiopathic scoliosis is an effective procedure that achieves high patient satisfaction while providing excellent correction of both the thoracic and lumbar curves. Unlike rotational corrective techniques (CD), clinical decompensation requiring further treatment did not occur in any patient treated with this method.     

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     

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.     

Anterior surgery with short fusion using the Zielke procedure for thoracic scoliosis: focus on the correction of compensatory curves

Anterior instrumentation is recommended to correct idiopathic thoracolumbar or lumbar scoliosis through short fusion within the major curve. Only a few reports exist of anterior surgical correction for thoracic scoliosis. This study assessed the results of Zielke instrumentation for thoracic curve and analyzed the three-dimensional correction of deformity, especially correction of the uninstrumented compensatory curve. Seventeen patients, who had undergone selective thoracic correction and fusion using the Zielke procedure to treat thoracic scoliosis, had been followed for at least 3 years. Three-dimensional correction was evaluated radiographically. Furthermore, three-dimensional back deformities were evaluated using a topographic body scanner. Twelve patients with a single thoracic curve and five with a double curve were all female, with a mean age of 14.6 years. The preoperative main thoracic curve was 54.8 degrees +/- 10.5 degrees (range, 40-78 degrees), and it was 23.8 degrees +/- 10.5 degrees (range, 7-40 degrees) at the final follow-up examination (p < 0.0001). The average correction rate of the main curves was 56.6%. By correcting the thoracic curve, the upper and lower compensatory curves were corrected spontaneously without surgical instrumentation, with average correction rates of 45.1% and 50.2%, respectively. The average correction loss of the main curve was 2.3 degrees. The hump angle measured using a topographic body scanner decreased from 12.8 degrees +/- 4.5 degrees to 8.4 degrees +/- 4.3 degrees after surgery (p = 0.0001). Of the three patients in whom the rod broke up, only one showed a correction loss of 10 degrees; however, bony fusion was obtained. Anterior short fusion for thoracic scoliosis appears to offer significant correction, stabilization, and spontaneous correction of the compensatory lumbar curve without limiting lumbar motion.     

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.     

No relationship exists between the correction of the thoracic and the lumbar curves after selective thoracic fusion for adolescent idiopathic scoliosis King type II

In this study we focus on idiopathic scoliosis with a primary thoracic curve and a secondary lumbar curve. We were interested in how the lumbar curve corrects following selective thoracic fusion and whether one can explain or predict the behaviour of the lumbar curve. In the literature it is said that, if the lower level of fusion is properly selected, the lumbar curve spontaneously corrects to balance the thoracic curve after selective thoracic fusion. Most authors have assumed a mechanism whereby improvement of the lumbar curve occurs through counterbalancing the surgical correction of the thoracic curve. The correction of the lumbar curve is said to echo the correction obtained for the thoracic curve. Because of these hypotheses, we postulate there should be a correlation between the correction of the lumbar and the thoracic curves of a scoliosis. To validate this hypothesis, we performed a retrospective study on 27 patients with King type II adolescent idiopathic scoliosis treated by selective thoracic fusion. The mean preoperative Cobb angles were 54 degrees for the thoracic curve and 34 degrees for the lumbar curve. Postoperatively they were 31 degrees and 22 degrees respectively. Using Pearson correlation analysis, we found no significant correlation between the relative corrections of the individual thoracic and lumbar curves. Moreover, there was a decrease in the correlation between the thoracic and lumbar curve after operation (preoperative R=0.787, postoperative R=0.364). These results show that the correction of the lumbar curve is not a reflection of the thoracic correction. The exact mechanism by which the lumbar spine corrects remains to be elucidated.     

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.     

短节段融合对退变性腰椎侧凸邻近节段椎间角的影响

目的 研究退变性腰椎侧凸短节段融合后邻近节段椎间角的变化特点.方法 回顾性分析2001年1月至2007年5月28例退变性腰椎侧凸患者的临床资料.其中男性6例,女性22例;平均年龄62岁;侧凸范围3～6个椎节,平均4.8个椎节.采用后方椎板切除减压、椎弓根螺钉内固定、后外侧植骨融合术;融合范围限制在侧凸范围内,平均融合3.3个椎节.术前、术后即刻及随访时拍摄站立腰椎正侧位X线片,测量冠状面侧凸Cobb角、近端融合椎上方邻近节段正位及侧位椎间角,并观察植骨融合及并发症发生情况.结果 患者均获随访,随访时间25～97个月,平均50个月.术后即刻侧凸Cobb角平均矫形率33.7%,末次随访时矫形丢失平均3.7°,术前及末次随访侧凸Cobb角与术后即刻比较差异均有统计学意义(P<0.05).末次随访时正位椎间角与术前、术后即刻相比差异均有统计学意义(P<0.05).末次随访时均未发现明显假关节形成及内植物相关并发症.结论 退变性腰椎侧凸短节段融合后对近端融合椎上方邻近节段正位椎间角的矫正有限,且不能阻止其进一步加重.     

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?     

Posterior fusion only for thoracic adolescent idiopathic scoliosis of more than 80°: pedicle screws versus hybrid instrumentation

The treatment of thoracic adolescent idiopathic scoliosis (AIS) of more than 80° traditionally consisted of a combined procedure, an anterior release performed through an open thoracotomy followed by a posterior fusion. Recently, some studies have reassessed the role of posterior fusion only as treatment for severe thoracic AIS; the correction rate of the thoracic curves was comparable to most series of combined anterior and posterior surgery, with shorter surgery time and without the negative effect on pulmonary function of anterior transthoracic exposure. Compared with other studies published so far on the use of posterior fusion alone for severe thoracic AIS, the present study examines a larger group of patients (52 cases) reviewed at a longer follow-up (average 6.7 years, range 4.5–8.5 years). The aim of the study was to evaluate the clinical and radiographic outcome of surgical treatment for severe thoracic (>80°) AIS treated with posterior spinal fusion alone, and compare comprehensively the results of posterior fusion with a hybrid construct (proximal hooks and distal pedicle screws) versus a pedicle screw instrumentation. All patients (n = 52) with main thoracic AIS curves greater than 80° (Lenke type 1, 2, 3, and 4), surgically treated between 1996 and 2000 at one institution, by posterior spinal fusion either with hybrid instrumentation (PSF–H group; n = 27 patients), or with pedicle screw-only construct (PSF–S group; n = 25 patients) were reviewed. There were no differences between the two groups in terms of age, Risser’s sign, Cobb preoperative main thoracic (MT) curve magnitude (PSF–H: 92° vs. PSF–S: 88°), or flexibility on bending films (PSF–H: 27% vs. PSF–S: 25%). Statistical analysis was performed using the t test (paired and unpaired), Wilcoxon test for non-parametric paired analysis, and the Mann–Whitney test for non-parametric unpaired analysis. At the last follow-up, the PSF–S group, when compared to the PSF–H group had a final MT correction rate of 52.4 versus 44.52% (P = 0.001), with a loss of −1.9° versus −11.3° (P = 0.0005), a TL/L correction of 50 versus 43% (ns), a greater correction of the lowest instrumented vertebra translation (−1.00 vs. −0.54 cm; P = 0.04), and tilt (−19° vs. −10°; P = 0.005) on the coronal plane. There were no statistically significant differences in sagittal and global coronal alignment between the two groups (C7-S1 offset: PSF–H = 0.5 cm vs. PSF–S = 0 cm). In the hybrid series (27 patients) surgery-related complications necessitated three revision surgeries, whereas in the screw group (25 patients) one revision surgery was performed. No neurological complications or deep wound infection occurred in this series. In conclusion, posterior spinal fusion for severe thoracic AIS with pedicle screws only, when compared to hybrid construct, allowed a greater coronal correction of both main thoracic and secondary lumbar curves, less loss of the postoperative correction achieved, and fewer revision surgeries. Posterior-only fusion with pedicle screws enabled a good and stable correction of severe scoliosis. However, severe curves may be amenable to hybrid instrumentation that produced analogous results to the screws-only constructs concerning patient satisfaction; at the latest follow-up, SRS-30 and SF-36 scores did not show any statistical differences between the two groups. Presented at 8th Annual Meeting of the Spine Society of Europe, October 2006, Istanbul, Turkey.     

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.     

Adolescent idiopathic thoracic scoliosis: apical correction with specialized pedicle hooks

Forty-one patients with thoracic adolescent idiopathic scoliosis (AIS) treated with only a posterior spine fusion using specialized pedicle hooks (SPH) (hooks augmented with 3.2-mm screws) at the apex of the curve were reviewed in order to assess the effectiveness of this correction method. Inclusion in the study group required a minimum of 2 years’ follow-up and the same strategy of correction where the apical vertebrae (3 or 4 vertebrae on the concave side) were instrumented with SPH. The mean preoperative Cobb angle was corrected from 55° (42°–80°) to 18° (67%) postoperatively and to 23° (58%) at the last follow-up (28–50 months) for a flexibility index of 46%. Apical vertebral translation was corrected to 70% at the last follow-up. Thoracic kyphosis remained unchanged, from 23° to 26°, and the lumbar lordosis went from –53° to –59°. The lumbar curve was corrected from 38° to 18°. Coronal balance improved from 10 to 1 mm; shoulder balance was improved from 15 to 5 mm. The rib hump was improved from an average of 30 mm preoperatively to 15 mm postoperatively, but only to 25 mm at the last follow-up (17% of correction). One case of a spastic bladder was observed postoperatively, which resolved completely after 8 months. Three patients had to have their instrumentation removed because of pain. There was no complication related to the use of the SPH. The authors conclude that apical correction with SPH allows effective scoliosis correction without spinal distraction and does not require supra- or infralaminar hook in the spinal canal. Received: 1 July 1998 Revised: 25 March 1999 Accepted: 21 April 1999