Adolescent Idiopathic Scoliosis Curves Research Articles

The Height-Width-Depth Ratios of the Intervertebral Discs and Vertebral Bodies in Adolescent Idiopathic Scoliosis vs Controls in a Chinese Population

Adolescent idiopathic scoliosis (AIS) patients have been reported to be taller and more slender than normal controls, suggesting less mechanical stiffness of their trunk and spine. For assessment of mechanical stiffness, to our best knowledge this is the first to study height-width-depth relations at the level of the individual vertebra and disc in 3-D and to evaluate its relation with the Cobb angle severity. A unique series of high-resolution pre-operative computed tomographic (CT) scans of a total of 105 Chinese patients with moderate to severe AIS and 11 age-matched non-scoliotic controls were used for this study. It was found that some geometric relations differed between primary thoracic curves, secondary curves and normal controls at the individual affected vertebra and disc level. The scoliotic discs in the primary curves were relatively more slender (taller and thinner) than in secondary curves and as compared to controls. In the lumbar spinal area, the vertebral bodies were more slender in the primary as well as secondary AIS curves as compared to the controls. Therefore, if all material properties remain the same, our finding indicates that scoliotic spines may be mechanically less stiff than normal spines. No significant correlation between any of the measures and Cobb angle severity was found.

Intraoperative image guidance compared with free-hand methods in adolescent idiopathic scoliosis posterior spinal surgery: a systematic review on screw-related complications and breach rates

Background ContextSevere adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity requiring surgery to stop curve progression. Posterior spinal instrumentation and fusion with pedicle screws is the standard surgery for AIS curve correction. Vascular and neurologic complications related to screw malpositioning are concerns in surgeries for AIS. Breach rates are reported at 15.7%, implant-related complications at 1.1%, and neurologic deficit at 0.8%. Free-hand screw insertion remains the prevailing method of screw placement, whereas image guidance has been suggested to improve placement accuracy. PurposeThis study aimed to systematically review the screw-related complication and breach rates from posterior spinal instrumentation and fusion with pedicle screws for patients with AIS when using free-hand methods for screw insertion compared with image guidance methods. Study DesignThis is a systematic review of prognosis, comparing image guidance with no image guidance in surgery. Patient SampleOne randomized controlled trial and multiple prospective cohort studies that reported complication or breach rates in posterior spinal instrumentation and fusion with pedicle screws for AIS. Outcome MeasuresNumber of complications and breaches reported in databases or recorded from postoperative imaging. MethodsDatabases searched included MEDLINE, Embase, CINAHL, CENTRAL, and Web of Science. Studies of Level 3 evidence or greater as defined by the Centre for Evidence-Based Medicine were included. Articles were screened to focus on patients with AIS undergoing posterior fusion with pedicle screws or hybrid systems. Two independent reviewers screened abstracts, full texts, and extracted data. The Quality in Prognostic Studies (QUIPS) appraisal tool was used to determine studyrisk of bias (ROB). Level of evidence summary statements were formulated based on consistency and quality of reporting. ResultsSeventy-nine cohort studies were identified, including four comparing computed tomography (CT) guidance with free-hand methods head-to-head, eight on image guidance, and 671. on free-hand methods alone. Moderate evidence from individual head-to-head studies show CT guidance has lower breach rates than free-hand methods. No complications were found in these studies. From individual cohort studies, moderate evidence shows CT guidance has lower point estimates of breach rates than free-hand methods at 7.9% compared with 9.7%–17.1%. Screw-related complication rates are conflicting at 0% in CT navigation compared with 0%–1.7% in 13 low- and moderate-quality studies. ConclusionsAlthough point estimates on breach rates are decreased with CT navigation compared with free-hand methods, complication rates remain conflicting between the two methods. Current evidence is limited by small sample sizes, lack of comparison groups, and poorly predefined complications. Randomized controlled trials with larger samples with standardized definitions and recording of predefined breach and complication occurrences are recommended.

Effect of Direct Vertebral Rotation on the Uninstrumented Lumbar Curve in Thoracic Adolescent Idiopathic Scoliosis.

Study DesignRetrospective study.PurposeTo determine the effect and direction of direct vertebral rotation (DVR) in the lowest instrumented vertebra (LIV) on the uninstrumented lumbar curve depending on the lumbar modifier used for the correction of thoracic adolescent idiopathic scoliosis.Overview of LiteratureDVR in the LIV should be implemented in a different direction to obtain better spontaneous lumbar correction depending on the preoperative lumbar spine modifier.MethodsWe retrospectively analyzed 160 patients with thoracic adolescent idiopathic scoliosis treated by pedicle screw instrumentation and rod derotation. Patients who had a distal fusion level between T11 and L1 were divided into two groups: the DVR group versus the No-DVR group. Each group was divided into subgroups depending on the lumbar modifier used: the DVR-A, B, and C groups versus the No-DVR-A, B, and C groups. The DVR-A group was subdivided into two subgroups depending on the direction of screw rotation in the LIV: the DVR-A-O group (opposite direction) and the DVR-A-S group (same direction).ResultsThere were no significant differences in the preoperative curve characteristics between the two groups. The preoperative lumbar curve was corrected in 70% of the patients in the DVR group and in 56% in the No-DVR group. Spontaneous coronal correction of the lumbar curve was better in the DVR-A-S group than that in the No-DVR-A group. However, the DVR-A-O group had the higher incidence of adding-on deformity. The DVR-B and C groups showed better spontaneous correction of lumbar coronal magnitude, apical vertebral translation, and rotation and the LIV tilting.ConclusionsIn lumbar modifiers B and C, screws in the LIV have to be rotated opposite to the direction of the screw rotation of the main thoracic curve; however, in modifier A, the screws have to be rotated in the same direction.

The association of lumbar curve magnitude and spinal range of motion in adolescent idiopathic scoliosis: a cross-sectional study

BackgroundSpinal deformities affect the overall alignment of the spine and thus the vectors of loading on the lumbar region and intervertebral discs. Due to wedging of the disc or vertebrae of unbalanced spinal segments, alignment change may affect the range of motion (ROM) of individual spinal segments or the global spine. This is particularly important in adolescent idiopathic scoliosis (AIS) patients who may suffer from early degeneration, back stiffness and pain. Hence, this study aimed to determine the correlation between spine range of motion (ROM) and adolescent idiopathic scoliosis (AIS) curve magnitude.MethodsConsecutive recruitment of all AIS patients with Lenke 5 (thoracolumbar/lumbar) curves within one month was performed with ROM assessments in the coronal, sagittal and axial planes using the change in C7-S1 distance on standing upright, active flexion and extension positions, change in finger-floor distance on forward bending position and lateral bending, lateral bending angles, modified Schober’s test, and trunk rotation in seating position. Patients were further stratified into two groups based on their lumbar spine curve magnitude: Group A with curves of 10 to 39 degrees and Group B with 40 degrees or greater. Univariate and multivariate analyses were conducted, with lumbar curve magnitude severity being the dependent variable.ResultsIn total, 58 patients (n = 12 males, n = 46 females; mean age: 15.7 years) were recruited. The mean curve magnitudes were 25 ± 6.5 degrees in Group A and 48 ± 10.6 degrees in Group B. Mean axial rotation (Group A: 90 ± 21.7 degree; Group B: 76 ± 19.6 degrees; p = 0.038) and lateral bending ROM (Group A: 67 ± 13.4 degrees; Group B: 58 ± 14.3 degrees; p = 0.045) decreased in more severe curves. These two parameters continued to remain significant irrespective of the curve severity cut-off values.ConclusionsThis is the first study to determine associations between spinal ROM parameters with the lumbar curve magnitude in AIS patients. We found that the coronal curve severity is associated with reduced axial and coronal ROM. This is a platform for future studies assessing lumbar spine biomechanics in AIS and to determine the effects of altered spine motion in this context and its implication in patient management and outcomes.

The Spinopelvic Geometry in Different Lenke Curve Types of Adolescent Idiopathic Scoliosis

BackgroundThe Lenke classification is well established in differentiation of curve types in adolescent idiopathic scoliosis (AIS) and guides selection of fusion levels. However, to date, it has neglected the spinopelvic parameters that have been associated with compensatory mechanisms in balancing the human erect posture and adjacent segment problems after spinal fusion. The aim of this study was to investigate spinopelvic parameters in different types of AIS curves. Material and MethodsPreoperative whole-spine radiographs from 100 patients with AIS were reviewed and the curves were classified according to Lenke. In addition, sagittal spinopelvic parameters (pelvic incidence, sacral slope, pelvic tilt) were measured and compared between different curve types and to normal population values. ResultsThe spinopelvic balance was not statistically distinguishable in different Lenke curve types. Slight differences of the spinopelvic balance, compared with normal population values, were found in AIS Lenke Type 5 and 6 curves (major curve at the lumbar/thoracolumbar region) with a pelvic incidence of 44° ± 8° (norm 49°), sacral slope of 34° ± 7° (norm 41°), and pelvic tilt of 10° ± 7° (norm 8°). ConclusionOverall, the variances of spinopelvic parameters in different AIS curve types do not seem statistically large enough for a potential clinical relevance. However, the sacrum is more verticalized in AIS curves with major curves located in the lumbar/thoracolumbar region. It remains to be investigated whether such a verticalized sacrum might be a compensatory mechanism to keep the whole spine balanced and if it reverses with correction of the scoliosis.

Maintenance of spontaneous lumbar curve correction following thoracic fusion of main thoracic curves in adolescent idiopathic scoliosis.

The aims of our study were to provide long-term information on the behaviour of the thoracolumbar/lumbar (TL/L) curve after thoracic anterior correction and fusion (ASF) and to determine the impact of ASF on pulmonary function. A total of 41 patients (four males, 37 females) with main thoracic (MT) adolescent idiopathic scoliosis (AIS) treated with ASF were included. Mean age at surgery was 15.2 years (11 to 27). Mean follow-up period was 13.5 years (10 to 18). For the TL/L curve, the mean curve flexibility evaluated with supine pre-operative bending radiographs was 78.6% (standard deviation 16.5%), with no significant loss of correction observed. On comparing patients with an increase of the TL/L curve increase (> 4º, n = 9, 22%) to those without, significant differences were observed in the correction rate of the MT curve at the final follow-up (p = 0.011), correction loss of the MT curve (p = 0.003) and the proportion of patients who had semi-rigid instrumentation (p = 0.003). Pre-operative percentage predicted forced vital capacity (%FVC) was 80%, dropping to 72% at final follow-up (p < 0.001). The Scoliosis Research Society questionnaire score was not significantly different between patients with and without a TL/L curve increase (p = 0.606). Spontaneous lumbar curve correction (SLCC) was maintained up to 18 years following selective ASF in most patients and demonstrated significant correlation with maintenance of MT curve correction. Maintenance of MT curve correction using rigid instrumentation provided stable SLCC over time. An observed 8% decrease in %FVC indicates that ASF should be reserved for patients with no or only mild pulmonary impairment. Cite this article: Bone Joint J 2016;98-B:997-1002.

Electrophysiological and histological changes of paraspinal muscles in adolescent idiopathic scoliosis.

The pathogenesis of adolescent idiopathic scoliosis (AIS) remains poorly understood. To date, potentially involved local changes in the deep paraspinal muscles still remain unknown. Needle electromyography (EMG) and muscle biopsy of paraspinal muscles at convexity and concavity of the AIS main thoracic curve were performed in 25 subjects. In this group, EMG was performed in 16 AIS subjects (12 females, 12-27years), muscle biopsy in 18 AIS subjects (15 females, 11-31years) compared to 10 non-scoliotic controls (6 females, 12-55years). Samples of muscle tissue were removed during corrective surgery and were examined histologically, enzyme histochemically and immunohistochemically. Both methods of EMG and muscle biopsy were performed in 9 subjects (7 women, 12-27years). Right curve convexity was found in 24 AIS subjects. Amplitudes of motor unit action potentials (MUPs) were significantly increased on the AIS curve convexity versus concavity. Turns, duration and phases of MUPs were without any significant changes. In all 18 subjects, the histological examination revealed muscle fiber redistribution with numerical predominance of type I on the curve convexity which strongly correlated with the progression of the Cobb angle. Our findings demonstrate significant changes of muscle fiber redistribution in the paraspinal muscles of AIS with increased proportion of type I on the convexity corresponding to a significantly higher amplitude of MUPs on the same side. A possible explanation of this alteration is a secondary adaptation due to chronic high load demand.

Correlation analysis between change in thoracic kyphosis and multilevel facetectomy and screw density in main thoracic adolescent idiopathic scoliosis surgery

Background ContextControversy exists regarding the effects of multilevel facetectomy and screw density on deformity correction, especially thoracic kyphosis (TK) restoration in adolescent idiopathic scoliosis (AIS) surgery. PurposeThis study aimed to evaluate the effects of multilevel facetectomy and screw density on sagittal plane correction in patients with main thoracic (MT) AIS curve. Study DesignA retrospective correlation and comparative analysis of prospectively collected, consecutive, non-randomized series of patients at a single institution was undertaken. Patient SampleSixty-four consecutive patients with Lenke type 1 AIS treated with posterior correction and fusion surgery using simultaneous double-rod rotation technique were included. Outcome MeasuresPatient demographics and preoperative and 2-year postoperative radiographic measurements were the outcome measures for this study. MethodsMultiple stepwise linear regression analysis was conducted between change in TK (T5–T12) and the following factors: age at surgery, Risser sign, number of facetectomy level, screw density, preoperative main thoracic curve, flexibility in main thoracic curve, coronal correction rate, preoperative TK, and preoperative lumbar lordosis. Patients were classified into two groups: TK<15° group defined by preoperative TK below the mean degree of TK for the entire cohort (<15°) and the TK≥15° group, defined by preoperative TK above the mean degree of kyphosis (≥15°). Independent sample t tests were used to compare demographic data as well as radiographic outcomes between the two groups. There were no study-specific biases related to conflicts of interest. ResultsThe average preoperative TK was 14.0°, which improved significantly to 23.1° (p<.0001) at the 2-year final follow-up. Greater change in TK was predicted by a low preoperative TK (p<.0001). The TK <15° group showed significant correlation between change in TK and number of facetectomy level (r=0.492, p=.002). Similarly, significant correlation was found between change in TK and screw density (r=0.333, p=.047). Conversely, in the TK ≥15° group, correlation was found neither between change in TK and number of facetectomy level (r=0.047, p=.812), nor with screw density (r=0.030, p=.880). Furthermore, in patients with preoperative TK<15°, change in TK was significantly correlated with screw density at the concave side (r=0.351, p=.036) but not at the convex side (r=0.144, p=.402). ConclusionsIn patients with hypokyphotic thoracic spine, significant positive correlation was found between change in TK and multilevel facetectomy or screw density at the concave side. This indicates that in patients with AIS who have thoracic hypokyphosis as part of their deformity, the abovementioned factors must be considered in preoperative planning to correct hypokyphosis.

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

AIMTo 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).METHODSA 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.RESULTSFor 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.CONCLUSIONSurgeons 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.

Lenke 5C Curves in Adolescent Idiopathic Scoliosis: Anterior vs Posterior Selective Fusion.

The optimal treatment of Lenke 5C curves in adolescent idiopathic scoliosis is still unclear. To compare the outcomes and the spontaneous correction behavior between anterior and posterior selective fusion techniques in a large case series. Demographic and surgical data for patients with Lenke 5C curves treated with anterior or posterior fusion were collected from July 2002 to September 2011. Clinical assessment and radiographic parameters were compared preoperatively and postoperatively and at a minimum of 2 years of follow-up. Fifty-three Lenke 5C adolescent idiopathic scoliosis cases with an average follow-up of 4 years (range, 2-9.6 years) were included. The clinical scores were similar between the 2 groups. Postoperative major thoracic curvature changes were similar. The minor thoracic curve demonstrated a higher spontaneous correction rate in the posterior group. At follow-up, the minor thoracic curve showed a greater loss of correction in the posterior group, and finally both groups were comparable. Surgical time, intraoperative blood loss, and complications were comparable. A total of 5 patients had a final thoracic curve larger than the preoperative degrees. Selective fusion of the major thoracolumbar/lumbar curve in Lenke 5C adolescent idiopathic scoliosis can be achieved by anterior and posterior techniques. The spontaneous correction of the unfused thoracic curve was comparable after an average of 4 years follow-up.

Do Ponte Osteotomies Enhance Correction in Adolescent Idiopathic Scoliosis? An Analysis of 191 Lenke 1A and 1B Curves

Study DesignRetrospective review of a prospectively collected multicenter database of patients with adolescent idiopathic scoliosis (AIS). ObjectiveTo determine if Ponte osteotomies improve correction in Lenke 1A and 1B AIS curves treated with pedicle screws. Summary of Background DataThere is little data studying the risks and benefits of Ponte osteotomies in AIS. MethodsWe identified patients with Lenke 1A and 1B curve types treated with pedicle screw constructs and a 2-year follow-up. They were grouped based on whether they did (PO) or did not (NoPO) have Ponte osteotomies. Demographic, surgical, and radiographic data collected preoperatively and at 2 years were statistically analyzed using unpaired Student t test and Fisher exact test. ResultsOne hundred ninety-one patients met the inclusion criteria (mean age of 14.7 ± 2.2 years), and among those, 125 patients (65.4%) had Ponte osteotomies (average of 4.3 ± 1.5 Pontes per patient). The patients treated with Ponte osteotomies had similar clinical and radiographic parameters (major Cobb: PO = 51.5°, NoPO = 50.8°, p = .6) to the patients who did not have Ponte osteotomies except that they had stiffer and more lordotic curves (Flexibility Index: PO = 47.3%, NoPO = 54.5%, p = .04; T5–T12 kyphosis: PO = 18.7°, NoPO = 23.2°, p = .02). At 2 years, the patients treated with Ponte osteotomies had significantly better thoracic Cobb angle correction (Correction Index: PO = 67.1%, NoPO = 61.8%, p = .01) and an increase in T5–T12 kyphosis (PO = +3.0°, NoPO = −0.4°, p = .045). The Ponte group demonstrated greater rib prominence correction (PO = 53.2%, NoPO = 38.4%, p = .02). There were no neurologic events in this cohort. ConclusionsAlthough the use of Ponte osteotomies was not randomized, these data suggest that greater deformity correction in all 3 planes may be possible when Ponte osteotomies are performed for the stiffer and more lordotic Lenke 1A and 1B curves. The clinical significance of these overall small statistical differences remains to be determined. Level of EvidenceIII.

Selection of the upper vertebra to be instrumented in the treatment of thoracolumbar and lumbar adolescent idiopathic scoliosis by anterior correction and fusion surgery using dual-rod instrumentation: a minimum 12-year follow-up study

BackgroundContextConsensus regarding the optimal upper vertebra to be instrumented during surgical treatment of Lenke 5C thoracolumbar and lumbar adolescent idiopathic scoliosis (AIS) remains limited. PurposeThis study aimed to assess whether a short fusion strategy is appropriate for correction of a Lenke 5C AIS curve by anterior correction and fusion surgery using dual-rod instrumentation. Study DesignThis study design used retrospective comparative analysis of a prospectively collected, consecutive, non-randomized series of patients at a single institution. Patient SampleThirty consecutive patients with Lenke 5C AIS treated with anterior correction and fusion surgery using dual-rod instrumentation were included. Outcome MeasuresPatient demographics, radiographic measurements, and Scoliosis Research Society-22 questionnaire (SRS-22) scores were the outcome measures for this study. MethodsThirty patients were treated surgically for AIS with a Lenke 5C curve (mean age, 14.4 years [11–19 years)]) and followed up for a mean period of 17.2 years (12–23 years). Radiographical parameters and clinical outcomes were compared between patients treatment with the end vertebra (EV) instrumented (n=14) and those treated by short fusion (S group) with instrumentation starting at the vertebra one level caudal to the EV (n=16 patients). There were no study-specific biases related to conflicts of interest. ResultsIn the EV group, a mean preoperative Cobb angle of 56° was corrected to 5° after surgery and to 8° at the final follow-up. In the S group, a mean preoperative Cobb angle of 55° was corrected to 10° after surgery and 14° at the final follow-up. The mean correction rate at the final follow-up was significantly lower in the S group (74%) than in the EV group (86%; p=.020). The coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated using SRS-22 did not differ between the two groups. ConclusionsThe short fusion strategy, which involves instrumentation of the vertebra one level caudal to the upper EV, can be considered as an alternative to the conventional strategy, which includes instrumentation of the upper EV, for treating Lenke 5C curves via anterior spinal fusion.

Selective Thoracic Fusion of Lenke I and II Curves Affects Sagittal Profiles But Not Sagittal or Spinopelvic Alignment: A Case-Control Study.

Literature review and retrospective case-control study (level 3 evidence) examining 50 adolescent idiopathic scoliosis (AIS) (Lenke I or II curve) cases with 32 healthy controls of the same age. The sagittal profiles were measured preoperatively, 6 months, and 2 years after surgery and compared with those of age-matched controls at baseline. The purpose of this study is to compare baseline sagittal profiles of AIS Lenke I and II curves with age-matched healthy controls and at 6 months and 2 years after surgery, as well as with previously published reports. Sagittal alignment and profiles have gained significant attention in spinal deformity outcomes. The sagittal profile of patients with AIS has been previously reported, as well as the effects of surgical correction, with inconsistent results and no clear references to nonscoliotic controls. Baseline sagittal profiles of 50 patients presenting with Lenke I or II AIS curves treated with selective thoracic fusion were compared with 32 age-matched controls without spinal pathology. These values were also measured at 6 months and 2 years postoperatively to examine effects of selective thoracic fusion over time. Sagittal parameters examined include pelvic incidence, pelvic tilt, C7 plumb line (sagittal vertical alignment), thoracic kyphosis, and lumbar lordosis. A literature review was performed comparing previously published data. Data are presented as mean (95% confidence interval). P value of less than 0.05 was considered significant. Interobserver reliability (Cohen κ= 0.49-0.95). All demographic and preoperative sagittal alignment parameters were comparable between controls and patients with AIS prior to surgery. After selective thoracic fusion, thoracic kyphosis decreased significantly from baseline (25.4º [21.6-29.2] vs. 15.3º [12.8-17.8]; P < 0.001) at 6 months and at 2 years (10.3º [7.5-13.1]; P < 0.001). The lumbar lordosis significantly decreased at 6 months from baseline (54.5º [28.6-80.5] vs. 61.8º (33.4-90.1); P < 0.001) and at 2 years (55.4º [29.0-81.9]; P < 0.001). Sagittal vertical alignment, pelvic tilt, and pelvic incidence were comparable between controls and patients with AIS at baseline and did not change with surgery. Adolescents with Lenke I or II curves have comparable sagittal profiles with those of healthy controls of the same age. This suggests that Lenke I and II curves may not be hypokyphotic as previously thought. After selective thoracic fusion, patients with AIS have a significantly decreased thoracic kyphosis, which is accompanied by reciprocal changes in the noninstrumented lumbar curve. Sagittal vertical alignment and pelvic tilt are not significantly affected. These results agree with previous reports, which suggest that constructs with pedicle screws have a higher impact on sagittal curves but do not affect sagittal or spinopelvic alignment. The long-term effects of abnormal sagittal profiles need further clarification. 3.

Does Disc Wedging Contribute to the Flexibility of Thoracic Curve in Adolescent Idiopathic Scoliosis?

Introduction The appreciations of curve flexibility and segmental mobility in patients with adolescent idiopathic scoliosis (AIS) are important for determining structural curves, defining the safe range of correction, selecting the segment length for fusion, determining the most appropriate surgical procedure, and predicting the results of correction. However, the role of disc wedging in predicting spinal flexibility has not been well defined. The objective of this study was, therefore, to investigate the effect of disc wedging on curve flexibility and gain insight into segmental mobility by comparing disc wedging in upright and side bending radiographs in thoracic AIS. Patients and Methods This study included a total of 116 consecutive patients with AIS with main thoracic curve. According to thoracic curve flexibility index (TCFI), 56 patients with TCFI &lt; 50% were assigned to group A (Stiff), and the other 60 patients with TCFI ≥ 50% were assigned to group B (Flexible). Age, curve magnitude, disc wedging, and disc wedging percentage were compared between the two groups. Segmental flexibility indices ([upright disc angle-bending disc angle]/[upright disc angle]) were computed and compared between periapical and remote levels. Correlations were estimated using Pearson correlation coefficients. After adjustment of covariates, logistic multivariate regression analysis of independent factors for TCFI was performed. Results Significant differences with respect to the age and curve magnitude were observed between the two groups (16.33 ± 3.08 vs. 13.50 ± 1.97, p &lt; 0.01 and 56.06 ± 8.34 vs. 48.60 ± 7.87 degrees). The wedging angle and wedging percentage of discs in group B were significantly higher than those in group A (21.86 ± 6.18 vs. 17.52 ± 6.37 degrees, p &lt; 0.01 and 43.55% ± 8.5 vs. 26.56% ± 9.1, p &lt; 0.01). There was a significant correlation between disc wedging percentage and TCFI ( r = 0.766, p = 0.001). Multivariate regression analysis showed that the disc wedging percentage was the single greatest predictor of TCFI. And the disc wedging showed symmetric periapical distribution with significant decrease (all p values &lt; 0.01) for every cephalad (+) and caudad (−) level change. The apical level +1 and −1 wedged at 6.3 and 6.7 degrees (range, 3.5–10.8 degrees), respectively. We noted mean periapical flexibility indices of 41% (+1), 44% (−1), 53% (+2) and 97% (−2), which were significantly less ( p &lt; 0.01) than for the group of remote levels 90% (+3), 160% (−3), 116% (+4), and 208% (−4). Conclusion Disc wedging contributes to the spinal flexibility in thoracic AIS. The average flexibility indices of the periapical discs are significantly less than that of the remote discs. These may offer useful information in the evaluation of surgical options and preoperative planning.

Randomized Clinical Study on Surgical Techniques with Different Pedicle Screw Densities in the Treatment of Adolescent Idiopathic Scoliosis Types Lenke 1A and 1B

Introduction Advances in surgical instrumentation for the correction of vertebral deformities have been followed by the use of an increased number of implants in the construct. These advances have allowed greater correction, especially in complex cases. The use of pedicle screws throughout all anatomical levels of the spine has provided satisfactory correction of spinal deformities of large curves (between 70 and 100) through a single posterior approach, thus avoiding thoracotomy for intervertebral disc release. Nonetheless, the impact of the screw density on clinical, functional, and radiographic results of adolescent idiopathic scoliosis (AIS) treatment is still controversial. To the authors' knowledge, there is no clinical randomized study to date correlating two different surgical techniques using different pedicle screws densities (defined as the proportion of screws and number of pedicles being fused) and costs in patients with AIS. Material and Methods Forty-six patients with Lenke 1A/1B AIS and main thoracic curves to the right, 45 to 70, were operated using a posterior approach and free-hand technique. Once included in the study, patients were randomly allocated to one of the two groups with different techniques for surgical correction of the thoracic deformities. A member of the nursing team who was not involved in the research made the randomization using 46 identical, opaque, sealed envelopes, each containing one of the two group allocations and mixed them up in a box before the beginning of patient recruitment for this study. Group 1 was treated with 10 screws in strategically determined vertebrae: 4 in the base, 3 in the central vertebrae, and 3 in the superior vertebrae. In Group 2, the principles of segmental instrumentation were followed, treating all pedicles on the concavity side, except for the apical vertebra, and alternate pedicles on the convexity side, using 10 to 14 screws. Screw density was calculated as the ratio between the number of screws and pedicles fused. Results Groups were homogeneous regarding preoperative clinical and functional variables, surgery time, and intraoperative bleeding volume. Group 2 had a higher number of screws, average density of pedicle screws, and cost of treatment ( p = 0.000). The number of fused levels was similar between the groups. Two years postoperatively, all radiographic variables were homogeneous between the groups (mean correction of main thoracic curve was 68.5% in Group 1 and 67.9% in Group 2), but Group 2 achieved better clinical correction of the thoracic hump ( p = 0.000). Both presented significant improvement in the five domains of Scoliosis Research Society Score 30. Conclusion In AIS patients with Lenke 1A/B curves of 45 to 70, treatment with a higher pedicle screw density construct was significantly more expensive but had statistically similar functional results and radiographic correction. The denser construct achieved better correction of the thoracic hump 2 years after surgery.

A replication study for association of 53 single nucleotide polymorphisms in ScoliScore test with adolescent idiopathic scoliosis in French-Canadian population.

A replication association study that used genomic data generated from French-Canadian case and control cohorts. To determine whether the 53 single nucleotide polymorphisms (SNPs) that were previously associated with spinal deformity progression in an American Caucasian cohort are similarly associated in French-Canadian population. It is widely accepted that genetic factors contribute to adolescent idiopathic scoliosis. The identification of genetic variants associated with the predisposition or progression of curvature could facilitate diagnostic/prognostic tool development. Although 53 SNPs have been associated with spinal curve progression in Caucasian cohorts in the United States, these associations were not replicated in a large Japanese population study, arguing that such a discrepancy could be explained by ethnicity, thus raising the importance of a replication study in an independent Caucasian population of European descent. Genomic data were collected from the French-Canadian population, using the Illumina HumanOmni 2.5M BeadChip. Fifty-two SNPs, tested in ScoliScore or in high linkage disequilibrium with SNPs in the test, were selected to assess their association with scoliosis generally, and with spinal curve progression. One SNP in ScoliScore, rs16909285, could not be evaluated in our Genome-Wide association study. None of the SNPs used in ScoliScore were associated with adolescent idiopathic scoliosis curve progression or curve occurrence in French-Canadian population. We evaluated 52 SNPs in severe patients by comparing risk allele frequencies with those in nonsevere patients and with those in control individuals. There was no significant difference between the severe group and the nonsevere group or between the severe group and the control group. Although the 52 SNPs studied here were previously associated with curve progression in an American population of European descent, we found no association in French-Canadian patients with adolescent idiopathic scoliosis. This second replication cohort suggests that the lack of association of these SNPs in a Japanese cohort is not due to ethnicity. 4.

"Bone-οn-Bone" surgical reconstruction of moderate severity, flexible single curve adolescent idiopathic scoliosis: continuing improvements of the technique and results in three scoliosis centers after almost twenty years of use.

The “bone-on-bone” reconstruction for adolescent idiopathic scoliosis is reviewed in this article. Extensive use over the past 18 years has identified it’s functional benefits outstanding clinical results, and very limited complications. This is an extensive update of it’s application, since it’s introduction, 18 years ago.Electronic supplementary materialThe online version of this article (doi:10.1186/s13013-015-0032-0) contains supplementary material, which is available to authorized users.

Mechanism of right thoracic adolescent idiopathic scoliosis at risk for progression; a unifying pathway of development by normal growth and imbalance.

Adolescent idiopathic scoliosis is regarded as a multifactorial disease and none of the many suggested causal etiologies have yet prevailed. I will suggest that adolescent idiopathic scoliosis has one common denominator, namely that initial curve development is mediated through one common normal physiological pathway of thoracic rotational instability. This is a consequence of gender specific natural growth of the passive structural components of thoracic spinal tissues for the adolescent female. This causes an unbalanced mechanical situation, which progresses if the paravertebral muscles cannot maintain spinal alignment. The alteration in the coronal plane with the lateral curve deformity is an uncoupling effect due to a culmination of a secondary, temporary sagittal plane thoracic flattening and of a primary, temporary transverse plane rotational instability for the adolescent female. Treatment of adolescent idiopathic scoliosis should address this physiological pathway and the overall treatment strategy is early intervention with strengthening of thoracic rotational stability for small curve adolescent idiopathic scoliosis.

Postoperative behavior of thoracolumbar/lumbar curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C adolescent idiopathic scoliosis

Background Controversy still exists around surgical strategies for Lenke type 1C and 2C curves with primary thoracic and compensatory lumbar curves in adolescent idiopathic scoliosis (AIS). The benefit of selective thoracic fusion (STF) for these curve types is spontaneous lumbar curve correction while saving more mobile lumbar segments. However, a risk of postoperative coronal decompensation after STF has also been reported. This multicenter retrospective study was conducted to evaluate postoperative behavior of thoracolumbar/lumbar (TLL) curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C AIS.

A rule-based algorithm can output valid surgical strategies in the treatment of AIS.

Variability in surgical strategies for the treatment of adolescent idiopathic scoliosis (AIS) has been demonstrated despite the existence of classifications to guide selection of AIS curves to include in fusion. Decision trees and rule-based algorithms have demonstrated their potential to improve reliability of AIS classification because of their systematic approach and they have also been proposed in algorithms for selection of instrumentation levels in scoliosis. Our working hypothesis is that a rule-based algorithm with a knowledge base extracted from the literature can efficiently output surgical strategies alternatives for a given AIS case. Our objective is to develop a rule-based algorithm based on peer-reviewed literature to output alternative surgical strategies for approach and levels of fusion. A literature search of all English Manuscripts published between 2000 and December 2009 with Pubmed and Google scholar electronic search using the following keywords: "adolescent idiopathic scoliosis" and "surgery" alternatively with "levels of fusion" or "approach". All returned abstracts were screened for contents that could contain rules to include in the knowledge base. A dataset of 1,556 AIS cases treated surgically was used to test the surgical strategy rule-based algorithm (SSRBA) and evaluate how many surgical treatments are covered by the algorithm. The SSRBA was programmed using Matlab. Descriptive statistic was used to evaluate the ability of the rule-based algorithm to cover all treatment alternatives. A SSRBA was successfully developed following Lenke classification's concept that the spine is divided into three curve segments [proximal thoracic (PT), main thoracic (MT) and thoracolumbar/lumbar (TL)]. Each of the 1,556 AIS patients in the dataset was ran through the SSRBA. It proposed an average of 3.78 (±2.06) surgical strategies per case. Overall, the SSRBA is able to match the treatment offered by the surgeon in approach and level of fusion 70% of the time (with one vertebral level leeway). This study is to the author's knowledge the first attempt at proposing an algorithm to output all surgical alternatives for a given AIS case. It uses a rule-based algorithm with a knowledge base extracted from peer-reviewed literature in an area with great variability. When tested against a database of AIS patients treated surgically, the SSRBA developed has the ability to propose a surgical plan with respect to approach and levels of fusion that match the surgeon's plan in a great majority of cases. Since this SSRBA seems to output multiple valid surgical strategies, it could allow the comparisons of various strategies and the outcomes achieved in similar cases in large databases for a given case and guide surgical treatment.