3D reconstruction of ribcage geometry from biplanar radiographs using a statistical parametric model approach

Rib cage 3D reconstruction is an important prerequisite for thoracic spine modelling, particularly for studies of the deformed thorax in adolescent idiopathic scoliosis. This study proposes a new method for rib cage 3D reconstruction from biplanar radiographs, using a statistical parametric model approach. Simplified parametric models were defined at the hierarchical levels of rib cage surface, rib midline and rib surface, and applied on a database of 86 trunks. The resulting parameter database served to statistical models learning which were used to quickly provide a first estimate of the reconstruction from identifications on both radiographs. This solution was then refined by manual adjustments in order to improve the matching between model and image. Accuracy was assessed by comparison with 29 rib cages from CT scans in terms of geometrical parameter differences and in terms of line-to-line error distance between the rib midlines. Intra and inter-observer reproducibility were determined regarding 20 scoliotic patients. The first estimate (mean reconstruction time of 2’30) was sufficient to extract the main rib cage global parameters with a 95% confidence interval lower than 7%, 8%, 2% and 4° for rib cage volume, antero-posterior and lateral maximal diameters and maximal rib hump, respectively. The mean error distance was 5.4 mm (max 35mm) down to 3.6 mm (max 24 mm) after the manual adjustment step (+3’30). The proposed method will improve developments of rib cage finite element modeling and evaluation of clinical outcomes.This work was funded by Paris Tech BiomecAM chair on subject specific muscular skeletal modeling, and we express our acknowledgments to the chair founders: Cotrel foundation, Société générale, Protéor Company and COVEA consortium. We extend your acknowledgements to Alina Badina for medical imaging data, Alexandre Journé for his advices, and Thomas Joubert for his technical support

EOS 3D Imaging: assessing the impact of brace treatment in adolescent idiopathic scoliosis

One of the major revolutions in the field of adolescent idiopathic scoliosis (AIS) during the past 10 years is the development of 3D imaging devices in standing position, such as EOS (EOS Imaging). 3D vision of the spine is new; we need to be humble and learn how it may help in the management of AIS. But we now have access to the transverse plane deformity. We do not know how to heal idiopathic scoliosis. Thus, the main issue in the field of AIS management is to avoid progression of mild scoliosis. Brace treatment is the main treatment option for mild scoliotic patients during growth. However, the efficacy of brace treatment is not consensual. We have demonstrated through a 3D analysis of brace treatment that some braces are truly efficient, some are not and others worsen the spinal deformity. Therefore, we have to anticipate the effect of a brace on a specific patient. With 3D analysis we are now able to evaluate if a brace really improves the spinal shape in the 3 dimensions or not. Moreover, we have the patient 3D geometry (spine and rib cage) and we are able to collect objective clinical data that could help achieve relevant parametric finite element models. These models could help in the prediction of brace effect but they need to be validated with clinical data. We see a close future where we will all have the 3D trunk shape of our patients on our screens along with all computed angles we need and then an instant prediction for the best-fit brace geometry for our patient.The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties

In vitro implant-bone interface pressure measurements for a cementless femoral implant. A preliminary study

PURPOSE: Implants endurance as well as a good clinical tolerance depends on the recovery of a physiological stress distribution within bone after implantation. The purpose of the present work was to develop an alternative technique using Force Sensing Resistors (FSR) to gather in vitro pressure values at the implant-bone interface for a cementless implant. METHOD: Eight cementless femoral stems were instrumented with six calibrated FSR bonded on each facet and then implanted in eight cadaver femurs. Compression tests were performed until failure and FSR pressure values were recorded. RESULTS: The average failure load was 4241 N. The maximum contact pressure measured with the FSR averaged 1.965 MPa. CONCLUSION: FSR reached many of the requirements for an ideal implant-bone interfacial sensor. This experimentation provided in vitro quantitative data on contact pressure at the implant-bone interface, which could help understanding stress shielding phenomenon and developing relevant numerical model

Experiences with a new biplanar low-dose X-ray device for imaging the facial skeleton: A feasibility study

Methods We evaluated 48 biplanar radiographs from 12 patients (posteroanterior/lateral), originally taken for a scoliosis examination with a biplanar low-dose X-ray device. For this study, the images were further evaluated for the perceptibility of 38 facial skeleton landmarks. To determine the reliability and reproducibility of perceptibility, two independent observers determined the landmarks twice, during a time interval of at least two weeks. Results Both interoperator and intraoperator reliability were excellent for all landmarks [intraclass correlation coefficient (ICC) > 0.92]. Conclusions The biplanar low-dose X-ray device demonstrated good feasibility for precisely assessing the anatomical landmarks of the facial skeleton. Given its excellent precision, the biplanar low-dose X-ray device data sets should be forwarded from the treating orthopedic surgeon or neurosurgeon to the orthodontist or dentist for further assessment in their field.For this study, no author has received any funding. During the time this retrospective study took place, the institute/laboratory in which Prof. P. Rouch works and Dr. A. Laville worked received funding from the EOS-Imaging company for other EOS studies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Letter to the Editor: The Chêneau brace

International audienc

Recherche d'indicateurs cliniques tridimensionnels d'aggravation et de correction par orthèse des scolioses idiopathiques modérées

Scoliosis is a deformity of the spine in the 3 dimensions. The scoliosis curve is progressive during the whole growth. The mains issues are the prediction of the progression and early management of the deformity. Novel 3D Imaging modalities have made possible 3D reconstructions of the spine in standing position. A 3D pattern of progressive scoliotic curve has been described. This transverse plane 3D pattern is independent of the topography of the curve and may be described at an early stage of the development of the scoliosis. Prediction of the progression leads to anticipation of the treatment in progressive scoliosis. Brace treatment is the main option during growth. However, bracing is not consensual. The 3D effect of brace treatment has been studied on scoliotic patients. The results showed a high variability of the effect of the brace on all 3D spine and pelvic parameters. There is a lack of knowledge of the effect of brace treatment on the rib cage. A reason is the lack of accurate and reproducible method of 3D reconstruction of the rib cage in standing position. Such method based on calibrated biplanar X-rays, developed and validated in asymptomatic patients in our institution, was used and validated on scoliotic patients in this work. Analysis of the effect of brace treatment of the shape of the rib cage was therefore possible. A preliminary study was performed and showed a high variability of the effect of bracing on the rib cage. This study also put the basis of further clinical and biomechanical studies on correction mechanisms of brace treatment on the spine and the rib cage.La scoliose est une déformation du rachis dans les trois plans de l'espace. Cette déformation est évolutive pendant toute la croissance. Les enjeux sont pronostics et thérapeutiques. L'étude de la déformation scoliotique en 3D grâce aux méthodes d'imagerie actuelles a permis de décrire un schéma spécifique 3D de scoliose évolutive à partir de paramètres du plan transversal. Ce schéma spécifique 3D est indépendant de la topographie de la scoliose et apparaît tôt dans l'évolution de la scoliose. Prédire l'aggravation mène à pouvoir anticiper le traitement pour les scolioses à risque. Le traitement conservateur par corset reste le traitement de choix en période de croissance. Mais il n'est pas consensuel. L'étude de l'effet en 3D des corsets, au cas par cas, a permis de montrer la grande variabilité de l'effet des corsets sur l'ensemble des paramètres 3D rachidiens et pelviens. Les corsets prennent appui sur la cage thoracique. Leur effet sur la forme 3D de la cage thoracique est mal connu par manque de méthode d'analyse fiable et reproductible en position debout validée chez les patients scoliotiques. La méthode de reconstruction 3D de la cage thoracique à partir de radiographies biplanaires calibrées, développée et validée au LBM chez des patients sains, a fait l'objet dans ce travail, d'une validation chez les patients scoliotiques. L'accès à la morphologie 3D du rachis et de la cage thoracique a donc permis d'étudier de façon préliminaire l'effet des corsets sur la cage thoracique. Cette étude a montré une grande variabilité de l'effet des corsets et a permis de poser les bases de futures études cliniques et biomécaniques visant améliorer la compréhension de l'effet 3D des corsets sur le rachis et la cage thoracique

Safety and Efficacy of Stand-Alone Bioactive Glass Injectable Putty or Granules in Posterior Vertebral Fusion for Adolescent Idiopathic and Non-Idiopathic Scoliosis

Posterior spinal fusion (PSF) is the standard procedure for the treatment of severe scoliosis. PSF is a standard procedure that combines posterior instrumentation with bone grafting and/or bone substitutes to enhance fusion. The aim of this retrospective study was to evaluate and compare the post-operative safety and efficiency of stand-alone bioactive glass putty and granules in posterior spine fusion for scoliosis in a paediatric cohort. A total of 43 children and adolescents were included retrospectively. Each patient’s last follow-up was performed at 24 months and included clinical and radiological evaluations. Pseudarthrosis was defined as a loss of correction measuring >10° of Cobb angle between the pre-operative and last follow-up measurements. There was no significant loss of correction between the immediate post-operative timepoint and the 24-month follow-up. There was no sign of non-union, implant displacement or rod breakage. Bioactive glass in the form of putty or granules is an easily handled biomaterial but still a newcomer on the market. This study shows that the massive use of bioactive glass in posterior fusion, when combined with proper surgical planning, hardware placement and correction, is effective in providing good clinical and radiological outcomes

The future of academic innovation in the field of medical devices: is innovation still possible in orthopedics?

International audienceAcademic research is essential to bring disruptive innovation on medical devices market because the risk-taking is too high for companies and their investors. Performing clinical trials is essential to technical files but no one wants to accept responsibility for implanted off-label devices. The paper explains the academic process for innovation. We see that academic research depends, at the end, on the motivation of companies to develop a product. The key to innovation stands in the early collaboration between the surgeons, the research teams and the companies in a project. Innovation is a good idea supported by the expertise of the right people at the right moment. In orthopaedics, we need, more than ever, to stay focused on the patient benefits

Etude du transfert de charge entre une prothèse fémorale de révision non cimentée et le fémur

Le remodelage osseux est lié aux contraintes dans le fémur conséquence du transfert de charge entre l'implant et le fémur. L'objectif de cette étude était l'amélioration de la compréhension des mécanismes de transfert de charge entre le fémur et un implant non cimenté. Une étude expérimentale a été menée sur huit fémurs de cadavres implantés d'une tige fémorale révision non cimentée instrumentée de six capteurs de pression. Huit essais en compression quasi-statique jusqu'à rupture ont été réalisés. La pression mesurée par les capteurs, le chargement et le déplacement ont été collectés. Cette étude a permis d'obtenir la pression à l'interface os-implant. Cette étude est l'étape préliminaire au développement et à la validation d'une modèle en éléménts finis.GRENOBLE1-BU Médecine pharm. (385162101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Recherche d'indicateurs cliniques tridimensionnels d'aggravation et de correction par orthèse des scolioses idiopathiques modérées

La scoliose est une déformation du rachis dans les trois plans de l'espace. Cette déformation est évolutive pendant toute la croissance. Les enjeux sont pronostics et thérapeutiques. L'étude de la déformation scoliotique en 3D grâce aux méthodes d'imagerie actuelles a permis de décrire un schéma spécifique 3D de scoliose évolutive à partir de paramètres du plan transversal. Ce schéma spécifique 3D est indépendant de la topographie de la scoliose et apparaît tôt dans l'évolution de la scoliose. Prédire l'aggravation mène à pouvoir anticiper le traitement pour les scolioses à risque. Le traitement conservateur par corset reste le traitement de choix en période de croissance. Mais il n'est pas consensuel. L'étude de l'effet en 3D des corsets, au cas par cas, a permis de montrer la grande variabilité de l'effet des corsets sur l'ensemble des paramètres 3D rachidiens et pelviens. Les corsets prennent appui sur la cage thoracique. Leur effet sur la forme 3D de la cage thoracique est mal connu par manque de méthode d'analyse fiable et reproductible en position debout validée chez les patients scoliotiques. La méthode de reconstruction 3D de la cage thoracique à partir de radiographies biplanaires calibrées, développée et validée au LBM chez des patients sains, a fait l'objet dans ce travail, d'une validation chez les patients scoliotiques. L'accès à la morphologie 3D du rachis et de la cage thoracique a donc permis d'étudier de façon préliminaire l'effet des corsets sur la cage thoracique. Cette étude a montré une grande variabilité de l'effet des corsets et a permis de poser les bases de futures études cliniques et biomécaniques visant améliorer la compréhension de l'effet 3D des corsets sur le rachis et la cage thoracique.Scoliosis is a deformity of the spine in the 3 dimensions. The scoliosis curve is progressive during the whole growth. The mains issues are the prediction of the progression and early management of the deformity. Novel 3D Imaging modalities have made possible 3D reconstructions of the spine in standing position. A 3D pattern of progressive scoliotic curve has been described. This transverse plane 3D pattern is independent of the topography of the curve and may be described at an early stage of the development of the scoliosis. Prediction of the progression leads to anticipation of the treatment in progressive scoliosis. Brace treatment is the main option during growth. However, bracing is not consensual. The 3D effect of brace treatment has been studied on scoliotic patients. The results showed a high variability of the effect of the brace on all 3D spine and pelvic parameters. There is a lack of knowledge of the effect of brace treatment on the rib cage. A reason is the lack of accurate and reproducible method of 3D reconstruction of the rib cage in standing position. Such method based on calibrated biplanar X-rays, developed and validated in asymptomatic patients in our institution, was used and validated on scoliotic patients in this work. Analysis of the effect of brace treatment of the shape of the rib cage was therefore possible. A preliminary study was performed and showed a high variability of the effect of bracing on the rib cage. This study also put the basis of further clinical and biomechanical studies on correction mechanisms of brace treatment on the spine and the rib cage.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF