How do implants overlying the spine influence "The Law of Diminishing Returns" in early-onset scoliosis patients?

PURPOSE: The "law of diminishing returns" (LODR) in early-onset scoliosis (EOS) is well-known. We hypothesized that previously observed variations between constructs may be related to the lateral distance that each construct lies from the spine. We therefore sought to determine whether the curve magnitude improvement and spinal length gains for distraction-based constructs in EOS are positively correlated with the collinearity of the spine and the convex-sided implant on posteroanterior radiographs. METHODS: A prospectively-collected, multicenter EOS registry was queried for all patients who underwent non-fusion, distraction-based instrumentation surgery. Post-index radiographs were graded from 1 to 5 based on amount of overlap between the convex-sided rod and the apical vertebra. Grade 1: convex rod is lateral to convex-sided pedicle; Grade 2: overlaps the convex-sided pedicle; Grade 3: lies between pedicles; Grade 4: overlaps concave-sided pedicle; Grade 5: medial to concave-sided pedicle. ANOVA assessed the correlations between post-index overlap grade and change in (a) curve magnitude and (b) T1-T12 height. Multivariable regression modeling further assessed these associations. RESULTS: 284 patients met all selection criteria and were included. On ANOVA, post-index grade was associated with curve magnitude (p <0.001) and T1-12 height (p = 0.028) change. Better curve correction and height change were associated with higher grade. On regression modeling, curve correction (R = 0.574) and T1-T12 height change (R = 0.339) remained significantly associated with grade when controlling for time, anchor locations, age, underlying diagnosis, and pre-index curve magnitude. CONCLUSION: More apical overlap by the convex rod was associated with better spinal deformity control and improved height gain. LEVEL OF EVIDENCE III: Therapeutic.

Do Rib-Based Anchors Impair Chest Wall Motion in Early Onset Scoliosis (EOS)?

Purpose: There is a concern in pediatric surgery practice that rib-based fixation may limit chest wall motion in early onset scoliosis (EOS). The purpose of this study is to address the above concern by assessing the contribution of chest wall excursion to respiration before and after surgery. Methods: Quantitative dynamic magnetic resonance imaging (QdMRI) is performed on EOS patients (before and after surgery) and normal children in this retrospective study. QdMRI is purely an image-based approach and allows free breathing image acquisition. Tidal volume parameters for chest walls (CWtv) and hemi-diaphragms (Dtv) were analyzed on concave and convex sides of the spinal curve. EOS patients (1-14 years) and normal children (5-18 years) were enrolled, with an average interval of two years for dMRI acquisition before and after surgery. Results: CWtv significantly increased after surgery in the global comparison including all EOS patients (p < 0.05). For main thoracic curve (MTC) EOS patients, CWtv significantly improved by 50.24% (concave side) and 35.17% (convex side) after age correction (p < 0.05) after surgery. The average ratio of Dtv to CWtv on the convex side in MTC EOS patients was not significantly different from that in normal children (p=0.78), although the concave side showed the difference to be significant. Conclusion: Chest wall component tidal volumes in EOS patients measured via QdMRI did not decrease after rib-based surgery, suggesting that rib-based fixation does not impair chest wall motion in pediatric patients with EOS.

Virtual Growing Child (VGC): A general normative comparative system via quantitative dynamic MRI for quantifying pediatric regional respiratory anomalies with application in thoracic insufficiency syndrome (TIS).

Background: A normative database of regional respiratory structure and function in healthy children does not exist. Methods: VGC provides a database with four categories of regional respiratory measurement parameters including morphological, architectural, dynamic, and developmental. The database has 3,820 3D segmentations (around 100,000 2D slices with segmentations). Age and gender group analysis and comparisons for healthy children were performed using those parameters via two-sided t-testing to compare mean measurements, for left and right sides at end-inspiration (EI) and end-expiration (EE), for different age and gender specific groups. We also apply VGC measurements for comparison with TIS patients via an extrapolation approach to estimate the association between measurement and age via a linear model and to predict measurements for TIS patients. Furthermore, we check the Mahalanobis distance between TIS patients and healthy children of corresponding age. Findings: The difference between male and female groups (10-12 years) behave differently from that in other age groups which is consistent with physiology/natural growth behavior related to adolescence with higher right lung and right diaphragm tidal volumes for females(p<0.05). The comparison of TIS patients before and after surgery show that the right and left components are not symmetrical, and the left side diaphragm height and tidal volume has been significantly improved after surgery (p <0.05). The left lung volume at EE, and left diaphragm height at EI of TIS patients after surgery are closer to the normal children with a significant smaller Mahalanobis distance (MD) after surgery (p<0.05). Interpretation: The VGC system can serve as a reference standard to quantify regional respiratory abnormalities on dMRI in young patients with various respiratory conditions and facilitate treatment planning and response assessment. Funding: The grant R01HL150147 from the National Institutes of Health (PI Udupa).

Interactive Segmentation of Lung Tissue and Lung Excursion in Thoracic Dynamic MRI Based on Shape-guided Convolutional Neural Networks.

Purpose: Lung tissue and lung excursion segmentation in thoracic dynamic magnetic resonance imaging (dMRI) is a critical step for quantitative analysis of thoracic structure and function in patients with respiratory disorders such as Thoracic Insufficiency Syndrome (TIS). However, the complex variability of intensity and shape of anatomical structures and the low contrast between the lung and surrounding tissue in MR images seriously hamper the accuracy and robustness of automatic segmentation methods. In this paper, we develop an interactive deep-learning based segmentation system to solve this problem. Material & Methods: Considering the significant difference in lung morphological characteristics between normal subjects and TIS subjects, we utilized two independent data sets of normal subjects and TIS subjects to train and test our model. 202 dMRI scans from 101 normal pediatric subjects and 92 dMRI scans from 46 TIS pediatric subjects were acquired for this study and were randomly divided into training, validation, and test sets by an approximate ratio of 5:1:4. First, we designed an interactive region of interest (ROI) strategy to detect the lung ROI in dMRI for accelerating the training speed and reducing the negative influence of tissue located far away from the lung on lung segmentation. Second, we utilized a modified 2D U-Net to segment the lung tissue in lung ROIs, in which the adjacent slices are utilized as the input data to take advantage of the spatial information of the lungs. Third, we extracted the lung shell from the lung segmentation results as the shape feature and inputted the lung ROIs with shape feature into another modified 2D U-Net to segment the lung excursion in dMRI. To evaluate the performance of our approach, we computed the Dice coefficient (DC) and max-mean Hausdorff distance (MM-HD) between manual and automatic segmentations. In addition, we utilized Coefficient of Variation (CV) to assess the variability of our method on repeated dMRI scans and the differences of lung tidal volumes computed from the manual and automatic segmentation results. Results: The proposed system yielded mean Dice coefficients of 0.96±0.02 and 0.89±0.05 for lung segmentation in dMRI of normal subjects and TIS subjects, respectively, demonstrating excellent agreement with manual delineation results. The Coefficient of Variation and p-values show that the estimated lung tidal volumes of our approach are statistically indistinguishable from those derived by manual segmentations. Conclusions: The proposed approach can be applied to lung tissue and lung excursion segmentation from dynamic MR images with high accuracy and efficiency. The proposed approach has the potential to be utilized in the assessment of patients with TIS via dMRI routinely.

Assessment of 3D hemi-diaphragmatic motion via free-breathing dynamic MRI in pediatric thoracic insufficiency syndrome.

Purpose: Thoracic insufficiency syndrome (TIS) affects ventilatory function due to spinal and thoracic deformities limiting lung space and diaphragmatic motion. Corrective orthopedic surgery can be used to help normalize skeletal anatomy, restoring lung space and diaphragmatic motion. This study employs free-breathing dynamic MRI (dMRI) and quantifies the 3D motion of each hemi-diaphragm surface in normal and TIS patients, and evaluates effects of surgical intervention. Materials and Methods: In a retrospective study of 149 pediatric patients with TIS and 190 healthy children, we constructed 4D images from free-breathing dMRI and manually delineated the diaphragm at end-expiration (EE) and end-inspiration (EI) time points. We automatically selected 25 points uniformly on each hemi-diaphragm surface, calculated their relative velocities between EE and EI, and derived mean velocities in 13 homologous regions for each hemi-diaphragm to provide measures of regional 3D hemi-diaphragm motion. T-testing was used to compare velocity changes before and after surgery, and to velocities in healthy controls. Results: The posterior-central region of the right hemi-diaphragm exhibited the highest average velocity post-operatively. Posterior regions showed greater velocity changes after surgery in both right and left hemi-diaphragms. Surgical reduction of thoracic Cobb angle displayed a stronger correlation with changes in diaphragm velocity than reduction in lumbar Cobb angle. Following surgery, the anterior regions of the left hemi-diaphragm tended to approach a more normal state. Conclusion: Quantification of regional motion of the 3D diaphragm surface in normal subjects and TIS patients via free-breathing dMRI is feasible. Derived measurements can be assessed in comparison to normal subjects to study TIS and the effects of surgery.

Auto-segmentation of thoraco-abdominal organs in pediatric dynamic MRI.

Purpose: Analysis of the abnormal motion of thoraco-abdominal organs in respiratory disorders such as the Thoracic Insufficiency Syndrome (TIS) and scoliosis such as adolescent idiopathic scoliosis (AIS) or early onset scoliosis (EOS) can lead to better surgical plans. We can use healthy subjects to find out the normal architecture and motion of a rib cage and associated organs and attempt to modify the patient's deformed anatomy to match to it. Dynamic magnetic resonance imaging (dMRI) is a practical and preferred imaging modality for capturing dynamic images of healthy pediatric subjects. In this paper, we propose an auto-segmentation set-up for the lungs, kidneys, liver, spleen, and thoraco-abdominal skin in these dMRI images which have their own challenges such as poor contrast, image non-standardness, and similarity in texture amongst gas, bone, and connective tissue at several inter-object interfaces. Methods: The segmentation set-up has been implemented in two steps: recognition and delineation using two deep neural network (DL) architectures (say DL-R and DL-D) for the recognition step and delineation step, respectively. The encoder-decoder framework in DL-D utilizes features at four different resolution levels to counter the challenges involved in the segmentation. We have evaluated on dMRI sagittal acquisitions of 189 (near-)normal subjects. The spatial resolution in all dMRI acquisitions is 1.46 mm in a sagittal slice and 6.00 mm between sagittal slices. We utilized images of 89 (10) subjects at end inspiration for training (validation). For testing we experimented with three scenarios: utilizing (1) the images of 90 (=189-89-10) different (remaining) subjects at end inspiration for testing, (2) the images of the aforementioned 90 subjects at end expiration for testing, and (3) the images of the aforesaid 99 (=89+10) subjects but at end expiration for testing. In some situations, we can take advantage of already available ground truth (GT) of a subject at a particular respiratory phase to automatically segment the object in the image of the same subject at a different respiratory phase and then refining the segmentation to create the final GT. We anticipate that this process of creating GT would require minimal post hoc correction. In this spirit, we conducted separate experiments where we assume to have the ground truth of the test subjects at end expiration for scenario (1), end inspiration for (2), and end inspiration for (3). Results: Amongst these three scenarios of testing, for the DL-R, we achieve a best average location error (LE) of about 1 voxel for the lungs, kidneys, and spleen and 1.5 voxels for the liver and the thoraco- abdominal skin. The standard deviation (SD) of LE is about 1 or 2 voxels. For the delineation approach, we achieve an average Dice coefficient (DC) of about 0.92 to 0.94 for the lungs, 0.82 for the kidneys, 0.90 for the liver, 0.81 for the spleen, and 0.93 for the thoraco-abdominal skin. The SD of DC is lower for the lungs, liver, and the thoraco-abdominal skin, and slightly higher for the spleen and kidneys. Conclusions: Motivated by applications in surgical planning for disorders such as TIS, AIS, and EOS, we have shown an auto-segmentation system for thoraco-abdominal organs in dMRI acquisitions. This proposed setup copes with the challenges posed by low resolution, motion blur, inadequate contrast, and image intensity non-standardness quite well. We are in the process of testing its effectiveness on TIS patient dMRI data.

Outcomes after completing growth-friendly surgical treatment for early-onset scoliosis in patients with skeletal dysplasia.

Aims: The aim of this study was to compare outcomes after growth-friendly treatment for early-onset scoliosis (EOS) between patients with skeletal dysplasias versus those with other syndromes. Methods: We retrospectively identified 20 patients with skeletal dysplasias and 292 with other syndromes (control group) who had completed surgical growth-friendly EOS treatment between 1 January 2000 and 31 December 2018. We compared radiological parameters, complications, and health-related quality of life (HRQoL) at mean follow-up of 8.6 years (SD 3.3) in the dysplasia group and 6.6 years (SD 2.6) in the control group. Results: Mean major curve correction per patient did not differ significantly between the dysplasia group (43%) and the control group (28%; p = 0.087). Mean annual spinal height increase was less in the dysplasia group (9.3 mm (SD 5.1) than in the control group (16 mm (SD 9.2); p < 0.001). Mean annual spinal growth adjusted to patient preoperative standing height during the distraction period was 11% in the dysplasia group and 14% in the control group (p = 0.070). The complication rate was 1.6 times higher (95% confidence interval (CI) 1.3 to 2.0) in the dysplasia group. The following complications were more frequent in the dysplasia group: neurological injury (rate ratio (RR) 5.1 (95% CI 2.3 to 11)), deep surgical site infection (RR 2.2 (95% CI 1.2 to 4.1)), implant-related complications (RR 2.0 (95% CI 1.5 to 2.7)), and unplanned revision (RR 1.8 (95% CI 1.3 to 2.5)). Final fusion did not provide additional spinal height compared with watchful waiting (p = 0.054). There were no significant differences in HRQoL scores between the groups. Conclusion: After growth-friendly EOS treatment, patients with skeletal dysplasias experienced a higher incidence of complications compared to those with other syndromes. Surgical growth-friendly treatment for skeletal dysplasia-associated EOS should be reserved for patients with severe, progressive deformities that are refractory to nonoperative treatment.

Quantifying Normal Diaphragmatic Motion and Shape and their Developmental Changes via Dynamic MRI.

Background: The diaphragm is a critical structure in respiratory function, yet in-vivo quantitative description of its motion available in the literature is limited. Research Question: How to quantitatively describe regional hemi-diaphragmatic motion and curvature via free-breathing dynamic magnetic resonance imaging (dMRI)? Study Design and Methods: In this prospective cohort study we gathered dMRI images of 177 normal children and segmented hemi-diaphragm domes in end-inspiration and end-expiration phases of the constructed 4D image. We selected 25 points uniformly located on each 3D hemi-diaphragm surface. Based on the motion and local shape of hemi-diaphragm at these points, we computed the velocities and sagittal and coronal curvatures in 13 regions on each hemi-diaphragm surface and analyzed the change in these properties with age and gender. Results: Our cohort consisted of 94 Females, 6-20 years (12.09 + 3.73), and 83 Males, 6-20 years (11.88 + 3.57). We observed velocity range: ∼2mm/s to ∼13mm/s; Curvature range -Sagittal: ∼3m -1 to ∼27m -1 ; Coronal: ∼6m -1 to ∼20m -1 . There was no significant difference in velocity between genders, although the pattern of change in velocity with age was different for the two groups. Strong correlations in velocity were observed between homologous regions of right and left hemi-diaphragms. There was no significant difference in curvatures between genders or change in curvatures with age. Interpretation: Regional motion/curvature of the 3D diaphragmatic surface can be estimated using free-breathing dynamic MRI. Our analysis sheds light on here-to-fore unknown matters such as how the pediatric 3D hemi-diaphragm motion/shape varies regionally, between right and left hemi-diaphragms, between genders, and with age.

Timing of intraoperative neurophysiological monitoring (IONM) recovery and clinical recovery after termination of pediatric spinal deformity surgery due to loss of IONM signals.

BACKGROUND CONTEXT: Intraoperative neurophysiological monitoring (IONM) is used to reduce the risk of spinal cord injury during pediatric spinal deformity surgery. Significant reduction and/or loss of IONM signals without immediate recovery may lead the surgeon to acutely abort the case. The timing of when monitorable signals return remains largely unknown. PURPOSE: The goal of this study was to investigate the correlation between IONM signal loss, clinical examination, and subsequent normalization of IONM signals after aborted pediatric spinal deformity surgery to help determine when it is safe to return to the operating room. STUDY DESIGN/SETTING: This is a multicenter, multidisciplinary, retrospective study of pediatric patients (<18 years old) undergoing spinal deformity surgery whose surgery was aborted due to a significant reduction or loss of IONM potentials. PATIENT SAMPLE: Sixty-six patients less than 18 years old who underwent spinal deformity surgery that was aborted due to IONM signal loss were enrolled into the study. OUTCOME MEASURES: IONM data, operative reports, and clinical examinations were investigated to determine the relationship between IONM loss, clinical examination, recovery of IONM signals, and clinical outcome. METHODS: Information regarding patient demographics, deformity type, clinical history, neurologic and ambulation status, operative details, IONM information (eg, quality of loss [SSEPs, MEPs], laterality, any recovery of signals, etc.), intraoperative wake-up test, postoperative neurologic exam, postoperative imaging, and time to return to the operating were all collected. All factors were analyzed and compared with univariate and multivariate analysis using appropriate statistical analysis. RESULTS: Sixty-six patients were enrolled with a median age of 13 years [IQR 11-14], and the most common sex was female (42/66, 63.6%). Most patients had idiopathic scoliosis (33/66, 50%). The most common causes of IONM loss were screw placement (27/66, 40.9%) followed by rod correction (19/66, 28.8%). All patients had either complete bilateral (39/66, 59.0%), partial bilateral (10/66, 15.2%) or unilateral (17/66, 25.8%) MEP loss leading to termination of the case. Overall, when patients were returned to the operating room 2 weeks postoperatively, nearly 75% (40/55) had monitorable IONM signals. Univariate analysis demonstrated that bilateral SSEP loss (p=.019), bilateral SSEP and MEP loss (p=.022) and delayed clinical neurologic recovery (p=.008) were significantly associated with having unmonitorable IONM signals at repeat surgery. Multivariate regression analysis demonstrated that delayed clinical neurologic recovery (> 72 hours) was significantly associated with unmonitorable IONM signals when returned to the operating room (p=.006). All patients ultimately made a full neurologic recovery. CONCLUSIONS: In children whose spinal deformity surgery was aborted due to intraoperative IONM loss, there was a strong correlation between combined intraoperative SSEP/MEP loss, the magnitude of IONM loss, the timing of clinical recovery, and the time of electrophysiological IONM recovery. The highest likelihood of having a prolonged postoperative neurological deficit and undetectable IONM signals upon return to the OR occurs with bilateral complete loss of SSEPs and MEPs.

Predicting early return to the operating room in early-onset scoliosis patients using machine learning techniques.

PURPOSE: Surgical treatment of early-onset scoliosis (EOS) is associated with high rates of complications, often requiring unplanned return to the operating room (UPROR). The aim of this study was to create and validate a machine learning model to predict which EOS patients will go on to require an UPROR during their treatment course. METHODS: A retrospective review was performed of all surgical EOS patients with at least 2 years follow-up. Patients were stratified based on whether they had experienced an UPROR. Ten machine learning algorithms were trained using tenfold cross-validation on an independent training set of patients. Model performance was evaluated on a separate testing set via their area under the receiver operating characteristic curve (AUC). Relative feature importance was calculated for the top-performing model. RESULTS: 257 patients were included in the study. 146 patients experienced at least one UPROR (57%). Five factors were identified as significant and included in model training: age at initial surgery, EOS etiology, initial construct type, and weight and height at initial surgery. The Gaussian naïve Bayes model demonstrated the best performance on the testing set (AUC: 0.79). Significant protective factors against experiencing an UPROR were weight at initial surgery, idiopathic etiology, initial definitive fusion construct, and height at initial surgery. CONCLUSIONS: The Gaussian naïve Bayes machine learning algorithm demonstrated the best performance for predicting UPROR in EOS patients. Heavier, taller, idiopathic patients with initial definitive fusion constructs experienced UPROR less frequently. This model can be used to better quantify risk, optimize patient factors, and choose surgical constructs. LEVEL OF EVIDENCE: Prognostic: III.

A New Look at Vertebral Body Tethering (VBT): Through the Modified Clavien-Dindo-Sink (mCDS) Classification.

INTRODUCTION: Anterior vertebral body tethering (AVBT) is increasingly popular as an option for surgical treatment of idiopathic scoliosis (IS). While the technology remains new, it is important for families and patients to be able to compare it to the current standard of care, posterior spinal fusion (PSF). The purpose of this study is to describe the complication rate of AVBT in IS using the mCDS and to compare it to the recently reported complication rate of PSF in IS. METHODS: A multicenter pediatric spine deformity database was queried for all idiopathic scoliosis patients who underwent vertebral body tethering. There were 171 patients with a minimum 9-month follow-up included in this study. Complications were retrospectively graded by 2 attending pediatric spine surgeons using the mCDS classification system. RESULTS: Data from 171 patients with idiopathic scoliosis was available for analysis, with 156/171 (91%) of patients being female and an average age of 12.2 years old at surgery. There were 156 thoracic tethers (1 with an LIV below L2), 5 lumbar tethers, 9 staged double tethers, and only 1 patient with same-day double tether. Fifty-five (55) (32%) patients experienced a total of 69 complications. The most common complication type for VBT by mCDS was Grade IIIb, encompassing 29/69 (42%) of complications. The second most frequent complication grade was Grade I at 23/69 (33%). Thirty-four (34) out of 69 (49%) of the VBT complications reported required either procedural/surgical intervention or admission to the ICU. CONCLUSIONS: This is the first study to directly compare the complication profile of VBT to PSF using the mCDS. Forty-nine percent (49%) of the VBT complications reported were at least Grade III, while only 7% of complications in the control PSF cohort from the literature were Grade III or higher. The mCDS complication classification brings light to the early learning experience of a new technique compared to the widely accepted standard of PSF for IS. LEVEL OF EVIDENCE: III - Retrospective comparative study.

Rotation and Asymmetry of the Axial Plane Pelvis in Cerebral Palsy: A CT-Based Study.

Spinopelvic malignment is commonly seen with non-ambulatory cerebral palsy (CP). Axial plane deformation is not well described in the literature. The purpose of this study was to describe and quantify the axial plane deformity in CP using CT scans and compare it to normal controls. We retrospectively collected data using CT scans of the abdomen and pelvis of 40 patients with GMFCS IV/V CP and neuromuscular scoliosis (CPP) and normal controls (NP) matched by age and sex. Pre-operative Cobb angle was recorded for the CP patients. Pelvic anatomy was evaluated at the supra-acetabular region of bone using two angles-iliac wing angle and sacral ala angle, measured for each hemipelvis. The larger of each hemipelvis angle was considered externally rotated while the smaller angle was considered internally rotated, termed as follows-iliac wing external (IWE) and internal (IWI); sacral ala external (SAE), and internal (SAI). Differences were noted using an independent t-test while correlations with Cobb angle were performed using Pearson's correlation. Iliac wing measurements showed the externally rotated hemipelvis showed a significantly greater magnitude compared with normal controls at 47.3 ± 18.1 degrees vs. 26.4 ± 3.7 degrees in NP (p < 0.001) while no internal rotation was observed (p > 0.05). Sacral ala measurements showed greater magnitude in both external and internal rotation. SAE was 119.5 ± 9.5 degrees in CPP vs. 111.2 ± 7.7 degrees in NP (p < 0.001) while SAI was 114.1 ± 8.5 degrees in CPP vs. 107.9 ± 7.5 degrees in NP (p = 0.001). In the CP cohort, the mean Cobb angle was 61.54 degrees (n = 37/40). Cobb angle correlated with the degree of external iliac wing rotation-IWE (r = 0.457, p = 0.004) and degree of absolute difference in the rotation of the iliac wing (r = 0.506, p = 0.001). The pelvis in a patient with CP scoliosis is asymmetrically oriented exhibiting a greater external rotation of one hemipelvis relative to normal controls. The severity of neuromuscular scoliosis is related to the pelvic axial rotation in CP patients. Axial plane deformity exists in the CP pelvis and this deformity warrants consideration when considering spinopelvic instrumentation strategies and outcomes of supra-pelvic and infra-pelvic pathologies.

Incidence of Tether Breakage in Anterior Vertebral Body Tethering.

BACKGROUND: Thoracic anterior vertebral body tethering (TAVBT) is an emerging treatment for adolescent idiopathic scoliosis. Tether breakage is a known complication of TAVBT with incompletely known incidence. We aim to define the incidence of tether breakage in patients with adolescent idiopathic scoliosis who undergo TAVBT. The incidence of tether breakage in TAVBT is hypothesized to be high and increase with time postoperatively. METHODS: All patients with right-sided, thoracic curves who underwent TAVBT with at least 2 and up to 3 years of radiographic follow-up were included. Tether breakage between 2 vertebrae was defined a priori as any increase in adjacent screw angle >5 degrees from the minimum over the follow-up period. The presence and timing of tether breakage were noted for each patient. A Kaplan-Meier survival analysis was performed to calculate expected tether breakage up to 36 months. χ 2 analysis was performed to examine the relationship between tether breakage and reoperations. Independent t test was used to compare the average final Cobb angle between cohorts. RESULTS: In total, 208 patients from 10 centers were included in our review. Radiographically identified tether breakage occurred in 75 patients (36%). The initial break occurred at or beyond 24 months in 66 patients (88%). Kaplan-Meier survival analysis estimated the cumulative rate of expected tether breakage to be 19% at 24 months, increasing to 50% at 36 months. Twenty-one patients (28%) with a radiographically identified tether breakage went on to require reoperation, with 9 patients (12%) requiring conversion to posterior spinal fusion. Patients with a radiographically identified tether breakage went on to require conversion to posterior spinal fusion more often than those patients without identified tether breakage (12% vs. 2%; P =0.004). The average major coronal curve angle at final follow-up was significantly larger for patients with radiographically identified tether breakage than for those without tether breakage (31 deg±12 deg vs. 26 deg±12 deg; P =0.002). CONCLUSIONS: The incidence of tether breakage in TAVBT is high, and it is expected to occur in 50% of patients by 36 months postoperatively. LEVEL OF EVIDENCE: Level IV.

Kagami Ogata syndrome: a small deletion refines critical region for imprinting.

Kagami-Ogata syndrome is a rare imprinting disorder and its phenotypic overlap with multiple different etiologies hampers diagnosis. Genetic etiologies include paternal uniparental isodisomy (upd(14)pat), maternal allele deletions of differentially methylated regions (DMR) in 14q32.2 or pure primary epimutations. We report a patient with Kagami-Ogata syndrome and an atypical diagnostic odyssey with several negative standard-of-care genetic tests followed by epigenetic testing using methylation microarray and a targeted analysis of whole-genome sequencing to reveal a 203 bp deletion involving the MEG3 transcript and MEG3:TSS-DMR. Long-read sequencing enabled the simultaneous detection of the deletion, phasing, and biallelic hypermethylation of the MEG3:TSS-DMR region in a single assay. This case highlights the challenges in the sequential genetic testing paradigm, the utility of long-read sequencing as a single comprehensive diagnostic assay, and the smallest reported deletion causing Kagami-Ogata syndrome allowing important insights into the mechanism of imprinting effects at this locus.

Fifteen Years of Spinal Fusion Outcomes in Children With Cerebral Palsy: Are We Getting Better?

STUDY DESIGN: Retrospective multicenter study. OBJECTIVE: We reviewed 15-year trends in operative factors, radiographic and quality of life outcomes, and complication rates in children with cerebral palsy (CP)-related scoliosis who underwent spinal fusion. SUMMARY OF BACKGROUND DATA: Over the past two decades, significant efforts have been made to decrease complications and improve outcomes of this population. MATERIALS AND METHODS: We retrospectively reviewed a multicenter registry of pediatric CP patients who underwent spinal fusion from 2008 to 2020. We evaluated baseline and operative, hospitalization, and complication data as well as radiographic and quality of life outcomes at a minimum 2-year follow-up. RESULTS: Mean estimated blood loss and transfusion volume declined from 2.7±2.0 L in 2008 to 0.71±0.34 L in 2020 and 1.0±0.5 L in 2008 to 0.5±0.2 L in 2020, respectively, with a concomitant increase in antifibrinolytic use from 58% to 97% (all, P <0.01). Unit rod and pelvic fusion use declined from 33% in 2008 to 0% in 2020 and 96% in 2008 to 79% in 2020, respectively (both, P <0.05). Mean postoperative intubation time declined from 2.5±2.6 to 0.42±0.63 days ( P< 0.01). No changes were observed in preoperative and postoperative coronal angle and pelvic obliquity, operative time, frequency of anterior/anterior-posterior approach, and durations of hospital and intensive care unit stays. Improvements in the Caregiver Priorities and Child Health Index of Life with Disabilities postoperatively did not change significantly over the study period. Complication rates, including reoperation, superficial and deep surgical site infection, and gastrointestinal and medical complications remained stable over the study period. CONCLUSIONS: Over the past 15 years of CP scoliosis surgery, surgical blood loss, transfusion volumes, duration of postoperative intubation, and pelvic fusion rates have decreased. However, the degree of radiographic correction, the rates of surgical and medical complications (including infection), and health-related quality of life measures have broadly remained constant.

Who gets staged surgery in severe pediatric and adolescent spine deformity?

BACKGROUND: There is significant debate regarding the indications of staged surgery for severe adolescent spinal deformity, and the factors associated with the decision to perform staged compared to same-day surgery have not been previously investigated. Thus, the purpose of this study was to determine which factors were most strongly associated with this decision. METHODS: A prospective multicenter registry of adolescent patients with severe spinal deformity was reviewed. Two cohorts were identified: those who underwent a planned staged surgical procedure for deformity correction and those who underwent a same-day procedure. Patients who underwent an unplanned staged procedure secondary to complications during the initial procedure were excluded. Comparisons were made between these cohorts with respect to preoperative patient and radiographic variables to determine which factors were associated with the decision to perform a staged procedure. Surgical data was also compared to evaluate for differences in the intraoperative management of staged versus same-day patients. RESULTS: Two hundred and twenty-nine patients with severe spinal deformities were identified. Forty patients (17%) underwent a planned staged procedure and 189 patients (80%) underwent a same-day procedure. On univariate analysis of preoperative variables, patients who underwent staged surgery had a significantly younger age at surgery, greater major curve magnitude, greater major curve AVT to CSVL, lesser thoracic spine height, greater radiographic trunk shift, and a greater proportion of patients undergoing revision surgery (as opposed to primary correction) compared to those who underwent a planned single-stage procedure. Multivariate logistic regression of pre-operative variables showed that age < 16 years, maximum cobb angle ≥ 120 degrees, major curve AVT to CSVL of ≥ 3.5 cm, and revision surgery were independently associated with the decision to perform a staged procedure. Intraoperatively, patients in the staged cohort more frequently underwent combined anterior and posterior procedures, grade 4 or higher Schwab osteotomies, and had a greater number of levels fused. CONCLUSION: There is substantial variability with respect to the decision to perform surgery for severe adolescent spine deformities in a staged versus same-day fashion. This large analysis of prospectively collected data is the first to describe the factors most strongly associated with the decision to perform a staged procedure and may help guide the surgical decision-making for these patients.

Pregnancy and Childbirth After Spinal Fusion for Adolescent Idiopathic Scoliosis.

BACKGROUND: Little data exist on pregnancy and childbirth for adolescent idiopathic scoliosis (AIS) patients treated with a spinal fusion. The current literature relies on data from patients treated with spinal fusion techniques and instrumentation, such as Harrington rods, that are no longer in use. The objective of our study is to understand the effects of spinal fusion in adolescence on pregnancy and childbirth. METHODS: Prospectively collected data of AIS patients undergoing posterior spinal fusion that were enrolled in a multicenter study who have had a pregnancy and childbirth were reviewed. Results were summarized using descriptive statistics and compared with national averages using χ 2 test of independence. RESULTS: A total of 78 babies were born to 53 AIS patients. As part of their pre-natal care, 24% of patients surveyed reported meeting with an anesthesiologist before delivery. The most common types of delivery were spontaneous vaginal delivery (46%, n=36/78) and planned cesarean section (20%, n=16/78). Compared with the national average, study patients had a higher rate of cesarean delivery ( P =0.021). Of the women who had a spontaneous vaginal birth, 53% had no anesthesia (n=19/36), 19% received intravenous intermittent opioids (n=7/36), and 31% had regional spinal or epidural anesthesia (n=11/36). spontaneous vaginal delivery patients in our study cohort received epidural or spinal anesthesia less frequently than the national average ( P <0.001). Of those (n=26 pregnancies) who did not have regional anesthesia (patients who had no anesthesia or utilized IV intermittent opioids), 19% (n=5 pregnancies) were told by their perinatal providers that it was precluded by previous spine surgery. CONCLUSION: The majority of AIS patients reported not meeting with an anesthesiologist before giving birth and those who had a planned C-section did so under obstetrician recommendation. The presence of instrumentation after spinal fusion should be avoided with attempted access to the spinal canal but should not dictate a delivery plan. A multidisciplinary team consisting of obstetrician, anesthesiologist, and orthopaedic surgeon can provide the most comprehensive information to empower a patient to make her decisions regarding birth experience anesthesia based on maternal rather than provider preference. LEVEL OF EVIDENCE: IV.

Update on the Diagnosis and Management of Early-onset Scoliosis.

PURPOSE OF REVIEW: In this article, we review the most recent advancements in the approaches to EOS diagnosis and assessment, surgical indications and options, and basic science innovation in the space of early-onset scoliosis research. RECENT FINDINGS: Early-onset scoliosis (EOS) covers a diverse, heterogeneous range of spinal and chest wall deformities that affect children under 10 years old. Recent efforts have sought to examine the validity and reliability of a recently developed classification system to better standardize the presentation of EOS. There has also been focused attention on developing safer, informative, and readily available imaging and clinical assessment tools, from reduced micro-dose radiographs, quantitative dynamic MRIs, and pulmonary function tests. Basic science innovation in EOS has centered on developing large animal models capable of replicating scoliotic deformity to better evaluate corrective technologies. And given the increased variety in approaches to managing EOS in recent years, there exist few clear guidelines around surgical indications across EOS etiologies. Despite this, over the past two decades, there has been a considerable shift in the spinal implant landscape toward growth-friendly instrumentation, particularly the utilization of MCGR implants. With the advent of new biological and basic science treatments and therapies extending survivorship for disease etiologies associated with EOS, the treatment for EOS has steadily evolved in recent years. With this has come a rising volume and variation in management options for EOS, as well as the need for multidisciplinary and creative approaches to treating patients with these complex and heterogeneous disorders.

Rib-to-spine and rib-to-pelvis magnetically controlled growing rods: does the law of diminishing returns still apply?

PURPOSE: The Law Of Diminishing Returns (LODR) has been demonstrated for traditional growing rods, but there is conflicting data regarding the lengthening behavior of Magnetically Controlled Growing Rods (MCGR). This study examines a cohort of patients with early-onset scoliosis (EOS) with rib-to-spine or rib-to-pelvis-based MCGR implants to determine if they demonstrate the LODR, and if there are differences in lengthening behaviors between the groups. METHODS: A prospectively collected multicenter EOS registry was queried for patients with MCGR with a minimum 2-year follow-up. Patients with rib-based proximal anchors and either spine- or pelvis-based distal anchors were included. Patients with non-MCGR, unilateral constructs, < 3 lengthenings, or missing > 25% datapoints were excluded. Patients were further divided into Primary-MCGR (pMCGR) and Secondary-MCGR (sMCGR). RESULTS: 43 rib-to-spine and 31 rib-to-pelvis MCGR patients were included. There was no difference in pre-implantation, post-implantation and pre-definitive procedure T1-T12 height, T1-S1 height, and major Cobb angles between the groups (p > 0.05). Sub-analysis was performed on 41 pMCGR and 19 sMCGR rib-to-spine patients, and 31 pMCGR and 17 sMCGR rib-to-pelvis patients. There is a decrease in rod lengthenings achieved at subsequent lengthenings for each group: rib-to-spine pMCGR (rho = 0.979, p < 0.001), rib-to-spine sMCGR (rho = 0.855, p = 0.002), rib-to-pelvis pMCGR (rho = 0.568, p = 0.027), and rib-to-pelvis sMCGR (rho = 0.817, p = 0.007). Rib-to-spine pMCGR had diminished lengthening over time for idiopathic, neuromuscular, and syndromic patients (p < 0.05), with no differences between the groups (p > 0.05). Rib-to-pelvis pMCGR neuromuscular patients had decreased lengthening over time (p = 0.01), but syndromic patients had preserved lengthening over time (p = 0.65). CONCLUSION: Rib-to-spine and rib-to-pelvis pMCGR and sMCGR demonstrate diminished ability to lengthen over subsequent lengthenings.

Perioperative Complications and Health-related Quality of Life Outcomes in Severe Pediatric Spinal Deformity.

STUDY DESIGN: Prospective multicenter cohort study. OBJECTIVE: To evaluate perioperative complications and mid-term outcomes for severe pediatric spinal deformity. SUMMARY OF BACKGROUND DATA: Few studies have evaluated the impact of complications on health-related quality of life (HRQoL) outcomes in severe pediatric spinal deformity. METHODS: Patients from a prospective, multicenter database with severe pediatric spinal deformity (minimum of 100 degree curve in any plane or planned vertebral column resection (VCR)) with a minimum of 2-years follow-up were evaluated (n=231). SRS-22r scores were collected preoperatively and at 2-years postoperatively. Complications were categorized as intraoperative, early postoperative (within 90-days of surgery), major, or minor. Perioperative complication rate was evaluated between patients with and without VCR. Additionally, SRS-22r scores were compared between patients with and without complications. RESULTS: Perioperative complications occurred in 135 (58%) patients, and major complications occurred in 53 (23%) patients. Patients that underwent VCR had a higher incidence of early postoperative complications than patients without VCR (28.9% vs. 16.2%, P =0.02). Complications resolved in 126/135 (93.3%) patients with a mean time to resolution of 91.63 days. Unresolved major complications included motor deficit (n=4), spinal cord deficit (n=1), nerve root deficit (n=1), compartment syndrome (n=1), and motor weakness due to recurrent intradural tumor (n=1). Patients with complications, major complications, or multiple complications had equivalent postoperative SRS-22r scores. Patients with motor deficits had lower postoperative satisfaction subscore (4.32 vs. 4.51, P =0.03), but patients with resolved motor deficits had equivalent postoperative scores in all domains. Patients with unresolved complications had lower postoperative satisfaction subscore (3.94 vs. 4.47, P =0.03) and less postoperative improvement in self-image subscore (0.64 vs. 1.42, P =0.03) as compared to patients with resolved complications. CONCLUSION: Most perioperative complications for severe pediatric spinal deformity resolve within 2-years postoperatively and do not result in adverse HRQoL outcomes. However, patients with unresolved complications have decreased HRQoL outcomes.