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In July 2010, the International Research Society of Spinal Deformities (IRSSD) will hold its 8th biennial meeting in Montreal, Canada. The meeting is returning to one of its important venues. The 1992 meeting in Montreal marked the turning point of a series of preceding meetings that had a primary interest in morphological aspects of spine deformities and trunk asymmetry, towards three-dimensional evaluation and interpretation of scoliotic deformities and their biomechanics. Since then, the IRSSD and the biennial meetings have played an instrumental role in the advancement of scientific research on problems affecting the spine. Over the years, the interest has evolved and diversified towards improved understanding of mechanisms involved in the etiology, biology, biomechanics, metabolism, genetics, and treatment of spinal deformities. It is attended by researchers and clinicians from all over the world, providing a collegial forum for presentations, discussion and collaboration on subjects relating to spinal deformities. A Pre-Meeting on Clinical applications of 3D technologies and research in biomechanics, biology and genetics of scoliosis also is to be held at Sainte-Justine University Hospital Center to allow the participants to see directly how research activities of our group are linked to the clinical world. This book contains the Proceedings of the IRSSD 2010 Conference in the form of either peer-reviewed short papers or abstracts summarizing the 140 papers and posters that will be presented. It covers to all aspects of spinal deformity research, including etiology, genetics, biology, metabolism, biomechanics, imaging technologies, innovations in treatment, and treatment outcomes. These scientific proceedings provide the opportunity for readers to learn more about the latest development in this field that will be presented and discussed during the meeting. This meeting represents a multidisciplinary taskforce giving scientific and clinical experts from around the world an opportunity to meet and discuss the latest developments in the fields of scoliosis research, on the search for the underlying mechanisms that cause scoliosis as well as the clinical effectiveness of a wide range of interventions. I would like to thank all participants, and authors for submitting their work, as well as the members of the scientific committee, chaired by Ian Stokes, that provided very valuable comments and critics that helped in adding to the impact of the work that will be presented at the meeting. I hope this meeting will be a unique opportunity to meet, exchange, and discuss of subjects of mutual interest related to spinal deformities, and to advance the study and research into spinal deformities for the patients' benefit. Carl-Eric Aubin, Montreal, Quebec, Canada, April 2010 [ABSTRACT FROM AUTHOR]

Lumbosacral kyphosis (LSK) is considered to be an important aspect of the deformity in adolescent developmental spondylolisthesis, but its clinical impact is not known. The purpose of this study was to clarify if slip angle (SA), a parameter commonly used to measure LSK, has a significant impact on the quality of life of patient with spondylolisthesis. Eighty-six patients with lumbosacral developmental spondylolisthesis were evaluated. There were 67 low-grade and 19 high-grade spondylolisthesis. All patients completed the SF-12v2 questionnaires. The score of the mental and physical component summary (MCS and PCS) of SF-12v2 were correlated with the slip angle. The correlation of SA was only significant with PCS and not with MCS. PCS decreased significantly with increasing SA (Spearman's rho=-0.40, p<0.001). LSK has a significant impact on the physical aspect of the quality of life of adolescent with spondylolisthesis. LSK is an important part of the deformity in developmental spondylolisthesis and should be included in the routine radiological evaluation of patient with spondylolisthesis. [ABSTRACT FROM AUTHOR]

We used a microarray approach to evaluate gene expression profiles in human AIS osteoblasts, and to identify genes that are differentially expressed following estrogen exposure in non-AIS and AIS human osteoblasts. We found that more than one gene is likely responsible for AIS. Furthermore, some of these genes are estrogen-regulated, suggesting a possible role of estrogens in the etiology of scoliosis. [ABSTRACT FROM AUTHOR]

Background: Scoliosis with vertebral wedging is thought to be caused by asymmetric growth (Hueter-Volkmann law), but vertebral diaphyseal remodeling (Wolff's law) may also contribute to the deformity. We investigated whether vertebral wedging in scoliosis might involve both mechanisms. Methods: An external fixator was used to impose a 30° scoliosis and compression of 0.1 or 0.2 MPa to the tails of 10 5-week-old and 20 14-week-old Sprague-Dawley rats for 6 weeks. The rats were divided into three groups of 10 animals each: Group 1: 5-week-old animals with 0.1 MPa compression; Group 2: 14-week-old animals with 0.1 MPa compression; Group 3: 14-week-old animals with 0.2 MPa compression. Vertebral wedging and diaphyseal curvature were measured from micro CT scans performed at weeks 1, 3, and 6. Wedging due to asymmetrical growth and remodeling was calculated from a Calcein label administered at week 3 and a Xylenol label at week 6. Results: The growth rate of the loaded vertebrae as a per cent of control vertebrae was 60% in Group 1, 40% in Group 2, and 30% in Group 3. The growth rate of control vertebrae in 14-week-old animals was 16% that of 5-week-old animals. The animals in all 3 groups developed a scoliosis with vertebral wedging that averaged 18.7° in Group 1, 8.2° in Group 2, and 10.1° in Group 3. Asymmetric growth was much greater in Group 1 (5-week-old) animals. The ossified epiphyses became wedged and diaphyseal remodeling occurred in all groups. Conclusions: The major contribution to the vertebral wedging was asymmetric growth in the 5-week-old animals and diaphyseal remodeling in the 14-week-old animals. The results support the concept that if appropriate loads can be applied to human vertebrae through minimally invasive techniques, scoliosis and vertebral wedging can be corrected without a spinal fusion in both adolescents and adults. [ABSTRACT FROM AUTHOR]

In subjects with scoliosis the thoracic cage deformity is a complex 3D phenomenon. There is a deficiency of simple clinical methods of thorax shape evaluation. The study aimed to introduce and assess an anthropometric technique measuring transverse plane deformity of the thorax in patients with idiopathic scoliosis. Thirty scoliotic girls, aged 14.4±1.5 years, thoracic scoliosis type Lenke 1, mean Cobb 54.1±24.7°, and 30 healthy volunteers matched for sex and age were examined. Using a Martin anthropometric caliper the length of the long and the short horizontal axes of the thorax were measured at the level of the xiphoid process (upper index) and of the costal arch (lower index), both on maximum inspiration and expiration. Asymmetry index, defined as difference of the length of the long and the short axes expressed as the percentage of the short one, was calculated. The upper asymmetry index in the study group was 35.2±18.6 (inspiration) while in the control group it was 13.6±13.6, difference significant, p<0.001. The lower asymmetry index in the study group was 26.2±12.9 (inspiration) while in the control group it was 12.5±11.7, difference significant, p<0.001. In conclusion, thorax asymmetry index revealed significantly higher values in scoliotic patients. Asymmetry of respiratory movements could be measured. This simple technique may be used as a helpful tool for clinicians. [ABSTRACT FROM AUTHOR]

Quantec raster stereography has been recognized as an accurate and reliable tool for evaluating back contour and posterior truncal rotation in patients with scoliosis. In this prospective study, 35 patients with adolescent idiopathic scoliosis underwent both spinal radiography and Quantec three-dimensional evaluation of their idiopathic scoliosis before and after surgical intervention, consisting of anterior and/or posterior spinal fusion, with or without thoracoplasty. Comparison of established key parameters showed significant improvement in thoracic and thoracolumbar Cobb angle, as well as Quantec Q-angle. Thoracic rotation, Suzuki rib hump sum, and posterior trunk asymmetry also improved due to spinal fusion. [ABSTRACT FROM AUTHOR]

Measured back surface topographies can be useful to monitor the external manifestation of scoliosis to avoid exposure to large doses of radiation. Manual shape fitting of back surface topographies from successive clinical visits can then be used to detect differences. Automated matching of the measured topographies has been seen as a possible improvement on manual comparisons. Recognizing that two changed surface cannot be expected to be simple rigid replicas of each other, the goal of this research has been to develop a new algorithm based on a non-rigid surface matching algorithm, suited to matching the surfaces into same reference frame while also estimating the parameters of the scoliosis deformities, and eliminating noise due to normal body change caused by growth. Back surface topography data from laser optical scanning have been automatically matched by a least squares non-rigid matching algorithm. The algorithm includes new parameters able to model shape changes caused by normal growth and scoliosis deformation. This non-rigid matching algorithm returned r.m.s. values for surface closeness which were improved by at least 10% over rigid matching. Experiments on various scoliosis data demonstrate that the non-rigid matching algorithm is able to accurately match the surfaces while simultaneously extracting parameters representing patient shape change. The non-rigid algorithm has proven to be an improvement on the classical rigid surface matching approach which allows positional fit rather than shape fit. Measured back surface topographies can be closely matched to monitor the external manifestation of scoliosis. [ABSTRACT FROM AUTHOR]

Spinal orthosis is generally applied to the patients with adolescent idiopathic scoliosis (AIS) during puberty to mechanically support the spine and prevent further deterioration. However, the optimum location of pressure is not easy to be determined and the X-ray taken is not a real time presentation of the spinal curvature. With the advancement of clinical ultrasound, tracing spinal processes along a scoliotic spine becomes possible, which means spinous process angle (SPA) can be obtained from ultrasound images. Moreover, SPA is found to be highly correlated with Cobb's angle. Since the outcome of orthotic intervention for AIS is considered to be associated with accurate orthosis fitting, this study seeks to apply three-dimensional (3-D) ultrasound in the fitting procedure of spinal orthosis for patients with AIS. The accuracy of pressure pad location in brace can help to improve the effectiveness of spinal orthosis treatment. By means of the ultrasound assessments, spinous process angle is examined and used as the parameter to evaluate the optimal location for pressure pad. The intra-rater reliability [ICC (1, 3)] for using ultrasound to measure SPA is >0.9 (p<0.05). Furthermore, the correlation between Cobb's angle estimated from the measurement of SPA in 3-D ultrasound images and Cobb's angle measured from X-ray is highly significant (R=0.98, p<0.01). According to these findings, ultrasound can be further developed as a non-invasive real-time assessment tool for spinal curvature especially in fitting stage to improve the treatment effect of the spinal orthosis. [ABSTRACT FROM AUTHOR]

Magnetic Resonance Imaging (MRI) offers a valuable research tool for the assessment of 3D spinal deformity in AIS, however the horizontal patient position imposed by conventional scanners removes the axial compressive loading on the spine. The objective of this study was to design, construct and test an MRI compatible compression device for research into the effect of axial loading on spinal deformity using supine MRI scans. The device was evaluated by performing unloaded and loaded supine MRI scans on a series of 10 AIS patients. The patient group had a mean initial (unloaded) major Cobb angle of 43±7°, which increased to 50±9° on application of the compressive load. The 7° increase in mean Cobb angle is consistent with that reported by a previous study comparing standing versus supine posture in scoliosis patients (Torell et al, 1985. Spine 10:425-7). [ABSTRACT FROM AUTHOR]

Scoliosis surgery involves the insertion of screws and/or hooks into selected vertebrae to secure a pre-bent rod placed along the concave side of the spine. Usually conventional x-rays will be taken before the surgery to plan the alignment and positioning of the pedicle screws. However, reports state that perforation rate range from 6% to 54%. A misalignment of a pedicle screw can potentially cause permanent neurological spinal cord injury or even a lifethreatening vascular injury. Because of the importance of positioning and aligning of pedicle screws, we are working on an ultrasound method to guide the insertion of pedicle screws in real time. A pulse-echo immersion experiment was set up to study how well the edges of cortical bone could be detected using a bovine spinous process in-vitro. Two ultrasound frequencies (3.5 MHz and 5.0 MHz) were considered in this study. This preliminary study shows that ultrasound is able to penetrate cortical bone and reflect back from the outer boundary. All interfaces are clearly identified for both frequencies. Strong reflection signals are obtained when the beam is normal to the interface. Derived thickness values from the reflections are comparable with those from micro-CT image. The 5.0MHz ultrasound frequency provided better resolution than the 3.0 MHz frequency. [ABSTRACT FROM AUTHOR]

Minimally invasive surgical (MIS) techniques for the correction of scoliosis are under development. The installation of fusionless implants targeting the vertebral growth plate requires precise identification of spinal micro-structures. During ex vivo studies, we demonstrate that optical coherence tomography (OCT) allows visualization of spinal tissues including the growth plate, the intervertebral disc and the vertebral body. This study aims at designing a handheld probe using OCT and assessing its potential for use in MIS. An OCT handheld probe was built which satisfies criteria for resolution, penetration and field of view required for spinal MIS techniques. Ex vivo images of rat tail and porcine vertebrae enabled differentiating musculoskeletal tissues of the spine (growth plate, intervertebral disc and vertebral body). Pending in vivo studies on porcine models, we evaluated the probe on a human finger and demonstrated its ability to image human tissues at video rate (25 fps) with proper imaging depth and resolution. These preliminary results showed the potential of the OCT probe for dynamic and precise imaging of spinal tissues. [ABSTRACT FROM AUTHOR]

Multimodal fusion of 2D thoracoscopic images with a pre-operative 3D anatomical model of the spine is useful for minimally invasive surgical procedures using an angled monocular endoscope with varying focal length. An offline calibration procedure has been developed to compute initial endoscope parameters, such as lens distortion, focal length and optical center before surgery. An optical tracking system is used to update extrinsic parameters describing the position and orientation of the endoscope in real-time during the procedure. This calibration allows the registration of the thoracoscopic image sequence with a pre-operative MRI 3D model of the spine. Two visualization methods merging the 3D model and thoracoscopic image sequence have been developed using both augmented reality and augmented virtuality paradigms primarily as an aid for discectomy. Augmented views are generated by adding annotations and projecting the MRI 3D model onto real thoracoscopic images. Virtual views are generated by projecting the real thoracoscopic images on a virtual view of the 3D model. Experimental results showed that the calibration procedure accuracy obtained by computing the relative 3D reconstruction error on a known object was 1.0 mm. Two orthopedic surgeons assessed the generated views, confirming the relevance and added value of the proposed visualization tool for minimally invasive discectomy assistance. [ABSTRACT FROM AUTHOR]

The development of scoliosis in animal models with induced asymmetric rib growth suggested the possible role of asymmetric rib growth in the etiopathogenesis of adolescent idiopathic scoliosis (AIS). Asymmetric rib length is well recognized in idiopathic scoliosis, however, whether this rib asymmetry was primary or secondary has not been clearly documented. We measured the lengths of all ribs in 48 patients with AIS and 29 patients with scoliosis associated with syringomyelia and Chiari I malformation (SS). In both groups, ribs on the concave side were significantly longer than those on the convex side in apical area. The rib length difference was significantly associated with magnitude of the Cobb angle of thoracic curve. However, the rib length discrepancy showed no difference between AIS and SS group. The finding of similar asymmetry of rib length in both AIS and SS patients with thoracic curve indicated the discrepancy found in AIS might be secondary to the spinal deformity rather than its etiological factor. [ABSTRACT FROM AUTHOR]

Human bipedalism appears to be a prerequisite for the development of idiopathic scoliosis. The objective of this study was to examine the effect of different positions of the human spine on vertebral rotation in vivo. Thirty asymptomatic volunteers underwent MRI scanning of the spine in three different body positions; upright, quadrupedal-like and supine. Vertebral rotation in the local transverse plane was measured and compared at different spinal levels between the three body positions. It was shown that in all three positions the mid and lower thoracic vertebrae were predominantly rotated to the right. However, rotation was significantly less in certain areas of the spine in the quadrupedal-like position than in both the standing upright and supine positions. We hypothesize that the erect position of the human spine, but also the supine position, increases dorsally directed shear loads that may increase the tendency of certain spinal segments to rotate. [ABSTRACT FROM AUTHOR]

The value of the lateral bending test is important in the assessment of spinal curve mobility and prediction of surgical outcome in the treatment of adolescent idiopathic scoliosis (AIS). However, radiographic bending tests are unable to assess the reducibility of trunk asymmetry. This study aims to exploit surface topography measurement in order to evaluate the changes in shape of the trunk (a) between bending and neutral standing positions, and (b) between standing pre- and post-operative visits, in a cohort of adolescents with AIS having undergone surgical correction; and to correlate the differences measured in cases (a) and (b). Our cohort includes 13 patients with right thoracic AIS. Each patient had their 3D trunk surface digitized with a multi-head InSpeck system in standing posture (at the pre-op and post-op visits) and in maximum voluntary right and left bending (at the pre-op visit). We developed a novel trunk shape analysis method which produces a set of inclined trunk cross-sections allowing comparison between different postures. Two asymmetry indices, trunk rotation (TR) and back surface rotation (BSR), were computed in all cases and a statistical analysis was performed. Our correlation study (Pearson test) showed fair correlations in most cases between the changes in side-bending and those post-surgery, with the strongest relationship (p-value < 0.01) when combining the TR measurements from both bendings. These results provide evidence that the bending test can be used to assess trunk asymmetry reducibility. The proposed approach could provide a non-invasive trunk asymmetry reducibility test for routine clinical use in AIS surgery planning. [ABSTRACT FROM AUTHOR]

There is no consensus on which surface topography (ST) parameters may be used to detect scoliosis progression. The sensitivity to change of common ST parameters has not yet been compared. The goal of this study was to determine which ST parameters are most sensitive to scoliosis progression in patients with adolescent idiopathic scoliosis (AIS) receiving conservative treatment. Fifty-eight subjects with AIS were included whose Cobb angle had progressed by at least 5° during a 1 year interval. All had had ST scans and frontal radiographs at a 12 month interval at our clinic. Commonly used back-only ST parameters and contributing scores were derived by one evaluator. Standardized response mean (SRM) and 95% confidence intervals (CI) were calculated using the absolute value of the changes between baseline and follow-up to reflect change in deformity, independent of direction. Decompensation, cosmetic score, Deformity in the Axial Plane Index (DAPI), trunk rotation, Hump Sum, and lordosis angle were highly sensitive to scoliosis progression (SRM>0.8). Cosmetic score, Posterior Trunk Symmetry Index (POTSI), and kyphosis angle had significantly poorer SRM values than the Cobb angle. All other ST parameters had SRM estimates that did not differ significantly from the Cobb angle, suggesting that they have a similar ability to detect progression The ST measures that were most sensitive to detection of scoliosis progression in the frontal, transverse, and sagittal planes were decompensation, trunk rotation, and lordosis angle, respectively. Absolute changes in surface parameters representing either worsening or improvement externally could reflect worsening of the internal deformity. The majority of ST parameters are potentially sensitive to scoliosis progression. [ABSTRACT FROM AUTHOR]

A multi-functional positioning frame (MFPF) has been developed which includes a number of positioning features allowing for hip flexion and extension, thorax vertical displacement, lateral leg displacement, pelvic torsion and thorax lateral displacement. The objective of this study was to develop a method allowing for optimized combined use of the MFPF features. Finite element models (FEMs) representing the osseo-ligamentous structures of the spine, ribcage, pelvis and lower limbs, including muscles, were created for three different curve types (main thoracic, double major, and triple major) using a radiographic bi-planar reconstruction technique. Each FEM was subjected to an experimental design in which MFPF features were independently and simultaneously varied between extreme positions and the resultant changes in spinal geometry measured. Optimization of individual spinal geometrical parameters showed variability between curve types and some patterns such as minimum Cobb with lower limbs displaced laterally towards the convexity, pelvis raised on the side of concavity, and thorax laterally displaced towards the thoracic concavity. A weighted and normalized global optimization equation was developed which accounts for the relative importance and desired values of each geometrical parameter. Combined use of MFPF features and adjustments offers a wider range of possible intra-operative spinal geometries than their individual use. [ABSTRACT FROM AUTHOR]

Fusionless growth sparring implants seek to restore spinal alignment through the early intervention of pediatric scoliosis. Amongst a growing number of concepts, the stainless steel (SS) staple, flexible tether and shape memory alloy (SMA) staple have demonstrated their validity by retarding convex vertebral growth while modifying spinal alignment. The purpose of this study was to explore the biomechanics of these devices in a human scoliotic finite element model (FEM) constructed from patient data. A FEM of a scoliotic anterior spine (28° thoracic curve) was developed to include growth dynamics and shown to represent typical scoliotic progression. The explored implant concepts were alternatively introduced around the apical vertebra of the FEM (T5–T9). Immediate impact (asymmetrical loading of the vertebral growth plates and correction of scoliotic curve) and long term impact (correction of scoliotic curve after 2 years of growth) were simulated and compared to the behavior of the non-instrumented model and patient data. Results of the difference in asymmetrical growth plate stress between instrumented and non-instrumented models reveal: insignificant initial impact by the SS staple, a 52% reduction with the flexible tether, and a 31% reduction with the SMA staple. Initial and long term modifications of coronal spinal alignment following simulated growth was respectfully 28° to 62°in non-instrumented model and patient data, 28° to 31° with SS staple, 23° to 31° with flexible tether, and 27° to 34° with SMA staple. The interpretation of such methods suggests that the long term correction, achieved via growth modulation, would benefit from improved control of asymmetrical stresses within the growth plates. From a biomechanical perspective, fusionless growth sparring techniques for the early treatment of idiopathic scoliosis show promising preliminary results. [ABSTRACT FROM AUTHOR]

The intra-operative prone position used for the posterior instrumentation of scoliotic patients has been shown to reduce the spinal deformities prior to instrumentation by 37% on average. However, the effects of the lateral decubitus position used for anterior approaches and minimally invasive techniques have not been investigated. The objectives were to characterize, model and study the biomechanics of this intra-operative posture. Several clinical indices were measured on the pre- and intra-operative radiographs of six scoliotic patients. A personalized finite element mode (FEM) was developed using the pre-op 3D reconstruction, and a three-step method was developed to simulate the lateral decubitus positioning. Two additional intra-op postures, simulating different pelvic obliquities, were also tested by varying the inclination of L5. The radiographic evaluation of the lateral decubitus position showed a significant reduction of 44% of the major curve with 18 mm of apical vertebra translation. The FEM was able to reproduce the intra-op spine geometry with no significant difference with the measured values. Simulations also showed that the pelvic obliquity had different effects on the lumbar and major Cobb angles depending on the scoliotic curve type. The lateral decubitus posture reduces significantly the scoliotic curvatures prior to instrumentation, which was dependent on the pelvic obliquity. [ABSTRACT FROM AUTHOR]

Introduction: Adolescent idiopathic scoliosis (AIS) can affect spine mobility and gait mechanisms. Nowadays little is known about the effects of scoliosis on gait. Objectives: To evaluate the effects of untreated scoliosis on gait. Materials and Methods: Fifty-four females (13 healthy girls and 41 AIS with thoracolumbar/lumbar curve) were assessed by gait analysis. Xrays allowed classifying AIS patients into three groups, depending on the scoliosis severity. Gait analysis included synchronous bilateral kinematic and electromyographic (EMG) measurements, assessment of external (Wext), internal (Wint), total mechanical work (Wtot), oxygen consumption (V& O2), energy cost (C) and muscular efficiency (Wtot/C). Results: Shoulder, pelvis and hip motions were significantly reduced in all AIS patients. The reduced motion correlated with decreased Wtot. V& O2 and C were increased by 30 %. Muscle efficiency was decreased by 29 %. Increased C correlated with prolonged timing activity of lumbo-pelvic muscles (LPMTA). Discussion: Reduction of Wtot can be explained by decrease of external work. Increase of V& O2 and energy cost could be due to bilateral increase of LPMTA. Conclusion: Similar gait alterations were observed in all AIS patients, whatever the severity of the scoliosis. The observed alterations may be considered as the manifestation of an underlying neuromuscular disease or as a consequence of the stiffening effect of scoliosis. The observed “careful walking” strategy could also be a compensatory mechanism to minimize energy expenditure. [ABSTRACT FROM AUTHOR]

The internal forces in the human body in motion could provide valuable information for the evaluation and follow-up of subjects with musculo-skeletal pathologies, such as scoliosis, but are still difficult to accurately measure. In this context, the objective of this study is to quantify the global intervertebral torques along the spine during walking, in order to compare the dynamical behavior between two subjects with different scoliosis severities. Practically, two patients, both with left lumbar adolescent idiopathic scoliosis (lumbar Cobb angles: 40°), but with different apical axial rotations (20° and 30°) and different thoracic Cobb angles (20° and 30°), walked on a treadmill at 4 km/h. The acquisition system included optokinetic sensors (reflective markers), recording the 3D-joint coordinates, and a treadmill equipped with strain gauges, measuring the external forces independently applied to both feet. The global intervertebral torques were computed using an inverse dynamic model of the human body in 3D. As results, significant differences of the subject kinematics and ground reaction forces were recorded, which lead to different internal torque behavior in magnitude, maxima and minima when normalized to the subject mass. In conclusion in this preliminary study, different dynamical behavior was found between two subjects with different scoliosis severities, suggesting that the scoliosis severity could be affected by abnormal internal torques along the spine during gait (different than in the standing posture), which could lead to a supplementary asymmetric growth modulation of the vertebrae and the further progression of the scoliotic deformities in the framework of the Hueter-Volkman principle. Finally, this is a pilot study and the results will inform future studies and biomechanical modeling. [ABSTRACT FROM AUTHOR]

Despite years of extensive research, the etiology of idiopathic scoliosis still has not been resolved. A hypothesis on the role of posteriorly directed shear loads was studied in several biomechanical and imaging studies. So far, it has been shown that: on the human erect spine these posteriorly directed shear loads act; these loads decrease the rotational stability of the spine vitro and in vivo; once rotation occurs, it logically follows an already built-in vertebral rotational pattern, that is pre-existent in the human spine; this pre-existent rotational pattern is related to organ anatomy, and not to handedness; certain areas in the female spine are more subject to posteriorly directed shear loads as certain areas in the female spine are more backwardly inclined. Although it is appreciated that the cause of idiopathic scoliosis is multi-factorial, we believe that the delicate upright spinal sagittal balance and the unique posteriorly directed shear loads acting on the erect human spine play a crucial role in the rotational stability of the human spine, and thus in the pathogenesis of idiopathic scoliosis. [ABSTRACT FROM AUTHOR]

Spine and posture disorders cover large interest in rehabilitation. Quantitative functional evaluation represents the main goal in Movement/Gait analysis. However very few studies outline the behaviour of spine during Posture and Movement/Gait analysis. To overcome such limits, several years ago our group started, a project to transfer into a complete fully 3D reliable and detailed representation, different segmental biomechanical models presented in literature. As result a complete 3D parametric biomechanical skeleton model has been developed to be used in quantitative analysis. Posture and Movement/Gait analysis are performed by 3D Opto-electronic stereophotogrammetric measurements of body landmarks labelled by passive markers. Depending on different analysis purposes, the model can work at different stages of complexity. Examples on the application of such model into biomechanical and clinical fields have been presented in literature. Our group is continuously working to add new features to such model, which is now able to fully integrate data deriving from force platforms, SEMG, foot pressure maps. By means of data fusion and optimisation procedures all these inputs are used in the model to assess lower limbs internal joint forces, torques and muscular efforts. The possibility to compute the average of cyclic or repetitive tasks has been included as well. Recently we added the possibility to assess internal joint forces and torques at each spine vertebral level and to correlate these latter with all the other model's features. The aim of this study is to present the methodological aspects of such new features and their potential applicability in clinical and biomechanical fields. [ABSTRACT FROM AUTHOR]

This study uses experimental data acquired from adolescents with idiopathic scoliosis to assess their postural control during quiet standing before and after posterior spinal fusion. Statistically significant differences were seen when comparing the pre- and post-surgical measures of balance calculated from data for three different test conditions. [ABSTRACT FROM AUTHOR]

Spondylolysis occurs in 6 % of the general population. Of these, approximately 75% will develop spondylolisthesis. According to multiple studies, an increased prevalence of spondylolysis and spondylolisthesis exists in groups of athletes practicing certain sports such as gymnastics. In the literature, prevalence of spondylolisthesis in gymnasts can reach up to 40 to 50 %. However, the specific risk factors associated with the development of spondylolisthesis in gymnasts are not known. The main purpose of this study was to evaluate the prevalence of spondylolysis and spondylolisthesis in a population of gymnasts, as well as the associated epidemiological characteristics. In order to achieve this goal, we presented our project to the two most renowned gymnastics centers in the city of Montreal, which allowed us to recruit a total of 93 gymnasts (19 males and 74 females). A radiological evaluation, with the low emission radiographic system, EOS, allowed us to identify the subjects that were affected by spondylolysis and spondylolisthesis. Additionally, standardized questionnaires allowed us to evaluate and compare different epidemiologic parameters such as age, height, weight, number of years of practice, number of hours of training per week. Of the 93 gymnasts evaluated clinically and radiographically, we identified 6 (1 male, 5 females) gymnasts presenting a spondylolysis and/or spondylolisthesis. This 6.5% prevalence found in our population is similar to the one reported in the general population. Gender did not seem to be a determinant factor. Also, gymnasts with and without spondylolysis and/or spondylolisthesis seemed to be similar in terms of height. However, gymnasts with spondylolysis and/or spondylolisthesis seemed to be heavier than gymnasts without one of these two affections, older and training with greater intensity. These results suggest that the real prevalence rate of spondylolysis and spondylolisthesis in gymnasts may have been overestimated in previous studies. A selection bias, due to the high competitive level in the two gymnastics centers where our recruitment took place, could be involved. Our findings could also be the result of new or different training methods compared to those used in past studies. This might suggest that with intense training schedules, heavier individuals could potentially be prone to increased loads at the lumbo-sacral junction, thus favoring the development of spondylolysis and spondylo-listhesis. These hypotheses should be explored in further details in the near future, especially with investigation of radiological parameters of the spine and pelvis. [ABSTRACT FROM AUTHOR]

Introduction: Decompensation of un-fused vertebrae is a potential complication of spinal instrumentation performed for adolescent idiopathic scoliosis (AIS). This can result in problems requiring revision surgery. The purpose of this study was to compare patients who decompensated in the sagittal/coronal plane and those who do not and to identify risk factors. Methods: The Spinal Deformity Study Group data-base for AIS identified 908 patients at 2 years post-op. Coronal measures analyzed included coronal balance (CB), coronal position of the lower instrumented vertebra (CPL) and LIV tilt angle (LTA). Sagittal measures included sagittal balance (SB) and distal-junctional kyphosis (DJK). The incidence of decompensation at 2 years was: CB-16.83%, LTA-37.53%, CPL-21.17%, negative SB-51.88%, positive SB-7.62%, DJK-6.8%. Decompensated patients were compared to those who were not using preoperative, and 4-16 weeks post-op values. Results: Numerous significant differences were found between patients who decompensated at 2 years and those who did not. CB was significantly influenced by larger height/weight, increased Cobb, preexisting CB and a thoracic LIV. In addition to other factors LTA decompensation was more likely to occur in JIS. CPL was associated with pelvic-obliquity and thoracic LIV. Post-operative sagittal balance could be predicted by pre-operative sagittal balance. DJK was also associated with larger weight and preoperative sagittal measures. Discussion and Conclusion: Less correction in sagittal/coronal planes is a risk factor for decompensation. Curve correction was significant in predicting coronal decompensation. Failure to control sagittal alignment was a risk factor in sagittal decompensation. [ABSTRACT FROM AUTHOR]

We applied a new surgical technique utilizing conventional hybrid instrumentation to achieve better correction of trunk deformity in adolescent idiopathic scoliosis. The purpose of this study is to introduce our “Super Hybrid Method” and to analyze the results at minimum 2-year follow-up. The technique consists of rib mobilization (2006), a rod rotation maneuver (1997) and a hook rotation maneuver (2007). Forty-four idiopathic cases (female: 43) with minimum 2-year follow-up were reviewed (24-39months, average 32). The average age at surgery was 20.4 years (12-57). The average pre-operative Cobb angle was 56.7 degrees (40-93). The average pre-operative rib hump was 23.2mm in height and 14.3 degrees by scoliometer. The average post-op Cobb angle was 13.3 degrees at 3 weeks and 18.1 degrees at follow-up. The average initial overall correction at 3 weeks post-op was 78% (83% for age<18, 73% for age ≤18) and 70% at later follow up (75% for age<18, 67% for age ≤18). The average rib hump 2 years post-operatively was 12.4mm in height and 7.3 degrees. Sixty nine percent of patients (18/26) with a pre-operative rib hump ≤20mm (20-49) had a decrease in hump height by more than 10mm (10-34). In Moiré analysis, the hump-sum measure (Suzuki) showed a statistically significant decrease from 13.4 preoperatively to 9.2 at 1 year post-op (p<0.001). Correction of deformity was excellent with our new technique. It is a less expensive procedure and carries little inherent risks. [ABSTRACT FROM AUTHOR]

Even if braces for scoliosis are broadly used, there are no data on the orthopaedic medical practice to evaluate the circumstances of brace prescription. This study aims at comparing scoliosis brace prescription patterns with generally recognized standards. A cross-sectional study was carried out in 2006-2007 on all confirmed AIS patients referred to a paediatric scoliosis clinic for a first visit. Agreement between the actual brace prescription patterns and standards for immediate prescription was analyzed, following the recommendations of the Quebec Scoliosis Network (QSN), as well as the Scoliosis Research Society (SRS) therapeutic inclusion criteria. In addition, chi-2 tests and logistic regression models were used to identify variables related to brace prescription. Amongst the 321 AIS patients, immediate brace treatment was recommended in 70 cases, for about 50% of concordance with the defined criteria. Variables describing the patients' maturity (age, Risser, onset of menses) and deformity magnitude (Cobb angle and rib hump), as well as the treating physician, were the main determinants of brace prescription. Despite the professional consensus on immediate bracing norms, under and over-prescription of brace were documented in this study. Better understanding of these patterns would require documentation of motives associated with prescription at the individual level. [ABSTRACT FROM AUTHOR]

A systematic examination of the braces commonly used in Europe lacks in literature. Therefore the objective of this report is the description of the European braces widely used. The history, design rationale, indications, biomechanics, outcomes and comparison between some braces are reported. Chêneau Brace is used in France and other European Countries. There are two Cheneau derivatives, namely the Rigo System Cheneau Brace used in Spain and the ScoliOlogiC® “Chêneau light” used in Germany. The Lyonnaise Brace is used in France and Italy. The Dynamic Derotating Brace DDB is used in Greece. The TriaC brace is applied in the Netherlands. The Sforzesco brace based on the SPoRT concept and the Progressive Action Short Brace PASB are used in Italy. Correction of spinal deformities is achieved in conservative treatment with passive and active brace mechanisms. The mode of operation of modern braces is in accordance with various principles of correction, namely active or passive extension with the aid of a neck ring and correction by lateral pads, lateral pressure according to 3 – point principle, compression, bending the trunk towards the opposite side, active bracing and correction by means of pressure exerted by bands during movement and by means of metallic blades. Recently there has been an effort to expand our insight on the biomechanics, the treatment management principles and the outcome description of the above mentioned braces. The peer review publications on these studies mandate the use of the SOSORT and SRS inclusion and assessment criteria for conservative scoliosis treatment. [ABSTRACT FROM AUTHOR]

In spinal instrumentation surgery, the optimal placement of pedicle screws that takes into account the cortical/cancellous bone quality, geometry and property distribution, and screw design is still undetermined despite several in vitro experiments. The objective of this study was to evaluate the feasibility of using a detailed finite element model (FEM) of an instrumented vertebra to simulate screw axial pull-out and to analyze the bone-screw mechanical interaction. The FEM was built using CT-scan images of the L3 vertebra (0.6mm thick contiguous slices) of a 50th percentile human male volunteer, in order to virtually implant a fully customizable pedicle screw in a straight-forward position. The 753,000 elements model takes into account local cortical bone thickness and integrates advanced material behavior (elasto-plastic) laws that simulate bone failure. Screw axial pull-out was simulated and compared to in vitro experimental data, and the stress distribution at the screw thread-bone interface was analyzed. The simulated screw pull-out force (non-linear response with a failure at 640N) was within the range of experimental data (500-660N). Von Mises stresses in the bony structures were concentrated around the root of each internal thread, with the maximum stress located near the first proximal thread, in the cortical bone of the posterior wall of the pars. This study shows the feasibility and relevance of using a detailed FEM to simulate screw pull-out and to analyze the bone-screw mechanical interaction. [ABSTRACT FROM AUTHOR]

Introduction: Treatment of children with early onset scoliosis (EOS) seeks to improve natural history and health related quality of life (QOL). QOL measurement presents a significant challenge given the young age, comorbidities, and heterogeneity of this population. Objective: To develop a disease specific measure reflecting issues of importance to EOS patients and caretakers. Materials and Methods: Review of the literature and relevant measures informed development of semi-structured qualitative interviews. Interviews of caregivers of EOS patients were interpreted through the framework technique. A master-list of 75-items was created and responses were scaled on a 5-point Likert-scale. Psychometric analysis was performed to group items into domains, to maintain score distribution, to create a responsive instrument, and to identify question redundancy. Results: Content validation revealed 8-items with low content validity indices. Item distribution analysis demonstrated 19-items with skewed distribution. Item reliability demonstrated redundant items within domains (r≥0.5). Construct validity demonstrated unique domains measuring intended issues of interest. The resulting Early Onset Scoliosis Questionnaire (EOSQ) includes 33-items in 13-domains: General Health, Pain, Physical Function, Pulmonary Function, Daily Living, Fatigue, Emotion, Surgical Concerns, Satisfaction, Transfer, Financial Burden, Parental Burden, and Treatment Outcomes. Conclusion: The EOSQ reflects QOL and caregiver burden in the EOS population. The EOSQ will expand options for outcome assessment in this unique population. [ABSTRACT FROM AUTHOR]

Objective: To describe and compare the quality of life of patients with pediatric high-grade spondylolisthesis managed non-operativelyand operatively. Summary of Background Data: Some authors consider pediatric high-grade spondylolisthesis as an absolute indication for surgery, regardless of symptomswhile others sometimes recommend observation in asymptomatic patients. Very little is known about the indications and outcome of non-operatively managed high-grade spondylolisthesis. Methods: A prospective database comprising all the spondylolisthesis cases from a single pediatric institution was reviewed in order to identify all cases of high gradespondylolisthesis. Quality of life data from Short form (SF)-12 and Scoliosis Research Society (SRS)-22 questionnaires were collected. Non-operatively treated patients were identified and compared to surgically treated patients at baseline and at last follow-up. Results: 34 spondylolisthesiswere identified as high grade and 5 of them were non-operatively treated. Quality of life questionnaires showed less impairment in the non-operativegroup when compared to the surgical group preoperatively. Moreover at last follow-up, quality of life questionnaires were similar between the two groups. There was no worsening of quality of life observed in non-operativepatients during follow-up. Conclusion: The quality of life after surgical treatment of high grade spondylolisthesisissimilar to that of patients with high grade spondylolisthesis and mild symptoms undergoing non–operative treatment. [ABSTRACT FROM AUTHOR]

Introduction: Understanding how to classify and quantify three-dimensional (3D) spinal deformities remains an open question in adolescent idiopathic scoliosis. Recent studies have investigated into pattern classification based on explicit parameters. An emerging trend however seeks to synthesize complex data in a sub-space domain to capture the intrinsic variability of anatomical shape. Objective: The objective of this study is to analyze populations of 3D scoliotic patients using a novel geometrically intuitive statistical tool for pathological cases. Materials and Methods: Personalized 3D reconstructions of thoracic (T)/lumbar (L) spines from two cohorts: 68 Lenke Type-1 patients and 28 surgical patients with directvertebral-derotation (DVD) manoeuvres were analyzed with a non-linear manifold embedding algorithm in order to reduce the high-dimensionality of the data, using statistical properties of neighbouring spine models. We extract sub-groups of the data from the underlying manifold structure to understand the inherent distribution. Results: For Lenke Type-1 patients, three clusters were detected from the low-dimensional manifold of 3D models: 1-hypo-kyphotic (T) with normal to high lordosis (L) (35 cases), 2-hyper-kyphotic (T) (6 cases) and 3-hypo-kyphotic (T) with loss of lordosis (L) (27 cases) (Figure1). In the case of surgical patients with DVD, the method was able to cluster both pre and post-operative spine geometries. Conclusion: Quantitative evaluation illustrates that the complex space of spine variability can be modeled by a low-dimensional manifold and demonstrates for the first time the existence of a third class in three-dimensional shape differences for Lenke Type-1 patients. Significance: The manifold representation can potentially be useful for classification of 3D spinal pathologies such as idiopathic scoliosis and serve as a tool for understanding the progression of deformities in longitudinal studies. [ABSTRACT FROM AUTHOR]

Introduction: The effects of dynamic loading on growth are presently poorly understood. Studies investigating static/dynamic loadings do not use matched and normalized loading parameters. Objectives: This study aimed at characterizing the effects of static/dynamic loading of growth plate explants, matched in terms of average strain, on the histomorphometry. Methods: Growth plate explants were extracted from distal ulnae of 4-week-old swine. Four groups were implemented: normal, culture control, static loading, matched dynamic loading. Normal samples were immediately fixed. The static samples underwent 10% strain. The dynamic samples underwent equivalent cyclic strain at 0.1 Hz. Matched control samples were kept in identical conditions. Sections were made from methymetacrylate embedded samples and stained with Toluidine Blue. The total growth plate thickness and the combined thickness of the hypertrophic/proliferative zones were measured. Results: The chondrocytes columnar arrangement from the dynamic samples was disorganized, especially in the hypertrophic/proliferative zones, when compared to the other groups. A decrease was observed in all parameters when comparing the static/dynamic groups to the control group. These reductions were statistically significant for the static group only. Conclusion: Explants responded differently to static/dynamic loading. The loss of columnar arrangement was more severe in the dynamically loaded explants, but decreases in all histological parameters were more significant following static loading. Complementary mechanobiological data is required to fully interpret these results. Significance: The exact response of the physis to static/dynamic stresses will help improve current treatment approaches and develop new approaches for the treatment of pediatric musculoskeletal deformities, such as scoliosis. [ABSTRACT FROM AUTHOR]

Finite Element Models can be a helpful tool to investigate new, motion preserving means of treatment of spinal deformities. However, an effective validation is even more challenging than for a healthy spine, as in-vitro experiments are very hard to perform due to the limited availability of human cadaver specimens. Measuring the stiffness of scoliotic motion segments intra-operatively offers the possibility to acquire data in an in-vivo situation and at the pathology of interest. We developed a measurement setup to determine the lateral bending stiffness of motion segments after the opening of the back and before the corrective surgery of Adolescent Idiopathic Scoliosis. The apparatus includes a distraction forceps modified to measure force and displacement and an optelectronic camera to track motion. The combination of geometric computer models (vertebral models derived from MRI or CT), motion tracking and forceps data enables the determination of moment and angular displacement measurements for each distraction. The feasibility of this method was validated in a cadaver study using lumbar ovine spines. Measurements were performed with the distraction forceps and compared to equivalent experiments on a spinal loading simulator, as we consider this to be the gold standard for the determination of spinal stiffness. The stiffness computed with the proposed concept was within a range of 15% compared to data obtained with the spinal loading simulator under applied loads of less than 3 Nm. First, intraoperative trials have been performed. The preliminary results confirm the observation that the coupling is such that the anterior portion of the vertebra always rotates into the convexity of the curve when exposed to a left lateral bending. [ABSTRACT FROM AUTHOR]

Introduction: Scoliosis progresses within a biomechanical process involving asymmetrical vertebral loading and growth modulation. There is a growing interest in fusionless technique of vertebral stapling for the correction of scoliosis, as it presents less surgical risks and complications than the traditional fusion surgery. Objectives: This study aims at characterizing the effects of vertebral stapling on vertebral growth rate and growth plate histomorphometry. Materials and Methods: Twelve female Yorkshire-Landrace pigs aged three months were divided into three groups: loaded (6), sham (3) and control (3). Loaded animals had five staples implanted at levels T6 to T11 for two months. For all animals, postoperative radiographic follow-up included imaging of the spine every two weeks. Growth rate was evaluated using calceine labelling, injected 8 and 2 days prior to sacrifice. Vertebrae were then extracted, fixed and embedded in methymetacrylate. Thin sections of vertebra-disc-vertebra complexes were imaged for growth rate measurements and histomorphometrical analyses. Results: A scoliotic curve was developed in two loaded animals. Mean growth rates evaluated at the T8-disc-T9 complex reached 15,0, 21,4 and 19,8 for the loaded, sham and control groups respectively. Conclusion: Vertebral stapling induces spinal curvatures and decreases vertebral growth rate. Staple positioning is critical in the performance to modulate vertebral growth. Complementary histomorphometrical analyses will provide insight on the growth plate response to stapling. Significance: In vivo mechanobiological studies on the technique of vertebral stapling are required to better characterize the outcome of these fusionless approaches for the correction of scoliosis. [ABSTRACT FROM AUTHOR]

Introduction: Three-dimensional spine reconstruction methods currently used to study scoliosis require manual identification of several anatomical features, which is time-consuming, costly and error-prone. Objectives: To provide fast 3D reconstructions of the spine that may be accomplished by non-expert users. More specifically, recovering the 3D position of 6 anatomical landmarks per vertebra based on a pair of radiographs with minimal user interaction. Materials and Methods: Splines approximating the spine midline were identified by end-users using a small number of control points (typically 4 to 7 points on each radiograph). Then, vertebrae location, rotation and 3D anatomical landmarks were recovered by deforming a statistical articulated model that captures intervertebrae variability (compiled using 291 prior reconstructions). The deformation optimizes both the fit with the user's splines and the prior probability given by the statistical model. A set of 14 in vivo exams of scoliotic patients were used for validating the method. 3D reconstructions obtained using a previously validated method were compared with reconstructions using the proposed method performed by 2 volunteers with limited knowledge on spine radiology. Volunteers only had 20 minutes of training with the software tool (figure 1). Results: The mean reconstruction errors were 3.4mm for the endplates and 4.8mm for the pedicles. Furthermore, the average reconstruction time was 1min28s. Conclusion and Significance: Results show that rough reconstructions of the spine may be rapidly achieved by non-expert users with very little training. This makes the method attractive when fast reconstructions are required, or when dedicated personnel would be too expensive. [ABSTRACT FROM AUTHOR]

Introduction: Characterizing and classifying torso deformities associated with scoliosis is very challenging. One of the problems hindering the achievement of a consensus about these issues is the absence of a centralized and intuitive resource where scoliotic torso deformities can be visualized and interpreted by anyone in the spinal deformity research community. Objectives: To provide an easy to use and readily available tool to help clinicians interpret databases of scoliotic torso surfaces. Materials and Methods: An initial sample of torso surfaces comprised of preoperative scoliotic patients was selected (details about the sample composition are available online). Those surfaces were registered non-rigidly together using a method developed for 3D anthropometric measurements in order to build a common parameterization. Then, a web-based visualization tool was developed to visualize animated 3D torso models reconstructed by interactively combining the principal modes of variations found using the re-parameterized models. Also, because this visualization tool uses the Java Web Start technology, it is readily available to most authorized users equipped with an Internet connection and a recent web-browser. Results: All the torso surfaces were successfully registered and re-parameterized. Clinicians and researchers can thus now easily visualize the typical torso shape variations associated with a group of scoliotic patients by accessing a simple website. Those results are available at: www.humanshape.net/scoliosis/irssd2010.html. Conclusion and Significance: The proposed tool is a very efficient platform to share information about 3D models, which is extremely useful for a wide variety of research problems such as the classification and characterization of external torso deformities. [ABSTRACT FROM AUTHOR]

Introduction: Leg discrepancy is known as a symptomatic skeletal asymmetric in scoliosis. We hypothesized that leg discrepancy is correlated to the pelvic frontal alignment which in turn is correlated to the entire spinal deformities. Objective: To investigate the correlation between leg discrepancy, pelvic alignment and spinal parameters in AIS. Methods: Three-dimensional reconstructions of the spine and pelvis of 80 adolescents with right main thoracic (MT, Lenke1), 80 with left thoracolumbarlumbar (TL/L, Lenke 5) idiopathic scoliosis and 36 asymptomatic control subjects were included in this study. Also 4 anatomical landmarks on the pelvis (contralateral ASIS and PSIS) and two femoral heads were selected to define pelvic alignment i.e. pelvic tilt in the coronal plane and pelvic rotation in the transverse plane and leg discrepancy in subjects. Results: The 160 subjects were classified in four classes (PC1 to PC4) based on the pelvic transverse and coronal planes orientation. A majority of Lenke1 subjects had their pelvis rotated towards the major carve (58% in the frontal and 84% in the transverse plane). 72% of Lenke 5 subjects had their pelvis tilted in the coronal plane towards the thoracolumbar curve while the pelvis rotation tends to be more affected by the direction of the main thoracic curve (70% of subjects)(Fig 1). Pelvic frontal tilt (Obliquity) found to be correlated to the leg discrepancy in Lenke1 (r=0.70) and Lenke5 (r=0.80) p<0.001. 91% of the controls had pelvic tilted counter clockwise in the posterior view and less than 4° ccw pelvic axial rotation. Conclusion: The findings suggest that pelvic rotation is more affected by the direction of main thoracic rotation while pelvis aligns itself towards the direction of the major curve i.e. thoracic in Lenke 1 and lumbar in Lenke 5 in the frontal plane and is correlated to the lower limb discrepancy. [ABSTRACT FROM AUTHOR]

Nickel-titanium (NiTi) shape memory alloys have been used as surgical implants in orthopaedic procedures. However, nickel ion release remains a concern. Therefore, an advanced surface technology using plasma immersion ion implantation (PIII) has been developed to address this issue. This paper describes serum nickel ion level monitoring of patients with scoliosis operated upon using nitrogen plasma implanted NiTi spinal rods compared with standard titanium alloy rods in a randomized human clinical trial. NiTi spinal rods with 50.8% Ni were treated by nitrogen PIII at 40kV with 100Hz. Seventeen patients with spinal scoliosis were surgically treated by either Ti alloy rods or nitrogen plasma implanted NiTi rods. The mean age at operation was 16.6 years. The mean number of treated spinal segments was 9. Blood samples were collected as baseline before surgery and up to 1 year post-surgery. Nickel levels were assayed by inductively coupled plasma mass spectrometry. Twelve patients (7M and 5F, 6=NiTi and 6=Ti) were followed up for 6 months, and five of them (2M and 3F, 2=NiTi and 3=Ti) had completed 1-year follow-up. In all cases, at Day 1 after surgery, patients who had NiTi rods implanted had a 2.5 times increase in the Ni level, compared with before surgery. However, all were within recommended safe limits. The Ni levels returned to baseline in all subjects between 7 days to 1 month postsurgery. No clinical signs and symptoms of Ni allergy or toxicity was observed. [ABSTRACT FROM AUTHOR]

Introduction: Restoration of the sagittal alignment in scoliosis correction surgery is generally achieved by rod pre-contouring intra-operatively. However clinical studies suggested that it could be affected by the inherent properties of the spine rather than the instrumentation or surgical maneuver. Objectives: To investigate the natural coupling behavior between the frontal and sagittal deformities, and to examine how the post-operative thoracic sagittal realignment relates to this natural coupling behavior. Methods: Ninety eight idiopathic scoliosis patients with thoracic curves treated with one-stage posterior spinal fusion using segmental spinal instrumentation were investigated. Pre- and postoperative frontal and sagittal alignments were measured by fulcrum bending and standing anteroposterior and lateral radiographs. Results: When thoracic frontal deformity was corrected under fulcrum bending, coupled changes in the thoracic kyphosis demonstrated three different patterns: thoracic kyphosis increased in 25 patients, decreased in 45 patients and remained unchanged in 28 patients. After surgery, the direction of correction of thoracic kyphosis significantly correlated with the coupling patterns demonstrated on fulcrum bending radiographs (r=0.579, p<0.001). However, the actual postoperative thoracic kyphosis angle cannot be predicted by the pre-operative lateral fulcrum bending radiograph. Conclusions & significance: Changes in thoracic kyphosis on fulcrum bending due to natural coupling of deformities are directed towards “self-normalization”. There is no difference in the sagittal plane deformity correction with the use of hook-rod system or pedicle screw-rod constructs. The findings also suggest that it is not how big or strong the implants are, but rather the natural curve behavior will at least partially determine the final sagittal outcome. [ABSTRACT FROM AUTHOR]

Introduction: The reported incidence of scoliosis in arthrogryposis varies from 30% to 67% and, in most cases, the curves progresses rapidly and becomes stiff from early age. Objectives: The Authors report six cases of scoliosis in arthrogryposis to assess the role of surgical treatment. Materials and Methods: Six cases (3 males, 3 females; mean age at surgery 13.2 years) with arthrogryposis multiplex congenita associated with the characteristic amyoplasia were reviewed: they were operated on for scoliosis at the Spine Surgery Department of the Rizzoli Orthopaedic Institute between 1987 and 2008. Surgery was performed using the Harrington-Luque instrumentation (2 cases), the Luque system (1), a hybrid segmental technique with hooks and screws (1) and spinal anchoring with pedicle screws (2). Results: The patients were clinically and radiologically reviewed at a mean follow-up of 4.2 years, ± 2.7 (range, 1 to 9 years). Three minor postoperative complications were encountered; a long-term complication was seen only in one case and required instrumentation removal. Surgery was successful in the other 5 cases, where solid arthrodesis was achieved and no significant curve progression was observed at follow-up. Conclusions: The experience acquired on the present case series leads the authors to assert that prompt action should be taken when treating such aggressive forms of scoliosis. Significance: In case of mild spinal deformities in arthrogryposis, brace treatment should be attempted, the evolution of the curves being unpredictable; however, when the curve exceeds 40° and presents with marked hyperkyphosis, hyperlordosis or pelvic obliquity, surgery should not be delayed. [ABSTRACT FROM AUTHOR]

Introduction: Idiopathic scoliosis (IS) is referred as a cause of a back pain in adults, probably on the basis of spinal overload and degeneration. Back pain in children and youths has been assessed only occasionally. Objectives: The aim of the study was to determine the occurrence of back pain in adolescent with IS. Material and methods: Poll assessment and medical documentation analysis of 70 patients (65F and 5M) with IS was conducted. Mean age of researched group was 15 years (SD=1.7), mean value of body mass index (BMI) was 18.7 (SD=2.3), mean Cobb angle 26.4° (SD=13.8), apical vertebra rotation (AVR) 13.4° (SD=8.2), thoracic kyphosis 26.1° (SD=12.2) and lumbar lordosis 33° (SD=9.4). Severity of back pain was evaluated by visual analogue scale (VAS). Results: Back pain was present in 2/3 of subjects (65.7%). Severity of pain ranged from 1 to 7 points of VAS (mean 3.3, SD=1.6). Pain arose usually in static positions. Cobb angle correlated positively with severity of pain, reaching level of statistical significance (Pearson's coefficient r=0.24, p<0.05). Weak, statistically insignificant correlation between AVR and pain severity was also observed (r=0.13, p>0.05), as well as between BMI and pain (r=0.2, p>0.05). Thoracic kyphosis (r=-0.2, p>0.05) and lumbar lordosis (r=-0.21, p>0.05) revealed weak, negative, insignificant correlation with intensity of pain. Conclusions: 1.Back pain occurs commonly in youths with idiopathic scoliosis. 2. Statistically significant relation between severity of back pain and Cobb angle was observed. Significance: Further evidence of common occurrence of back pain in adolescents with IS. [ABSTRACT FROM AUTHOR]

Introduction: Various means have been attempted to enhance osteogenesis of posterior spinal fusion (PSF) surgery. Stem cells treatment and biophysical intervention have been shown to enhance PSF. Before optimizing the treatment effect, it is necessary to understand the temporal and spatial pattern of osteogenesis during the PSF. With the advanced high-resolution peripheral quantitative computed tomography (HR-pQCT), the fusion mass can be monitored with relatively smaller number of animals. Objective: The study used HR-pQCT and image analysis program to depict the temporal and spatial pattern of osteogenesis in rabbit PSF model with bioceramic, osteogenic cells, and low-intensity pulsed ultrasound(LIPUS). Materials and Methods: Eight rabbits undergone standardized posterior spinal fusion surgery with mesenchymal stem cells were randomly divided into 2 groups with or without LIPUS treatment. The animals were followed at week 1,4,10 with HR-pQCT to depict the bone formation at the fusion site qualitatively and quantitatively. Results: Bone formation was not limited to the transverse processes at the fusion site but also around and within the implanted material. The bone mineral content of the fusion mass in LIPUS treated animal enhanced by 15–20%. Different pattern of bone formation was observed in LIPUS treated animal. Conclusion: HR-pQCT is a feasible and non-invasive method allowing the uncoverage of important, new information of bone microstructure in spinal fusion sequentially. The LIPUS can enhance the bone formation in the implant of posterior spinal fusion. Significance: The new HR-pQCT monitor enables better understanding of the biology mechanism and sequence of bony fusion in vivo for further research in enhancement of spinal fusion. [ABSTRACT FROM AUTHOR]

The psychosocial impact of the cosmetic defect on Adolescent Idiopathic Scoliosis patients is an important factor that must be considered when developing treatment plans and monitoring outcomes. There is new emphasis on finding ways to quantify reliably paraspinous back surface volumetric asymmetry numerically, with the objective of providing a scoring that can give an impression of the severity of the deformity at each clinical presentation. The aim of this study was to establish the effects of posture, breathing, sway and asymmetry, not resulting from any musculoskeletal condition or abnormality, on the locations of the means of the areas of coronal plane cross-sections of the volumes each side of the spine over time to determine if there were any correlations between the measures that could be useful in describing cosmetic defect. Five sequential, twenty second (1,200 sample) acquisitions of the back surface shape from thirty skeletally mature subjects were described by the threedimensional location of projected point clouds. Corrections for stance were made for each subject sample so that all surface data were related to body axes and time. The relative locations of the means of the areas of coronal cross-sections within each volume averaged across all samples were similar between each subject acquisition but there were significant differences in the ranges implying that multisample analysis offers a better and more reliable avenue to describe cosmesis in terms of a severity scoring. Comparisons were also made between the results obtained from all subjects to determine if any trends exist within a healthy population. [ABSTRACT FROM AUTHOR]

Introduction: A variety of noninvasive methods of curve analysis, such as Moir photography, Integrated Shape Imaging System (ISIS), and the Quantec Spinal Imaging System (QSIS), were developed. Based upon our experience with the use of QSIS for more than 12 years in clinics, recently we have developed a new userfriendly raster stereography system (Milwaukee Spinal System, MSS). Objectives: The goal of the current study is to evaluate variability of this system with respect to trunk position. Materials and Methods: A dummy cast was created using a plastic model of one patient with adolescent idiopathic scoliosis. Optical color-coded markers were placed on each of the cast's spinous process landmarks from T1 to L5 and at each PSIS. Two investigators completed a series of three MSS scans of the dummy cast in each of four different positions: flexed 10° to 20° in the sagittal and transversal plane, and shaking (SH) for a total of 24 scans. After scanning, 13 metrics were extrapolated from the MSS 3D data. Results: All measurements of intra-rater and inter-observer reliability were goodexcellent (0.8-1.0) with the exception of Pelvic Tilt (inter-rater reliability=0.6). No significant variability was observed for the majority of tested metrics but for spinal deviation from midline (p<0.01). Conclusion and Significance: Trunk position does result in variability in MSS measurements but only in extreme positions. The MSS is a reliable and reproducible method of raster stereography to monitor the progression of the spinal curvature. [ABSTRACT FROM AUTHOR]

Objectives: Determine the relationship between the importance of spine deformity and postural control efficiency in mild adolescent idiopathic scoliosis (AIS). Introduction: AIS is related to postural control disorders where vision, proprioception and vestibule could be involved. The aim of the study was to investigate the postural control of early-detected AIS, of which the Cobb angle is still low, evaluating whether the amplitude spine deformation is an important balance destabilization parameter. Material & Methods: 71 patients with AIS (mean age: 11.5 ± 2.0 years) were submitted at time of diagnosis to clinical and radiological assessments and to posturographic evaluation including static with and without sensory conflict and dynamic tests. Two groups were constituted according to mean Cobb angle value of the primary curve of the whole population. Results: Mean Cobb angle being 14.6 ± 5.4°, 41 patients with AIS presented a Cobb angle comprised between 5 to 14° (Group I) and 30 patients presented a Cobb angle comprised between 15 to 25° (Group II). The latter displayed higher body sways in static tests (eyes open and eyes closed conditions) and higher lateral oscillations only in eyes closed condition. In sensory organization test, Group II patients displayed a weaker balance control mainly in visual and somatosensory conflicting conditions despite no significant difference in vestibular utilization. Moreover, Group II patients used less anticipatory strategies to stabilize body oscillations, especially in the more challenging sensory conflicting and dynamic situations. Conclusions: Patients with a Cobb angle greater or equal to 15° displayed lesser postural performances, especially in sensory conflicting situations. Significance: Posturographic tests represents an accurate tool to assess postural control in AIS even at the onset of their evolution. [ABSTRACT FROM AUTHOR]

Introduction: Spinal surgery is a complicated mechanical process that stops and corrects scoliosis. Monitoring the loads on the spinal instrument during and after scoliosis surgery may prevent overloading and improve patient safety. Also, collecting the data during and after provides information to better understand the biomechanics. Objectives: This preliminary study was to validate the design of an implantable wireless sensor platform for future spinal research. Materials and Methods: The wireless sensing system consisted of one or several sensor platforms and a base station. Each sensor platform could connect up to 8 sensors. Custom software was developed to manage the sensor network and visualize sensor values in real time. A prototype unit was developed. Experiments were performed to investigate the accuracy of the internal temperature sensor and the analog-to-digital converter, the power consumption and the range of communication. Results: The system was operated in the 402–405 MHz frequency band which has been dedicated for the implantable medical devices by the FCC. The resolution of the temperature sensor was 0.42oC with accuracy of ±2oC for a range of 22oC to 45oC. The power consumption of the system was 0.65 mW during sleep mode and 15.6 mW with sampling rate of 10 Hz. The communication range was 100% reliable up to 3 m and dropped down to 92% when the range was 3–6 m. Conclusion: The design of the prototype platform worked well within the FCC specifications. Significance: A biocompatible device to measure loads during and after scoliosis surgery may help us to better understand the biomechanics of scoliosis surgery. [ABSTRACT FROM AUTHOR]