Subjective evaluation of treatment outcomes of instrumentation with pedicle screws or hybrid constructs in Lenke Type 1 and 2 adolescent idiopathic scoliosis: what happens when judges are blinded to the instrumentation?

Superiority of pedicle screws over hybrid/hook instrumentation or vice versa in the treatment of Lenke Type 1 and 2 adolescent idiopathic scoliosis (AIS) remains unresolved for moderate curves. Our objective was therefore to compare the assessment of pedicle screw and hybrid/hooks instrumentation with special attention to cosmesis and uninstrumented spine using novel assessment methods. We carried out a retrospective study of radiographs and clinical photos of 40 cases of thoracic AIS between 40° and 70° of Cobb angle Lenke Type 1 and 2, treated with either pedicle screws or hybrid/hooks. The cases were subjectively assessed by four spine surgeons (SRS Travelling Fellows) for radiographic and operative cosmetic result, shoulder balance, trunk shift, rib hump, and waist asymmetry. Instrumentation in the radiographs was obscured with only the non-instrumented part visible, and the surgeons were asked to guess the instrumentation being used. Eighty photographs of patients before and after surgery were assessed for cosmesis by ten non-medical judges for overall cosmetic score, shoulder balance, waist asymmetry, and shoulder blade prominence. Objective assessment of radiographs and clinical photos was performed for Cobb angle of instrumented and non-instrumented spine, global coronal and sagittal balance, number of unfused vertebrae, disc angulation, tilt of last instrumented vertebra, shoulder balance, waist asymmetry, rib prominence, and percent correction. SRS-24 questionnaire was used to measure health-related quality of life in patients. Subjective assessments by surgeons and non-medical judges showed no significant difference by instrumentation (P ≥ 0.05) for all variables. Out of the 160 guesses by surgeons of the cases with instrumentation blocked in the radiographs, they were unable to guess the instrumentation in 92% of the cases. Objective assessment of all variables and SRS-24 scores of all five domains showed no significant difference by instrumentation (P ≥ 0.05). In this first-ever conducted study in a blinded-fashion, we conclude that there is no significant difference between the pedicle screw and hybrid/hooks instrumentations used to treat AIS for Lenke Type 1 and 2 curves for moderate curves between 40° and 70°.     

Classification of adolescent idiopathic scoliosis (AIS)

In 1983 Howard King presented his classification system for adolescent idiopathic scoliosis (AIS) based on the experience with Harrington rod instrumentation. Curves were divided into five types and guidelines and recommendations for which levels should be instrumented were given to preserve motion as much as possible. As segmental instrumentation systems began to gain favor over the Harrington rods this system failed and led to the development of a new classification system which was presented by Lawrence Lenke in 2001. In order to define a curve type by the Lenke classification, one must identify the curve type, the lumbar modifier and, for the first time in any classification system for scoliosis, the sagittal profile was also included. The Lenke classification showed higher inter and intra-reliability compared to the King classification. It also provided a better and more reliable tool to assist surgeons in choosing the best method of treatment for each curve pattern. Although the Lenke classification is more comprehensive and reliable than the King classification it is still far from perfect. It does not address the rotational component of the deformity. New technologies which provide three-dimensional (3D) reconstruction of the spine may serve as a basis for a truly 3D classification of scoliosis and for new therapeutic concepts.     

Interbody cage support improves reconstruction of sagittal balance after anterior selective fusion in Lenke type 5 idiopathic scoliosis patients

Objective: To investigate the effect of interbody cage support on reconstruction of the sagittal profile after anterior selective correction in Lenke type 5 adolescent idiopathic scoliosis (AIS) patients. Methods: In this retrospective study, a total of 40 AIS patients with a Lenke type 5 curve who underwent anterior selective fusion (ASF) using a single rod were studied. They were divided into two groups: Group A, bone grafting with an interbody titanium mesh cage (TMC); and Group B, bone grafting without a TMC. There were 19 female and 1 male patient aged 12–18 years in Group A, and 17 female and 3 male patients aged 13–20 years in Group B. All patients were followed up for more than 18 months. The coronal correction of the scoliosis and reconstruction of the sagittal profile were evaluated retrospectively. Results: By final follow‐up, more than 70% correction had been achieved for the primary curve and a spontaneous correction for the secondary curve in both groups. Satisfactory reconstructions on the sagittal plane were also observed. Similar changes were found in Group A and Group B, including increases in thoracic kyphosis, slight changes in thoracolumbar junctional kyphosis, no significant losses of lumbar lordosis, mild increases in proximal junctional measurement, and remarkable lordosis losses in the instrumented segments. With lessening of the sagittal balance and L₁ offset, a significant anterior shift of the C₇ plumb line was noted during follow‐up in Group A, indicating a more balanced spine in this group. Conclusion: Anterior selective single rod instrumentation and fusion is a recommended method for Lenke type 5C AIS. A structural interbody cage does not appear to improve the regional profile, nor the profiles in the instrumented area and the adjacent proximal and distal segments; yet could result in a better total balance in the long‐term.     

Right adolescent idiopathic thoracic curve (Lenke 1 A and B): does cost of instrumentation and implant density improve radiographic and cosmetic parameters?

In adolescent idiopathic scoliosis (AIS) there has been a shift towards increasing the number of implants and pedicle screws, which has not been proven to improve cosmetic correction. To evaluate if increasing cost of instrumentation correlates with cosmetic correction using clinical photographs. 58 Lenke 1A and B cases from a multicenter AIS database with at least 3 months follow-up of clinical photographs were used for analysis. Cosmetic parameters on PA and forward bending photographs included angular measurements of trunk shift, shoulder balance, rib hump, and ratio measurements of waist line asymmetry. Pre-op and follow-up X-rays were measured for coronal and sagittal deformity parameters. Cost density was calculated by dividing the total cost of instrumentation by the number of vertebrae being fused. Linear regression and spearman’s correlation were used to correlate cost density to X-ray and photo outcomes. Three independent observers verified radiographic and cosmetic parameters for inter/interobserver variability analysis. Average pre-op Cobb angle and instrumented correction were 54° (SD 12.5) and 59% (SD 25) respectively. The average number of vertebrae fused was 10 (SD 1.9). The total cost of spinal instrumentation ranged from $6,769 to $21,274 (Mean $12,662, SD $3,858). There was a weak positive and statistically significant correlation between Cobb angle correction and cost density (r = 0.33, p = 0.01), and no correlation between Cobb angle correction of the uninstrumented lumbar spine and cost density (r = 0.15, p = 0.26). There was no significant correlation between all sagittal X-ray measurements or any of the photo parameters and cost density. There was good to excellent inter/intraobserver variability of all photographic parameters based on the intraclass correlation coefficient (ICC 0.74–0.98). Our method used to measure cosmesis had good to excellent inter/intraobserver variability, and may be an effective tool to objectively assess cosmesis from photographs. Since increasing cost density only improves mildly the Cobb angle correction of the main thoracic curve and not the correction of the uninstrumented spine or any of the cosmetic parameters, one should consider the cost of increasing implant density in Lenke 1A and B curves. In the area of rationalization of health care expenses, this study demonstrates that increasing the number of implants does not improve any relevant cosmetic or radiographic outcomes.     

Lenke 5型脊柱侧凸前路单棒矫形术中放置钛网对术后矢状面重建的影响

目的 探讨放置钛网对Lenke 5型青少年特发性脊柱侧凸(adolescent idiopathic scoliosis, AIS)行选择性前路单棒矫形加植骨融合术后矢状面重建的影响.方法 40例Lenke 5型AIS患者,根据术中植骨方式分为两组,均接受选择性前路单棒矫形术.术中椎间融合植骨时,A组患者放置钛网,B组则单纯以剪碎的自体肋骨和髂骨骨粒植骨.A组女19例,男1例;年龄12～18岁.B组女17例,男3例;年龄13～20岁.两组患者获得1.5年以上的随访.对术前、术后和末次随访时的冠状面矫形与矢状面重建指标进行分析.结果 在术后和随访中,两组患者主弯的矫正率大于70%,继发弯也获得较满意的自发性纠正.无内固定相关和假关节形成等并发症发生.两组患者术后和随访中也获得较满意的矢状面重建.其中,术后和随访中胸椎后凸增加,胸腰交界性后凸轻微变化,腰椎前凸无明显丢失,内固定近端后凸成角轻度增大,内固定区成角前凸轻度减小,这些指标在两组间差别无统计学意义.末次随访时,A组患者SVA和L1到C7PL线的距离平明显小于其术前和术后的测量值,而这些指标在B组均无显著变化.结论 选择性前路单棒矫形加椎间植骨融合术是治疗Lenke 5型脊柱侧凸的有效方法.与自体植骨相比,钛网植骨可较好地改善矢状面的整体平衡.     

Selective posterior thoracic fusion by means of direct vertebral derotation in adolescent idiopathic scoliosis: effects on the sagittal alignment

The objectives of this retrospective study were to evaluate the effect of direct vertebral derotation on the sagittal alignment of the spine after selective posterior thoracic fusion for Lenke Type I adolescent idiopathic scoliosis (AIS). Preservation of the sagittal alignment has become critical in the management of spinal deformity. Better coronal and rotational corrections in posterior selective thoracic fusion for AIS have been reported with direct vertebral derotation as compared with the simple rod rotation technique. A greater lordogenic effect has been anticipated with direct vertebral derotation; however, data comparing those two techniques in terms of correction in the sagittal plane are still lacking. Standing full-spine PA and standard lateral serial X-rays of a total of 30 consecutive patients with adolescent idiopathic scoliosis treated between 2002 and 2008 at a single institution were evaluated. All the patients had Lenke Type I curves and underwent selective posterior thoracic fusion with pedicle screw instrumentation. Patients who were treated with additional osteotomies and concave or convex thoracoplasty or concomitant anterior releases were excluded. Minimum follow-up period was 24 months. Preoperative and postoperative coronal and sagittal spinal alignments in both the groups were compared. In 13 patients, the correction was achieved by means of a simple rod rotation (SRR). In 17 patients, the technique of direct vertebral derotation (DVD) was used. Scoliosis correction averaged 67 and 69%, respectively, and was similar in both groups (p > 0.05). Thoracic kyphosis and lumbar lordosis remained unchanged in the SRR group (p > 0.1). In the direct vertebral derotation group, a significant decrease of both thoracic kyphosis and lumbar lordosis of 8.1° and 11.8°, respectively, was observed (p < 0.0001). Global sagittal balance remained within normal limits in all the patients at the latest follow-up. Decrease in thoracic kyphosis and lumbar lordosis should be taken into account when using direct vertebral derotation for selective posterior thoracic fusion in AIS. In order to preserve sagittal alignment in these patients, ultra hard rods or maneuvers that pull posteriorly the concave side of the spine, thus avoiding the application of additional flattening forces should be considered.     

低骨密度对Lenke Ι型青少年特发性脊柱侧凸患者手术疗效的影响

目的:探讨低骨密度对LenkeⅠ型青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者后路矫形内固定术后矫形疗效的可能影响。方法:选取2007年6月～2008年8月在南京鼓楼医院脊柱外科行后路椎弓根螺钉矫形内固定融合术的LenkeⅠ型AIS女性患者37例,年龄11~17岁(14.3±1.3岁),术前Cobb角40°~66°(48.9°±6.7°)。术后随访12~36个月,平均20.8±7.4个月。术前均接受双能X线吸收骨密度仪扫描测定骨密度,根据股骨颈骨密度Z值将AIS患者分为骨密度正常组(Z值>-1.0)与骨密度减低组(Z值≤-1.0),分别测量两组患者术前、术后早期(术后3个月)及末次随访时的主弯Cobb角、胸椎后凸角(TK)、腰椎前凸角(LL)、冠状位顶椎偏移(AVT)、C7中垂线与骶骨中线的距离(C7-CSVL)和C7中垂线与骶骨后上缘的距离(SVA),比较两组间的差异。结果:37例患者中,15例骨密度正常(骨密度正常组),22例骨密度减低(骨密度减低组)。两组患者术前平均年龄、Risser征、内固定节段数、置入物密度及术后随访时间均无显著性差异(P>0.05);两组术前平均Cobb角、AVT和C7-CSVL无显著性差异(P>0.05)。术后3个月及末次随访时两组平均Cobb角和平均矫正率、末次随访时平均矫正丢失及矫正丢失率无显著性差异(P>0.05);术后3个月及末次随访时两组平均AVT、C7-CSVL无统计学差异(P>0.05);C7-CSVL改变亦无显著性差异(P>0.05)。两组术前、术后3个及末次随访时的平均TK、LL、SVA均无显著性差异(P>0.05),SVA改变亦无显著性差异(P>0.05)。结论:低骨密度状态对LenkeⅠ型AIS患者后路矫形内固定融合术的疗效无明显影响。     

Anterior surgery for adolescent idiopathic scoliosis

Anterior open scoliosis surgery using the dual rod system is a safe and rather effective procedure for the correction of scoliosis (50–60 %). Thoracic hypokyphosis and rib hump correction with open anterior rather than posterior instrumentation appear to be the better approaches, although the latter is somewhat controversial with current posterior vertebral column derotation devices. In patients with Risser grade 0, hyperkyphosis and adding-on may occur with anterior thoracic spine instrumentation. Anterior thoracoscopic instrumentation provides a similar correction (65 %) with good cosmetic outcomes, but it is associated with a rather high risk of instrumentation (pull-out, pseudoarthrosis) and pulmonary complications. Approximately 80 % of patients with adolescent idiopathic scoliosis (AIS) curves of >70° have restrictive lung disease or smaller than normal lung volumes. AIS patients undergoing anterior thoracotomy or anteroposterior surgery will demonstrate a significant decrease in percentage of predicted lung volumes during follow-up. The thoracoabdominal approach and thoracoscopic approach without thoracoplasty do not produce similar changes in detrimental lung volume. In patients with severe AIS (>90°), posterior-only surgery with TPS provides similar radiographic correction of the deformity (44 %) with better pulmonary function outcomes than anteroposterior surgery. Vascular spinal cord malfunction after segmental vessel ligation during anterior scoliosis surgery has been reported. Based on the current literature, the main indication for open anterior scoliosis instrumentation is Lenke 5C thoracolumbar or lumbar AIS curve with anterior instrumentation typically between T11 and L3.     

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.     

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.