Structure-respiration function relationships before and after surgical treatment of early-onset scoliosis

Imaging in Pediatric Lung Disease: Current Practice and Future Directions

Pediatric diseases present differently from adult diseases and imaging forms a cornerstone of modern pediatric care through differential diagnosis, disease monitoring, and measuring response to therapy. Imaging is especially well suited to providing novel insights into the underlying mechanisms driving disease through structural and functional imaging. In this review, we describe key imaging findings in standard-of-care and state-of-the-art techniques in pediatric and adult diseases with origins in childhood. We examine applications in small airways disease, large airway disease, diseases of maturity, interstitial lung disease, neuromuscular disease, congenital disease, and pulmonary infection.

Validity of machine learning algorithms for automatically extract growing rod length on radiographs in children with early-onset scoliosis

The magnetically controlled growing rod technique is an effective surgical treatment for children who have early-onset scoliosis. The length of the instrumented growing rods is adjusted regularly to compensate for the normal growth of these patients. Manual measurement of rod length on posteroanterior spine radiographs is subjective and time-consuming. A machine learning (ML) system using a deep learning approach was developed to automatically measure the adjusted rod length. Three ML models-rod model, 58 mm model, and head-piece model-were developed to extract the rod length from radiographs. Three-hundred and eighty-seven radiographs were used for model development, and 60 radiographs with 118 rods were separated for final testing. The average precision (AP), the mean absolute difference (MAD) ± standard deviation (SD), and the inter-method correlation coefficient (ICC[2,1]) between the manual and artificial intelligence (AI) adjustment measurements were used to evaluate the developed method. The AP of the 3 models were 67.6%, 94.8%, and 86.3%, respectively. The MAD ± SD of the rod length change was 0.98 ± 0.88 mm, and the ICC[2,1] was 0.90. The average time to output a single rod measurement was 6.1 s. The developed AI provided an accurate and reliable method to detect the rod length automatically.

Current Concepts in the Treatment of Early Onset Scoliosis

Despite many surgical advances in the treatment of early onset scoliosis (EOS) over the past two decades, this condition remains a challenge to address. While otherwise healthy children can have EOS, many of these patients have complicated comorbidities making proper treatment algorithms extraordinarily difficult. Non-operative measures can be successful when initiated early, but are many times utilized as a delay tactic until growth-friendly operative procedures can be safely performed. This article will summarize the current concepts in the treatment of EOS with a focus on the surgical advances that have recently been made.

Myelomeningocele: Long-Term Neurosurgical Management

Open spina bifida, also known as myelomeningocele (MMC), is the most challenging and severe birth defect of the central nervous system compatible with life and it is due to a failure in the dorsal fusion of the nascent neural tube during embryonic development. MMC is often accompanied by a constellation of collateral conditions, including hydrocephalus, Arnold - Chiari II malformation, brainstem disfunction, hydrosyringomyelia, tethered cord syndrome and scoliosis. Beyond early surgical repair of the dorsal defect, MMC requires lifelong cares. Several additional surgical procedures are generally necessary to improve the long-term outcomes of patients affected by MMC and multidisciplinary evaluations are crucial for early identification and management of the various medical condition that can accompany this pathology. In this chapter, the most common pathological entities associated with MMC are illustrated, focusing on clinical manifestations, treatment strategies and follow up recommendations.

Impairments in pulmonary functions in paediatric spinal tuberculosis: a cross-sectional study

PURPOSE

This study aimed to investigate the impact of vertebral column destruction and kyphotic deformity due to spinal tuberculosis on pulmonary functions in paediatric patients.

METHODS

A cross-sectional study was conducted, involving 30 patients diagnosed with healed spinal tuberculosis, aged 7-18 years. Detailed radiographic measurements, including the level of involvement, kyphosis angle, Spinal Deformity Index (SDI), and drug-resistance status, were compared with various pulmonary function parameters.

RESULTS

The mean age of the study group was 12.8 ± 2.7 years (range 7-17 years), consisting of 11 males and 19 females. Fourteen patients were managed conservatively and 16 were managed operatively. The mean SDI was 5.2 ± 4.7. The mean kyphotic angle was 31.3° ± 25.3. The average number of involved vertebrae was 2.6 ± 1.5. Pulmonary functions were classified as restrictive in 24 patients, normal in 4 patients, obstructive in 1 patient, and mixed in 1 patient. Multidrug-resistant tuberculosis (MDR-TB) was detected in 5 (16.7%) patients, while the remaining 25 (83.3%) patients were sensitive to conventional antitubercular drugs. The correlation coefficients between the percentage reduction in forced vital capacity (FVC) and kyphosis angle, SDI, and number of vertebrae were 0.4 (p = 0.026), 0.4 (p = 0.028), and 0.19 (p = 0.295), respectively. The mean percentage reduction in FVC and total lung capacity (TLC) were 35.8 ± 15.7 and 6.2 ± 2.3, respectively. No significant association was observed between pulmonary functions and drug sensitivity status (p = 0.074).

CONCLUSIONS

Paediatric spinal tuberculosis can lead to thoracic insufficiency due to progressive destruction and shortening of the spinal column, spinal growth inhibition, and kyphotic deformity. Management of these cases should focus on promoting normal lung development while ensuring disease resolution and deformity correction. Further research should explore growth conserving or growth guiding systems to address or prevent growth retardation and simultaneously provide spinal stabilization.

Evaluation of Pulmonary Function After Halo-Pelvic Traction for Severe and Rigid Kyphoscoliosis Utilizing CT with 3D Reconstruction

BACKGROUND

The purpose of the present study was to evaluate changes in pulmonary function, caused by preoperative halo-pelvic traction (HPT) for the treatment of extremely severe and rigid kyphoscoliosis, with use of 3-dimensional computed tomography (3D-CT) reconstruction and pulmonary function tests (PFTs).

METHODS

Twenty-eight patients with severe and rigid scoliosis (Cobb angle, >100°) underwent preoperative HPT and staged posterior spinal fusion. CT, radiographic assessment, and PFT were performed during pre-traction and post-traction visits. The changes in total lung volume were evaluated with use of 3D-CT reconstruction, and the changes in pulmonary function were evaluated with PFTs at each time point. Differences were analyzed with use of 2-tailed paired Student t tests, and correlations were analyzed with use of Spearman rank tests.

RESULTS

None of the patients had pulmonary complications during traction, and all radiographic spinal measurements improved significantly after HPT. The main Cobb angle was corrected from 143.30° ± 20.85° to 62.97° ± 10.83° between the pre-traction and post-traction evaluations. Additionally, the C7-S1 distance was lengthened from 280.48 ± 39.99 to 421.26 ± 32.08 mm between the pre-traction and post-traction evaluations. Furthermore, 3D lung reconstruction demonstrated a notable increase in total lung volume (TLV) (from 1.30 ± 0.25 to 1.83 ± 0.37 L) and maximum lung height (from 176.96 ± 27.44 to 202.31 ± 32.45 mm) between the pre-traction and post-traction evaluations. Moreover, PFTs showed that total lung capacity (TLC) improved between the pre-traction and post-traction evaluations (from 2.06 ± 0.32 to 2.98 ± 0.82 L) and that the changes in T1-T12 distance and maximum lung height were correlated with changes in TLV (p = 0.0288 and p = 0.0007, respectively).

CONCLUSIONS

The application of HPT is a safe and effective method for improving pulmonary function in patients with extremely severe and rigid scoliosis before fusion surgery. The TLV as measured with CT-based reconstruction was greatly increased after HPT, mainly because of the changes in thoracic height.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Early Onset Scoliosis and Adolescent Idiopathic Scoliosis: A Review of the Literature and Correlations With Pulmonary Dysfunction

In the management of early onset scoliosis (EOS) and adolescent idiopathic scoliosis (AIS), orthopedic surgeons are tasked with considering the effects that curves and their treatment can have on the respiratory system, possibly the most relevant being pulmonary dysfunction due to thoracic cage changes. The pulmonary impairment that occurs as a result of scoliosis varies widely and requires a multimodal response, including physiologic testing, such as pulmonary function tests (PFTs) and consistent psychosocial monitoring of the patient. This forces healthcare providers to consider all factors affecting the patient's quality of life (QOL) and not just the primary pathology they are treating. One method that could be utilized to ensure a more holistic approach to treatment is the use of patient-reported outcome measures (PROMs) to assess the QOL domains. Thus, this review serves to highlight the importance of addressing and correcting pulmonary dysfunction in the care of children with EOS and AIS in a holistic manner.

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.

Long-Term Radiographic and Pulmonary Function Outcomes After Dual Growing-Rod Treatment for Severe Early-Onset Scoliosis

BACKGROUND

We evaluated long-term outcomes (radiographic parameters and pulmonary function) at a minimum follow-up of 5 years after use of dual growing rods (DGRs) to treat severe early-onset scoliosis (sEOS).

METHODS

Among a total of 112 patients who were diagnosed with early-onset scoliosis (EOS) and were treated with DGRs between 2006 and 2015, 52 patients had sEOS, with a major Cobb angle of >80°. Of these patients, 39 with a minimum follow-up of 5 years had complete radiographic and pulmonary function test results and were included. The Cobb angle of the major curve, T1-S1 height, T1-T12 height, and maximum kyphosis angle in the sagittal plane were measured on radiographs. Pulmonary function test results were collected in all patients before the initial operation (preoperatively), 12 months after the initial operation (postoperatively), and at the last follow-up. The changes in pulmonary function and complications during treatment were analyzed.

RESULTS

The mean age of patients before the initial operation was 7.7 ± 1.2 years, and the mean follow-up period was 75.0 ± 14.1 months. The mean number of lengthenings was 4.5 ± 1.3, and the mean interval between lengthenings was 11.2 ± 2.1 months. The Cobb angle improved from 104.5° ± 18.2° preoperatively to 38.1° ± 10.1° after the initial surgical procedure (postoperatively) and 21.9° ± 8.6° at the final follow-up. The T1-S1 height increased from 25.1 ± 4.0 cm preoperatively to 32.4 ± 3.5 cm postoperatively and to 39.5 ± 4.0 cm at the final follow-up. However, no significant difference was detected between the increased pulmonary function parameters at 1 year and those before the operation (p > 0.05), except for residual volume, whereas pulmonary function parameters had significantly increased at the final follow-up (p < 0.05). During the treatment period, 17 complications occurred in 12 patients.

CONCLUSIONS

DGRs are effective in treating sEOS in the long term. They allow longitudinal growth of the spine, and the correction of the spinal deformity can provide conditions that make improving pulmonary function possible in patients with sEOS.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Thoracic insufficiency syndrome: Approaches to assessment and management

Thoracic insufficiency syndrome (TIS) was described in 2003 as the inability of the thorax to support normal respiration or lung growth. TIS includes a broad and disparate group of typically degenerative thoracospinal conditions. Although TIS arises due to a heterogeneous group of disorders and thus its incidence is not well quantified, general approaches to management and treatment exist. Evolving imaging techniques and measurements of health-related quality of life augment tests of pulmonary function to quantify disease burden, longitudinally and pre- and post-intervention. Intervention is primarily via growth-sparing surgery, for which several device options exist, to preserve vertical growth prior to a definitive spinal fusion at skeletal maturity.

Evaluation of the Parameters Affecting Respiratory Functions at Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

This was a retrospective observational study.

OBJECTIVE

The objective of the study was to evaluate the spinal and extraspinal factors responsible for pulmonary dysfunction in adolescent idiopathic scoliosis patients.

SUMMARY OF BACKGROUND DATA

Development of thoracic deformity due to scoliosis results with the restrictive ventilatory pattern and the reduced pulmonary function. To prevent pulmonary function deterioration, it is imperative to understand which factors are causing the restrictive lung disease in adolescent idiopathic scoliosis patients.

MATERIALS AND METHODS

An online database search was conducted in a hospital computerized archive between 2008 and 2018 years. Cobb angle of >30 degrees, Lenke type 1 and 2 patients treated in a single spine unit were included. Coronal and sagittal Cobb angle, bending correction rate for evaluation of flexibility, Risser score, apical vertebra rotation (AVR), and pulmonary function test of patients were obtained.

RESULTS

There was a moderate negative correlation between forced expiratory volume in the first second, forced vital capacity, and AVR. There was no correlation between forced expiratory volume in the first second and forced vital capacity with age, sex, Cobb angle, Risser score, kyphosis, and bending correction rate.

CONCLUSIONS

When considering the results of the current study and the other studies in the literature there is not any strong correlation between the features of scoliotic curvature and respiratory functions. In the current study, 52 (72.22%) of 72 patients with moderate to severe scoliosis had mild to severe respiratory dysfunction. Considering the age-related physiological respiratory loss, to evaluate the necessity of surgical treatment in patients with moderate and severe scoliosis, especially in patients with high AVR, the respiratory functions of the patient should also be evaluated.

LEVEL OF EVIDENCE

Level III.

The Type of Conservative Management Could Be Related to the Strength of the Inspiratory Muscles of Adolescents with Idiopathic Scoliosis—A Case Series

Adolescent idiopathic scoliosis (AIS) is a lateral curvature of the spine with a Cobb angle of at least 10° with an unknown etiology. It is recognized that AIS may affect respiratory function. This study aims to describe and compare respiratory function in a case series of patients with scoliosis who underwent different types of therapeutic management: no intervention, orthotic brace, and global postural reeducation (GPR). Fifteen AIS patients were included in this study (seven no intervention, four orthotic brace and four GPR). Lung function and inspiratory muscle strength were measured and analyzed, as well as sociodemographic, clinical, and anthropometric variables. Significant correlations were observed between height (cm) and maximum inspiratory pressure (MIP) reference (cmH2O) and forced vital capacity (FVC) (liters) (r = 0.650 and r = 0.673, respectively; p < 0.01); weight (Kg) and MIP reference (cmH2O) (r = 0.727; p < 0.01); and Main curve degrees (Cobb angle) and FVC% (r = −0.648; p < 0.01). The AIS cases that underwent GPR treatment presented a greater MIP (% predictive) compared to the no intervention and brace cases (201.1% versus 126.1% and 78.4%, respectively; p < 0.05). The results of this case series show a possible relation whereby patients undergoing treatment with the GPR method have greater inspiratory muscle strength compared to the no intervention and brace cases. Studies with larger samples and prospective designs must be performed to corroborate these results.

Inter- and intrarater reliability of measuring lengthening of magnetically controlled growing rods on digital radiographs

PURPOSE

The aim of this study was to determine inter- and intraobserver reliability of delta rod extension, and total rod length measured on digital x-rays in patients with early onset scoliosis (EOS) treated with magnetically controlled growing rods (MCGR). For the last decade, patients with EOS have been treated with MCGR. Replacement of MCGR relies heavily on the measurement done at every lengthening session. Only a few studies have looked at inter- and intraobserver reliability of rod lengthening, and none have used the delta extension before.

METHODS

202 radiographs presented in random order were rated and measured twice with at least a 14-day interval and differing order of the radiographs. The measuring was done at both rods. All x-rays came from 15 patients diagnosed with EOS and treated with MCGR from 2009 until 2019. The total extension length and the delta extension (the difference in total extension length between two lengthening in succession) were measured, and the intraclass correlation coefficient (ICC) calculated for both measurements RESULTS: Intrarater ICC scores varied from moderate to good, but non-significantly. Interrater reliability increased significantly from moderate (ICC 0.72 [0.68; 0.76] and 0.73 [0.69; 0.77] to excellent (ICC 0.91 [0.88; 0.93] and 0.97 [0.96: 0.98]), when examining delta extension every sixth instead of every second month.

CONCLUSION

Measuring rod lengthening on x-rays can be done every 6 months, with an ample reliability. The ICC's for the delta extension with 2-3 months interval were only moderately precise, compared to the near perfect ICC's for the total extension length.

Three-dimensional reconstruction image by biplanar stereoradiography reflects pulmonary functional states inadolescent idiopathic scoliosis

This study investigated whether the rib cage parameters estimated based on reconstructed three-dimensional (3D) images with biplanar stereoradiography reflect pulmonary functional states in adolescent idiopathic scoliosis (AIS) patients. A total of 67 Lenke type 1 or 2 AIS patients (59 females and 8 males, mean age 14.4 years) were enrolled. All patients underwent preoperative pulmonary functional tests (PFT) and biplanar stereoradiography. Vital capacity (VC) and forced vital capacity (FVC) pulmonary functional data were collected. Rib-cage parameters (maximum thickness, maximum width, thoracic index (TI), rib hump (RH), rib-cage volume (RCV), spinal penetration index (SPI), endothoracic hump ratio (EHR), vertebra-sternum angle (VSA), rib vertebral angle difference (RVAD), and vertebral lateral decentering (VLD)) were quantified from 3D images. Patients were divided into two groups: restrictive lung disorder (RLD) (%FVC < 80%) and non-RLD (%FVC ≥ 80%). The maximum width and RCV were significantly correlated with VC (p < 0.0001), and FVC (p < 0.0001). RH, EHR, and VSA were negatively correlated with %FVC (p < 0.01). TI, SPI, and RVAD were not correlated with any pulmonary parameters. The maximum widths of RLD patients were significantly shorter than those of the non-RLD patients (218.3 mm vs. 229.7 mm, p < 0.01). The RCV of RLD patients was significantly smaller than that of the non-RLD patients (3.94 L vs. 4.49 L, p < 0.0001). The maximum width and RCV measured by 3D images with biplanar stereoradiography reflected pulmonary functional variables in patients with AIS.

Association between health-related quality of life outcomes and pulmonary function testing

INTRODUCTION

Investigations in associations between subjective health-related quality of life (HRQoL) measures and objective clinical assessments in patients with early-onset scoliosis (EOS) are limited. The purpose of this study is to investigate the association between pulmonary function rated by parents and pulmonary function testing (PFT) in patients with EOS.

MATERIALS/METHODS

In this cross-sectional study, patients with EOS at any stage of treatment from 2011 to 2018 were identified in 2 registries including 33 centers. Parents' perception of pulmonary function was evaluated using pulmonary function (PF) domain in the Early-Onset Scoliosis 24 item Questionnaire (EOSQ-24). PFT measures included FVC% predicted, FEV1/FVC, and TLC% predicted. All PFT predicted values utilized arm span. PFT and EOSQ-24 questionnaire were completed within 180 days of each other with an average day difference of 26 days.

RESULTS

176 patients (mean age: 10.4 years old, female: 56%) were identified. 33% of patients were of congenital/structural etiology, 27% neuromuscular, 26% syndromic, and 14% idiopathic. Wide variance and lower scores of PF domain were reported by parents at lower FVC% predicted values (< 50%). As FVC% predicted values increased, PFD scores increased with simultaneous decreases in variance with few exceptions.

CONCLUSION

More variability and frequent lower pulmonary function values are reported by parents when percent forced vital capacity (FVC%) is < 50%. This likely reflects the degree to which children adapt to restrictive lung disease and the limits on adaptation that occur increasingly as lung function falls below 50% predicted. As a direct linear association with high correlation was expected, more research into the character of what the PF domain is measuring is necessary.

LEVEL OF EVIDENCE

IV.

Systematic investigation of metallosis associated with magnetically controlled growing rod implantation for early-onset scoliosis

AIMS

To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod.

METHODS

This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining.

RESULTS

Titanium (Ti), vanadium (V), and neodymium (Nd) concentrations in the biopsies taken near the wear marks were found to be significantly higher than those in the control tissue samples. Significantly increased Nd concentrations were also found in the tissues near the barrel of the MCGR. Chronic inflammation was revealed by the histological studies with fibrosis and macrophage infiltration. Black particles were present within the macrophages in the fibrotic tissues.

CONCLUSION

Ti and V were generated mainly at the BO due to metal-on-metal contact, whereas the Nd from the rotor of the MCGR is likely released from the BO during distraction sessions. Phagocytotic immune cells with black particles inside raise concern regarding the long-term implications of metallosis. Cite this article: Bone Joint J 2020;102-B(10):1375-1383.

Image Distortion in Biplanar Slot Scanning: Patient-specific Factors

BACKGROUND

Error within imaging measurements can be due to processing, magnification, measurement performance, or patient-specific factors. Previous length measurement studies based on radiographs have shown good intraclass correlation coefficients (ICCs) on single images; but have not assessed interimage distortion. In our study, "image distortion in biplanar slot scanning: technology-specific factors" we determined that there is minimal image distortion due to the image acquisition when using biplanar slot scanning. In this study, we aim to determine the role of patient-specific factors in image distortion, specifically evaluating interimage distortion.

METHODS

Digital radiographs and biplanar slot scanner images were reviewed in 43 magnetically controlled growing rod (MCGR) patients. Fifty-five postoperative anteroposterior digital radiographs, 184 follow-up biplanar slot-scanner scanner posteroanterior and 76 biplanar slot-scanner scanner laterals were measured by 2 residents and 1 attending. The manufacturer reported average actuator diameter of 9.02 mm was used as our reference width.

RESULTS

Overall, within image interobserver ICC were moderate to excellent (0.635 to 0.983), but the interimage ICCs were poor (0.332). Digital radiographs consistently overestimated the MCGR actuator width (mean=9.655) and biplanar slot-scanner scanner images underestimated it (mean=8.935). The measurement range was large with biplanar slot-scanner scanner posteroanterior (up to 15%) and lateral (22%) measurements and with digital radiographs (39%). Patients with abnormal muscle tone had higher degrees of measurement variability.

CONCLUSIONS

We found that neither biplanar slot scanning nor digital radiography was precise or accurate. Digital radiographs consistently overestimated MCGR actuator width and biplanar slot scanning underestimated it. The poor ICC's within and between image subtypes and large standard error of measurement reflected a magnitude of distortion that needs to be accounted for when using length measurements clinically. Unlike the clinically insignificant error that we noted in our previous study "image distortion in biplanar slot scanning: technology-specific factors" (0.5% to 1.5% of the measurement), the error noted in this study (0.2% to 38.5% of the measurement) has the potential to be clinically significant. Patients who have abnormal muscle tone had larger measurement errors, likely stemming from motion during the slot scanning process.

LEVEL OF EVIDENCE

Level III.

Preoperative 6-Minute Walk Performance in Children With Congenital Scoliosis

BACKGROUND

The 6-minute walk test (6MWT) is used to assess the function of cardiopulmonary and neuromuscular conditions in adults and children. The primary research question was to determine the relationship between 6MWT distance and forced vital capacity (FVC) and the major curve among children with congenital scoliosis with rib anomalies.

METHODS

The authors recorded 6MWT distance in meters, FVC as a percentage of predicted normal value using arm span for height (FVC%), and Cobb angle in 20 children (13 girls; average age, 6.7±1.3 y) with congenital scoliosis before outpatient surgical treatment. The 6MWT uses a standardized protocol and measures distance traveled in 6 minutes on a flat surface. The authors then determined the correlation between these measures using linear regression analysis.

RESULTS

The Cobb angle of the major curvature was 55.4±20.5 degrees. The type of vertebral anomaly was mixed in 17 cases, formation failure in 2 cases, and segmentation failure in 1 case. The range of rib anomalies was 3.4±3.9 levels; 15 and 5 patients, respectively, had unilateral and bilateral rib anomalies. FVC and FVC% were 0.7±0.2 L and 60%±19%, respectively. The ratio of forced expiratory volume at 1 second to FVC (FEV1/FVC), which indicates obstructive lung disease, was normal at 93%±7%. The 6MWT distance was 386.3±59.4 m, which was ≤10% of the predicted distance for normal children. No child was able to walk the normal distance on the basis of published norms. 6MWT distance was significantly correlated with arm span (ρ=0.46, P=0.04) and major curve (ρ=-0.61, P=0.004), but not with FVC% (ρ=0.17, P=0.49).

CONCLUSIONS

The 6MWT distance is a feasible measure of function and is substantially reduced before surgery in children with thoracic congenital scoliosis with rib anomalies. The 6MWT distance was significantly correlated with a major curve but not with FVC%. 6MWT distance is not affected by moderate lung function impairment.

LEVEL OF EVIDENCE

Level IV-retrospective cohort study.

Growing-rod Graduates With Idiopathic Early-onset Scoliosis Have Comparable Exercise Tolerance to Patients With Surgically Treated Adolescent Idiopathic Scoliosis

BACKGROUND

Growing-rod (GR) treatment is the current standard for progressive idiopathic early-onset scoliosis (I-EOS) in young children. Despite good radiographic outcomes, the impact of scoliosis treatment on pulmonary functions is not well-defined in this patient population. The aim of this study was to evaluate pulmonary functions and exercise tolerance in I-EOS patients graduated from GR treatment and to compare them with age-matched, surgically treated adolescent idiopathic scoliosis (AIS) patients and healthy controls.

METHODS

Eight GR graduates with I-EOS with pulmonary function tests and complete radiographic results were compared with a group of 9 thoracic AIS patients at least 2 years out from posterior fusion. Both groups were also compared with a set of 10 healthy individuals. All subjects underwent cardiopulmonary exercise testing and spirometry to evaluate pulmonary function.

RESULTS

Age, sex, height, arm span, weight, residual deformity, and level of instrumentation in GR and AIS patients were similar. In the GR group, forced vital capacity % and forced expiratory volume in 1 second % values were reduced compared with the healthy controls and AIS group (P<0.001, <0.001 and 0.036, 0.046, respectively). Breathing reserve index at lactate threshold (BRILT) was higher in GR and AIS patients (P=0.001 and 0.002, respectively), and was similar between GR and AIS patients (P=0.916). Heart rate at lactate threshold was higher in GR and AIS groups compared with controls (P<0.001 and 0.001, respectively).

CONCLUSIONS

AIS and GR patients demonstrated reduced pulmonary reserve and exercise tolerance compared with their peers with no spinal deformity. However, exercise tolerance of I-EOS patients treated with the GR method was similar to that of operated AIS patients. These results suggest a positive impact of GR treatment in children with I-EOS.

LEVEL OF EVIDENCE

Level III-cross-sectional comparative study.

Current status of the magnetically controlled growing rod in treatment of early-onset scoliosis: What we know after a decade of experience

The magnetically controlled growing rod (MCGR) has had approximately 10 years of clinical experience worldwide. Clinical effectiveness to control early-onset scoliosis is consistent even at final surgery. MCGRs have significantly lower relative percentage of infection or wound complications as compared to traditional growing rods. Most common complications include foundation failure and failure of distraction. Contouring of the rod especially at the proximal segment while accommodating for the straight actuator remains a difficult task and its failure may lead to proximal junctional kyphosis. Unique complications of MCGR include clunking, temporary diminishing distraction gains, and metallosis. Temporary reductions in distraction gains are observed as the MCGR lengthens but return to normal baseline distraction gains after rod exchange. Lack of standardization for rod configuration, distraction strategies and decisions of whether to keep the rods in situ, remove without fusion surgery or to perform spinal fusion at skeletal maturity will require further study.

Clinical Issues for Pediatric Pulmonologists Managing Children With Thoracic Insufficiency Syndrome

Thoracic insufficiency Syndrome (TIS) is a recently coined phrase to describe children with spine and chest wall deformities, inherited and acquired, who have respiratory impairment, and are skeletally immature. This population has both restrictive and less often obstructive lung disease due to changes in spine and rib configuration which reduce lung volume, stiffen the chest wall, and reduce respiratory muscle strength. Although the population is heterogeneous with regard to age of onset, etiology, severity of deformity, and rate of progression of the deformity, there are common issues that arise which can be addressed by pediatric pulmonologists. These are illustrated in this review by using Early Onset Scoliosis as a common form of TIS. The pulmonary issues pertaining to TIS require collaboration with multi-disciplinary teams, particularly spine surgeons, in order to make decisions about non-surgical and surgical strategies, timing of surgery and medical supportive care over time. Pulmonary input about respiratory function should be used in conjunction with structural features of each deformity in order to determine the impact of the deformity and the response to various treatment options. In those patients with residual lung function impairment as young adults, pediatric pulmonologists must also ensure successful transition to adult care.

The effect of magnetically controlled growing rods on three-dimensional changes in deformity correction

STUDY DESIGN

Prospective radiographic study.

OBJECTIVES

To determine the three-dimensional (3D) changes in deformity correction with magnetically controlled growing rod (MCGR) distractions. MCGRs can achieve similar coronal plane correction as traditional growing rods. The changes in the sagittal and axial planes are unknown and should be studied as these factors reflect potential for proximal junctional kyphosis and rotational deformity. Frequent MCGR distractions may potentially improve axial plane deformities to the same extent as coronal and sagittal plane deformities.

METHODS

Early onset scoliosis (EOS) patients who underwent dual MCGRs with minimum 2-year follow-up were included in this study. 3D reconstructions of 6-monthly biplanar images were used to study changes in coronal, sagittal and axial planes. Changes in growth parameters (body height and arm span) were scaled to changes in coronal Cobb angles, sagittal profile (T1-12, T4-12, L1-L5, L1-S1), and rotational profile at the proximal thoracic, main thoracic and lumbar curves, and pelvic parameters (sagittal pelvic tilt, lateral pelvic tilt and pelvis rotation).

RESULTS

A total of 10 EOS patients were studied. The mean age at index surgery was 8.2 ± 3.0 years and mean postoperative follow-up of 34.3 ± 9.5 months. Six patients had rod exchange at mean 29.5 ± 11.8 months after initial implantation. Despite consistent gains in body height and arm span, the main changes in coronal and rotational profiles only occurred at the initial rod implantation surgery with only small changes occurring with subsequent follow-ups. Patients with higher preoperative proximal junctional angles had flattening of the sagittal plane occurring at initial surgery with early rebound. No changes in pelvic parameters were observed.

CONCLUSIONS

The 3D changes with MCGR are mainly observed with initial rod implantation and no significant changes are observed with distractions. The MCGR can prevent deformity progression in the axial plane.

LEVEL OF EVIDENCE

IV.

Two-stage posterior spinal fusion for early-onset scoliosis: Two case reports

RATIONALE

Fusionless techniques for early-onset scoliosis (EOS) have evolved to allow near-normal growth while maintaining the correction achieved during the initial surgery. However, such procedures require repeated surgeries and have increased complication rates. We have developed a 2-stage fusion technique using pedicle screws for EOS to reduce patient burden and complication risk. This series describes the clinical and radiological features of 2 patients with EOS who received 2-stage posterior spinal fusion. This surgical method for EOS represents the first of its kind.

PATIENT CONCERNS

Case 1 was a 10-year-old girl who was diagnosed as having scoliosis with Prader Willi syndrome at the age of 2 years. Her preoperative major curve Cobb angle was 100 degrees at age 10 years. Case 2 was an 11-year-old boy who was found to have scoliosis with 22q11.2 deletion syndrome at the age of 4 years. His preoperative major curve Cobb angle was 77 degrees at age 11 years.

DIAGNOSIS

Whole-spine radiographs were performed to diagnose scoliosis.

INTERVENTIONS

Both patients received 2-stage posterior spinal fusion.

OUTCOMES

Postoperative Cobb angle of the major curve improved to 46 and 48 degrees, respectively. Thoracic height respectively improved from 160 and 148 mm before surgery to 206 and 211 mm at final follow-up. Surgical outcome as evaluated by Scoliosis Research Society-22 patient questionnaires revealed acceptable results without any severe complications.

LESSONS

Based on the present case report, 2-stage posterior spinal fusion for EOS achieves good radiological and clinical outcomes without severe complications.

Ventilation/perfusion SPECT/CT in patients with severe and rigid scoliosis: An evaluation by relationship to spinal deformity and lung function

OBJECTIVE

Structural changes of the spine and chest wall associated with SRS result in poor cardiopulmonary function. Comprehensive assessment of pulmonary function is extremely important for patients with SRS before a correction operation. We explore the changes of distribution of lung ventilation and perfusion function in patients with SRS using SPECT/CT and describe the relation between these changes with Cobb angle and FVC%.

PATIENTS AND METHODS

From March 2015 to August 2016, 16 consecutive SRS patients with a mean age of 20.1 years(range 11-36 years) were included in the study. Scoliotic parameters on radiographs were analyzed. FVC% were obtained by spirometry test. Lungs ventilation/perfusion single photon emission computed tomography scans was performed preoperatively in all patients to explore pulmonary ventilation and perfusion function changes. These changes were measured as the deviation form the normal perfusion and ventilation function distribution in right and left lung and correlated with the Cobb angle of main curve and FVC%.

RESULTS

The regional lung ventilation and perfusion function defects were not found in all SRS patients. Ventilation function deviation was a mean 5.7%(range, -3.6% to 10.1%), significantly less than perfusion function deviation of 8.2%(range, -0.3% to 22.2%) (P = 0.015, t = -2.732). Lung ventilation and/or perfusion function deviation did not correlated with Cobb angle and FVC%, respectively. There was significant correlation between lungs ventilation and perfusion function deviation(P = 0.001, r = 0.753).

CONCLUSION

The ventilation and perfusion function distribution were favourable in convex and concave side lung of SRS. Deformity bring about greater lungs perfusion function changes than ventilation function. The measurement of lung ventilation and perfusion function changes may represents an additional functional feature to assess pulmonary function of SRS more comprehensively.

Expansion Thoracoplasty in Rabbit Model: Effect of Timing on Preserving Pulmonary Growth and Correcting Spine Deformity

STUDY DESIGN

In a treatment-control animal study expansion thoracoplasty (ET) was performed in a juvenile rabbit model of thoracic insufficiency syndrome (TIS) and benefits to thoracic development and respiratory function quantified. Rabbits treated early versus late were compared to age-matched normal and disease control rabbits through to skeletal maturity.

OBJECTIVE

Evaluate (1) how ET changes the natural TIS disease trajectory and (2) how timing of ET affects changes in spine growth, lung growth, and respiratory mechanics.

SUMMARY OF BACKGROUND DATA

Pulmonary growth potential is thought to diminish with age; thus, early therapeutic intervention may increase pulmonary growth in children with TIS. However, no direct empirical evidence exists to support this treatment paradigm.

METHODS

Convex left scoliosis and resultant TIS was induced in 3-week-old rabbits via surgical rib tethering. We compare the efficacy of ET performed at 7 weeks and expanded at 11 weeks (early, n = 7) versus only at 11 weeks of age (late, n = 7) in preserving lung growth and respiratory function relative to normal (n = 8) and disease (n = 10) rabbits. Sequential computed tomography images and pulmonary function testing was performed to quantify spine curvature, lung growth, and respiratory volumes. At 28 weeks of age chest wall elastance was measured in vivo then acinar complexity analyzed histologically via radial alveolar counts.

RESULTS

ET performed early or late altered the predicted trajectory of spine deformity, pulmonary growth inhibition, and respiratory dysfunction seen in disease rabbits. Growth was not significantly different between early and late rabbits and post-treatment gains remained below those of age-matched normal rabbits. Chest wall elastance was impaired by ET and more so in early rabbits, there were no differences in pulmonary elastance.

CONCLUSION

ET interrupted the natural progression of deformity and pulmonary hypoplasia associated with spine curvature in disease rabbits. However, growth benefits are only seen in cases of the most severe initial deformity and must be balanced against the further impairment to chest wall function associated with repetitive surgery.

LEVEL OF EVIDENCE

N/A.

Early-onset Scoliosis: Contemporary Decision-making and Treatment Options

Early-onset scoliosis (EOS) describes a wide array of diagnoses and deformities exposed to growth. This potentially life-threatening condition is still 1 of the biggest challenges in pediatric orthopaedics. The enlightenment of Bob Campbell's thoracic insufficiency syndrome concept and the negative impact of the earlier short and straight spine fusion approach on respiratory function and survival have fueled the evolution of EOS care. Despite all the progress made, growth-friendly spine surgery remains to be a burden to patients and caregivers. Even down-sized implants and remote-controlled noninvasive rod expansions do not omit unexpected returns to the operating room: failures of foundations, rod breakage, difficulties to keep the sagittal balance, progressive transverse plane deformities, stiffening, and the need for final instrumented fusion are still common. However, past experience and the current multitude of surgical strategies and implants have sharpened the decision-making process, patients with thoracic insufficiency syndrome require earliest possible vertical expandable prosthetic titanium ribs application. Flexible deformities below 60 degrees, with normal spinal anatomy and without thoracic involvement, benefit from serial Mehta casting which revived as a long available but not-used strategy. In case of progression, standard double growing rods or-if available, affordable, and applicable-magnetically controlled motorized rods provide deformity control and growth promotion. Shilla growth-guiding technique is a less costly alternative. Its lack of stiff lengthening boxes or actuators may be beneficial in difficult deformities. Anterior convex flexible tethering promises benefits of sparing the trunk muscles and keeping mobility. However, this step towards a true nonfusion concept has yet to stand the test of broad clinical application.

The Final 24-Item Early Onset Scoliosis Questionnaires (EOSQ-24): Validity, Reliability and Responsiveness

INTRODUCTION

The goal of early-onset scoliosis (EOS) treatment is to improve health-related quality of life (HRQoL) for patients and to reduce the burden on their parents or caregivers. The purpose of this study is to develop and finalize the 24-item Early-Onset Scoliosis Questionnaire (EOSQ-24), and examine the validity, reliability, and responsiveness of the EOSQ-24 in measuring patients' HRQoL, the burden on their caregivers, and the burden on their caregiver's finances. The study also established aged-matched normative values for the EOSQ-24.

METHODS

The EOSQ-24 was administered to caregivers of male and female patients aged 0 to 18 years with EOS. Patients with EOS are diagnosed before 10 years of age. Criterion validity was investigated by measuring agreement between its scores and pulmonary function testing. Construct validity was established by comparing values across different etiology groups using the known-group method, and measuring internal consistency reliability. Content validity was confirmed by reviewing caregiver and health provider ratings for the relativity and clarity of the EOSQ-24 questions. Test-retest reliability was examined through intraclass correlation coefficients. Responsiveness of the EOSQ-24 before and after surgical interventions was also investigated. Age-matched, healthy patients, without spinal deformity, were enrolled to establish normative EOSQ-24 values.

RESULTS

The pulmonary function subdomain score in the EOSQ-24 was positively correlated with pulmonary function testing values, establishing criterion validity. The EOSQ-24 scores for neuromuscular patients were significantly decreased compared with idiopathic or congenital/structural patients, demonstrating known-group validity. Internal consistency reliability of patients' HRQoL was excellent (0.92), but Family Burden was questionable (0.64) indicating that Parental Burden and Financial Burden should be in separate domains. All 24 EOSQ items were rated as essential and clear, confirming content validity. All EOSQ-24 domains demonstrated good to excellent agreement (0.68 to 0.98) between test and retest scores. Neuromuscular patients improved their HRQoL postoperatively, whereas idiopathic patients worsened their HRQoL postoperatively, indicating the ability of the instrument to respond to different trajectories of HRQoL according to etiology in patients with EOS.

DISCUSSION

The developed and finalized EOSQ-24 is a valid, reliable, and responsive instrument that is able to serve as a patient-reported outcome measure evaluating health status for patients with EOS and burden of their caregivers. This instrument will be able to serve as an outcome measure for future research including clinical trials evaluating the effectiveness of various treatments. In addition, the EOSQ-24 allows assessment of patients' HRQoL, and the burden on their caregivers relative to age-matched healthy peers.

LEVEL OF EVIDENCE

Level II-diagnostic study with consecutive patients enrolled in national registries.

Traditional growing rod versus magnetically controlled growing rod for treatment of early onset scoliosis: Cost analysis from implantation till skeletal maturity

PURPOSE

To compare the yearly cost involved per patient in the use of magnetically controlled growing rod (MCGR) and traditional growing rods (TGRs) in the treatment of early onset scoliosis (EOS) and to assess the overall cost burden of MCGR with reference to patient and health-care infrastructure.

METHODS

For a hypothetical case of a 5-year-old girl with a diagnosis of EOS, a decision-tree model using TreeAge Software was developed to simulate annual health state transitions and compare the 8-year accumulative direct, indirect, and total cost among the four groups: (1) dual MCGRs with exchange every 2 years, (2) dual MCGRs with exchange every 3 years, (3) TGR with surgical distraction every year, and (4) TGR with surgical distraction every 6 months. Base-case values and ranges of clinical parameters reflecting complication rate after each type of surgical distraction were determined from a review of literature and expert opinion. Government gazette and expert opinion provided cost estimation of growing rods, surgeries, surgical complications, and routine follow-up. Microsimulation of 1000 individuals was conducted to test the variation in total direct costs (in 2016 Hong Kong dollars (HKD)) between individuals, and estimated the standard deviations of total direct costs for each group.

RESULTS

Over the projected treatment period, indirect costs incurred by patients and family were higher for the MCGR as compared to the TGR. However, the total costs incurred by MCGR groups (group 1: HKD164k; group 2: HKD138k) were lower than those incurred by TGR groups (group 3: HKD191k; group 4: HKD290k). Although the accumulative costs of three groups (TGR with distraction every year and MCGR replacing every 2 and 3 years) were approaching each other in the first 2 years after initial implantation, at year 3 the accumulative cost of MCGR exchange every 2 years was HKD36k more than the yearly TGR surgery due to the cost of implant exchange. The cost incurred by both the MCGR groups was less than that incurred by the TGR groups from year 4 to skeletal maturity.

CONCLUSIONS

The use of dual MCGRs, regardless of its 2- or 3-year exchange, was only cost saving and less expensive than the dual TGRs for EOS treatment from the fourth year of continuous treatment. Despite higher patient-related costs during MCGR treatment, it is important to consider the reduced risks and mental burden suffered by these children during repeat surgeries. With improved knowledge of the costs associated with long-term MCGR use, better constructed cost-effectiveness studies can be performed in the future.

Adolescent Idiopathic Scoliosis Thoracic Volume Modeling: The Effect of Surgical Correction

BACKGROUND

Scoliosis has been shown to have detrimental effects on pulmonary function, traditionally measured by pulmonary function tests, which is theorized to be correlated to the distortion of the spine and thorax. The changes in thoracic volume with surgical correction have not been well quantified. This study seeks to define the effect of surgical correction on thoracic volume in patients with adolescent idiopathic scoliosis.

METHODS

Images were obtained from adolescents with idiopathic scoliosis enrolled in a multicenter database (Prospective Pediatric Scoliosis Study). A convenience sample of patients with Lenke type 1 curves with a complete data set meeting specific parameters was used. Blender v2.63a software was used to construct a 3-dimensional (3D) computational model of the spine from 2-dimensional calibrated radiographs. To accomplish this, the 3D thorax model was deformed to match the calibrated radiographs. The thorax volume was then calculated in cubic centimeters using Mimics v15 software.

RESULTS

The results using this computational modeling technique demonstrated that surgical correction resulted in decreased curve measurement as determined by Cobb method, and increased postoperative thoracic volume as expected. Thoracic volume significantly increased by a mean of 567 mm (P<0.001). The percent change in thoracic volume after surgical correction averaged 40% (range, 3% to 87%). The smaller the baseline volume, the greater the change in volume postoperatively (r=-0.86).Evaluation of postoperative data demonstrated that spinal curve measurement as determined by Cobb method was significantly reduced from a mean of 69 degrees (range, 50 to 96 degrees) preoperatively to 27 degrees (range, 13 to 33 degrees) postoperatively (P<0.001).

CONCLUSIONS

This pilot study demonstrates methodologic plausibility for measuring 3D changes in thoracic volumes using 2-dimensional imaging. This is an assessment of the novel modeling technique, to be used in larger future studies to assess clinical significance.

LEVEL OF EVIDENCE

Level 3-retrospective comparison of prospectively collected data.

Maximal Respiratory Muscle Strength and Vital Capacity in Children With Early Onset Scoliosis

STUDY DESIGN

Descriptive cross-sectional study.

OBJECTIVE

To measure respiratory muscle function in children with early onset scoliosis (EOS), determine the frequency of respiratory muscle weakness, and correlate these measures with vital capacity, body mass index, and Cobb angle.

SUMMARY OF BACKGROUND DATA

Progressive restrictive respiratory disease is common among children with moderate to severe EOS. Reduced respiratory muscle strength is associated with the loss of lung function in adolescents and adults with scoliosis. We hypothesized that reduced inspiratory and expiratory respiratory muscle strength also occur in children with EOS and correlate with reduced vital capacity, poor nutritional status, and severity of the spine deformity.

METHODS

We measured maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), forced vital capacity (FVC), body mass index IBMI), and Cobb angle in 49 children with EOS but with no diagnosis of underlying muscle weakness. We measured these indices in 12 children serially over 18 months to see if abnormal respiratory muscle function was sustained.

RESULTS

FVC averaged 51% (SD 21) of predicted norms with 26 subjects having an FVC <50% predicted. The mean MIP was 57% (SD 25) and the mean MEP was 53% (SD 23) of predicted norms. Thirteen (27%) of the group had MIP values >2SD below the age and sex-based norms. BMI ranged between 1% and 99% of age-based norms. Cobb angle averaged 59° (SD27). MIP% and MEP% significantly correlated with FVC% (r =0.37, P = 0.01 and r = 0.52, P < 0.001 respectively)) but not with BMI or Cobb angle. Reduced MIP% and MEP% were sustained over 7 to 41 months.

CONCLUSION

Respiratory muscle weakness is common and persistent in children with EOS and correlates with reductions in vital capacity. Mechanisms for abnormal respiratory function are unclear but must be determined to develop surgical treatment strategies that preserve respiratory muscle function in children with EOS throughout childhood.

LEVEL OF EVIDENCE

2.

Managing the Pediatric Spine: Growth Assessment

Management of pediatric spinal deformities requires an accurate prediction of growth spurts to allow for timely initiation of treatment and prevention of curve progression. Determining remaining growth potential is also important for avoiding prolonged unnecessary treatment, e.g. bracing for patients nearing skeletal maturity. Many clinical and radiological growth parameters have been developed to aid clinicians in growth prediction. Of these, several commonly used measures such as height and arm span growth trends, timing of menarche, and the Risser sign are mostly retrospective and lack strong predictive utility. Bone age assessments, such as digital skeletal age and the distal radius and ulna classification, are more accurate parameters, but further research is required to determine interethnic variations and develop their role in management decisions.

Pulmonary function tests correlated with thoracic volumes in adolescent idiopathic scoliosis

Scoliosis deformity has been linked with deleterious changes in the thoracic cavity that affect pulmonary function. The causal relationship between spinal deformity and pulmonary function has yet to be fully defined. It has been hypothesized that deformity correction improves pulmonary function by restoring both respiratory muscle efficiency and increasing the space available to the lungs. This research aims to correlate pulmonary function and thoracic volume before and after scoliosis correction. Retrospective correlational analysis between thoracic volume modeling from plain x-rays and pulmonary function tests was conducted. Adolescent idiopathic scoliosis patients enrolled in a multicenter database were sorted by pre-operative Total Lung Capacities (TLC) % predicted values from their Pulmonary Function Tests (PFT). Ten patients with the best and ten patients with the worst TLC values were included. Modeled thoracic volume and TLC values were compared before and 2 years after surgery. Scoliosis correction resulted in an increase in the thoracic volume for patients with the worst initial TLCs (11.7%) and those with the best initial TLCs (12.5%). The adolescents with the most severe pulmonary restriction prior to surgery strongly correlated with post-operative change in total lung capacity and thoracic volume (r²  = 0.839; p < 0.001). The mean increase in thoracic volume in this group was 373.1 cm³ (11.7%) which correlated with a 21.2% improvement in TLC. Scoliosis correction in adolescents was found to increase thoracic volume and is strongly correlated with improved TLC in cases with severe restrictive pulmonary function, but no correlation was found in cases with normal pulmonary function. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:175-182, 2017.

Exercise Tolerance in Children With Early Onset Scoliosis: Growing Rod Treatment "Graduates"

STUDY DESIGN

Prospectively enrolled early-onset scoliosis (EOS) patients undergoing growing rod treatment, who have had no surgery for >1 year and/or have received definitive fusion (growing rod "graduates").

OBJECTIVES

To assess oxygen consumption during exercise and determine if a diminished conventional pulmonary function test (PFT) correlates with metabolic, pulmonary, and cardiovascular measures during exercise.

SUMMARY OF BACKGROUND DATA

Based on clinical impression and sequential PFT values, EOS patients who have undergone extensive treatment are thought to have limited capacity during exercise. The use of PFTs in this population has been a primary outcome measure of respiratory capacity; however, PFTs are dependent on effort, and thus subjective. This led us to find a new assessment of outcome, to better understand their pulmonary capacity.

METHODS

Patients underwent oxygen consumption (VO₂) testing while walking at self-selected speed over-ground and during a graded exercise test. Maximal VO₂ was predicted in those who completed the test to 85% of maximal heart rate (HR). Statistical analysis included Mann-Whitney U test and Spearman correlation coefficient (α = 0.05).

RESULTS

12 patients participated. Over-ground walking showed that EOS graduates chose to walk at the same speed, but at a higher VO₂ Cost (0.28 mL/kg/m) than controls (0.22 mL/kg/m; p < .001). Treadmill exercise testing showed 9 of 12 subjects able to complete the 85% of predicted maximum protocol. The EOS group had lower VO₂ during the final stage (27.9 mL/kg/min) compared to controls (34.2 mL/kg/min; p = .021); however, their heart rate reached the same values. Subjects completing the protocol had lower predicted VO₂ max (38.5 mL/kg/min) compared with controls (45.0 mL/kg/min), but this was not significant.

CONCLUSIONS

Although PFT data suggest clinically relevant pulmonary compromise in EOS patients, the current study shows that these children are able to keep up with their peers in daily activities and also have the capacity to exercise.

LEVEL OF EVIDENCE

Level II, therapeutic.

Thoracic Insufficiency Syndrome

Thoracic insufficiency syndrome (TIS) is a broad grouping of disorders that have a substantial impact on the chest wall, spine, and in many situations, both. While the conditions are varied, they share a potentially substantial impact on respiratory capacity and development over time and a presentation and need for intervention that is often in early childhood. Addressing these conditions has required a new paradigm that involves both deformity correction and a preservation of growth capacity. While there are now a number of options to treat severe spinal deformity early in life, when the deformity causes or is caused by a chest wall deformity, the Vertical Expandable Prosthetic Titanium Rib(VEPTR) is able to support surgical correction of both. The skeletal correction is often quite dramatic, but the functional measurements of quality of life and pulmonary function often do not show as dramatic and improvement, but consistently show a stabilization indicating control of the progressive thoracospinal disorder that produced TIS.

Clinical utility of ultrasound to prospectively monitor distraction of magnetically controlled growing rods

BACKGROUND CONTEXT

Growing rods are commonly used for surgical treatment of skeletally immature patients with scoliosis, but require repeated surgeries for distractions and are fraught with complications. As an alternative, the use of magnetically controlled growing rods (MCGR) allows for more frequent non-invasive distractions to mimic normal growth. However, more plain radiographs are needed to monitor increased distraction frequency, thereby increasing ionizing radiation exposure to the developing child. The use of ultrasound, which emits no radiation, has been found in a cross-sectional study to be reliable in measuring MCGR distractions.

PURPOSE

The study aims to address the prospective clinical utility of ultrasound compared with plain radiographs for assessing MCGR distractions.

STUDY DESIGN

This is a prospective study.

PATIENT SAMPLE

The study includes patients with early-onset scoliosis undergoing distractions after MCGR implant.

OUTCOME MEASURES

The distraction length on plain radiographs and ultrasound was measured.

METHODS

This is a prospective study of patients treated with MCGR. Patients with both single- and dual-rod systems were included. Outpatient distractions were performed at monthly intervals, targeting 2 mm of distraction on each occasion. Assessment of distraction length was monitored by ultrasound at each visit; plain radiographs were taken every 6 months and were compared with ultrasound measurements.

RESULTS

Nine patients (5 female, 4 male), with a mean of 29 distractions (standard deviation [SD] ±14.3), were recruited. The mean distracted length per 6 months was 5.7 mm (SD ±3.6 mm) on plain radiographs and 5.2 mm (SD ±3.9 mm) on ultrasound for the concave rod, and 6.1 mm (SD ±3.6 mm) on plain radiographs and 5.9 mm (SD ±3.8 mm) on ultrasound for the convex rod. Excellent inter- and intra-rater reliabilities were observed for radiographic and ultrasound measurements. An excellent correlation was noted between the two imaging modalities (r=0.93; p<.0001).

CONCLUSIONS

This is the first prospective study to validate that ultrasound assessment of MCGR distraction lengths was highly comparable with that of plain radiographs. The present study has verified that ultrasound can be used to document length changes by distraction over time and that it had high clinical utility. Ultrasound can be a reliable alternative to plain radiographs, thereby avoiding radiation exposure and its potential detrimental sequelae in the developing child.

Early-Onset Scoliosis: A Review of History, Current Treatment, and Future Directions

Early-onset scoliosis (EOS) is defined as curvature of the spine in children >10° with onset before age 10 years. Young children with EOS are at risk for impaired pulmonary function because of the high risk of progressive spinal deformity and thoracic constraints during a critical time of lung development. The treatment of EOS is very challenging because the population is inhomogeneous, often medically complex, and often needs multiple surgeries. In the past, early spinal fusion was performed in children with severe progressive EOS, which corrected scoliosis but limited spine and thoracic growth and resulted in poor pulmonary outcomes. The current goal in treatment of EOS is to maximize growth of the spine and thorax by controlling the spinal deformity, with the aim of promoting normal lung development and pulmonary function. Bracing and casting may improve on the natural history of progression of spinal deformity and are often used to delay surgical intervention or in some cases obviate surgery. Recent advances in surgical implants and techniques have led to the development of growth-friendly implants, which have replaced early spine fusion as the surgical treatment of choice. Treatment with growth-friendly implants usually requires multiple surgeries and is associated with frequent complications. However, growth-friendly spine surgery has been shown to correct spinal deformity while allowing growth of the spine and subsequently lung growth.

Special article: Update on the magnetically controlled growing rod: tips and pitfalls

Magnetically controlled growing rods (MCGR) have become an important treatment option in young patients with spinal deformities. This device allows for gradual lengthening on an outpatient setting with continuous neurological monitoring in an awake patient. With its growing popularity and interest, this study reports the tips, pitfalls, and complications of the MCGR for management of scoliosis. On 3 June 2015 at the University of Hong Kong, 32 participants from 16 regions shared their experience with MCGR. Current indications for surgery include early-onset scoliosis patients. Adolescent idiopathic scoliosis and congenital scoliosis patients have less favourable outcomes. The number of instrumented levels should be minimised, as all instrumented levels must be included in the definitive fusion surgery. Rod contouring is important and owing to the straight portion of the rod housing the magnet, there is limited proximal rod portion for proper contouring, which may predispose to proximal junctional kyphosis. There is currently no consensus on the rod configuration, timing, frequency, technique, and amount of distraction. Risk factors for distraction failure include larger patients, internal magnets too close to each other, and magnets too close to the apex of the major curve. Future studies should resolve the issues regarding the technique of distraction, optimal frequency and amount of distraction per session. More comprehensive cost analyses should be performed.

Fusionless surgery in early-onset scoliosis

BACKGROUND

Surgical treatment of early-onset scoliosis has greatly developed in recent years. Early-onset scoliosis covers a variety of etiologies (idiopathic, neurologic, dystrophic, malformative, etc.) with onset before the age of 5 years. Progression and severity threaten respiratory development and may result in respiratory failure in adulthood. Many surgical techniques have been developed in recent years, aiming to protect spinal and thoracic development.

MATERIAL AND METHODS

Present techniques are based on one of two main principles. The first consists in posterior distraction of the spine in its concavity (single growing rod, or vertical expandable prosthetic titanium rib [VEPTR]), or on either side (dual rod); this requires iterative surgery, for lengthening, unless motorized using energy provided by a magnetic system. The second option is to use spinal growth force to lengthen the assembly; these techniques (Luque Trolley, Shilla), using a sliding assembly, are known as growth guidance.

RESULTS

These techniques are effective in controlling early scoliotic deformity, and to some extent restore spinal growth. However, they show a high rate of complications: infection, rod breakage, spinal fixation pull out and, above all, progressive spinal stiffness, reducing long-term efficacy. Respiratory gain is harder to assess, as thoracic expansion does not systematically improve respiratory function, particularly due to impaired compliance of the thoracic cage.

Pulmonary Function in Middle-Aged Patients With Idiopathic Scoliosis With Onset Before the Age of 10 Years

STUDY DESIGN

Consecutive patients with idiopathic scoliosis diagnosed before age 10 attended a clinical follow-up at least 10 years after treatment.

OBJECTIVES

To evaluate the pulmonary function in adulthood after treatment with brace or surgery before maturity.

SUMMARY OF BACKGROUND DATA

Long-term studies of these patients have not been published.

METHODS

One hundred twenty-four patients (69% of the original group) underwent radiography, spirometry, and answered symptom questionnaires. A total of 73 patients had spirometries before treatment enabling longitudinal evaluation. Overall, 68 braced only (BT) and 56 surgically treated (ST) were analyzed in detail. A population-based control group was used.

RESULTS

At follow-up, the mean age was 41.5 years and the mean curve size 36 degrees (26% of the curves >45 degrees). The full patient group had a significantly reduced pulmonary function (as measured by the forced vital capacity [FVC], percentage of predicted) compared with the control group, mean 85% versus 102% (p < .0001). Both subgroups of BT and ST patients showed a significant reduction, more in the ST than the BT group (means 79% and 90%, respectively, p = .0003). The most important risk factor for a low lung function at follow-up was a low initial FVC value. Initial curve size correlated with pulmonary function both before treatment and at follow-up. Most surgically treated patients, who had larger curves before treatment, did not improve their pulmonary function after surgery.

CONCLUSIONS

Both braced and surgically treated patients had reduced pulmonary function at the age of around 40 years. The pulmonary function did not worsen over time in most patients. There was no difference in terms of symptoms between patient groups and controls. Initial curve size was found to be of great importance for pulmonary function. Initial spirometry and follow-up in selected patients is important.

LEVEL OF EVIDENCE

III.

Extent of Spine Deformity Predicts Lung Growth and Function in Rabbit Model of Early Onset Scoliosis

Early onset deformity of the spine and chest wall (initiated <8 years of age) is associated with increased morbidity at adulthood relative to adolescent onset deformity of comparable severity. Presumably, inhibition of thoracic growth during late stage alveolarization leads to an irreversible loss of pulmonary growth and thoracic function; however the natural history of this disease from onset to adulthood has not been well characterized. In this study we establish a rabbit model of early onset scoliosis to establish the extent that thoracic deformity affects structural and functional respiratory development. Using a surgical right unilateral rib-tethering procedure, rib fusion with early onset scoliosis was induced in 10 young New Zealand white rabbits (3 weeks old). Progression of spine deformity, functional residual capacity, total lung capacity, and lung mass was tracked through longitudinal breath-hold computed tomography imaging up to skeletal maturity (28 weeks old). Additionally at maturity forced vital capacity and regional specific volume were calculated as functional measurements and histo-morphometry performed with the radial alveolar count as a measure of acinar complexity. Data from tethered rib rabbits were compared to age matched healthy control rabbits (N = 8). Results show unilateral rib-tethering created a progressive spinal deformity ranging from 30° to 120° curvature, the severity of which was strongly associated with pulmonary growth and functional outcomes. At maturity rabbits with deformity greater than the median (55°) had decreased body weight (89%), right (59%) and left (86%) lung mass, right (74%) and left (69%) radial alveolar count, right lung volume at total lung capacity (60%), and forced vital capacity (75%). Early treatment of spinal deformity in children may prevent pulmonary complications in adulthood and these results provide a basis for the prediction of pulmonary development from thoracic structure. This model may also have future use as a platform to evaluate treatment effectiveness.

Effects of consecutive application of stretching, Schroth, and strengthening exercises on Cobb's angle and the rib hump in an adult with idiopathic scoliosis

[Purpose] To report the effects of consecutive application of stretching, Schroth, and strengthening exercises in an adult with idiopathic scoliosis. [Subject] A 26-year-old woman with idiopathic scoliosis, Cobb’s angle of 20.51°, and back pain. [Methods] The exercise program consisted of 3 sessions: 10 minutes of stretching exercises, 20 minutes of Schroth exercises, and 10 minutes of strengthening exercises. This program was implemented 3 times a week, for 8 weeks. [Results] The thoracic Cobb’s angle decreased from 20.51° to 16.35°, and the rib hump decreased from 15° to 9°. [Conclusion] Consecutive application of stretching, Schroth, and strengthening exercises may help reduce Cobb’s angle and the rib hump in adults with idiopathic scoliosis.

Parasol Rib Deformity in Hypotonic Neuromuscular Scoliosis: A New Radiographical Definition and a Comparison of Short-term Treatment Outcomes With VEPTR and Growing Rods

STUDY DESIGN

Retrospective review of 2 multicenter national databases, Growing Spine Study Group and Chest Wall and Spine Deformity.

OBJECTIVE

To derive an objective measure of parasol rib deformity from spine radiographs and to compare efficacy of rib-based (vertical expandable prosthetic titanium rib (VEPTR)) versus spine-based growing rods ("GR") instrumentation to improve parasol rib deformity and pulmonary function.

SUMMARY OF BACKGROUND DATA

Children with low tone neuromuscular scoliosis often develop collapse of the rib cage ("parasol rib deformity") that may be associated with poor pulmonary function.

METHODS

We compared patients with hypotonic neuromuscular scoliosis treated by VEPTR or GR with greater than 1 year follow-up. Preoperative and final spine radiographs were assessed for parasol rib collapse, spine asymmetry, and thoracic deformity. Multivariable analysis was performed on these measurements to identify the best descriptor of parasol rib deformity. Using this measurement, the ability of VEPTR versus GR to control parasol rib deformity was then compared. Assisted ventilation rating (AVR) at preoperative and final follow-up was compared between the 2 groups.

RESULTS

Twenty-three patients treated with VEPTR (average age 6.7 years, average f/u = 3.3 years) were compared with 22 patients treated with GR (average age 7.7 years, average f/u = 2.9 years). The equation Parasol Score = (T6 convex hemithoracic width/T6 concave hemithoracic width) × (T6 thoracic width/T12 thoracic width) was the most accurate descriptor rib collapse (AUC = 0.927). Parasol Score was correlated with AVR. Parasol Score did not change over time for the patients treated with GR, but had a tendency to worsen for patients treated with VEPTR. AVR did not change significantly in either group. Spine deformity was better corrected using GR.

CONCLUSION

Parasol rib deformity, measured on x-ray by the metric = (T6 width convex hemithorax/T6 width concave hemithorax)*(T6 thoracic width/T12 thoracic width), did not improve after treatment with VEPTR or GR. AVR did not change significantly in either group.

LEVEL OF EVIDENCE

4.

Primary thoraco-spinal disorders of childhood

Primary structural deformities of the spine and thorax were at one time rare and reportable in case series. With the development of new "growth friendly" implantable devices, children with these disorders are living longer and receiving both surgical and pulmonary care. As a result, there has been growing interest in the functional cardiopulmonary consequences of these deformities, the current surgical and non-surgical treatments, and the role of long-term supportive care. This article reviews current literature in this rapidly changing field, where new devices are developed and outcomes are changing. The respiratory consequences of early-onset thoraco-spinal disorders are emphasized and the roles of the pulmonologist and surgeons are discussed. There are more questions than answers as no long-term outcome data yet exists.

Apical and intermediate anchors without fusion improve Cobb angle and thoracic kyphosis in early-onset scoliosis

BACKGROUND

The main goal of treatment in early-onset scoliosis is to obtain and maintain curve correction while simultaneously preserving spinal, trunk, and lung growth. This study introduces a new surgical strategy, called the modified growing rod technique, which allows spinal growth and lung development while controlling the main deformity with apical and intermediate anchors without fusion. The use of intraoperative traction at the initial procedure enables spontaneous correction of the deformity and decreases the need for forceful correction maneuvers on the immature spine and prevents possible implant failures. This study seeks to evaluate (1) curve correction; (2) spinal length; (3) number of procedures performed; and (4) complications with the new approach.

DESCRIPTION OF TECHNIQUE

In the initial procedure, polyaxial pedicle screws were placed with a muscle-sparing technique. Rods were placed in situ after achieving correction with intraoperative skull-femoral traction. The most proximal and most distal screws were fixed and the rest of the screws were left with nonlocked set screws to allow vertical growth. The lengthening reoperations were performed every 6 months.

METHODS

Between 2007 and 2011, we treated 19 patients surgically for early-onset scoliosis. Of those, 16 (29%) were treated with the modified growing rod technique by the senior author (AH); an additional three patients were treated using another technique that was being studied at the time by one of the coauthors (CO); those three were not included in this study. The 16 children included nine girls and seven boys (median, 5.5 years of age; range, 4-9 years), and all had progressive scoliosis (median, 64°; range, 38°-92°). All were available for followup at a minimum of 2 years (median, 4.5 years; range, 2-6 years).

RESULTS

The initial curve Cobb angle of 64° (range, 38°-92°) improved to 21° (range, 4°-36°) and was maintained at 22° (range, 4°-36°) throughout followup. Preoperative thoracic kyphosis of 22° (range, 18°-46°) was maintained at 23° (range, 20°-39°) throughout followup without showing any substantial change. There was a 47 mm (range, 38-72 mm) increase in T1-S1 height throughout followup. The mean number of lengthening operations was 5.5 (range, 4-10). The mean T1-S1 length gain from the first lengthening was 1.18 cm (range, 1.03-2.24 cm) and decreased to 0.46 cm (range, 0,33-1.1 cm) after the fifth lengthening procedure (p = 0.009). The overall complication rate was 25% (four of 16 patients) and the procedural complication rate was 7% (seven of 102 procedures). We did not experience any rod breakages or other complications apart from two superficial wound infections managed without surgery during the treatment period. The only implant-related complications were loosening of two pedicle screws at the uppermost foundation in one patient.

CONCLUSIONS

In this preliminary study, the modified growing rod technique with apical and intermediate anchors provided satisfactory curve control, prevented progression, maintained rotational stability, and allowed continuation of trunk growth with a low implant-related complication rate.

Early Onset Scoliosis: A Pulmonary Perspective

Early-onset scoliosis impairs lung function, often severely as it progresses. This review depicts current understanding of the changes in respiratory function resulting from early-onset scoliosis and how pulmonologists and their assessment tools affect clinical treatment decisions by spine surgeons.

Is there a relationship between thoracic dimensions and pulmonary function in early-onset scoliosis?

STUDY DESIGN

Cross-sectional retrospective analysis.

OBJECTIVE

To examine the degree of correlation between thoracic dimension outcome measures and pulmonary function in early-onset scoliosis (EOS).

SUMMARY OF BACKGROUND DATA

Change in thoracic dimension (TD) measurements and spine length are commonly reported outcome measures after treatment for EOS. Although ultimately improving or maintaining pulmonary function is the goal of EOS treatment strategies, it is unclear whether commonly reported 2-dimensional TD measurements represent good predictors of pulmonary function.

METHODS

A cross-sectional analysis of patients including all diagnoses obtained from 2 EOS databases containing TD measurements and pulmonary function data was performed. Relationships between individual TD measurements and pulmonary function measurements were assessed using the Pearson correlation analysis. TD measurements (pelvic inlet width, T1-T12 height, T1-S1 height, and coronal chest width) and standard pulmonary function measurements were compared. TD percentiles normalized for pelvic inlet width were also calculated and correlated with pulmonary function measurement percentiles. Univariate and multivariate linear regression analyses determined whether TD measurements could predict pulmonary function.

RESULTS

There were 121 patients (65 females, 56 males) in the study. Mean age at evaluation was 9.3 years (range, 2.7-18.1 yr). T1-T12 height, T1-S1 height, maximal chest width, and pelvic inlet width were all significantly correlated with forced air volume expelled in 1 second, total forced air volume, and total lung capacity (correlation coefficients [r] 0.33-0.61; all P<0.001). T1-T12 predicted percentile (normalized for pelvic width) was significantly correlated with forced air volume expelled in 1 second and total forced air volume predicted percentiles (r=0.32, P<0.001 and r=0.27, P=0.004, respectively). Regression analysis determined that T1-T12 percentile was a significant predictor of forced air volume expelled in 1 second percentile and total forced air volume percentiles. Regression analysis found no predictive factors of total lung capacity percentile.

CONCLUSION

Traditional 2-dimensional TD measurements (T1-T12 height) used to measure outcomes in EOS can be used as weak predictors of pulmonary function outcome. However, better outcome measures need to be developed, such as 3-dimensional and dynamic measurements.

LEVEL OF EVIDENCE

3.

Chest wall abnormalities and their clinical significance in childhood

The thorax consists of the rib cage and the respiratory muscles. It houses and protects the various intrathoracic organs such as the lungs, heart, vessels, esophagus, nerves etc. It also serves as the so-called "respiratory pump" that generates the movement of air into the lungs while it prevents their total collapse during exhalation. In order to be performed these functions depend on the structural and functional integrity of the rib cage and of the respiratory muscles. Any condition (congenital or acquired) that may affect either one of these components is going to have serious implications on the function of the other. Furthermore, when these abnormalities occur early in life, they may affect the growth of the lungs themselves. The following article reviews the physiology of the respiratory pump, provides a comprehensive list of conditions that affect the thorax and describes their effect(s) on lung growth and function.

Improvement of pulmonary function in children with early-onset scoliosis using magnetic growth rods

STUDY DESIGN

Case series.

OBJECTIVE

To determine whether there is improvement in pulmonary function in children with early-onset scoliosis (EOS) using magnetic growth rods (MGRs).

SUMMARY OF BACKGROUND DATA

EOS deformities have large impacts on lung function and volumes. Deterioration of pulmonary function in scoliosis is multifactorial, including severity, location of apex vertebra, and medical comorbidities. MGR insertion has benefits including reduction in operative procedures with repeated anesthetics, cost-effectiveness, and minimizing surgical and psychological distress. Pulmonary function tests provide objective and quantitative information about functional impairment caused by scoliosis. This is the first study that observes the MGR lengthening and changes in pulmonary function during a minimum period of 2.2 years.

METHODS

Six cases of EOS secondary to neuromuscular disease were identified. Mean age at diagnosis was 2.8 year (2.1-4.9 yr), mean age at surgery was 7.5 year (5-10 yr), and mean follow-up was 2.5 year (2.2-2.8 yr). Pulmonary function test (forced vital capacity [FVC] + forced expired volume in 1 second [FEV1] both % predicted) was measured before and after insertion of MGR and at every lengthening clinic subsequently for a minimum 2 years. Coronal and sagittal Cobb angles were measured pre- and postoperatively as were length extension of growth rods. All except 1 patient had dual MGRs inserted (the other had a single rod). Lengthening was commenced and data was collected at 6-month intervals.

RESULTS

Average correction was 34° ± 18° and 36° ± 15° for coronal and sagittal Cobb angles, respectively. Mean lengthening achieved was 24.9 mm. Mean improvement in postoperative FVC and FEV1 was 14.1% and 17.2%, respectively. There was significant difference between the median preoperative and postoperative Cobb angle, P = 0.028.

CONCLUSION

This study demonstrates early intervention using MGR in patients with EOS is associated with significant improvement in postoperative pulmonary function tests; and significant improvement in deformity correction with use of MGR with added benefits of reduction in repeat anesthesia, reduction in surgical and psychological distress, and cost-effectiveness.

LEVEL OF EVIDENCE

4.