Predictability of the spontaneous lumbar curve correction after selective thoracic fusion in idiopathic scoliosis

In this study we tried to achieve a better understanding of the biodynamic mechanism of balance in the scoliotic spine. Therefore we focused on the pre- and postoperative spine of patients with idiopathic scoliosis with a primary thoracic curve and a secondary lumbar curve. Several studies showed that the lumbar curve spontaneously corrects and improves after selective thoracic fusion. We try to understand and describe this spontaneous compensatory lumbar curve correction after selective thoracic correction and fusion. We performed a retrospective examination of pre- and postoperative radiographs of the spine of 38 patients with idiopathic scoliosis King type II and III. Frontal Cobb angles of the thoracic and lumbar curves were assessed on pre- and postoperative antero-posterior and side bending radiographs. We determined the postoperative corrections of the thoracic and lumbar curves. Relative (%) corrections and correlations of the postoperative corrections were calculated. The group was divided in three subgroups, depending on lumbar curve modifier, according to Lenkes classification system. The calculations were done for the whole group as for each subgroup. As expected, significant correlations were present between the relative correction of the main thoracic and the lumbar curve (mean R = 0.590; P = 0.001). The relation between relative thoracic and lumbar correction decreased with the lumbar modifier type. This study shows a highly significant correlation between the relative corrections of the main thoracic curve and the lumbar curve after selective thoracic fusion in idiopathic scoliosis. This correlation depends on lumbar curve modifier type. This new classification system seems to be of great predictable value for the spontaneous correction of the lumbar curve. Depending on the curve-type, a different technique for predicting the outcome should be used. The lumbar curve correction does not occur throughout the whole lumbar curve. Most correction is achieved in the upper part of the curve. The distal lumbar curve seems to be more rigid and less important in the spontaneous curve correction.     

Radiographic evaluation of selective anterior thoracolumbar or lumbar fusion for adolescent idiopathic scoliosis

According to Lenke classification of adolescent idiopathic scoliosis (AIS), patients with type 5 curve in which the structural major curve is thoracolumbar or lumbar curve with nonstructural proximal thoracic and main thoracic curves, could be surgically treated with selective anterior thoracolumbar or lumbar (TL/L) fusion. This study retrospectively analyzed the radiographies of selective anterior TL/L fusion in 35 cases of AIS with Lenke type 5 curve. Segmental fixation with a single rigid rod through anterior thoracoabdominal approach was applied in all patients. Measurements of scoliosis curve in preoperative, immediate postoperative and follow-up radiographies were analyzed. The average follow up time was 36 months (24-42 months). The average preoperative Cobb angle of the TL/L curve was 45.6 degrees and improved into 9.7 degrees immediate postoperatively, with 79.7% curve correction. In addition, the minor thoracic curve decreased from 29.7 degrees preoperatively to 17.6 degrees postoperatively, with a spontaneous correction of 41.5%. During the follow-up, a loss of 4.6 degrees correction was found and the average Cobb angle of TL/L increased to 14.4 degrees . Also, the minor thoracic curve increased to average 20.1 degrees with a loss of 2.4 degrees correction. Trunk shift deteriorated slightly immediate postoperatively and improved at the follow-up. The lowest instrumented vertebra (LIV) tilt was improved significantly and maintained its results at the follow-up. During the follow-up, the coronal disc angle immediately above the upper instrumented vertebra (UIVDA) and below the LIV (LIVDA) aggravated, while the sagittal contours of T5-T12 and T10-L2 were well maintained. The lumbar lordosis of L1-S1 and the sagittal Cobb angle of the instrumented segments were reduced slightly postoperatively and at the follow-up. There were no major complications or pseudarthrosis. The outcomes of this study show that selective anterior thoracolumbar or lumbar fusion with solid rod instrumentation is effective for surgical correction of AIS with Lenke type 5 curve. The TL/L curve, minor thoracic curve, and LIV title can be improved significantly, with good maintenance of sagittal contour. However, the UIVDA and LIVDA aggravate postoperatively when the trunk rebalances itself during follow-up. The degeneration of LIV disc warrants longer-term follow-up.     

Lenke 5+型青少年特发性脊柱侧凸患者后路选择性融合术后胸弯的转归

目的:探讨Lenke 5+型脊柱侧凸患者不同融合策略疗效及选择性融合术后胸弯自发矫正情况.方法:回顾性分析2010年1月～2018年12月期间在我院接受手术治疗且随访2年以上Lenke 5+型青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者资料,共80例,男13例,女6...     

特发性胸椎侧凸选择性融合术后远端叠加现象

【摘要】 目的：探讨主胸弯型青少年特发性脊柱侧凸（adolescent idiopathic scoliosis,AIS）单次前或后路胸弯融合术后远端叠加现象的发生率,并对其影响因素进行分析。方法：回顾性分析110例行单次前或后路主胸弯融合术的主胸弯型（Lenke 1A型）AIS患者。其中男20例,女90例;年龄10～18岁,平均14.2±2.0岁;主胸弯Cobb角40°～80°,平均为48.2°±7.8°。所有患者在术前、术后及术后随访时均摄站立位全脊柱正侧位X线片。测量侧凸Cobb角,记录患者的年龄、Risser征、Y软骨形态、手术方式、稳定椎及融合节段,统计术后远端叠加现象的发生率,分析其影响因素。结果：随访时间为12～46个月,平均21±5个月。术后Cobb角平均为16.7°±6.1°,末次随访时Cobb角平均为22.0°±8.5°。共有19例出现远端叠加现象,发生率为17.3%。与非叠加组相比,叠加组患者的Risser征较低（2.1±1.4∶3.1±1.3,P=0.002）,月经来潮后时间较短（11.2±14.2∶21.9±18.9个月,P=0.002）,代偿性腰弯柔软度较高[（97.0±9.1）%∶（90.5±15.5）%,P=0.017],远端融合椎（LIV）的位置约高出0.8个椎体。关于叠加现象发生率,低Risser征患者高于高Risser征患者,Y软骨开放组高于Y软骨闭合组,月经初潮未至和来潮小于1年组高于月经来潮大于1年组,腰弯高柔软度组高于低柔软度组,LIV高位置组[相对于稳定椎（SV）]高于低位置组。经过Logistic回归分析,LIV-SV≤-2、Y软骨开放和腰弯高柔软度是术后发生远端叠加现象的三个独立的危险因素。结论：部分主胸弯型AIS患者前或后路矫形术后可发生远端叠加现象。LIV的选择、患者的生长发育成熟度和代偿性腰弯的柔软度是影响远端叠加现象的重要因素。     

后路选择性胸腰弯或腰弯融合治疗Lenke 5C型青少年特发性脊柱侧凸

目的:评价后路选择性胸腰弯或腰弯融合治疗青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)的临床效果。方法:回顾性分析45例行后路选择性胸腰弯(20例)或腰弯(25例)融合的Lenke 5C型AIS病例,男4例,女41例,平均年龄14.9±2.1岁(12~20岁)。所有病例均行后路椎弓根螺钉内固定矫形融合,平均随访36±20个月(24~105个月)。术前、术后及末次随访时均摄站立位全脊柱正侧位X线片,对躯干偏移、融合节段邻近椎间盘开角、远端融合椎的倾斜、冠状面和矢状面Cobb角进行测量分析。测量数据使用SPSS 17.0统计学软件进行分析。结果:术前胸腰弯或腰弯Cobb角平均47.3°±7.2°,术后矫正至6.4°±4.6°,矫正率(84.8±11.6)%,末次随访时为9.1°±5.4°,矫形丢失2.7°±4.6°。胸弯术前25.7°±7.4°,凸侧Bending像Cobb角7.6°±5.8°,柔韧性(72.7±23.0)%,术后矫正至13.2°±6.7°,自动矫正率(48.5±29.4)%,末次随访14.2°±7.6°,矫形丢失1°±6°。躯干偏移:术前21.3±11.5mm,术后19.5±13.3mm,末次随访10.9±8.9mm。术后近端与远端融合椎邻近椎间盘开角较术后明显减小,且在随访过程中无明显加重。远端融合椎倾斜术后及末次随访时均显著改善。末次随访时,交界性后凸1例,躯干失衡3例,胸弯失代偿并行融合延长手术1例。所有病例末次随访时均未见假关节形成。结论:后路选择性胸腰弯或腰弯融合对Lenke 5C型特发性脊柱侧凸可获得满意矫形效果,胸弯可获得良好的自动矫正,有效缩短了融合节段。     

选择性前路或后路手术治疗Lenke5型AIS胸弯自发矫正比较及策略分析

[目的]比较选择性前路或后路手术治疗Lenke5型青少年特发性脊柱侧凸未融合胸弯术后自发矫正情况.[方法]1997年5月～2005年10月,共72例接受手术的Lenke5型青少年特发性脊柱侧凸患者,其中40例采用选择性前路手术(A组),32例采用选择性后路手术(B组),随访时间最少2年.[结果]末次随访发现,两组患者无1例发生术后相关并发症,A组术前胸弯平均30°,术后平均16°;B组术前33°,术后18°.两组患者术后末融合胸弯大多得到了明显改善,且两组患者改善率没有差别,但末次随访发现,72例患者中,4例患者(C组)术后胸弯加重,躯干发生了失平衡,A组、B组各2例.该4例患者(TL/L:T)Cobb's比率均值为1.09,其余68例(D组)比率均值为1.59.C、D组患者胸弯柔韧性也有差别,C组较D组僵硬(分别34.2%和57.3%).[结论]选择性前路或后路手术治疗Lenke5型青少年特发性脊柱侧凸,未融合胸弯自发矫正效果相当,但术前对患者(TI/L:T)Cobb's比率和胸弯柔韧性进行评估非常重要.     

选择性前路手术治疗胸腰段或腰段青少年特发性脊柱侧凸的参数分析

目的 探讨Lenke5、6型青少年特发性脊柱侧凸(AIS)患者选择性前路手术的筛选指标.方法 回顾性分析我院1999年3月至2004年5月期间收治的52例Lenke5、6型AIS患者,随访2～4年(平均34个月),评估术前各相关参数.按术后结果 分成两组:满意组(胸弯减小)A组,不满意组(胸弯加重)B组.结果 A组(n=46)术前胸弯平均33°,术后平均18°,腰弯术前平均49°,术后平均21°.B组(n=6)术前胸弯平均38°,术后平均45°.腰弯术前平均46°,术后平均25°.B组患者中2例由于术后脊柱失平衡,进行了后路翻修术.结论 胸椎柔韧性和患者的成熟度决定了该方案外科手术的效果.在各种结构参数中,(TL/L:T)Cobb比率和胸椎柔韧性,是筛选患者的较好指标.     

Lenke 5型青少年特发性脊柱侧凸患者前路选择性融合术后腰椎后滑脱的发生率及危险因素分析

目的 ：分析Lenke 5型青少年特发性脊柱侧凸（AIS）患者行前路选择性融合术后腰椎后向滑脱的发生率及其危险因素。方法：回顾性分析2005年1月～2010年12月在我院接受前路选择性胸腰椎融合手术的49例Lenke 5型AIS患者的临床资料。在术前、术后3个月及末次随访时的站立位全脊柱正侧位X线片上测量胸腰弯Cobb角、胸弯Cobb角、腰椎前凸角（lumbar lordosis,LL）、胸椎后凸角（thoracic kyphosis,TK）、胸腰段后凸角（thoracolumbar junctional kyphosis,TJK）、骶骨倾斜角（sacral slope,SS）、骨盆倾斜角（pelvic tilt,PT）、骨盆入射角（pelvic incidence,PI）、C7矢状位垂直距离（C7 sagittal vertical axis,SVA）。统计患者性别、年龄、Risser征、随访时间、融合椎体数、下端固定椎位置。按照Roussouly分型对患者术前矢状面形态进行分型。根据末次随访时发生腰椎后滑脱与否将患者分为滑脱组与非滑脱组。对两组患者术前、术后3个月及末次随访时的各参...     

Short anterior correction of the thoracolumbar/lumbar curve in King 1 idiopathic scoliosis: the behaviour of the instrumented and non-instrumented curves and the trunk balance

This is a retrospective clinical, radiological and patient outcome assessment of 21 consecutive patients with King 1 idiopathic adolescent scoliosis treated by short anterior selective fusion of the major thoracolumbar/lumbar (TL/L) curve. Three-dimensional changes of both curves, changes in trunk balance and rib hump were evaluated. The minimal follow-up was 24 months (max. 83). The Cobb angle of the TL/L curve was 52 degrees (45-67 degrees) with a flexibility of 72% (40-100%). The average length of the main curve was 5 (3-8) segments. An average of 3 (2-4) segments was fused using rigid single rod implants with side-loading screws. The Cobb angle of the thoracic curve was 33 degrees (18-50 degrees) with a flexibility of 69% (29-100%). The thoracic curve in bending was less than 20 degrees in 17 patients, and 20-25 degrees in 4 patients. In the TL/L curve there was an improvement of the Cobb angle of 67%, of the apex vertebral rotation of 51% and of the apex vertebral translation of 74%. The Cobb angle of the thoracic curve improved 29% spontaneously. Shoulder balance improved significantly from an average preoperative imbalance of 14.5-3.1 mm at the last follow-up. Seventy-five percent of the patients with preoperative positive shoulder imbalance (higher on the side of the thoracic curve) had levelled shoulders at the last follow-up. C7 offset improved from a preoperative 19.8 (0-40) to 4.8 (0-18) mm at the last follow-up. There were no significant changes in rotation, translation of the thoracic curve and the clinical rib hump. There were no significant changes in thoracic kyphosis or lumbar lordosis. The average score of the SRS-24 questionnaire at the last follow-up was 91 points (max. 120). We conclude that short anterior selective fusion of the TL/L curve in King 1 scoliosis with a thoracic curve bending to 25 degrees or less (Type 5 according to Lenke classification) results in a satisfactory correction and a balanced spine. Short fusions leave enough mobile lumbar segments for the establishment of global spinal balance. A positive shoulder imbalance is not a contraindication for this procedure. Structural interbody grafts are not necessary to maintain lumbar lordosis.     

Anterior lumbar instrumentation improves correction of severe lumbar Lenke C curves in double major idiopathic scoliosis

Fifteen skeletally immature patients with double major adolescent idiopathic scoliosis with large lumbar curves and notable L4 and L5 coronal plane obliquity were retrospectively studied. Seven patients who underwent anterior release and fusion of the lumbar curve with segmental anterior instrumentation and subsequent posterior instrumentation ending at L3 were compared with eight patients treated with anterior release and fusion without anterior instrumentation followed by posterior instrumentation to L3 or L4. At 4.5 years follow-up (range 2.5-7 years), curve correction, coronal balance and fusion rate were not statistically different between the two groups; however, the group with anterior instrumentation had improved coronal plane, near normalangulation in the distal unfused segment compared with the group without anterior instrumentation. In cases involving severe lumbar curvatures in the context of double major scoliosis, when as a first stage anterior release is chosen, the addition of instrumentation appears to restore normal coronal alignment of the distal unfused lumbar segment, and may in certain cases save a level compared with traditional fusions to L4.     

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.     

Rip hump correction and rotation of the lumbar spine after selective thoracic fusion

In this study a series of 32 patients with idiopathic scoliosis, managed with selective thoracic fusion, was reviewed. Classified according to King and instrumented with the H-frame, the patients were evaluated for curve correction, rib hump correction and postoperative shift in lumbar rotation. Age and follow-up averaged 19.4 and 2.4 years, respectively. The 32 patients had an average primary and lumbar curve correction of, respectively, 66% (6.0% correction loss) and 53% (3.4% correction loss). The respective values for postoperative rib hump correction and shift in apical lumbar rotation averaged 8° and 9.4° in type II King curves, 4.4° and 3.5° in type III and 11° and-5° in Type IV. Significant differences were noted between the curve types in rib hump correction and shift in lumbar rotation. The study showed that en bloc postoperative rotation of the compensatory lumbar segment, directed towards the rib hump, positively influences rib hump correction. This en bloc rotation of the unfused lumbar segments is induced by the correcting forces applied by the instrumentation. The unfused lumbar spine of a patient with a King type II curve shows a larger lumbar rotation shift and subsequent rib hump correction than that of a patient with a King type III curve. Together with factors such as lateral angulation, rib-vertebra angles and structural limitations, the rotational dynamics of the unfused lumbar spine seem to form an important component in the understanding and surgical management of scoliosis.     

Lenke 1型和2型青少年特发性脊柱侧凸选择性胸弯融合术后腰弯自发性纠正的研究进展

<正>青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)手术治疗的主要目标是在尽可能减少融合节段的同时恢复良好的脊柱冠状面和矢状面平衡。对于Lenke 1型和2型AIS患者而言,选择性胸弯融合(selective thoracic fusion,STF)可最大限度保留患者腰部的活动度,进而提高患者术后生活质量^[1、2]。既往研究表明,大多数Lenke 1型和2型AIS患者STF术后长期随访中可以获得良好的腰弯自发性纠正(spontaneous lumbar curve correction,SLCC)^[3]。     

Radiological and clinical outcome of selective thoracic fusion for patients with Lenke 1C and 2C adolescent idiopathic scoliosis with a minimum follow-up of 2 years

Background Context

In Lenke 1C and 2C curves, the choice between selective thoracic fusion (STF) versus non-selective thoracic fusion as the optimal surgical treatment is controversial.

Lenke 5型脊柱侧凸前路选择性融合术后胸弯的转归及其影响因素

目的 探讨Lenke 5型脊柱侧凸前路选择性融合术后胸弯的转归及其可能的影响因素.方法 回顾性分析伴有胸弯的29例女性Lenke 5型脊柱侧凸患者,年龄12～20岁,平均(15.3±2.0)岁;Risser征0～5级,平均(3.8±0.8)级.所有患者均行前路选择性融合术,随访24～58个月,平均33个月,分析术后胸弯的转归及其与术前相关指标的关系.结果所有患者行前路选择性融合术后,主弯Cobb角减小至11.9°±7.3°(矫正率为74.7%±15.3%),胸弯Cobb角减小至16.7°±7.5°(矫正率为40.4%±21.8%).胸弯Cobb角矫正丢失2°以上的9例患者术前胸弯Bending相矫正率较低(F=5.408,P=0.028).在发生显著胸弯矫正丢失的3例患者中,2例术前胸弯Cobb角均达35°以上,2例胸弯柔软度低于50%,1例主弯和胸弯Cobb角比值低于1.25,1例Risser征为0级.末次随访时,胸弯Cobb角与术前胸弯Cobb角、胸弯Bending相Cobb角以及胸弯和主弯Cobb角比值均正相关(分别为r=0.664,19<0.001;r=0.555,P=0.001;r=0.515,P=0.002).而末次随访时胸弯矫正率则与术前胸弯Bending相矫正率正相关(r=0.495,P=0.006).结论 Lenke 5型患者行前路选择性融合术后胸弯的自发性矫正可能与术前胸弯Cobb角、柔软度以及生长潜能等密切相关,但术前胸弯柔软度小能完全反映术后自发性矫正的程度.     

Spontaneous correction of coronal imbalance after selective thoracolumbar-lumbar fusion in patients with Lenke-5C adolescent idiopathic scoliosis

Background Context

Coronal imbalance is a complication of corrective surgeries in adolescent idiopathic scoliosis (AIS). However, few studies about immediate coronal decompensation in Lenke-5C curves have reported its incidence, prognosis, and related factors.

Surgical assessment of the proximal thoracic curve in adolescent idiopathic scoliosis

Existing predictive signs as available in current literature may miss potential proximal thoracic (PT) curve deterioration and shoulder imbalance, following selective main thoracic (MT) curve correction in adolescent idiopathic scoliosis (AIS). The present study is an attempt to evaluate and complement these signs, through a retrospective study of 56 AIS patients who underwent correction and fusion from 1986 till 2003 with follow-up 4–16 years. Forty-nine had fusion of MT curve, 7 of MT and PT. Cotrel–Dubousset instrumentation in 45, Luque in 12. Preoperative data: MT 50° (40°–80°), PT 25° (0°–50°), shoulder elevation from −4 cm (right) to 2 cm (left), clavicle angle from −14° to 5°, PT bending correction from 0 to 100% and T1 tilt from −15° to 14°. We introduced the first rib index (FRI), i.e., the difference between the diameter of right and left first rib arch as a percentage of the sum of both diameters, averaging from −22.7 to 14.3%. (Minus signs refer to or predict right, while positive left shoulder elevation.) Evaluation included all predictive parameters as related principally to postoperative left shoulder elevation ≥1 cm, patient satisfaction and surgeon fulfillment. Postoperative correction MT curve 53% (23–83%) and PT 35% (0–100%). One progressive paraplegic started 40 min following normal wake-up test. Immediate decompression, full recovery. Three cases with wound infection recovered after late removal of instrumentation. Loss of correction ≥10° in five. Fifteen had postoperative persisting left shoulder elevation ≥1 cm. Seven of these expressed dissatisfaction. Statistically FRI proved valuable predictive factor always in combination with previously described signs. We concluded that a postoperative left shoulder elevation ≥2 cm is a potential cause of dissatisfaction and may be prevented with thorough validation of all predictive signs, principally the FRI. Part of this paper was presented at the 62nd annual meeting of the Hellenique Orthop. Society (October 2006) and received the 1st award for best clinical paper.     

Surgical treatment of Lenke 5 adolescent idiopathic scoliosis: Comparison of anterior vs posterior approach

AIM To compare the posterior vs anterior approaches for fusion of Lenke 5 adolescent idiopathic scoliosis curves,matched for curve magnitude and for the distal level of fixation(dLOF) standardized to the third lumbar vertebrae(L3).METHODS A prospectively collected multicenter database was used for this retrospective comparative study. Our dependent variables included sagittal and coronal radiographic measurements, number of fused vertebrae, estimated blood loss, length of hospitalization and SRS total and individual domain scores at the two-year follow-up. Subject demographics were similar for all group comparisons.Independent t-test was used to compare groups for all analyses at P 0.01.RESULTS For all matched cases of Lenke 5 curves, a selective approach was used only 50% of the time in cases undergoing a posterior fusion. When comparing a posterior selective approach to an anterior selective approach,surgeons utilizing a posterior approach fused significantly more levels than surgeons using an anterior approach with no other significant differences in radiographic or SRS outcomes(Ant = 4.8 ± 1.0 levels vs post = 6.1 ± 1.0 levels, P 0.0001). When the dLOF was standardized to L3, the anterior approached provided significantly greater lumbar Cobb percent correction than the posterior approach(Ant = 69.1% ± 12.6% vs post =54.6% ± 16.4%, P = 0.004), with no other significant radiographic or SRS score differences between approaches.CONCLUSION Surgeons treating Lenke 5c curves with a posterior instrumentation and fusion vs an anterior approach include more motion segments, even with a selective fusion. When controlled for the distal level of fixation,the anterior approach provides greater correction of the thoracolumbar curve.     

The changes of relative position of the thoracic aorta after anterior or posterior instrumentation of type I Lenke curve in adolescent idiopathic thoracic scoliosis

The risk of impingement of the aorta associated with thoracic vertebral screw or pedicle screw instrumentation in the treatment of thoracic scoliosis has been an important concern. To understand this phenomenon more systematically, the relative position of the aorta with reference to the thoracic vertebrae in right thoracic adolescent idiopathic scoliosis (AIS) following anterior and posterior spinal instrumentation was analyzed in detail quantitatively; 34 patients underwent anterior (n = 14) or posterior (n = 20) spinal instrumentation were recruited in the present study. The relative position of the thoracic aorta, vertebral rotation, apical vertebral translation and thoracic kyphosis were measured from pre- and post-operative CT images from T5 to T12. The aorta was found to shift antero-medially in the anterior instrumentation group but not in the posterior spinal instrumentation group. It is likely that the disc removal, soft tissue release and spontaneous vertebral derotation of the scoliosis could account for the antero-medial shifting of the aorta. By the shifting, the space for contralateral screw penetration was reduced.