Curve Flexibility Research Articles

Emergence of constant tilt angle for vector fields on flexible curves

AbstractA model for the evolution of vector fields on flexible curves is investigated. Explicit solutions with radial symmetry demonstrate global existence. Numerical simulations show that configurations with constant tilt angle emerge as stationary states.

Does Curve Regression Occur During Underarm Bracing in Patients with Adolescent Idiopathic Scoliosis?

Does Curve Regression Occur During Underarm Bracing in Patients with Adolescent Idiopathic Scoliosis?

The correlations between the anchor density and the curve correction of adolescent idiopathic scoliosis surgery

BackgroundThe optimal anchor density in adolescent idiopathic scoliosis (AIS) surgery to achieve good curve correction remains unclear. The purpose of the study is to analyze the correlations between three-dimensional curve correction and anchor density in the pedicle screw-based posterior fusion of AIS.MethodsOne hundred and twenty-seven AIS patients receiving primary posterior fusion with pedicle screw instrumentation were retrospectively reviewed. Anchor density (AD) was defined as the screws number per fused spinal segment. The correlations between three-dimensional curve correction radiographic parameters and anchor density were analyzed with subgroup analysis based on different curve types, curve magnitudes, and curve flexibilities. The differences of curve correction parameters between the low-density (AD ≤1.4), middle-density (1.4 < AD ≤1.7) and high-density (AD > 1.7) groups were also calculated. Independent t-test, analysis of variance (ANOVA), and Pearson’s correlation coefficient were used for statistical analysis.ResultsThere were no correlations between the anchor density and the coronal curve correction or apical vertebral rotation (AVR) correction. In the sagittal plane, mild positive correlations existed between anchor density and thoracic kyphosis correction in all patients (r = 0.27, p = 0.002). Subgroup analysis revealed similar mild positive correlations in Lenke 1 (r = 0.31, p = 0.02), Lenke 1–3 (r = 0.27, p = 0.01), small curves (40°-60°, r = 0.38, p < 0.001), and flexible curves (flexibility > 40%, r = 0.34, p = 0.01).There were no differences between low-density (mean 1.31), middle-density (mean 1.55), and high-density (mean 1.83) in terms of coronal or axial curve correction parameters. Low-density group has longer fused level (mean difference 2.14, p = 0.001) and smaller thoracic kyphosis correction (mean difference 9.25°, p = 0.004) than high-density group.ConclusionIn our study, the anchor density was not related to coronal or axial curve corrections. Mild positive correlations with anchor density were found in thoracic kyphosis correction, especially in patients with smaller and flexible curves. Low anchor density with longer fusion level achieves similar curve corrections with middle or high anchor density in adolescent idiopathic scoliosis surgery.

Predictability of Coronal Curve Flexibility in Postoperative Curve Correction in Adolescent Idiopathic Scoliosis: The Effect of the Sagittal Profile.

Study Design:Retrospective cohort study.Objectives:To assess how the thoracic kyphosis affects the ability of the fulcrum bending radiograph (FBR) to predict the coronal thoracic curve correction.Methods:A retrospective study of prospectively collected data was conducted of 107 consecutive patients with thoracic adolescent idiopathic scoliosis (AIS) treated with a standard screw-fixation protocol. Radiographic variables were assessed preoperatively and at 2-year follow-up. Curve flexibility was determined based on the FBR and the Fulcrum Bending Flexibility Index (FBCI). Radiographic variables included preoperative Cobb angle, T5-T12 kyphosis, T12-S1 lordosis, sagittal vertical axis, list, T1-T12 length, truncal shift, and radiographic shoulder height. Patients were also categorized as hypo-, normo-, or hyperkyphotic.Results:Based on multivariate modeling, an increase in FBR Cobb angle and thoracic kyphosis were significantly associated with an increase in FBCI (increased mismatch between the FBR and postoperative Cobb angles) at 2-year follow-up (P < 0.001). In patients with hyperkyphosis, a longer instrumented length existed despite similar curve size and shorter curve length than the hypo- and normokyphotic groups. Based on these findings, we developed a new predictive postoperative curve correction index, known as the Multiprofile Flexibility Index (MFI).Conclusions:Our results show that an increase in preoperative thoracic kyphosis is associated with an increased difference between the preoperative coronal curve flexibility and the postoperative coronal curve correction. Our findings broaden the understanding of curve flexibility and indicate that selection of fusion levels may need to take into consideration the sagittal profile to improve clinical decision making and optimize outcome.

The Reliability of Pre-operative Prone Radiographs to Determine Spinal Curve Flexibility in Adolescent Idiopathic Scoliosis

The Reliability of Pre-operative Prone Radiographs to Determine Spinal Curve Flexibility in Adolescent Idiopathic Scoliosis

The Reliability of Pre-operative Prone Radiographs to Determine Spinal Curve Flexibility in Adolescent Idiopathic Scoliosis

Purpose: The Lenke classification requires full spine standing and bending radiographs to evaluate spinal flexibility. Because bending films are inherently variable, pre-operative assessment may also utilize full spine prone imaging that is not effort based. Few studies have addressed the correlation of different radiographic positions, specifically the prone position to the bending position, to assess spinal flexibility. The purpose of this study was to determine if prone position radiographs can be a surrogate for bending position …

Flexibility of the thoracic curve and three-dimensional thoracic kyphosis can predict pulmonary function in nonoperatively treated adult patients with adolescent idiopathic scoliosis

BackgroundAlthough several radiographic predictors for pulmonary function in adolescent patients have been reported, those in adult patients remain unclear. Therefore, we aimed to investigate the associations between spinal deformity and pulmonary function in nonoperatively treated adult patients with adolescent idiopathic scoliosis (AIS). MethodsOf 319 patients treated nonoperatively for AIS, 90 (average age, 40.0 ± 6.5 years) underwent both full-length standing radiographs and pulmonary function test. Standard two-dimensional (2-D) radiographic measurements were performed. Three-dimensional thoracic kyphosis (3-D TK) was calculated from 2-D standing radiograph data using a validated formula: 3-D TK (°) = 18.1 + 0.81 × (2-D TK) + 0.54 × (Cobb angle of thoracic curve). 3-D TK was defined as the sum of segmental kyphosis between T5 and T12, which eliminates the overestimation of TK in 2-D measurements due to rotational deformity. Bivariable correlation analysis, followed by a stepwise multiple linear regression analysis, was performed. ResultsThe average Cobb angle of the thoracic curve at the time of survey was 49.4° ± 14.6° with flexibility of 37.5% ± 18.2%. Thoracic curve magnitude, flexibility, apical vertebral rotation and translation, and 3-D TK were significantly correlated with percent-predicted forced vital capacity (%FVC) and expiratory volume in 1 s (%FEV1.0). Stepwise multiple regression analysis showed that curve flexibility and 3-D TK were significant, independent predictors of %FVC (R2 = 0.358) and %FEV1.0 (R2 = 0.335), curve flexibility having a greater impact (standardized coefficient > 0.45) than 3-D TK (<0.32). ConclusionsOur results indicate that nonoperatively treated patients with AIS should be recommended to maintain flexibility of the thoracic curve to prevent future pulmonary impairment. Moreover, 3-D TK is another independent predictor of pulmonary function, which suggests that segmental sagittal alignment is a component of deformity correction to focus on.

Do untreated intraspinal anomalies in congenital scoliosis impact the safety and efficacy of spinal correction surgery? A retrospective case-control study.

Intraspinal anomalies associated with congenital scoliosis (CS) complicate the decision-making process for spinal correction surgery in CS patients. Recently, deformity correction surgery without prior prophylactic neurological intervention has been recognized to be safe in CS patients with intact or stable neurological status. However, no case-control study has identified the surgical outcomes and risks of spinal correction surgery in this patient population. The authors sought to investigate the safety and efficacy of spinal correction surgery for CS associated with untreated intraspinal anomalies (split cord malformation [SCM], tethered cord, and/or syringomyelia) with intact or stable neurological status. A group of CS patients with intraspinal anomalies (CS+IA) and another group of CS patients without intraspinal anomalies (CS-IA) undergoing 1-stage posterior correction surgery were retrospectively reviewed. The radiographic and clinical outcomes and postoperative complications were compared between the 2 groups. There were 57 patients in the CS+IA group and 184 patients in the CS-IA group. No significant difference was observed in age, sex, spinal curve pattern, main Cobb angle, and flexibility of the main curve between the 2 groups (p > 0.05 for all). The postoperative correction rates of the major curve were comparable between the 2 groups (53.5% vs 55.7% for the CS+IA and CS-IA groups, respectively, p > 0.05). No significant difference was observed in the incidence of either implant-related or neurological complications between 2 groups. No patients in the CS+IA group developed neurological complications, whereas 1 patient in the CS-IA group experienced transient weakness of the left lower extremity after surgery. Coexisting intraspinal anomalies (SCM, tethered cord, and/or syringomyelia) in CS patients with normal or stable neurological status do not significantly increase the risk of neurological complications of correction surgery. Prophylactic neurosurgical intervention for intraspinal anomalies before correction surgery might be unnecessary for these patients.

Scoliosis in Duchenne muscular dystrophy children is fully reducible in the initial stage, and becomes structural over time

BackgroundPatients with Duchenne muscular dystrophy (DMD) often develop scoliosis that progresses rapidly after loss of ambulation. Management of scoliosis is crucial because it affects both life expectancy and quality of life of patients with DMD. Spinal orthosis attempts to prevent or delay scoliosis using spinal support at three points of the controlling mechanism; the curve should be flattened by the pressure. Therefore, it is assumed that spine flexibility could be a significant influencing factor for the effectiveness of braces. Hence, we attempted to investigate the flexibility of scoliosis in non-ambulant patients with DMD.MethodsWe reviewed the medical records of 273 boys who were genetically identified as having DMD, and finally, 50 boys with serial records of radiographs after loss of ambulation were finally enrolled. And among them, only 31 patients developed scoliosis. Spine radiographs in sitting and supine positions were also reviewed to obtain Cobb angle, curve flexibility, and pelvic obliquity. Flexibilities (%) were calculated by the difference in angles between the sitting and supine positions divided by the angle at the sitting position, multiplied by 100.ResultsAmong 31 boys who had scoliosis, all but 2 boys with curves went through a sequential course of 1) no scoliosis, 2) nonstructural scoliosis, when scoliosis was only measurable in the sitting position, and 3) structural scoliosis, when scoliosis was also detectable in the supine position. Flexibility decreased each year after detection of scoliosis in those who developed scoliosis the first year, from 75.5 ± 5.0% to 57.1 ± 10.5% and to 49.1 ± 10.0% (mean ± standard deviation). Spinal flexibility was significantly correlated with curve magnitude of scoliosis in both sitting and supine position (p < 0.05, respectively).ConclusionsThere is a period of fully reducible curve in DMD patients at the initial stage of scoliosis. Afterward, as spinal curve progresses, flexibility decreases over time. To detect the scoliosis when the curve is fully reducible, scoliosis curve in DMD patients should be evaluated dynamically, including radiographs of at least in two different positions.

A Novel Posterior Rod-Link-Reducer System Provides Safer, Easier, and Better Correction of Severe Scoliosis

Study DesignRetrospective review. ObjectivesTo compare the Cobb >75° scoliosis correction obtained using a novel Rod-Link-Reducer (RLR) system versus traditional corrective techniques (TCT) in patients with severe adolescent idiopathic scoliosis (AIS). Summary of Background DataCurrent implant strategies provide for good correction, especially for moderate curves; however, severe scoliosis continues to be challenging to obtain correction in a safe and effective manner. MethodsA novel correction device was developed so that two provisional rods are placed on the convex side of the scoliosis proximally and distally, which are then linked to an external reduction device termed the RLR. A retrospective analysis was performed to compare the RLR versus the TCT in patients with curve >75° with the diagnosis of AIS with respect to the radiographic outcomes, operative time, intraoperative blood loss, complications, and SRS-30 scores of a minimum 2-year follow-up. ResultsA total of 36 patients were evaluated (RLR-18, TCT-18). The data sets were similar for age, gender, coronal Cobb, curve flexibility, and follow-up period. The mean preoperative Cobb for the RLR group was 91.7° (76°–113°) and 91.8° (78°–108°) for the TCT group. The mean coronal Cobb correction rate was significantly greater for the RLR group (73.1% vs. 56.6%, p < .0001). The mean operative time was 74.8 minutes shorter in the RLR group (316.6 minutes vs. 391.4 minutes, p = .03). There were 2 late-developing infections and 3 intraoperative neuro-monitoring changes during the correction maneuvers in the TCT group compared with none in the RLR group (p = .02). ConclusionIn a matched cohort, the use of the RLR exhibited greater coronal Cobb correction, shorter operative time, and was less likely to have critical neuro-monitoring changes compared with the TCT group. The RLR provides safer and improved correction for severe curves without adding surgical risk. Level of EvidenceLevel III.

Use of Magnetic Spinal Growth Rods (MCGR) With and Without Preoperative Halo-gravity Traction (HGT) for the Treatment of Severe Early-onset Scoliosis (EOS).

Correction of severe scoliosis through distraction-based techniques poses a challenge. Magnetically controlled growing rod (MCGR) hardware complications are common with a 27.8% to 46.7% revision rate in under 2 years. Loss of correction and diminishing returns are the norm. Treatment of severe scoliosis with halo-gravity traction (HGT) before MCGR has not been previously reported. The purpose of this study was to assess initial correction, maintenance of correction, and complication rate in patients with severe scoliosis treated with and without HGT before MCGR. IRB-approved retrospective single site cohort study of a prospectively collected database. Forty-two patients underwent MCGR between 2014 and 2017 at a single site, 12 with prior growing constructs were excluded, 30 patients were included, 12 patients underwent preoperative HGT. Charts were reviewed for demographic, clinical, and radiographic information. The HGT group had larger major curves averaging 90 (69 to 114) degrees versus 77 (56 to 113) degrees in the non-HGT group P=0.018. Percent correction on preoperative flexibility films were 17% versus 40% for those in the HGT versus non-HGT group, P=0.000. An additional 22% correction of the curve magnitude occurred between the flexibility and in-traction films representing 43% of the total correction achieved, P=0.000, was achieved. EBL, and postoperative major curve and major curve correction were not significant. Thirteen percent of patients experienced complications. Average follow-up was 712 versus 561 days in the HGT versus non-HGT groups. Large, rigid curves can achieve equivalent correction to flexible curves with HGT. Forty-three percent of the total correction achieved occurred during traction. Thirty percent of the total correction occurred at implantation of the MCGR in the HGT group versus 28% in the non-HGT group. At most recent follow-up HGT patients had statistically maintained their major curve correction better than non-HGT patients. Level III-therapeutic study.

Posterior Multiple-Level Asymmetrical Ponte Osteotomies for Rigid Adult Idiopathic Scoliosis

To evaluate the efficacy and safety of posterior multiple-level asymmetrical Ponte osteotomies for rigid adult idiopathic scoliosis. A retrospective study was conducted for adult patients with rigid idiopathic scoliosis (flexibility of main curve <25%) who underwent one-stage multiple-level asymmetrical Ponte osteotomies with a minimum of 2-year follow-up between February 2009 and November 2015. The demographic data and surgical issues were collected, and the improvement of clinical function scores and radiologic parameters were obtained after surgery and during the follow-up to assess deformity correction, spinal balance, and clinical outcome. A total of 49 patients were included (10 male and 39 female) in this study, with an average age of 26.53 years old. The average follow-up was 28.37 ± 6.98 months. All the cases presented a significant improvement of the main curve and focal kyphosis from 85.62 ± 19.80° to 36.19 ± 16.74° and 53.98 ± 26.80° to 30.88 ± 18.69°, with a mean correction rate of 57.73% and 41.23%. The postoperative coronal and sagittal parameters were all significantly improved, except coronal balance. The mean operative time and blood loss were 267.86 ± 54.49 minutes and 838.78 ± 538.93 mL. All the clinical function scores of patients were significantly improved at the final follow-up. Only one patient had a complication related to surgical incision, with no neurologic complications occurring. The surgical procedure of multiple-level asymmetrical Ponte osteotomy is a safe and effective technique, with reduced operation time, blood loss, and complications, and may offer an appropriate option to address the problems of rigid adult idiopathic scoliosis.

Effectiveness analysis of Lenke type 1 adolescent idiopathic scoliosis with different proximal fixation vertebra

To investigate the short-term effectiveness of proximal fixation of one vertebra above to the upper end vertebra and the upper end vertebra in the treatment of Lenke type 1 adolescent idiopathic scoliosis (AIS) patients with preoperative right higher shoulder. The clinical data of 37 Lenke type 1 AIS patients treated with posterior correction between January 2010 and December 2015 were retrospectively analysed. According to proximal fixation vertebra, the patients were divided into 2 groups: group A ( n=17), proximal fixation of one vertebra above to the upper end vertebra; group B ( n=20), proximal fixation of the upper end vertebra. There was no significant difference in gender, age, Risser stage, radiographic shoulder height (RSH), flexibility of proximal thoracic curve, flexibility of main thoracic curve, flexibility of thoracolumbar/lumbar curve between 2 groups ( P>0.05). The main thoracic curve Cobb angle, proximal thoracic curve Cobb angle, thoracolumbar/lumbar curve Cobb angle, apical vertebral translation (AVT), clavicle angle (CA), RSH, coronal trunk shift, sagittal trunk shift, thoracic kyphosis (TK), and lumbar lordosis (LL) were measured by X-ray film before operation, and at 1 month, 1 year, and 2 years after operation. The correction indexes of main thoracic curve were evaluated, including the correction degree and correction rate of main thoracic curve and AVT correction at 1 month after operation, the loss degree and the loss rate of the correction of main thoracic curve at 2 years after operation. The operation time and intraoperation blood loss in group A were significantly greater than those in group B ( P<0.05). All the patients were followed up, and the follow-up time was 2-4 years (mean, 2.8 years) in group A and 2-3.5 years (mean, 2.6 years) in group B. No serious complication such as nerve damage occurred during perioperative period and follow-up period. No complication such as failure of fusion, loosening and rupture of internal fixator, adjacent segment degeneration, and proximal junctional kyphosis occurred. There was no significant difference between 2 groups in the correction degree and correction rate of main thoracic curve and AVT correction at 1 month after operation, the loss degree and the loss rate of the correction of main thoracic curve at 2 years after operation ( P>0.05). Comparison within the two groups: except for LL had no significant difference between pre- and post-operation ( P>0.05), the other indicators were significantly improved after operation ( P<0.05) in the two groups. There were significant differences in RSH, CA, proximal thoracic curve Cobb angle, and thoracolumbar/lumbar curve Cobb angle at each time point after operation ( P<0.05), and there were spontaneous correction during follow-up; however, there was no significant difference in main thoracic curve Cobb angle, AVT, TK, LL, trunk shift at each time point after operation ( P>0.05), and there was no significant loss during follow-up. Comparison between the two groups: there was no significant difference in all the radiographic indexes at pre- and post-operation ( P>0.05). For Lenke type 1 AIS patients with preoperative right high shoulder, proximal fixation vertebra be fixed to the upper end vertebral can obtain satisfactory short-term orthopedic effectiveness and reduce blood loss and operation time.

Over 70° thoracic idiopathic scoliosis: Results with screws or hybrid constructs.

Background:Adolescent idiopathic scoliosis is the most common type of scoliosis. High degrees curve can be treated with the anterior, posterior, or combined anterior–posterior approach. Contrarily to the anterior approach, the posterior one is widely used nowadays for its good correction outcomes and relatively low-complication rate.Materials and Methods:We evaluated retrospectively 27 patients, treated with posterior approach. Patients were divided into two groups, namely pedicle screws group (PSG) and hybrid group (pedicle screws + sublaminar bands). Radiographic measurements, including thoracic and lumbar Cobb° measurements of primary and secondary curves, coronal balance and sagittal balance, kyphosis and lordosis, curve flexibility, first and last vertebra included in the arthrodesis, and implant density were evaluated. Clinical patients' satisfaction was also evaluated with Scoliosis Research Society (SRS) 24 questionnaire.Results:Considering both groups, on preoperative X-rays, the average primary scoliotic curve angle was 83.56° ± 10.96° (range 70°–112°), whereas the global flexibility was 64° ± 7.63 (range 46°–72°). The curves were classified following the Lenke classification: 17 Type 1, 2 Type 2, and 8 Type 3. The primary curve resulted to be well corrected in both groups. In T0, the groups were homogeneous, but in T1 and follow-up, PSG stated a better mean value. No other significative differences can be found between groups for all other items (P > 0.05). Clinical results of SRS 24 were excellent in both groups.Conclusions:The posterior approach proved to be an excellent technique for obtaining good clinical and radiographic results if the surgeon adopts the third-generation high-density implants.Level of Evidence:III.

Does fusion to T2 compared with T3/T4 lead to improved shoulder balance in adolescent idiopathic scoliosis with a double thoracic curve?

Proximal fusion level selection in adolescent idiopathic scoliosis (AIS) with a double thoracic curve (Lenke-2) remains debatable. The aim of this study was to compare the radiological outcomes of corrective surgery for Lenke-2 AIS according to the upper instrumented vertebra (UIV). This study included 74 patients who underwent corrective surgery for Lenke-2 AIS with the right main thoracic and left proximal thoracic (PT) curve at a single center. Various radiological parameters were measured using whole-spine standing radiographs preoperatively and postoperatively. Patients were grouped by proximal fusion level: T2 (group F; fusion, N=15) or T3/T4 (group NF; nonfusion, N=59). Preoperative and postoperative radiological parameters were compared between the two groups. Group NF was divided on the basis of the existence of a postoperative shoulder imbalance (PSI; >15 mm) and a subgroup analysis was carried out. PT curve correction rate (58.5 vs. 46.3%, P=0.005), right shoulder depression (4.3 vs. 10.3 mm, P=0.020), and proximal adjacent wedging (1.1 vs. 3.5°, P<0.001) were different between groups F and NF postoperatively. In the subgroup analysis, the Risser grade (3.9 vs. 2.8, P=0.009) and the main thoracic curve flexibility (53.5 vs. 42.6%, P=0.038) were different between the PSI positive and the PSI negative group when T3 or T4 was chosen as the UIV in Lenke-2 AIS. If T2 is selected as the UIV in patients with Lenke-2 AIS, more PT curve correction, less right shoulder depression, and less adjacent disc wedging can be anticipated. If T3 or T4 is chosen as the UIV, then right shoulder depression can be a problem postoperatively. Greater skeletal maturity and higher flexibility of the main thoracic curve might be preoperative risk factors for PSI. Thus, extension of the proximal fusion to T2 can be considered if the patient shows greater skeletal maturation and more flexible main thoracic curve to prevent PSI in Lenke-2 AIS with the right main thoracic and left PT curve.

Evaluation of Efficacy and Safety of All Pedicle Screw Posterior-Only Surgery in Patients with Dystrophic Neurofibromatosis Scoliosis

Background Data: Neurofibromatosis type 1 (NF-1) patients with dystrophic changes of the spine develop severe spinal deformity and/or instability and always need early surgical treatment. Combined anterior-posterior fusion was the treatment of choice of such curves because of the risk of progression and pseudoarthrosis even in the presence of solid posterior fusion mass. Recent 3rd-generation posterior stabilization systems using pedicle screw fixation allow better 3-column purchase and 3D control and correction of deformity and stable posterior fixation of the spine preventing progression of the curves. Posterior-only surgery has been recently used in dystrophic NF-1 scoliosis due to use of pedicle screws fixation and development of different types of posterior release/osteotomies which lead to successful and sustained correction of these curves.Study Design: A retrospective clinical cohort study.Purpose: To study the results of posterior stabilization alone using all pedicle screws fixation in NF-1 patients with dystrophic scoliosis.Patients and Methods: 16 patients with NF-1 having dystrophic scoliosis were treated by posterior instrumentation using all pedicle screws. There were 5 female and 11 male patients and the average age was 13 years (range, 9–16 years). The study was done in the period between 2009 and 2016. Preoperative clinical examination included examination for neurofibromatosis, assessment of curve flexibility, and thorough neurological examination. Radiological examination included standard plain X-rays, anterior-posterior (A-P) and lateral and flexibility views, and MRI. Screw density of the whole construct and of the apical region (two vertebrae above and below the apex) was calculated. Functional outcomes were assessed by the ODI and SRS-30 scores at the last follow-up.Results: The mean follow-up was 5.15±1.78 years (range, 3–8). The mean Cobb angle improved in the coronal plane from 67.13±11.88 (range, 45–90◦) to 20±8.9 (range, 6–30◦) showing 70.1±11.2%. The mean preoperative sagittal plane deformity significantly improved from 61.82±20.28 (range, 35–90◦) to 25.91±7.68 (range, 10–35◦) postoperatively yielding 53.15±21.43 (range, 25–83.33%) mean correction with insignificant loss of correction at last follow-up. Loss of correction was 2±1.8% and 1.8±2.1% in the coronal and sagittal planes, respectively. At last follow-up the average SRS-30 score was 121±17.7 and the

Non-Fusion Surgical Correction of Thoracic Idiopathic Scoliosis Using a Novel, Braided Vertebral Body Tethering Device: Minimum Follow-up of 4 Years.

Background:Anterior vertebral body tethering to effect scoliosis correction in a growing spine has been shown to work with varying degrees of success. This report describes the mid-term results of this technique using a new device composed of a braided ultra-high molecular weight polyethylene (UHMWPE) cord anchored to bone screws applied without segmental compression.Methods:This was a single-center prospective observational study of an investigational device. Five female patients aged 9 to 12 years with thoracic scoliosis underwent thoracoscopic insertion of the UHMWPE tether. Radiographs and magnetic resonance imaging (MRI) were performed, and the Scoliosis Research Society (SRS)-22 was administered, preoperatively and at regular intervals after surgery, with a minimum of 4 years of follow-up.Results:All tethering devices spanning the end vertebrae (range, 7 to 8 vertebrae) were implanted successfully. Mean blood loss was 136 mL, and the mean operative time was 205 minutes. The mean preoperative main thoracic Cobb angle was 40.1°. Curve correction of the tethered segment ranged from 0% to 133.3% at 4 years. We observed greater correction in 2 patients with open triradiate cartilage (TRC), achieving full scoliosis correction at 2 years and 121.5% at 4 years. MRI showed improvement in periapical disc wedging morphology and 55% improvement of rotation at 3 years. There were 20 adverse events, of which 16 were mild and 4 were moderate in severity. The 4 moderate events of pneumonia, distal decompensation, curve progression, and overcorrection occurred in 3 patients, 2 of whom required fusion.Conclusions:Anterior vertebral body tethering resulted in scoliosis deformity correction in the coronal and axial planes, with preservation of curve flexibility. Actual correction by growth modulation was noted only in patients with open TRC, whereas curve stabilization was noted in patients with closed TRC. Overcorrection, curve progression, and distal decompensation are problems with this technique.Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Determination of optimal screw number based on correction angle for main thoracic curve in adolescent idiopathic scoliosis

BackgroundReducing the number of screw insertions while maintaining good clinical outcomes can improve the efficiency and cost-effectiveness of scoliosis surgery. However, the optimal minimum number of pedicle screws remains unclear. This study searched for factors to estimate the fewest number of pedicle screws required between end vertebrae in relation to preoperative main thoracic curve flexibility. MethodsSixty-nine subjects (4 male and 65 female, mean age: 14.8 ± 2.5 years) who underwent skip pedicle screw fixation for Lenke type 1–4 or 6 curves and were followed for at least 1 year were enrolled. Intervention technique was selected according to the size and flexibility of the preoperative main thoracic curve. Surgery-related variables included pedicle screw number, rod material and diameter, and extent of Ponte osteotomy. The effect on postoperative correction angle (i.e., the difference between the preoperative supine position maximum bending and postoperative standing Cobb angles of the main thoracic curve) according to surgical intervention technique was estimated using multiple linear mixed regression models with the preoperative supine position maximum bending correction angle (i.e., the difference between the standing preoperative and supine position maximum bending Cobb angles) as a random effect. ResultsThe preoperative maximum bending correction angle was 8–42° and had a moderate negative correlation with postoperative correction angle (r = −0.65, P < 0.01). Multivariate analysis revealed a 1.7° (95% CI 0.7–2.6; P < 0.01) correction gain per single-screw insertion and a 1.8° (95% CI 0.5–3.1; P < 0.01) gain per intervertebral level in Ponte osteotomy. ConclusionsThe number of pedicle screws necessary to correct main thoracic adolescent idiopathic scoliosis curves can be estimated by calculating correction gains of 1.7° per pedicle screw and 1.8° per Ponte osteotomy intervertebral level. Based on these results, it may be possible to reduce invasiveness and cost for patients requiring a smaller degree of correction.

Management of Cervical Instability as a Complication of Neurofibromatosis Type 1 in Children: A Historical Perspective With a 40-Year Experience

Study DesignLiterature review with supplementary case examples. ObjectivesThe objective of this article was to review neurofibromatosis type 1 (NF1) and the associated spinal pathology with a focus on the disorder’s manifestations in the immature cervical spine. Summary of Background DataNF1 is one of the most common inheritable genetic disorders. The disorder is associated with spinal deformities, long bone dysplasia, and osteoporosis. The manifestations of NF1 in the cervical spine commonly include instability secondary to kyphosis, neurofibromas, and dural ectasia. MethodsLiterature relevant to the evaluation and management of NF1 in the cervical spine was reviewed using the PubMed/NCBI database with a focus on recent clinical studies. The review was supplemented with a historical perspective and patient cases. ResultsThe prevalence of NF1 cervical spine lesions is difficult to define because many patients may be asymptomatic. Symptoms of cervical kyphosis can include pain or nerve deficits but some have a surprisingly high tolerance for deformity and may have frank dislocation of one vertebral body over another (spondyloptosis) with few associated symptoms. Cervical radiographs should be obtained in patients requiring traction, surgery, or intubation, and those with neck pain or symptoms that suggest spinal neurofibromas. Patients with progressive symptoms should be offered surgery. Careful planning is required because many patients will have small, dysplastic vertebral bodies, thin posterior elements, plexiform neurofibromas, or dural ectasia. The decision to use preoperative traction will vary from patient to patient. Combined anterior-posterior fusion is recommended for most cases of severe symptomatic kyphosis, and the fusion should extend from parallel to parallel vertebrae (or six or more levels). Anterior or posterior fusion alone may be an alternative for skeletally mature patients with smaller, flexible curves. ConclusionsSpinal deformity is the most common musculoskeletal manifestation of NF1. Cervical lesions are frequently asymptomatic, but patients with thoracolumbar scoliosis, dystrophic features, or a history of laminectomy should have the cervical spine carefully evaluated. For severe and progressive kyphotic deformities, most authors recommend a period of traction followed by a combined anterior-posterior fusion that is instrumented from parallel to parallel vertebra (or six or more levels). Close follow-up is very important because complications and progression are frequent.

Infantile Idiopathic Scoliosis: Factors Affecting EDF Casting Success

Study DesignIRB-approved retrospective single cohort study. ObjectivesTo review our ten-year history with EDF (Elongation Derotation Flexion) casting in patients with infantile idiopathic scoliosis (IIS) to better understand which factors predict successful outcomes. Summary of Background DataNumerous studies have demonstrated the efficacy of EDF casting in the treatment of progressive infantile idiopathic scoliosis. But none have reproduced the success of Mehta’s even with early intervention. MethodsPatients with IIS treated with EDF casting with a minimum 24-month follow-up were included. Radiographs and clinical records were reviewed. Age, sex, and curve type were documented. Precast, traction, in cast, in brace, and final Cobb angles were measured and recorded. Outcomes were defined by Cobb angle at final follow-up out of cast or brace. Patients were considered cured if the final Cobb angle was <10°, palliated at 10°–45°, and failed if they required surgical treatment. ResultsSixty-three patients with IIS were reviewed. Thirty-two were excluded for incomplete records or insufficient follow-up, leaving 31 patients. No patients progressed to surgical intervention during the study. Patients with a Cobb angle >10° in the final cast were 7.3 times more likely to fall into the palliative range at the most recent follow-up than if their Cobb angle was 10° or less even when adjusted for age. Earlier age at onset of casting (14.9 vs. 21.1 months) was not statistically significant (p=.073). Magnitude of initial curvature, flexibility, initial correction, sex, and curve type were also not found to be significant. ConclusionEDF casting is a valid treatment option for IIS with a high cure rate. Major Cobb angle at the end of casting is most predictive of outcome. Cobb angles >10° at the end of casting had a 7.3 times greater risk of falling into the palliated category versus Cobb angles less than or equal to 10° even when adjusted for age. Initial curve magnitude, curve flexibility, sex, and curve type were not predictive. Level of EvidenceLevel IV.