Scoliosis - Latest Articles

An FE investigation simulating intra-operative corrective forces applied to correct scoliosis deformity

J Little — 2013-05-16T00:00:00Z

Background: Adolescent idiopathic scoliosis (AIS) is a deformity of the spine, which may require surgical correction by attaching a rod to the patient's spine using screws implanted in the vertebral bodies. Surgeons achieve an intra-operative reduction in the deformity by applying compressive forces across the intervertebral disc spaces while they secure the rod to the vertebra. We were interested to understand how the deformity correction is influenced by increasing magnitudes of surgical corrective forces and what tissue level stresses are predicted at the vertebral endplates due to the surgical correction. Methods: Patient-specific finite element models of the osseoligamentous spine and ribcage of eight AIS patients who underwent single rod anterior scoliosis surgery were created using pre-operative computed tomography (CT) scans. The surgically altered spine, including titanium rod and vertebral screws, was simulated. The models were analysed using data for intra-operatively measured compressive forces -- three load profiles representing the mean and upper and lower standard deviation of this data were analysed. Data for the clinically observed deformity correction (Cobb angle) were compared with the model-predicted correction and the model results investigated to better understand the influence of increased compressive forces on the biomechanics of the instrumented joints. Results: The predicted corrected Cobb angle for seven of the eight FE models were within the 5[degree sign] clinical Cobb measurement variability for at least one of the force profiles. The largest portion of overall correction was predicted at or near the apical intervertebral disc for all load profiles. Model predictions for four of the eight patients showed endplate-to-endplate contact was occurring on adjacent endplates of one or more intervertebral disc spaces in the instrumented curve following the surgical loading steps. Conclusion: This study demonstrated there is a direct relationship between intra-operative joint compressive forces and the degree of deformity correction achieved. The majority of the deformity correction will occur at or in adjacent spinal levels to the apex of the deformity. This study highlighted the importance of the intervertebral disc space anatomy in governing the coronal plane deformity correction and the limit of this correction will be when bone-to-bone contact of the opposing vertebral endplates occurs.

Retraction: Soft braces in the treatment of Adolescent Idiopathic Scoliosis (AIS) ¿ Review of the literature and description of a new approach

Hans-Rudolf Weiss — 2013-05-13T00:00:00Z

No description available

Scoliogeny of adolescent idiopathic scoliosis: inviting contributions for a discussion based on evidence and theoretical interpretations aiming ultimately to prevention or aetiological treatment

R Burwell — 2013-05-10T00:00:00Z

Comparison of in-and outpatients protocols for providence night time only bracing in AIS patients ¿ compliance and satisfaction

Zaid Al-Aubaidi — 2013-04-12T00:00:00Z

Background: Skeletally immature patients diagnosed with adolescent idiopathic scoliosis (AIS) and a Cobb angle above 25degrees is usually treated with a brace. Standard protocols in many centers include hospitalisation for a few days for the purpose of brace adaptation and fitting. The aim of this study is to compare compliance and satisfaction in hospitalization and out patient clinic protocols, at the initiation phase of brace treatment.Materials and methodsTwenty-four consecutive patients with AIS were initiated with the Providence night time only brace at our department between October 2008 and September 2009. The first twelve patients were admitted for a maximum of 3 days during the initiation phase of brace treatment. The following twelve patients were initiated in an outpatient clinic set-up. In this later group, patients and parents were informed about the possibility to be admitted to the hospital, at the initiation phase but all patients chose to be treated as out patient’s protocol. All patients were evaluated by means of conventional x-ray and patients reported outcome measurements. The mean follow up was 6 months for the outpatient group (3-8) and 12 months for the hospitalisation group (9-14). Scoliosis Quality of Life Index (SQLI) was used together with the Odense Scoliosis questionnaire, which was developed for this study. Compliance was measured using the patients’ own statements and the Landauer compliance scoring system.Findings/resultsThe two groups’ matches regarding the age, Risser grad, Cobb angle and primary correction. There were no statistically significant differences between the two groups regarding the SQLI and the Odense Scoliosis questionnaire. The compliance was higher in the ambulatory group. Conclusion: Outpatient initiation of bracing in scoliosis seems to give the same correction but better compliance compared to initiation during hospitalization.

Reviewer acknowledgement 2012

Theodoros Grivas — 2013-03-22T00:00:00Z

Contributing reviewersThe Editor-in-Chief of Scoliosis would like to thank all our reviewers who have contributed to the journal in Volume 7 (2012).

Whither the etiopathogenesis (and scoliogeny) of adolescent idiopathic scoliosis? Incorporating presentations on scoliogeny at the 2012 IRSSD and SRS Meetings

R Burwell — 2013-02-28T00:00:00Z

This paper aims to integrate into current understanding of AIS causation, etiopathogenetic information presented at two Meetings during 2012 namely, the International Research Society of Spinal Deformities (IRSSD) and the Scoliosis Research Society (SRS). The ultimate hope is to prevent the occurrence or progression of the spinal deformity of AIS with non-invasive treatment, possibly medical. This might be attained by personalised polymechanistic preventive therapy targeting the appropriate etiology and/or etiopathogenetic pathways, to avoid fusion and maintain spinal mobility. Although considerable progress had been made in the past two decades in understanding the etiopathogenesis of adolescent idiopathic scoliosis (AIS), it still lacks an agreed theory of etiopathogenesis. One problem may be that AIS results not from one cause, but several that interact with various genetic predisposing factors. There is a view there are two other pathogenic processes for idiopathic scoliosis namely, initiating (or inducing), and those that cause curve progression. Twin studies and observations of family aggregation have revealed significant genetic contributions to idiopathic scoliosis, that place AIS among other common disease or complex traits with a high heritability interpreted by the genetic variant hypothesis of disease. We summarize etiopathogenetic knowledge of AIS as theories of pathogenesis including recent multiple concepts, and blood tests for AIS based on predictive biomarkers and genetic variants that signify disease risk. There is increasing evidence for the possibility of an underlying neurological disorder for AIS, research which holds promise. Like brain research, most AIS workers focus on their own corner and there is a need for greater integration of research effort. Epigenetics, a relatively recent field, evaluates factors concerned with gene expression in relation to environment, disease, normal development and aging, with a complex regulation across the genome during the first decade of life. Research on the role of environmental factors, epigenetics and chronic non-communicable diseases (NCDs) including adiposity, after a slow start, has exploded in the last decade. Not so for AIS research and the environment where, except for monozygotic twin studies, there are only sporadic reports to suggest that environmental factors are at work in etiology. Here, we examine epigenetic concepts as they may relate to human development, normal life history phases and AIS pathogenesis. Although AIS is not regarded as an NCD, like them, it is associated with whole organism metabolic phenomena, including lower body mass index, lower circulating leptin levels and other systemic disorders. Some epigenetic research applied to Silver-Russell syndrome and adiposity is examined, from which suggestions are made for consideration of AIS epigenetic research, cross-sectional and longitudinal. The word scoliogeny is suggested to include etiology, pathogenesis and pathomechanism.

The carbon brace

Jean-Claude Bernard — 2013-02-14T00:00:00Z

Background: The CMCR brace (Corset MonocoqueCarbone respectant la Respiration –which means Monoshell Carbon Brace respecting Breathing) is an innovative brace, used in orthopaedic treatment for progressive thoracic, thoraco-lumbar or combined scoliosis, whatever their etiology. It can be used at the very young age without disrupting the chest growth, but should be kept for reducible scoliosis in older teenagers.Brace description and principlesThe CMCR brace is monoshell while retaining the corrective principle of the polyvalve Lyon brace with one or two supports (brace “pads”) located on hump(s).In contrast to Lyon brace made of plexidur and structured by metal reinforcement with adjustable but fixed localized supports, the CMCR brace is made of polyethylene and carbon with adjustable and mobile supports. This mobility provides a permanent pressure, which varies depending on ribs and spine movements.The correction is obtained without spinal extension so that each respiratory movement takes part in a gradual return to dorsal kyphosis. Results: Results were presented in two published analysis:• In the first retrospective study about 115 patients, French-published in the Annals of Physical Medicine and Rehabilitation (2005), the CMCR brace stabilized moderate scoliosis, decreased the vital capacity (VC) of 13% compared to the VC without brace, and did not have sufficient impact on the hump reduction. Treatment had better results when started at Risser 3 or 4 than Risser 0, 1, 2. The brace was then modified to increase the dorsal pad pressure and the location of correction forces was defined more precisely through the use of 3D analysis.• The second study published in Scoliosis (2011) mainly focused on the impact on VC at brace setting up and followed a cohort of 90 patients treated with CMCR. Girls as well as boys increased VC during treatment, and at brace definitive removal, VC had increased of 21% from the initial value, whereas the theoretical VC at the same time rose by 18%.The difference between the time where the child actually wears its brace and the time asked by the clinician for the brace to be worn is only 1 hour, which means that this brace is accepted by teenagers. Conclusions: Orthopaedic treatment is still a heavy treatment for teenagers in growth period. This orthosis is designed to partly maintain spine and chest mobility. We hope so to have part in improving life conditions of these teenagers, compared to those treated with rigid braces.

Comparison of trunk and spine deformity in adolescent idiopathic scoliosis

Brandon Carlson — 2013-01-25T00:00:00Z

Background: Cobb measurement of standing radiographs is the standard for clinical assessment of coronal spinal deformity. Angle of trunk inclination (ATI) is an accepted clinical measurement of trunk asymmetry, and has variable reported correlations with Cobb angles. Transverse plane spine deformity is most accurately measured using axial computed tomography. Aaro and Dahlbourn’s technique for quantifying apical vertebral rotation with respect to the sagittal plane (RAsag) is commonly reported in the literature. To our knowledge no study has correlated ATI with RAsag. The purpose of this study was to determine the relationship between commonly used measures of trunk and spine deformity. Methods: Sixteen females that underwent preoperative apical vertebra(e) CT scans were retrospectively studied. Thoracic and thoracolumbar RAsag measurements were date-matched to clinically obtained ATI and Cobb measurements. Two-tailed Pearson correlations were calculated; α = 0.01. Results: Median patient age was 14.6 years (11–19); BMI 19.4 (16.0-25.5). Curve patterns: Lenke 1 (5); 2 (5); 3 (1); 4 (1); 5 (2): 6 (2). Twenty-six curves (15T; 11TL) with complete, date-matched data points were analyzed. In thoracic curves, ATI correlated with Cobb (r = 0.711, P < 0.004) and RAsag (r = 0.730, P <0.003). ATI was inversely correlated with Cobb flexibility (r = −0.647, P < 0.01). In thoracolumbar curves, ATI correlated with Cobb (r = 0.789, P < 0.005), and RAsag (r = 0.771, P < 0.006) but not Cobb flexibility (r = −0.452, P = 0.190). Conclusions: Trunk and spine thoracic and thoracolumbar transverse plane deformity are correlated, as are trunk transverse plane and spine coronal plane deformity. Increasing trunk deformity limits thoracic, but not thoracolumbar spine flexibility.

Right ventricular function impaired in children and adolescents with severe idiopathic scoliosis

Shujuan Li — 2013-01-14T00:00:00Z

Background: Although it is speculated that scoliosis may induce cardiac dysfunction, there is no report about evaluation of cardiac function, especially right cardiac function in patients with scoliosis. Therefore, we evaluated right ventricular function in idiopathic scoliotic patients with mild to severe curves and compared them with healthy children and adolescents matched in age, then explored relationship between scoliosis and right ventricular function. Methods: Thirty-seven patients diagnosed with idiopathic scoliosis with a mean age of 16y/o (range, 8-25y/o) and an average spine curve of 77.5°Cobb (range, 30-157°) were studied by echocardiography. TAD was obtained using M-mode echocardiography. Similar examination was performed in a control group of 17 healthy individuals in matched-age. According to the different curve degree, all patients were divided into 3 groups (mild, moderate and severe). Comparison was done among the groups and the relationship between TAD and spine curve of Cobb was analyzed. Results: Patients with severe scoliosis showed depressed TAD. There was good correlation between TAD and spine curve of Cobb. Conclusions: Patients with severe scoliosis showed a significant lower right ventricular systolic function.

Preoperative assessment and evaluation of instrumentation strategies for the treatment of adolescent idiopathic scoliosis: computer simulation and optimization

Younes Majdouline — 2012-11-26T00:00:00Z

Background: A large variability in adolescent idiopathic scoliosis (AIS) correction objectives and instrumentation strategies was documented. The hypothesis was that different correction objectives will lead to different instrumentation strategies. The objective of this study was to develop a numerical model to optimize the instrumentation configurations under given correction objectives. Methods: Eleven surgeons from the Spinal Deformity Study Group independently provided their respective correction objectives for the same patient. For each surgeon, 702 surgical configurations were simulated to search for the most favourable one for his particular objectives. The influence of correction objectives on the resulting surgical strategies was then evaluated. Results: Fusion levels (mean 11.2, SD 2.1), rod shapes, and implant patterns were significantly influenced by correction objectives (p < 0.05). Different surgeon-specified correction objectives produced different instrumentation strategies for the same patient. Conclusions: Instrumentation configurations can be optimized with respect to a given set of correction objectives.