Rigid Curves Research Articles

Regular and Rigid Curves on Some Calabi-Yau and General-Type Complete Intersections

Regular and Rigid Curves on Some Calabi-Yau and General-Type Complete Intersections

Posterior instrumented correction and fusion of adolescent idiopathic scoliosis

Balanced frontal curve correction with horizontal shoulder levels, restoration of sagittal plane and vertebral derotation with afusion length as short as possible. Curves larger than 40-50° Cobb angle; furthermore age, location, degree of rotation, and sagittal plane deviation have to be considered. Posteriorly, segmental pedicle screw instrumentation with ahigh screw density (80%) and both titanium alloy and cobalt chrome rods. Freehand screw placement under consideration of both natural and deformity-induced pedicle morphology. Correction via reduction screws or instruments. Combined correction technique with rod rotation, segmental screw approximation to the generally concave rod and segmental correction of vertebral translation. Moderate concave distraction and convex compression. If needed, final in situ bending of the rods. Schwab typeI osteotomies; in rigid curves typeII osteotomies. Fusion with local bone, allogenic bone and/or bone substitutes (i.e.,tricalcium phosphate). Intraoperative placement of athoracic epidural catheter for postoperative pain control. Neurological monitoring throughout the procedure. Mobilization on postoperative day1 with focus on pain management and nutrition. Return to school after 4weeks. Physiotherapy after 3months, cycling after 3-6months, and full sport activities after 1year. Frontal curve correction of 60-80%, sufficient sagittal plane correction. Correction of rib hump 40%. Patient satisfaction is high at 95% and long-term revision rates of < 10%.

Use of intra-operative internal distraction for the application of magnetically controlled growth rods (MCGR): a technique for maximizing correction in the rigid immature spine during index surgery.

Operative treatment of early onset scoliosis (EOS) with Magnetically Controlled Growing Rod (MCGR) in moderate-to-severe curves poses a challenge due to the limited amount of force and length available with the implant. The purpose of this study was to assess the use of the intra-operative internal spine distraction using Harrington Outrigger, before definitive implantation of MCGR, with regard to initial correction, maintenance of correction, truncal balance, and complication rates. 16 EOS patients treated with the application of MCGR using the intra-operative internal distractor technique were included in the study. More than 50% of cases were congenital scoliosis with multiple vertebral anomalies. All patients were followed up for a minimum of 2years. Radiological measurement of change in Cobb angle, thoracic kyphosis, lumbar lordosis, T1-S1 length, T1-T12l length, and sagittal balance were done at pre-op, immediate post-op, after 1year, and 2years. All the complications were noted and documented. The mean age of the operated patients was 8±1.7years, range (4-10years). Mean pre-operative Cobb angle was 70.4 degrees. The mean correction of major Cobb angle was 34.6°. The percentage correction achieved in post-operative Cobb angle was about 51%. Mean change in post-operative thoracic kyphosis was 18.5° (40%). The average gain in immediate post-operative spinal length (T1-S1) and thoracic height (T1-T12) was 46.7mm (18.3%) and 41mm (23%), respectively. Large and rigid curves in EOS can achieve a significant correction of Cobb angle and coronal imbalance during the index operation, by the use of intra-operative internal distraction at the time of MCGR insertion. Retrospective clinical study, level 4.

Implant Density and Curve Correction in Scoliosis Surgery using a Three-Dimensional-Based Correction Strategy

Introduction: The growing trend toward the use of pedicle screws for the operative treatment of patients with idiopathic scoliosis is to provide a three-dimensional (3D) deformity correction using a three-column fixation was observed. Reports have variable recommendations regarding the implant density as well as the configuration of the pedicle screws. This study re-evaluated implant density and curve correction currently based on the 3D correction strategy by comparing it to side-bending correction (SBC). Materials and Methods: Seventy-six adolescent idiopathic scoliosis (AIS) patients who had undergone posterior spinal fusion from 2017 to 2019 visited our specialized center were recruited. Demographic variables and radiological measurements were collected. Patients filled out the Scoliosis Research Society (SRS-22) questionnaire from a mobile device, of which the SRS-22 was digitally adopted using mobile technology and cloud computation. Results: In the 76 AIS patients, 28 (37%) were rigid curves and 48 (63%) were flexible curves. Of the 28 rigid curves (SBC &lt;30%), 13 (46%) patients had low pedicle screw density (PSD), while 15 (54%) had high PSD. Of the 48 flexible curves, 26 (55%) patients had low PSD, while 22 (45%) patients had high PSD. SBC index for the high PSD group (172) is almost the same compared to the low PSD group (174). Conclusions: Using high or low PSD makes the same amount of spinal correction for this group and additional screws do not make significant improvement on spinal correction. Higher screw density instrumentation is associated with the same amount of correction rate, whether in rigid or flexible curves, leading us to postulate that scoliosis correction relates more to intrinsic curve flexibility rather than instrument density.

Temporary Internal Distraction for Severe Scoliosis.

TID can be performed as a single or staged procedure. During the first part, cephalad anchors are placed on the spine or ribs, and caudad anchors are placed on the spine or pelvis. Temporary distraction rods are inserted, osteotomies and/or releases are performed, and iterative distractions are utilized for the duration of the procedure. If adequate correction is achieved, the final fusion may be completed at this time. If not, a staged approach may be performed: the wound is closed and the patient is returned to the operating room 1 to 3 weeks later, at which time the temporary rods are removed, further distraction is performed, and the final fusion instrumentation is placed. Around 80% to 90% cumulative correction of the major coronal angle should be achievable. The mainstay of treatment for large scoliotic curves is typically surgical correction and fusion. The main alternative to TID is traditional halo-gravity traction followed by fusion3-5. In rare cases, nonoperative treatment may be appropriate if comorbidities and/or prognoses that preclude surgery exist. Halo traction is an effective adjunct for the treatment of large scoliotic curves; nonetheless, it has several disadvantages. First, halo traction requires a prolonged hospital stay with restriction of mobility and interference with daily activities. Second, this procedure may be less effective in cases of lumbar deformity, in which halo traction achieves limited tensile forces. Third, this procedure is associated with several risks, such as cranial nerve injuries and pin track complications3-6. Finally, halo traction is contraindicated for certain conditions, such as cervical instability.TID, on the other hand, involves the application of iterative corrective forces directly to the area of deformity, allowing a stronger correction1. TID takes advantage of the viscoelastic nature of the spine to achieve a higher percent correction compared with halo traction, with a low risk of neurologic injury1,2. TID also avoids the prolonged hospital stay, mobility restriction, and complications associated with halo traction. When performed as a staged procedure, TID allows accurate assessment of neurologic function with the patient awake and moving.TID is most effective for severe scoliotic multisegment deformities rather than short rigid curves, which are better treated by osteotomies. This procedure provides satisfactory outcomes and a low risk of complications. In our retrospective case series, TID resulted in a mean major coronal angle correction of 53% after the first distraction and 80% to 90% after definitive fusion1. The overall percent correction was higher than that reported for halo traction1.The major risks of TID include infection and spinal injury. The risk of infection is decreased by antibiotic prophylaxis, perioperative nutritional optimization, and careful soft-tissue handling and wound closure. The risk of spinal cord injury is decreased by intraoperative neuromonitoring. Neuromonitoring changes occur in around 40% of cases, but these are almost always reversible and seldom lead to neurologic deficits if detected and appropriately treated, as described below2.Although risks exist, no complications have occurred among the 32 cases we presented in our series1,2. Temporary anchors should be expected to loosen during distraction. Therefore, temporary anchors must be placed strategically so as to not jeopardize the purchase of the final implants.Gradual corrections must be performed over time, utilizing the viscoelastic nature of the spine to minimize risk of neurologic injury.Accurate neuromonitoring is essential for this procedure.If neuromonitoring changes occur, distraction must be stopped and the correction attained must be decreased. TID = temporary internal distractionLIV = lowest instrumented vertebraAP = anteroposteriorTP = transverse processSAI = sacral-alar-iliacMAP = mean arterial pressureTPN = total parenteral nutritionVCR = vertebral column resectionJIS = juvenile idiopathic scoliosisAIS = adolescent idiopathic scoliosis.

Thoracolumbar and Lumbar Posterior Vertebral Resection for the Treatment of Rigid Congenital Spinal Deformities in Pediatric Patients: A Long-Term Follow-up Study

ObjectiveWe sought to determine whether a posterior vertebral resection on congenital deformities of thoracolumbar and lumbar vertebrae leads to more complications and provides less correction.MethodsTwenty-three patients underwent a posterior vertebral resection for a rigid congenital spinal deformity, which included scoliosis (13 patients), kyphoscoliosis (6 patients), and pure kyphosis (4 patients). The surgeries involved removing 1 to 2 vertebrae using multiaxial pedicle screws in all but 2 of the patients. All surgeries were performed under intraoperative spinal cord monitoring. Thoracic curve, lumbar lordosis, focal kyphosis, shift, and sagittal vertical axis were collected at baseline and during the last follow-up (taking place after at least 3 years) and were then statistically analyzed.ResultsThe major curve correction was about 55% in cases of scoliosis, with focal kyphosis improving from 54.3 ± 19.1 degrees to 21.3 ± 15 degrees. Two patients experienced intraoperative neuromonitoring changes, with data returning to baseline without any surgical intervention. Sensory or motor palsy after the surgery was not reported in patients.Despite improving sagittal or coronal deformities, 8 patients experienced excessive sagittal decompensation during follow-up, 1 of whom underwent revision surgery. Sagittal decompensation was by far the most common complication. Larger kyphoscoliosis or focal kyphosis angles were preoperative risk factors for postoperative sagittal imbalance (P value < 0.05).ConclusionsUsing a lumbar or thoracolumbar posterior vertebral resection enables surgeons to correct rigid curves in the pediatric population without major risk to nerve roots. The primary complications would be sagittal decompensation and the likelihood of undercorrection, which requires mindful addressing during the preoperative planning stages.

Clinical Outcomes of 3-column Osteotomy at Growing Rod Graduation.

Several different strategies were described on how to graduate a patient when skeletal maturity is reached after growing rod treatment. A final instrumentation and fusion is commonly performed, but the stiffness of the spine after numerous lenghthenings can be a major problem. When correction is needed in a severe and rigid curve, 3-column osteotomies (3CO) can be used as a method of bringing the spine back to a well-balanced position. This study aims to evaluate the clinical outcomes of 3CO osteotomies at growing rod graduation. A retrospective search of the database was performed between 1996 and 2018. Inclusion criteria were: diagnosis of early-onset scoliosis, underwent 3CO at the final fusion procedure, and ≥1 year of follow-up. Indications for this osteotomy were: significant sagittal and/or coronal off-balance or severe crankshaft deformity or significant distal and/or proximal adding-on. Clinical, radiographic, and operative data were analyzed. Complications were classified according to the modified Clavien-Dindo-Sink system. Eight patients were included in the study with a mean age of 13.5 at graduation (male/female: 2/6). The mean scoliosis angle significantly reduced from 65.6 to 39 degrees (P=0.012). Mean T1-T12 height increased from 19 to 20.5 (P=0.084) and T1-S1 from 29.6 to 31.6 (P=0.144). Five patients had a staged surgery. Average operative time was 338 minutes and blood loss was 1321 mL. Four grade 1, 1 grade 2, and 1 grade 3 complications occurred. This is the first case-series in the literature reporting on the use of 3CO at growing rod graduation. These procedures can be safely and effectively used to overcome significant multiplanar deformity and/or off-balance in the graduation of patients with early-onset scoliosis and significant correction can be achieved on these severe and rigid curves. Level IV-case series.

Sheaves of maximal intersection and multiplicities of stable log maps

A great number of theoretical results are known about log Gromov–Witten invariants (Abramovich and Chen in Asian J Math 18:465–488, 2014; Chen in Ann Math (2) 180:455–521, 2014; Gross and Siebert J Am Math Soc 26: 451–510, 2013), but few calculations are worked out. In this paper we restrict to surfaces and to genus 0 stable log maps of maximal tangency. We ask how various natural components of the moduli space contribute to the log Gromov–Witten invariants. The first such calculation (Gross et al. in Duke Math J 153:297–362, 2010, Proposition 6.1) by Gross–Pandharipande–Siebert deals with multiple covers over rigid curves in the log Calabi–Yau setting. As a natural continuation, in this paper we compute the contributions of non-rigid irreducible curves in the log Calabi–Yau setting and that of the union of two rigid curves in general position. For the former, we construct and study a moduli space of “logarithmic” 1-dimensional sheaves and compare the resulting multiplicity with tropical multiplicity. For the latter, we explicitly describe the components of the moduli space and work out the logarithmic deformation theory in full, which we then compare with the deformation theory of the analogous relative stable maps.

Solution for the degenerate scale for a rigid curve in antiplane elasticity by using a weakly singular integral equation

This paper provides a numerical solution for the degenerate scale for a rigid curve in antiplane elasticity. The degenerate scale problem for the rigid curve is formulated on the usage of the logarithmic potential. After assuming the displacement to be a vanishing value along the rigid curve, the boundary integral equation (BIE) is formulated. The problem can be first formulated in the degenerate scale. After making a coordinate transform, we can obtain the relevant BIE in the ordinary scale. Finally, a numerical solution is achieved. Several numerical examples are provided. In addition, the degenerate scale problem for the multiple rigid curves is also solved.

A simple method for assessing rotational flexibility in adolescent idiopathic scoliosis: modified Adam's forward bending test.

This study aimed to evaluate the diagnostic aptitude of a modified Adams forward bending test (MAFBT), which addresses the coupling phenomenon of axial rotation with reference to the side-bending movement. Also, this evaluation was facilitated by the introduction of our rotational flexibility index (RFI). Thirty-two female and eight male AIS patients were included in this study from a single institution. In the MAFBT, subjects were asked to bend to the convex side of the curve in the forward bending position. Scoliometric measurements were done during the AFBT and MAFBT. Utilizing anteroposterior standing plain radiographs curve flexibility indices were calculated. The diagnostic aptitude of the MAFBT was evaluated based on the receiver operating characteristic (ROC) curves and area under the curve (AUC). The RFI was also assessed, which considered AFBT and MAFBT parameters as a specified function. Significant correlations were noted between the Cobb angle and AFBT (p = 0.005), fulcrum bending and the MAFBT (p = 0.0001), side-bending and MAFBT (p = 0.0001). There were significant positive correlations between rotational flexibility as based on fulcrum bending radiograph to that of the RFI (r = 0.4, p = 0.036) and side-bending technique (r = 0.4, p = 0.008). Based on ROC analyses (AUC range 0.7-0.8), the MAFBT demonstrated high specificity and sensitivity rates for flexible and rigid curves, respectively. This is the first study to report that the MAFBT is a simple and reliable test for the clinical assessment of rotational flexibility in AIS patients. The study further noted that the novel RFI has clinical utility in the assessment of AIS.

Curve severity and apical vertebral rotation and their association with curve flexibility in adolescent idiopathic scoliosis

PurposeTo determine the association between coronal Cobb’s angle and Nash–Moe index in patients with adolescent idiopathic scoliosis. We also attempted to determine whether apical vertebral derotation depended upon the curve flexibility.Overview of literatureThe three-dimensional nature of adolescent idiopathic scoliosis (AIS) is well established. Knowledge of all components of this complex deformity is essential to formulate effective treatment strategies. Though the importance of quantifying all the components of the deformity, in AIS, has been analysed in detail, very few studies have been done to ascertain the relationship between the coronal plane deformity and apical vertebral rotation.MethodsDigitalised standing and supine stretch anteroposterior (AP) radiographs of 158 patients with AIS were analysed. The standing and supine stretch AP radiographs were compared to calculate the percentage reduction of Cobb’s angle to determine curve flexibility. The derotation of the apical vertebra on application of traction was also noted. The one-way repeated ANOVA was used to determine the association between Cobb’s angle and Nash–Moe index. The independent sample t test was used to determine whether a statistically significant difference was present, in the age of the patient, severity of the curve and percentage reduction of Cobb’s angle between those curves that derotated and those that did not, when stretched.ResultsThe one-way repeated ANOVA revealed an association between Cobb’s angle and Nash–Moe index on the standing and supine AP stretch radiographs (P < 0.01). The Independent sample t-test showed a statistically significant difference in percentage reduction of Cobb’s angle between those curves that derotated compared to those that did not, on stretch (P < 0.01).ConclusionsThis study demonstrates that there is an association between apical vertebral rotation and the coronal plane deformity. It also demonstrates that flexible curves derotate to a greater extent compared to rigid curves, when stretched.

Outcome of Posterior-Only Approach for Severe Rigid Scoliosis: A Retrospective Report.

The management of severe scoliosis may lead to significant complications, and adequate mobilization is a key step to achieve maximal correction, usually requiring extensive approaches. There is still no consensus on the management of these severe and rigid curves. In this study we evaluated the clinical and radiologic outcome of a posterior-only approach with multilevel asymmetric Ponte osteotomy with a minimum of 2 years' follow-up. In this retrospective study, 23 patients with severe and rigid adolescent idiopathic scoliosis who underwent surgery with a single-staged posterior-only approach were included. The surgical procedures in these patients were excision of posterior ligaments and spinous process, partial laminectomy in caudal part of lamina, excision of the ligamentum flavum, facetectomies, and multilevel asymmetric posterior column osteotomies (Ponte) followed by instrumented fusion. Clinical records-including demographic data; operating time; hospitalization time; blood loss; number of segments instrumented, fused, and osteotomized; functional improvement; follow-up duration; and complications-were recorded. The mean preoperative Cobb angle of major curve in coronal plan was 97.5° (range, 82°-131°) with the mean flexibility of 21.4° (range, 10°-25°) on bending radiography. The mean immediate postoperative Cobb angle of major curve was 34.8° (range, 17°-61°), showing a 64.2% correction. The mean preoperative coronal and sagittal imbalances of 3.8 and 4.2 cm were improved to 1.0 and 1.3 cm at postoperative measurements, respectively. A mean of 6.1 (range, 5-9) vertebral segments were osteotomized. We experienced no major complications. We found that a posterior-only procedure in patients with severe and rigid adolescent idiopathic scoliosis could provide correction rate, coronal and sagittal balance, and clinical outcomes comparable with other procedures. Using this technique can eliminate the need for the anterior release, with the associated complications related to anterior surgery, in the treatment of severe rigid scoliosis.

Staged instrumentation with magnetically controlled growing rods in early-onset scoliosis: indications and preliminary outcomes.

Severe scoliosis, kyphosis, stiffer curves, short trunk height, and poor bone density are known risk factors for instrumentation failure with traditional growing rods or magnetically controlled growing rods (MCGR). To minimize the risk of instrumentation failure in managing complex early-onset scoliosis (EOS) with MCGR, we propose a strategy for staged MCGR insertion. We performed a single-center retrospective review of all consecutive MCGR cases with 24months' minimum follow-up. Inclusion criteria included diagnosis of EOS of any etiology with severe and stiff curves in the coronal or sagittal planes, poor bone density, short trunk height (T1-T12 smaller than 150mm) or previous instrumentation failure managed with staged MCGR. During the first stage, anchor points and halo-gravity were applied, followed by halo-gravity traction. At a second stage, halo-gravity was removed and MCGR were inserted. Outcome measures included pre- and postoperative radiographic measurements and complications. Seventeen patients with a median age of 7 (range 6-9) years were managed in two stages. Indications for two-stage surgery were short trunk height (T1-T12 height less than 150mm) in six patients, five poor bone quality, three dislodgement of proximal anchor points in previous instrumentation, and three rigid curves. The rate of unplanned revision surgeries was 11.8%. No infections or traction-related complications were found. According to our results, the staged MCGR insertion strategy combined with halo-gravity traction to manage complex EOS yielded a relatively low instrumentation failure rate as compared with the rates previously reported in the current literature. To our knowledge, this is the first study reporting the staged strategy for instrumentation with MCGR. IV.

Posterior techniques for correcting deformity in adolescent idiopathic scoliosis––How much correction is optimal?

The optimal surgical treatment of adolescent idiopathic scoliosis is heavily debated in the literature. This study aimed to review posterior surgical techniques in the treatment of adolescent idiopathic scoliosis. Literature review was performed. In treating adolescent idiopathic scoliosis with posterior spine fusion, there are many factors to consider when determining where to start and end the fusion construct: skeletal maturity, stress/bending radiographs, and assessment of vertebral rotation and translation. When considering selective thoracic fusion, the relative magnitudes of the main thoracic (MT) and thoracolumbar/lumbar (TL/L) curves and the overall sagittal profile of the thoracolumbar junction are assessed. Selective thoracic fusion can be appropriate if two of the three are found to be true: the MT-to-TL/L Cobb angle ratio is >1.2, the MT-to-TL/L apical vertebral translation (AVT) ratio is >1.2, and/or the MT-to-TL/L apical vertebral rotation (AVR) ratio is >1.2. Moreover, selective thoracic fusion can be an option in the presence of a nonstructural lumbar curve (bending Cobb angle <25°) with thoracolumbar (T10-L2) kyphosis <20°. When choosing the uppermost and lowest instrumented vertebra, one must consider standing coronal balance and regional kyphosis to lessen risk of postoperative complication. The uppermost instrumented vertebra should be a stable, neutral vertebra with <5° of junctional kyphosis; and the lowest instrument vertebra should be touched by the central sacral vertical line and within two vertebrae proximal to the neutral vertebra. To aid in correction, the addition of posterior surgical releases improves the mobility of spine, especially in more rigid curves, but may increase intraoperative blood loss and operative time. Rod derotation and vertebral translation appear to have similar results in correcting coronal and sagittal deformities. The addition of direct vertebral rotation and segmental rotation plays a role in surgical correction as well.

The Research of Computational Method by Using Beam Element for Rope Structure

On the basis of in-depth study of mechanical behavior of rope, according to the catenary theory the equation of guy rope is built. Based on this equation, the guy rope is established in FEM which is analogized by using beam elements with little bending stiffness, and non-linear finite element calculations are applied for the guy rope. Take the theoretical shape of guy rope as study point, according to example calculations, computational accuracy about using beam element to simulate is quantificationally analyzed, and discipline curve of flexural rigidity to computational result is obtained and the results is also analyzed.

Anterior and Posterior Fusion for Large, Rigid Idiopathic Scoliosis: Does Implant Density Matter?

Despite advancements in surgical techniques, controversy remains regarding the optimal implant density for the correction of idiopathic scoliosis. Recent evidence has suggested that equivalent radiographic and clinical outcomes can be achieved with lower implant densities for those with moderate curves and good flexibility. Among the experts, the consensus has continued that higher implant densities should be used for larger, stiffer curves. The purpose of the present study was to compare the radiographic results between high-implant density (HID) and low-implant density (LID) constructs in patients with large (>65°), rigid (<50% flexibility) curves who had undergone anterior release and posterior spinal fusion. We reviewed the idiopathic scoliosis cases performed at a single institution from 2006 to 2014. Only those meeting the inclusion criteria were selected. The patients were divided into HID and LID groups. The postoperative radiographs were compared for coronal correction, thoracic kyphosis, pelvic tilt, lumbar lordosis, and sagittal vertical axis. A statistically significant improvement in coronal correction was detected in the HID group at all follow-up points (final follow-up: HID, 81.1% vs. LID, 70.4%; P= 0.01). When preoperative thoracic kyphosis was considered, no differences were found between the 2 groups. No differences were found in the other sagittal parameters. In patients with large, rigid idiopathic scoliosis undergoing anterior release and posterior spinal fusion, a small, but statistically, significant improvement in the coronal Cobb angle was seen. It remains to be determined whether this small difference in radiographic correction will have any influence on the clinical outcome.

How to Avoid Distal Adding-on Phenomenon for Rigid Curves in Major Thoracolumbar and Lumbar Adolescent Idiopathic Scoliosis? Identifying the Incidence of Distal Adding-on by Selection of Lowest Instrumented Vertebra

We sought to compare the radiologic outcomes for different distal fusion levels in a rigid curve with major thoracolumbar and lumbar (TL/L) adolescent idiopathic scoliosis (AIS) using rod derotation (RD) with direct vertebral rotation (DVR) after pedicle screw instrumentation (PSI). This study finally enrolled 28 patients who were diagnosed with AIS in rigid curve with major TL/L curves, treated by PSI with RD and DVR and with a minimum 2-year follow-up. Patients were divided into 2 groups, L3 and L4, on the basis of the distal fusion level at the lowest instrumented vertebra (LIV) of L3 or L4. There was no significant difference in TL/L curve, thoracic (minor), and compensatory (caudal) curves between the L3 and L4 groups either postoperatively (P= 0.162, 0.426, and 0.762, respectively) or at the last follow-up (P= 0.952, 0.620, and 0.562, respectively). The overall prevalence of unsatisfactory results was 42.9% (12/28 patients). The prevalence of unsatisfactory results was 61.1% (11/18) in the L3 group and 10% (1/10) in the L4 group, which was significantly different (P < 0.05). Unsatisfactory results occurred more often in the L3 group than in the L4 group, and unsatisfactory results had significant influence on progression of TL/L and distal compensatory curves. Such progression was closely correlated with deteriorating LIV disk angle in the L3 group. Therefore if the curve is rigid, LIV should be extended to L4 to avoid the adding-on phenomenon in the treatment of major TL/L AIS using RD with DVR after PSI.

Posterior vertebral column resection for congenital rigid spinal deformities

Background: The goal in surgical management of complex spinal deformities is to safely realign the spine as much as possible in both sagittal and coronal planes. Standard posterior and or middle column osteotomies are associated with limitations to correct the severe rigid curves. The purpose of this study was to assess the clinical and radiographic results of posterior vertebral column resection (PVCR) for surgical management of complex congenital rigid spinal deformities. Methods: Thirty-five patients with congenital rigid spinal deformities were enrolled in this prospective study. Preoperative measurement of curve magnitude and stiffness was done. Postoperative degrees of correction also were measured. The mean percentage of correction was calculated. Intraoperative and postoperative complications were reported. The minimum follow-up period was 2 yr. Results: Nineteen patients had rigid kyphosis and 16 had kyphoscoliosis. Their etiologies were due to congenital vertebral anomalies. An average of 1.5 vertebrae were resected intraoperatively. Radiographically the mean preoperative kyphosis was 68.9 degrees and in those patients with kyphoscoliosis, the mean preoperative value was 38 degrees. They improved on immediate follow-up to 24.5 and 11 degrees, respectively. At final follow-up the mean loss of correction in the sagittal plane was 3.6 degrees, which was statistically insignificant. All patients showed solid fusion at final follow-up. Complications were noted in seven patients, including dural tear, pleural tear, and postoperative wound infection that were managed accordingly. Conclusions: Single-stage PVCR is a highly effective option in the management of rigid spinal deformities with satisfactory clinical and radiographic outcomes.

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.

Serial CAD/CAM Bracing: An Alternative to Serial Casting for Early Onset Scoliosis.

Years of casting for infantile scoliosis can lead to significantly detrimental quality of life for both the child and parents. Concerns have been raised about the long-term negative neurodevelopmental effects of repeated anesthesia on young children. We developed an elongation bending derotation brace (EBDB) that uses primarily a bending derotation force applied to the curve to achieve the same goals as the cast. The goal of the study is to describe the preliminary results of a technique for creation of EBDB for infantile idiopathic scoliosis using computer-aided design/computer-aided milling (CAD/CAM) technology with at least 24 months follow-up. Nine patients with infantile idiopathic scoliosis had minimum 2-year follow-up (mean, 3.4 y; range, 2 to 6 y). Mean age at the treatment was 11 months (4 to 24 mo). There were 2 right thoracic, 7 left thoracic curves. CAD/CAM technology was used to create the EBDB after the child was placed in traction and a derotation strap applied. The same rotational forces that are used in the creation of the Mehta-type cast can also be utilized in creating the brace. A laser scanner was used to obtain the spinal geometry. Compliance can be monitored with a heat sensor. Four patients were full corrected with serial bracing alone (curve ≤10 degrees). Five patients with more rigid curves showed improvement from mean 57 degrees (48 to 62 degrees) to mean 21 degrees (10 to 44 degrees). This paper describes the preliminary results of a new methodology for creating a patient-specific brace for infantile scoliosis using CAD/CAM technology. This methods shows promising potential to treat the infantile curve without the drawbacks of casting. Level IV.