The third dimension of scoliosis: The forgotten axial plane

3D external shape analysis and barycentremetry can provide early signs of progression in adolescent idiopathic scoliosis

PURPOSE

Our objective was to analysis the barycentremetry, obtained from the external envelope reconstruction of biplanar radiographs, in adolescent idiopathic scoliosis (AIS) and to determine whether assessing would help predict the distinction between progressive and stable AIS at the early stage.

METHODS

A retrospective study with a multicentre cohort of 205 AIS was conducted. All AIS underwent a biplanar X-ray between 2013 and 2020. Inclusion criteria were Cobb angle between 10° and 25°; Risser sign lower than 3; age higher than 10 years; and no previous treatment. A 3D spine reconstruction was performed, and the barycentremetry parameters were computed, i.e., the center of mass position at the apex and the axial torque at the apex, the upper and lower junction. A severity index, helping to distinguish stable and progressive AIS, was computed on the first radiograph, and weighted according to these parameters. A clinical and radiographic monitoring determined if AIS were classified such a stable or progressive scoliosis.

RESULTS

One hundred and sixty-two AIS were included (i.e., 87 were classified as stable and 75 as progressive). The apex center of mass position was different between the stable and progressive AIS groups (6 mm, SD = 4 mm for the whole cohort; 5 mm, SD = 4 mm for stable AIS versus 7 mm, SD = 4 mm for progressive AIS; p = 0.02). In AIS thoracic, the specificity and positive predictive value of the severity index increased by 19% and 16%, respectively, by adding the apex vertebral axial torque.

CONCLUSION

Early assessment of the external envelope from biplanar X-ray reconstruction of idiopathic scoliosis showed that the apex centre of mass position was significantly different between progressive and stable scoliosis. The inclusion of the axial torque of the apex vertebra in the severity index is promising to help the clinician distinguish between stable and progressive thoracic AIS at an early stage.

LEVEL OF EVIDENCE

II - Prognostic studies.

Assessment of spinal alignment in standing position using Biplanar X-ray images and three-dimensional vertebral models

We developed two methods for three-dimensional (3D) evaluation of spinal alignment in standing position by image matching between biplanar x-ray images and 3D vertebral models. One used a Slot-Scanning 3D x-ray Imager (sterEOS) to obtain biplanar x-ray images, and the other used a conventional x-ray system and a rotating table. The 3D vertebral model was constructed from the CT scan data. The spatial position of the vertebral model was determined by minimizing the contour difference between the projected image of the model and the biplanar x-ray images. Verification experiments were conducted using a torso phantom. The relative positions of the upper vertebrae to the lowest vertebrae of the cervical, thoracic, and lumbar vertebrae were evaluated. The mean, standard deviation, and mean square error of the relative position were less than 1° and 1 mm in all cases for sterEOS. The maximum mean squared errors of the conventional x-ray system and the rotating table were 0.7° and 0.4 mm for the cervical spine, 1.0° and 1.2 mm for the thoracic spine, and 1.1° and 1.2 mm for the lumbar spine. Therefore, both methods could be useful for evaluating the spinal alignment in standing position.

Spinal axial torque assessment after surgical correction in adolescent idiopathic scoliosis: a new approach to 3D barycentremetry and mass distribution based on biplanar radiographs

PURPOSE

Barycentremetry in adolescent idiopathic scoliosis (AIS) allows the distribution of masses and their loading of the spine to be studied. In particular, the axial torque on the spine has been studied in AIS, but not after surgical correction. Spinal axial torque was studied in AIS before and after surgery.

METHODS

All AIS (Lenke 1 and 3) who underwent posterior spinal fusion surgery at our center in 2019 were included retrospectively. AIS underwent frontal and sagittal biplanar radiographs in the free-standing position before surgery, 4 months after surgery, and at the last follow-up. Their spine and external envelope were reconstructed with validated methods. Spinal axial torque at the apex and the upper and lower end vertebra was calculated. Finally, the preoperative and postoperative values were compared to a previously published reference corridor for asymptomatic subjects.

RESULTS

Twenty-nine patients were included (54 ± 11° Cobb angle, 15 ± 2 years old at surgery). The surgical procedure decreased the Cobb angle by 36° ± 11° and decreased the spinal axial torque at the upper end vertebra by 2.5 N/m (95% CI = [1.9; 3]; p < 0.001), at the apex by 0.6 N/m (95% CI = [0.4; 1]; p = 0.004), at the lower end vertebra by 2 N/m (95% CI = [1.5; 2.8]; p < 0.001). Compared to 95th percentile of torque, which was previously evaluated in asymptomatic subjects, more than 90% of patients had higher values at the upper and lower end vertebrae before surgery. Postoperatively, 62% of patients still had higher torque at the upper end vertebra than asymptomatic subjects, while only 38% patients showed abnormal values at the lower junction.

CONCLUSION

Results of this study confirm that AIS patients show abnormally high spinal axial torque, especially at the end vertebrae, and that this parameter is normalized postoperatively for only a small number of patients.

Exercise therapy for adolescent idiopathic scoliosis rehabilitation: a bibliometric analysis (1999-2023)

Background

Among the conservative treatments for rehabilitation of adolescent idiopathic scoliosis (AIS), exercise therapy has attracted a large number of studies as its advantages of good clinical effect, high operability, high compliance, few side effects and low cost. We conduct a bibliometric analysis of previous research to identify prevalent areas of study and inform research for the future directions in this paper.

Methods

Relevant publications and reviews were collected using the Science Citation Index Expanded from the Web of Science Core Collection. Information from the included studies was analyzed systematically using VOSviewer and Citespace software to identify patterns regarding publications, keywords, authors, citations, countries, institutions and journals.

Results

A total of 172 articles published from 1999 to 2023 were identified. Over the last decade, the number of publications has gradually increased, reaching a peak of 21 publications in 2021. China, North America and Western European countries and institutions are leading the way as far as the quantity of publications and the total number of citations are concerned. The current areas of focus are the efficacy of exercise therapy in relation to enhancing the quality of life of adolescents during rehabilitation.

Conclusions

This is the first bibliometric analysis that provides a comprehensive review of the research trends and advances in exercise therapy for the rehabilitation of AIS. The study identifies latest research frontiers and hot directions, providing a valuable reference for scholars in the field of exercise therapy.

Predictive analysis of the scoliotic curve using a subject's 3D model

A predictive analysis of the conservative scoliosis treatment is necessary, in which a 3D model of an optimal treatment algorithm is a basic part in the design of a prosthetic corset. Since CAD technology has proven to be very useful in the field of prosthetics and orthotics, we used an open-source software to plan the correction of the scoliotic curve on a virtual model of the subject's torso. The shape of the scoliosis was simplified by means of a directional polygon, which was drawn in a reverse manner depending on the directional arcs of the scoliotic curve. The resulting scoliosis correction, simulated in a predictive analysis, was defined by changing the Cobb angle, eccentricity, and torso height. With the proposed low-cost method of predictive analysis, it is possible to help CPOs to a more accurate and effective design of orthoses and corrective aids and to comprehensively determine the entire treatment procedure.

Imaging Methods to Quantify the Chest and Trunk Deformation in Adolescent Idiopathic Scoliosis: A Literature Review

Background context: Scoliosis is a three-dimensional deformity of the spine with the most prevalent type being adolescent idiopathic scoliosis (AIS). The rotational spinal deformation leads to displacement and deformation of the ribs, resulting in a deformity of the entire chest. Routine diagnostic imaging is performed in order to define its etiology, measure curve severity and progression during growth, and for treatment planning. To date, all treatment recommendations are based on spinal parameters, while the esthetic concerns and cardiopulmonary symptoms of patients are mostly related to the trunk deformation. For this reason, there is a need for diagnostic imaging of the patho-anatomical changes of the chest and trunk in AIS. Aim: The aim of this review is to provide an overview, as complete as possible, of imaging modalities, methods and image processing techniques for assessment of chest and trunk deformation in AIS. Methods: Here, we present a narrative literature review of (1) image acquisition techniques used in clinical practice, (2) a description of various relevant methods to measure the deformity of the thorax in patients with AIS, and (3) different image processing techniques useful for quantifying 3D chest wall deformity. Results: Various ionizing and non-ionizing imaging modalities are available, but radiography is most widely used for AIS follow-up. A disadvantage is that these images are only acquired in 2D and are not effective for acquiring detailed information on complex 3D chest deformities. While CT is the gold standard 3D imaging technique for assessment of in vivo morphology of osseous structures, it is rarely obtained for surgical planning because of concerns about radiation exposure and increased risk of cancer during later life. Therefore, different modalities with less or without radiation, such as biplanar radiography and MRI are usually preferred. Recently, there have been advances in the field of image processing for measurements of the chest: Anatomical segmentations have become fully automatic and deep learning has been shown to be able to automatically perform measurements and even outperform experts in terms of accuracy. Conclusions: Recent advancements in imaging modalities and image processing techniques make complex 3D evaluation of chest deformation possible. Before introduction into daily clinical practice, however, there is a need for studies correlating image-based chest deformation parameters to patient-reported outcomes, and for technological advancements to make the workflow cost-effective.

Thoracogenic scoliosis: coronal deformity progression in paediatric patients

PURPOSE

To assess the risk of developing thoracogenic scoliosis (THS) in paediatric patients, depending on the side of lateral thoracotomy (LT) and of spine deviation in the coronal plane by means of logistic regression and scoliosis-free survival analyses.

METHODS

A total of 307 consecutive patients undergoing LT were retrospectively reviewed; 32 patients met the inclusion criteria: 1) underwent LT and developed THS; 2) age < 15 years at LT; 3) clinical and radiographic follow-up ≥ 5 years. Patients were divided into ipsilateral group (convexity ipsilateral to LT) and contralateral group (convexity contralateral to LT).

RESULTS

The mean follow-up was 10 ± 4.7 in the ipsilateral group (n = 13) and 12 ± 4.8 years in the contralateral group (n = 19). The contralateral group underwent LT at a younger age (4.4 vs 6.4 years, p = 0.55), developed more severe coronal deformity (27.8° vs 18.9°, p = 0.15), had higher rate of THS > 20° (47.5% vs 38.4%; p = 0.34) and > 45° (21.1% vs 0%; p = 0.99). The mean time from LT to THS diagnosis was 4.2 ± 2.9 in ipsilateral group and 5.5 ± 4.2 years in contralateral group. Left-side LT (p = 0.03) and age > 5 years (p = 0.01) showed a lower risk of THS diagnosis. The group variable had a statistically significant effect on the risk of developing THS > 45° (p = 0.03).

CONCLUSION

In this series, children that developed THS with a convexity contralateral to the side of LT had more severe and progressive coronal spine deformity.

LEVEL OF EVIDENCE

III.

The Differences Between Same-Day and Staged (Circumferential) Fusion Surgery in Adult Spinal Deformity: Protocol for a Systematic Review

BACKGROUND

Adult spinal deformity (ASD) is a deformity in the curvature of the adult spine. ASD includes a range of pathology that leads to decreased quality of life for patients as well as debilitating morbidities. Treatment can range from nonoperative management to long-segment surgical corrections and depends greatly on the deformity and patient profiles. If surgical treatment is indicated, circumferential (a combined anterior and posterior approach) fusion is one of the tools in the spine surgeon's armamentarium. Depending on the complexity, the procedure is either completed on the same day or staged. Determining whether to perform a circumferential surgery in a staged fashion is based largely on the surgeon's preference and perception of the individual case complexity; at present, there is no high-quality evidence that can be used to support that decision.

OBJECTIVE

This paper presents the protocol for a systematic review that aims to investigate the differences between same-day versus staged circumferential fusion surgery in ASD both in patient selection and in outcomes.

METHODS

Searches will be performed on MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and Scopus. Gray literature and the reference lists of articles included in the full-text screening will also be screened for inclusion. Results will be exported to Covidence. Data will be collected on demographics, type of procedures performed, surgery levels, blood loss, total operation time, length of stay, disposition, readmissions (30 days and 90 days), and perioperative complications. Patient-reported outcomes will also be assessed. Data quality assessment of randomized controlled trials will be performed using the Cochrane Collaboration's tool for assessing risk of bias in randomized trials, and nonrandomized studies will be assessed with the ROBINS-I (Risk of Bias in Non-randomized Studies of Interventions) tool. All screening, quality assessment, and data extraction will be done by 2 independent reviewers. A descriptive synthesis will be performed, and data will be evaluated for further analysis.

RESULTS

This study is currently in the screening phase. There are no results yet. The search strategy has been developed and documented. Information has been exported to Covidence. Upon conclusion of the critical appraisal stage, screening and extraction, as well as a synthesis of the results, will be performed.

CONCLUSIONS

The intended review will summarize the differences in perioperative outcomes and complications between same-day and staged (circumferential) fusion surgery in adult spinal deformity. It will also describe the patients selected for such procedures based on their demographics and pathology. Identified gaps in knowledge will provide insight into current limitations and guide further studies on this topic.

TRIAL REGISTRATION

PROSPERO CRD42022339764; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=339764.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/42331.

Side bending radiographs and lowest instrumented vertebra in adolescent idiopathic scoliosis: A French quality-of-care study

BACKGROUND

Determining which spinal levels to instrument during surgical treatment of Lenke Type 1 adolescent idiopathic scoliosis (AIS) depends on the reducibility of the primary and secondary curve patterns. This reducibility can be evaluated in several ways, with the most popular being radiographs in bending for moderate thoracic and lumbar curvatures. Hypothesis Side-bending radiographs will alter the choice of the lowest instrumented vertebra (LIV) for the surgical treatment of AIS.

METHODS

Thirteen experienced French spine surgeons were invited to perform surgical planning on 23 patients based on stereoradiographs with and without (standing) side-bending views. The surgical planning was repeated a second time to assess the intra- and inter-rater reliability. Variations in the choice of LIV were analyzed for each evaluation.

RESULTS

The intra-rater reliability was moderate to substantial. The inter-rater reliability was low to moderate. The study compared 879 surgical plans. Selective fusion was chosen in 0.3% of the plans. The median LIV was L2. The availability of side bending views changed the plan in 39% of cases. However, 36% of the plans were changed in the control (test-retest) condition. No significant difference was found between the variations with side-bending radiographs and "control" variations (p>0.05).

CONCLUSION

The use of radiographs in bending has no significant effect on the LIV choice in this study. This result is derived from statistically robust analysis made possible by one of the largest datasets available on this topic. Large inter-rater variability was observed and will be explored further in a future study.

LEVEL OF EVIDENCE

II; non-randomized controlled comparative study.

The Adolescent Spine

Adolescent idiopathic scoliosis (AIS) is the most characteristic disorder of the adolescent spine. It is a three-dimensional (3D) disorder that occurs from 10 years of age and comprises 90% of all idiopathic scolioses. Imaging plays a central role in the diagnosis and follow-up of patients with AIS. Modern imaging offers 3D assessment of scoliosis with less radiation exposure. Imaging helps rule out occult conditions that cause spinal deformity. Various imaging methods are also used to assess skeletal maturity in patients with AIS, thus determining the growth spurt and risk of progression of scoliosis. This article provides a brief overview of the pathophysiology, biomechanics, clinical features, and modern imaging of AIS relevant to radiologists in clinical settings.

Physiotherapeutic Scoliosis-Specific Exercise Methodologies Used for Conservative Treatment of Adolescent Idiopathic Scoliosis, and Their Effectiveness: An Extended Literature Review of Current Research and Practice

Due to the multifactorial etiology of scoliosis, a comprehensive treatment plan is essential for conservative management. Physiotherapeutic scoliosis-specific exercise (PSSE) methods have lately gained popularity for the conservative treatment of scoliosis. The aim of this study was to analyze the PSSE methodologies used for conservative treatment of adolescent idiopathic scoliosis (AIS), as well as their effectiveness. The study was based on an extended literature search conducted in the PubMed, Google Scholar, PEDro, eLABA, and BioMed Central databases. A total of 123 articles were selected for this study (including articles overviewed in systematic reviews and meta-analyses) after applying the inclusion criteria. The study revealed that inappropriate management of AIS could result in serious health problems. Conservative interventions that aid in stabilizing spine curvature and improving esthetics are preferred for scoliosis treatment. Bracing has traditionally been the mainstay of treatment, but growing evidence suggests that PSSE physiotherapy allows effective management of idiopathic adolescent scoliosis. Currently, there are the following PSSE physiotherapy schools in Europe: Schroth, SEAS, BSPTS, FED, FITS, Lyon, Side Shift, and DoboMed. The methodologies of these schools are similar, in that they focus on applying corrective exercises in three planes, developing stability and balance, breathing exercises, and posture awareness. Although high-quality research supporting the effectiveness of PSSE physiotherapy in the treatment of AIS is lacking, existing evidence indicates that PSSE physiotherapy helps to stabilize spinal deformity and improve patients’ quality of life. Among the abovementioned methodologies, Schroth is the most widely studied and has been proven to be effective. However, both SEAS and BSPTS effectively stabilize and even reduce the Cobb angle of scoliosis. Data supporting the validity of other methodologies are very limited. Only the Schroth method significantly reduces the angle of trunk rotation, while both SEAS and Schroth methods greatly improve the quality of life indicators. In any case, the available evidence is insufficient to confirm the advantage of one specific physiotherapy technique over others.

A fresh look at spinal alignment and deformities: Automated analysis of a large database of 9832 biplanar radiographs

We developed and used a deep learning tool to process biplanar radiographs of 9,832 non-surgical patients suffering from spinal deformities, with the aim of reporting the statistical distribution of radiological parameters describing the spinal shape and the correlations and interdependencies between them. An existing tool able to automatically perform a three-dimensional reconstruction of the thoracolumbar spine has been improved and used to analyze a large set of biplanar radiographs of the trunk. For all patients, the following parameters were calculated: spinopelvic parameters; lumbar lordosis; mismatch between pelvic incidence and lumbar lordosis; thoracic kyphosis; maximal coronal Cobb angle; sagittal vertical axis; T1-pelvic angle; maximal vertebral rotation in the transverse plane. The radiological parameters describing the sagittal alignment were found to be highly interrelated with each other, as well as dependent on age, while sex had relatively minor but statistically significant importance. Lumbar lordosis was associated with thoracic kyphosis, pelvic incidence and sagittal vertical axis. The pelvic incidence-lumbar lordosis mismatch was found to be dependent on the pelvic incidence and on age. Scoliosis had a distinct association with the sagittal alignment in adolescent and adult subjects. The deep learning-based tool allowed for the analysis of a large imaging database which would not be reasonably feasible if performed by human operators. The large set of results will be valuable to trigger new research questions in the field of spinal deformities, as well as to challenge the current knowledge.

Magnetically controlled growing rods in the management of early onset scoliosis: a systematic review

Background

Early onset scoliosis (EOS) presents in patients younger than 10 years. Magnetically controlled growing rods (MCGR) were developed as an outpatient distraction system for EOS, allowing to avoid multiple surgeries. This systematic review investigated the efficacy and feasibility of MCGR in EOS.

Methods

This systematic review was conducted according to the PRISMA guidelines. PubMed, Google scholar, Embase, and Scopus were accessed in May 2022. All the clinical trials which investigate the role of MCGR for early onset scoliosis were accessed. Only studies reporting data in patients younger than 10 years with a preoperative Cobb Angle greater than 40° were eligible. The following data was extracted at baseline and at last follow-up: mean kyphosis angle, overall mean Cobb angle, mean T1–S1 length. Data from complication were also collected.

Results

Data from 23 clinical studies (504 patients) were included in the present study. 56% (282 of 504) were females. The average length of the follow-up was 28.9 ± 16.0 months. The mean age of the patients was 8.7 ± 1.9 years old. The mean BMI was 17.7 ± 7.6 kg/m². The mean kyphosis angle had reduced by the last follow-up (P = 0.04), as did the overall mean Cobb angle (P < 0.0001), while the overall T1–S1 length increased (P = 0.0002). Implant-associated complications, followed by spinal alignment failure, wound healing ailments, pulmonary complications, progressive trunk stiffness, persistent back pain, and fracture.

Conclusion

The management of EOS remains challenging. The current evidence indicates that MCGR may be effective to distract the spine and model the curve in EOS.

Postoperative changes in rib cage deviation in adolescent idiopathic scoliosis

BACKGROUND

Scoliosis causes changes in the thorax, but it is unclear what type of changes occur in the thoracic profile after scoliosis surgery.

OBJECTIVE

To investigate changes in rib cage deviation in the postoperative period after adolescent idiopathic scoliosis (AIS) surgery.

METHODS

Forty-four patients with AIS with a main right thoracic curvature underwent posterior surgical fusion (PSF), and radiological parameters of the spine and thorax were evaluated.

RESULTS

The correction rates of main thoracic curve (MT)-Cobb angle at immediate after surgery and postoperative follow-up (2 years) were 64% and 66%, respectively. At these two postoperative time points, the correction rates of height of thoracic vertebrae 1 to 12 (T1T12) were 10% and 12%; the correction rates of Rib-vertebra angle difference (RVAD) were 59% and 52%; the correction rates of Apical rib hump prominence (RH) were 58% and 76%; while the correction rates of Apical vertebral body-rib ratio (AVB-R) were 23% and 25%, respectively. Statistical analysis showed that all these radiological parameters at the two postoperative time points were significantly different from the preoperative values (p< 0.001). There were significant correlations between MT-Cobb angle and T1-T12 height (p< 0.001), RVAD (p< 0.001), RH (p< 0.001), and AVB-R (p< 0.001).

CONCLUSIONS

Posterior spinal fusion appears to be effective at correcting scoliosis, and the correction of rib cage deviation also plays an important role.

Cone of Economy with the Chain of Balance-Historical Perspective and Proof of Concept

A bipedal erect posture with a horizontal gaze is a distinctly human characteristic. The standing mechanism was described by Jean Felix Dubousset in the early 1970s as the "cone of economy," in which the axial skeleton is aligned in balance with the feet, lower limbs, and pelvis (pelvic vertebra) to the spinal segments, ending with the cranium (cephalic vertebra). All the components act in concert, allowing for adaptive motion in all directions on the horizontal plane. In a normal subject, the body maintains balance within a small "cone" using minimal muscle activity, and in a subject with pathologic lesions of the locomotor system, maintaining a standing posture requires a larger "cone" and greater muscle activity. Evidence from recent studies using the EOS imaging system, force plate measurements, surface electromyography, and full-body reflective markers with surface electromyography have gradually consolidated the "cone of economy" concept, a fundamental hypothetical theory of human locomotion.

Risk Factors, Lifestyle and Prevention among Adolescents with Idiopathic Juvenile Scoliosis: A Cross Sectional Study in Eleven First-Grade Secondary Schools of Palermo Province, Italy

Adolescent idiopathic scoliosis (AIS) has an incidence of 2–3% in the general population and a multifactorial etiology. The present study aims to analyze modifiable risk factors and their interactions in the development of AIS in order to increase knowledge about the disease and to prevent the evolution of AIS in young students with tailored public health strategies. A cross-sectional study was conducted over two consecutive school years among students attending 11 first-grade secondary schools in the province of Palermo, Italy. A self-administered questionnaire that investigated socio-demographical, physical and anamnestic characteristics and habits, focusing on possible risk factors associated with idiopathic scoliosis, was administered. In addition, a clinical evaluation was performed with Adams’ test and Bunnel’s inclinometer. Suspected AIS cases were associated with the practice of high-risk sports (p < 0.05), weekly physical activity lasting ≥3 h (p < 0.05), lower back pain (p < 0.001), posture disorders (p < 0.01) and having had no contact with a physician (p < 0.01). Practice of high-risk sports (adj OR = 1.83; CI 95% 1.11–4.76) and suffering of posture disorders (adj OR = 1.67; CI 95% 1.12–3.60) showed a significant association with a confirmed diagnosis of AIS (Cobb angle ≥ 10° at X-ray). The risk factors associated with AIS are still unclear. Therefore, it is crucial to identify early modifiable and multiple risk factors to prevent the evolution of scoliosis in school-age children.

Performance of Forward Roll Maneuvers Following Corrective Spinal Fusion for Idiopathic Scoliosis Patients

BACKGROUND

Fusion surgeries for scoliosis patients are believed to deteriorate sports performance; in particular, forward roll should deteriorate, but no literature is available to substantiate this claim.

HYPOTHESIS

The extent of postoperative deterioration can vary according to surgery type or curve type.

PATIENTS AND METHODS

Idiopathic scoliosis patients between 10 and 29 years of age who underwent correction and fusion surgeries at our hospital were included in this study. Forward roll was recorded on video preoperatively and 1-year postoperatively. Performances were evaluated twice on a 10-point scale by two blinded examiners. Preoperative and 1-year postoperative upright spinal radiographs were analyzed for the Lenke classification, number of fused vertebrae, upper and lower instrumented vertebrae, major curve Cobb angle, thoracic kyphosis, lumbar lordosis, and surgical procedures.

RESULTS

The average age was 16 years. Curve types according to the Lenke classification were: 15, type 1; 5, type 2; 14, type 5; 2, type 6. The mean number of fused vertebrae was 6.9 (3.2 for anterior surgeries and 9.3 for posterior surgeries). The mean preoperative assessment of forward roll was 9.6 points, and the 1-year postoperative assessment was lower at 8.8 points. Cluster analysis classified patients into 3 groups: long fusion with marked performance deterioration (C1), long fusion with minimal deterioration (C2), and short fusion with minimal deterioration (C3). The upper and lower instrumented vertebrae in C1 were more distal than those in C2.

CONCLUSION

Patients with thoracic curves were classified into two groups, and patients who underwent surgeries with more distal upper and lower instrumented vertebra levels exhibited lower postoperative performance. However, patients with Lenke 5 curves who underwent anterior surgery showed better preoperative performance than other patients who underwent posterior surgery, showing minimal postoperative deterioration.

LEVEL OF EVIDENCE

III;Therapeutic Study.

Validating Surface Topography for the Measurement of the Thoracic Kyphosis Angle in Patients With Scoliosis: A Prospective Study of Accuracy

OBJECTIVE

The purpose of this study was to test the validity and determine the accuracy of surface topography in relation to photogrammetry for measuring the thoracic kyphosis angle in patients with scoliosis.

METHODS

This was a prospective, cross-sectional study of diagnostic accuracy that followed the guidelines recommended by the Standards for Reporting Diagnostic Accuracy. We consecutively included 51 participants aged 7 to 18 years. Exclusion criteria were surgical treatment of the spine, neurological disease, lower limb discrepancy greater than 1.5 cm, and body mass index above 29 kg/m². Each participant was evaluated using both a surface topography scan and photogrammetry in random order. The measurement obtained through photogrammetry was used as a reference in this study. For statistical purposes, Pearson's correlation test, Bland-Altman graphical analysis, and the receiver operating characteristic curve (P < .05) were performed.

RESULTS

The correlation between the measurements was strong and significant (r = 0.76, P < .001) with an average difference of 0.4° in the Bland-Altman analysis. The receiver operating characteristic curve area was excellent for hypokyphosis (93.4%) and good for hyperkyphosis (86.4%), both being significant (P < .005).

CONCLUSION

The agreement and strong correlation between the 2 methods indicate the validity of surface topography to measure the thoracic kyphosis angle. The surface topography provides accurate measures for the thoracic kyphosis angle with cutoff points for hypo- (33.3°) and hyperkyphosis (40.8°) for individuals with scoliosis.

Preoperative and Postoperative Imaging in Idiopathic Scoliosis: What the Surgeon Wants to Know

The term idiopathic scoliosis covers a broad spectrum of spinal deformities in the pediatric population without an underlying congenital anomaly of the spine. Depending on the age of presentation, it has both characteristic clinical and imaging features and a different prognosis. The radiologist should provide the surgeon with critical information to assess the degree of deformity and eventually plan surgery. Thoracic deformities and lung volume must also be part of the preoperative assessment. Imaging has a critical role in postsurgical follow-up and in surgical complications. This review highlights the importance of common terminology and measurement methods to avoid incongruences. The different imaging modalities are discussed with their indications and limitations. We pay special attention to imaging modalities that can help the surgeon assess skeletal maturation reliably and thus predict the prognosis of scoliosis. Radiation protection and the risk of cumulative radiation exposure in these patients is emphasized.

Effect of curve location on the severity index for adolescent idiopathic scoliosis: a longitudinal cohort study

OBJECTIVES

Adolescent idiopathic scoliosis (AIS) is the most common spinal disorder in children. A severity index was recently proposed to identify the stable from the progressive scoliosis at the first standardized biplanar radiographic exam. The aim of this work was to extend the validation of the severity index and to determine if curve location influences its predictive capabilities.

METHODS

AIS patients with Cobb angle between 10° and 25°, Risser 0-2, and no previous treatment were included. They underwent standing biplanar radiography and 3D reconstruction of the spine and pelvis, which allowed to calculate their severity index. Patients were grouped by curve location (thoracic, thoracolumbar, lumbar). Patients were followed up until skeletal maturity (Risser ≥ 3) or brace prescription. Their outcome was compared to the prediction made by the severity index.

RESULTS

In total, 205 AIS patients were included; 82% of them (155/189, 95% confidence interval [74-90%]) were correctly classified by the index, while 16 patients were unclassified. Positive predictive ratio was 78% and negative predictive ratio was 86%. Specificity (78%) was not significantly affected by curve location, while patients with thoracic and lumbar curves showed higher sensitivity (≥ 89%) than those with thoracolumbar curves (74%).

CONCLUSIONS

In this multicentric cohort of 205 patients, the severity index was used to predict the risk of progression from mild to moderate scoliosis, with similar results of typical major curve types. This index represents a novel tool to aid the clinician and the patient in the modulation of the follow-up and, for progressive patients, their decision for brace treatment.

KEY POINTS

• The severity index of adolescent idiopathic scoliosis has the potential to detect patients with progressive scoliosis as early as the first exam. • Out of 205 patients, 82% were correctly classified as either stable or progressive by the severity index. • The location of the main curve had small effect on the predictive capability of the index.

Thoracic vertebral morphology in normal and scoliosis deformity in skeletally immature rabbits: A Longitudinal study

OBJECTIVE

To measure age-related changes in thoracic vertebral body heights (VBH) in skeletally immature normative and scoliotic rabbits to assess how VBH change during growth. To examine the potential link between the moment-arm of the rib tether and vertebral wedging as well as the sum of the curvature angles at the apical level (T7). To assess the correlation between the magnitude of initial spine curve and final spine curve in the scoliotic group.

METHODS

Eight healthy, skeletally immature normative New Zealand rabbits and ten skeletally immature scoliotic rabbits which underwent unilateral rib tethering were included retrospectively. Each rabbit was scanned at two to four time points (at 7, 11, 14 and 28 weeks). Three dimensional bone models of thoracic vertebrae (T1-T12) were digitally segmented and reconstructed. VBH were calculated using surface landmark points from each thoracic vertebra. Apical level (T7) ± 2 levels in scoliotic rabbits were compared to their corresponding levels and time points in the normative group. The moment-arms between the centroids of 2D projections of T3-T9 vertebral bodies and the line which connects the centroids of the end levels were calculated.

RESULTS

Bilateral left-right (L-R) symmetry and anterior-posterior (A-P) asymmetry were observed in normative VBH. Bilateral concave-convex (CC-CX) asymmetry and (A-P) asymmetry were observed in scoliotic VBH. No significant differences in growth rates were found between the normative and scoliotic groups. Vertebral wedging as well as curvature magnitude were positively correlated with the moment-arms.

CONCLUSION

Unilateral rib tether applies compressive forces on both concave and convex sides, whereas compressive forces are lower on the latter. Knowing the amount of vertebral wedging or curve magnitude would enable us to predict the applied force (moment-arms), which is important for planning a corrective surgery.

The Current Practice of Adult Idiopathic Scoliosis Surgical Treatment Among Spine Surgeons in Saudi Arabia

Background: Scoliosis is a spinal deformity consisting of lateral curvature and rotation of the vertebrae. The goal of corrective scoliosis surgery is to restore alignment of the spine and maintain motion. However, there is no global agreement among spine surgeons on the best method of surgical intervention, and little is known about the variations in practice among spine surgeons in Saudi Arabia.

Objectives: The aim of this study is to examine the current surgical practices relating to adolescent idiopathic scoliosis and to establish the degree of variation and consensus among spine surgeons in Saudi Arabia.

Methods: This was a cross-sectional study conducted among spine surgeons in Saudi Arabia, using a self-administered questionnaire. The questionnaire addressed four areas: surgeons’ demographics, pre-operative assessment, operative assessment, and infection control practices. There were a total of 27 questions. Data was analyzed using statistical package for social sciences (SPSS) software (SPSS Inc., Chicago, IL, USA).

Results: A total of 150 surgeons were included in this study. Of these, 73 responded to the questionnaire (response rate: 48.6%), 46 (63.01%) of whom were fellows. All respondents were males, and 37 (51.39%) were aged between 30 and 40 years. Fifty five (75.34%) were orthopedic surgeons. The most commonly used pre-operative health assessment test was an echocardiogram. Sixty six (90%) surgeons requested scoliosis anteroposterior (AP) view and lateral radiograph for curvature between 40 degrees and 90 degrees, and 65 (89%) requested it for curvature greater than 90 degrees. For the posterior construct, 29 (45.31%) did not use cross-links for fewer than 10 levels, and 23 (35.94%) did not use cross-links for more than 10 levels. In addition to a local bone graft, the most commonly used transplant method was allograft 37 (50.68%). Fifty five (85.94%) respondents favored an all-screw pedicle construct over a hybrid construct.

Conclusion: A large variation in surgical practices was observed. This was especially apparent in practices including the use of cross-links, intra-operative cell salvage, and the intra-operative use of traction. Some degree of variation was observed in pre-operative imaging assessment practices. Surgical guidelines should be developed to build a consensus among surgeons. A unified surgical training curriculum may help in achieving this goal.

A cluster analysis describing spine and torso shape in Lenke type 1 adolescent idiopathic scoliosis

Purpose

The purpose of this work is to identify the variability and subtypes of the combined shape of the spine and torso in Lenke type 1 adolescent idiopathic scoliosis (AIS).

Methods

Using ISIS2 surface topography, measures of coronal deformity, kyphosis and skin angulation (as a measure of torso asymmetry) in a series of children with Lenke 1 convex to the right AIS were analyzed using k-means clustering techniques to describe the combined variability of shape in the spine and torso. Following this, a k-nearest neighbor algorithm was used to measure the ability to automatically identify the correct cluster for any particular datum.

Results

There were 1399 ISIS2 images from 691 individuals available for analysis. There were 5 clusters identified in the data representing the variability of the 3 measured parameters which included mild, moderate and marked coronal deformity, mild, moderate and marked asymmetry alongside normal and hypokyphosis. The k-nearest neighbor identification of the correct cluster had an accuracy of 93%.

Conclusion

These clusters represent a new description of Lenke 1 AIS that comprises both coronal and sagittal measures of the spine combined with a measure of torso asymmetry. Automated identification of the clusters is accurate. The ability to identify subtypes of deformity, based on parameters that affect both the spine and the torso in AIS, leads to as better understanding of the totality of the deformity seen.

Vertebral rotation estimation from frontal X-rays using a quasi-automated pedicle detection method

PURPOSE

Measurement of vertebral axial rotation (VAR) is relevant for the assessment of scoliosis. Stokes method allows estimating VAR in frontal X-rays from the relative position of the pedicles and the vertebral body. This method requires identifying these landmarks for each vertebral level, which is time-consuming. In this work, a quasi-automated method for pedicle detection and VAR estimation was proposed.

METHOD

A total of 149 healthy and adolescent idiopathic scoliotic (AIS) subjects were included in this retrospective study. Their frontal X-rays were collected from multiple sites and manually annotated to identify the spinal midline and pedicle positions. Then, an automated pedicle detector was developed based on image analysis, machine learning and fast manual identification of a few landmarks. VARs were calculated using the Stokes method in a validation dataset of 11 healthy (age 6-33 years) and 46 AIS subjects (age 6-16 years, Cobb 10°-46°), both from detected pedicles and those manually annotated to compare them. Sensitivity of pedicle location to the manual inputs was quantified on 20 scoliotic subjects, using 10 perturbed versions of the manual inputs.

RESULTS

Pedicles centers were localized with a precision of 84% and mean difference of 1.2 ± 1.2 mm, when comparing with manual identification. Comparison of VAR values between automated and manual pedicle localization yielded a signed difference of - 0.2 ± 3.4°. The uncertainty on pedicle location was smaller than 2 mm along each image axis.

CONCLUSION

The proposed method allowed calculating VAR values in frontal radiographs with minimal user intervention and robust quasi-automated pedicle localization. These slides can be retrieved under Electronic Supplementary Material.