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Quantifying joint range of motion (RoM), the reachable poses at a joint, has many applications in research and clinical care. Joint RoM measurements can be used to investigate the link between form and function in extant and extinct animals, to diagnose musculoskeletal disorders and injuries or monitor rehabilitation progress. However, it is difficult to visually demonstrate how the rotations of the joint axes interact to produce joint positions. Here, we introduce the spherical frame projection (SFP), which is a novel 3D visualisation technique, paired with a complementary data collection approach. SFP visualisations are intuitive to interpret in relation to the joint anatomy because they 'trace' the motion of the coordinate system of the distal bone at a joint relative to the proximal bone. Furthermore, SFP visualisations incorporate the interactions of degrees of freedom, which is imperative to capture the full joint RoM. For the collection of such joint RoM data, we designed a rig using conventional motion capture systems, including live audio-visual feedback on torques and sampled poses. Thus, we propose that our visualisation and data collection approach can be adapted for wide use in the study of joint function.

The enthesis allows the insertion of tendon into bone thanks to several remarkable strategies. This complex and clinically relevant location often features a thin layer of fibrocartilage sandwiched between tendon and bone to cope with a highly heterogeneous mechanical environment. The main purpose of this study was to investigate whether mineralized fibrocartilage and bone close to the enthesis show distinctive three-dimensional microstructural features, possibly to enable load transfer from tendon to bone. As a model, the Achilles tendon-calcaneus bone system of adult rats was investigated with histology, backscattered electron imaging and micro-computed tomography. The microstructural porosity of bone and mineralized fibrocartilage in different locations including enthesis fibrocartilage, periosteal fibrocartilage and bone away from the enthesis was characterized. We showed that calcaneus bone presents a dedicated protrusion of low porosity where the tendon inserts. A spatially resolved analysis of the trabecular network suggests that such protrusion may promote force flow from the tendon to the plantar ligament, while partially relieving the trabecular bone from such a task. Focusing on the tuberosity, highly specific microstructural aspects were highlighted. Firstly, the interface between mineralized and unmineralized fibrocartilage showed the highest roughness at the tuberosity, possibly to increase failure resistance of a region carrying large stresses. Secondly, fibrochondrocyte lacunae inside mineralized fibrocartilage, in analogy with osteocyte lacunae in bone, had a predominant alignment at the enthesis and a rather random organization away from it. Finally, the network of subchondral channels inside the tuberosity was highly anisotropic when compared to contiguous regions. This dual anisotropy of subchondral channels and cell lacunae at the insertion may reflect the alignment of the underlying collagen network. Our findings suggest that the microstructure of fibrocartilage may be linked with the loading environment. Future studies should characterize those microstructural aspects in aged and or diseased conditions to elucidate the poorly understood role of bone and fibrocartilage in enthesis-related pathologies. ispartof: SCIENTIFIC REPORTS vol:11 issue:1 ispartof: location:England status: published

Purpose: Prognosis of extraskeletal osteosarcoma (ESOS) is reported to be poorer than that of skeletal osteosarcoma. This multicenter retrospective study aimed to evaluate factors influencing ESOS prognosis.Patients and methods: Members of the European Musculoskeletal Oncology Society (EMSOS) submitted institutional data on patients with ESOS.Results: Data from 274 patients treated from 1981 to 2014 were collected from 16 EMSOS centres; 266 patients were eligible. Fifty (18.7%) had metastases at diagnosis. Of 216 patients with localised disease, 211 (98%) underwent surgery (RO = 70.6%, R1 = 27%). Five-year overall survival (OS) for all 266 patients was 47% (95% CI 40-54%). Five-year OS for metastatic patients was 27% (95% CI 13-41%). In the analysis restricted to the 211 localised patients who achieved complete remission after surgery 5-year OS was 51.4% (95% CI 44-59%) and 5-year disease-free survival (DFS) was 43% (95% CI 35-51%). One hundred twenty-one patients (57.3%) received adjuvant or neoadjuvant chemotherapy and 80 patients (37.9%) received radiotherapy. A favourable trend was seen for osteosarcoma-type chemotherapy versus soft tissue sarcoma-type (doxorubicin +/- ifosfamide) regimens. For the 211 patients in complete remission after surgery, patient age, tumour size, margins and chemotherapy were positive prognostic factors for DFS and OS by univariate analysis.At multivariate analysis, patient age (40 years) (P = 0.05), tumour size (P = 0.0001) and receipt of chemotherapy (P = 0.006) were statistically significant prognostic factors for survival.Conclusion: Patient age and tumour size are factors influencing ESOS prognosis. Higher survival was observed in patients who received perioperative chemotherapy with a trend in favour of multiagent osteosarcoma-type regimen which included doxorubicin, ifosfamide and cisplatin. (C) 2017 Elsevier Ltd. All rights reserved.

������������ ������ ���������������� �������� �� �������������������� ������ �������������������������� �������������� ������ ���������������� ������ �������� ������������ ������ ������ ���������������� �������������� ���������� ��, ������ ������������ ���������������������� ���������������� ���� �� ���������� ������ �������������� ��������������������, �������� �������������������������� �������� ���������������������� ������ ������������������������ ������������ ������������. �������������������������� ������������ �������� ���� �������������������� ���� ���������� ���������������� ������������ ������ ������������������������ ������ ���������������� ������������ ������ ������������ ������ ���������������� ���������������� ������ ���������������� ������ ������ ������������������. ���� ���������������������� ������ ������������������ ������ ������ �������������� �������� ������ ���������������� �������� ������ �������� ���� ���������������� 20 �������������� ������ ������������������������ ���� ���������������� �������������������� ������ 20 �������������� ���������� ���������������� �������������������������������� ������ �������������������������� ������ 10 ��������������������������, 10 ������������������������, 10 ���������������� ������ 10 ������������ ��������������. ������ �������� ������������, ���� ������������ ������������������ ���� 7 ������������������ ������������������������������ ������ ������������ ������������������ �������������� (VAS) 100 mm. �������������������������� �� �������������������� ������ ���������������� ������ ������ ������������ ���������� ������ �� ���������������� ������������ ������ ������������ ������ ������������. �� �������������� two-way MANOVA ������������������������������ ������ ������ �������������������� ������ ���������������� ������������ ������ ������������������������ �������� ������ ������������. ������ ������������ �������������������� ������������������ �������������� ������������ ������ ������������ ������ ������ ���������������� ���������������� VAS ������ ���������������� ������ ���� ������������ ������������ �������� ����������������. �� ���������������������� �������������������� ICC ������������ ������������ ������ ������������ ������������ ���������������� ������ �������� ������ ������������ ������������. �� ������������������ ���������������� ������ �������������������� �������� ����������������. ���� ������������ ������������������������ �������������������� ���������������� ������ ���������������������� ���������������� �������� ���������� ������ ������������������ ������ ������������������, ������ ������ �������������� �������������������� ������������������ �������������� �������������� ���� ������ ������������ ������ ������������ ��������. �������������� ������������ �������������������� ���������������� ������������ ������ ������������ ������������ ���� ���� ������������ �������������� ���� ���������������������� ���������������������� ������������ ������ ������ ���������� ������������. ������ ������������������������ ���������� �������������� �������� ������ �������������������� ������������ ������ ���������� ������ ������������, The aim of the study was the investigation of the perceived changes in the smile and the lateral appearance of Class I patients, treated orthodontically with or without the extraction of four first premolars, as assessed through photographs by different panel groups. Secondary objectives were to assess any differences between the assessments of the various judges and between different areas of the face and smile. The profile and frontal smiling pre- and post-treatment photographs of 20 Class I extraction patients and 20 Class I non-extraction patients were used and assessed by 10 orthodontists, 10 dentists, 10 patients and 10 laypersons. For each patient, raters answered 7 questions using a 100 mm visual analogue scale (VAS). Intra-examiner reliability, intra-rater agreement, internal consistency for rater groups and inter-rater agreement were tested. Two-way multivariate analysis of variance was used to evaluate differences among the ratings of all groups. There was no statistically significant difference between the first and the second VAS measurement of the same investigator and the random error was minimal. The intraclass correlation coefficient showed strong to almost perfect intra-rater agreement for all groups of raters. The internal consistency of the responses was acceptable in all cases. Raters perceived higher improvement in the extraction cases regarding the smile measurements, while no statistically significant difference was found regarding the change in their profile. There were also significant differences among rater groups with laypersons assessing more positive than the other groups. No difference was found during comparisons between male and female raters

Needle insertion procedures under ultrasound guidance are commonly used for diagnosis and therapy. It is often critical to accurately reach a targeted region, and this can be difficult to achieve due to intraoperative tissue motion. In this letter, we present a method to steer a beveled-tip flexible needle toward a target embedded in moving tissue. Needle steering is performed using a needle insertion device attached to a robot arm. Closed-loop 3-D steering of the needle is achieved using tracking of an artificial target in 2-D ultrasound images and tracking of the needle tip position and orientation with an electromagnetic tracker. Tissue motion compensation is performed using force feedback to reduce targeting error and forces applied to the tissue. The method uses a mechanics-based interaction model that is updated online. A novel control law using task functions is proposed to fuse motion compensation, steering via base manipulation and tip-based steering. Validation of the tracking and steering algorithms are performed in gelatin phantom and bovine liver. Tissue motion up to 15 mm is applied and average targeting error is 1.2 $\pm$ 0.8 mm and 2.5 $\pm$ 0.7 mm in gelatin and liver, respectively, which is sufficiently accurate for commonly performed needle insertion procedures.

Aim: To assess the medium- term results of 8.5 mm implants supplied with a conventional platform- matched implant- abutment connection or a platform- switched design.Materials and Methods: Eighty patients with one or more missing teeth in the maxillary or mandibular posterior zone were randomly assigned for treatment with implants with a conventional (control group) or platform- switched (test group) implant- abutment connection. Follow- up visits were conducted 1 month, 1 year and 5 years after functional loading. Inter- proximal bone loss, assessed with standardized peri- apical radiographs, clinical parameters, survival of implants and satisfaction of patients were the outcome parameters studied.Results: After 5 years of loading, five of the 80 patients were lost to follow- up. The inter- proximal bone loss in the test group (0.38 +/- 0.61 mm) was comparable to the bone loss in the control group (0.41 +/- 0.47 mm; p = 0.201). Remarkably, bone loss has not progressed compared to the 1-year results. Implant survival, clinical parameters and satisfaction of the patients were favourable and comparable for the test and control group.Conclusion: The 5-years results showed that inter-proximal bone resorption was minor and comparable around platform-matched and platform-switched implants, and implant survival, peri-implant health and patients' satisfaction were favourable.

We report about the experimental identification of viscoelastic constitutive models for frequencies ranging within 0–10 Hz. Dynamic moduli data are fitted for several materials of interest to medical applications: liver tissue ( Chatelin et al., 2011 ), bioadhesive gel ( Andrews et al., 2005 ), spleen tissue ( Nicolle et al., 2012 ) and synthetic elastomer ( Osanaiye, 1996 ). These materials actually represent a rather wide class of soft viscoelastic materials which are usually subjected to low frequencies deformations. We also provide prescriptions for the correct extrapolation of the material behavior at higher frequencies. Indeed, while experimental tests are more easily carried out at low frequency, the identified viscoelastic models are often used outside the frequency range of the actual test. We consider two different classes of models according to their relaxation function: Debye models, whose kernel decays exponentially fast, and fractional models, including Cole–Cole, Davidson–Cole, Nutting and Havriliak–Negami, characterized by a slower decay rate of the material memory. Candidate constitutive models are hence rated according to the accurateness of the identification and to their robustness to extrapolation. It is shown that all kernels whose decay rate is too fast lead to a poor fitting and high errors when the material behavior is extrapolated to broader frequency ranges.

Aim: To assess the effect of platform switching on peri-implant bone remodeling around short implants (8.5mm) placed in the resorbed posterior mandibular and maxillary region of partially edentulous patients. Materials and Methods: Seventeen patients with one or more missing teeth at both sides in the posterior region were, according to a split-mouth design, randomly assigned to be treated with a platform-matched (control) implant on the one side and a platform-switched implant (test) on the other side. A total of 62 short implants (8.5mm) with a dual-acid etched surface with nanometer-sized calcium phosphate particles was placed. Follow-up visits were conducted one month and one year after placing the implant crown. Outcome measures were interproximal bone level changes, implant survival and clinical parameters. Results: One year after loading, peri-implant bone remodeling around test implants (0.530.54mm) was significant less than around control implants (0.85 +/- 0.65mm; p=.003). With regard to implant survival and clinical parameters no significant differences were observed between test and control implants. Conclusions: This study suggested that peri-implant bone remodeling is affected by platform switching. One year after loading, interproximal bone levels were better maintained at implants restored according to the platform switching concept.

This paper deals with application of 3D scanning technology in medicine. Important properties of 3D scanners are discussed with emphasize on medical applications. Construction of medical 3D scanner according to these specifications is described and practical application of its use in medical volumetry is presented. Besides volumetry, such 3D scanner is usable for many other purposes, like monitoring of recovery process, ergonomic splint manufacturing or inflammation detection. 3D scanning introduces novel volumetric method, which is compared with standard methods. The new method is more accurate compared to present ones. Principles of this method are discussed in paper and its accuracy is evaluated and experimentally verified.

The host lymphatic network represents an important conduit for pathogen dissemination. Indeed, the lethal human pathogen group A streptococcus has a predilection to induce pathology in the lymphatic system and draining lymph nodes, however the underlying basis and subsequent consequences for disease outcome are currently unknown. Here we report that the hyaluronan capsule of group A streptococci is a crucial virulence determinant for lymphatic tropism in vivo, and further, we identify the lymphatic vessel endothelial receptor-1 as the critical host receptor for capsular hyaluronan in the lymphatic system. Interference with this interaction in vivo impeded bacterial dissemination to local draining lymph nodes and, in the case of a hyper-encapsulated M18 strain, redirected streptococcal entry into the blood circulation, suggesting a pivotal role in the manifestation of streptococcal infections. Our results reveal a novel function for bacterial capsular polysaccharide in directing lymphatic tropism, with potential implications for disease pathology., Author Summary Pathogens are known to invade the host not only via the systemic circulation but also via the lymphatic network, however the mechanisms underlying the latter route and the consequences for disease outcome have not been well studied. The important human pathogen, group A streptococcus, is responsible for a number of clinical syndromes affecting both the lymphatic vessels and draining lymph nodes, such as lymphangitis and lymphadenitis. How such pathologies are orchestrated, and their significance in the development of serious infection are currently unknown. In this study, we show that the hyaluronan capsule secreted by group A streptococcus is critical for bacterial spread to draining lymph nodes, and we demonstrate that this occurs as a result of a specific interaction with the lymphatic vessel endothelial receptor-1. Genetic deletion or functional blockade of this receptor prevented streptococcal transit to draining lymph nodes in a murine model of infection, which in turn enhanced bacterial spread into the blood circulation. Together these results define a novel interaction between the group A streptococcal capsule and the lymphatic endothelial receptor-1 as a critical axis in the establishment of lymphatic tropism for this pathogen, with clear implications for disease severity in the host.

The study aimed to provide quantitative information about gender-related normative data and growth changes between childhood and young adulthood in the soft tissue facial profiles of Northern Sudanese individuals. The three dimensional coordinates of 50 landmarks on the facial soft tissues were obtained using a hand-held laser scanner in 654 healthy Northern Sudanese subjects (327 males and 327 females) aged 4-30 years. The subjects were divided into 8 nonoverlapping age groups [1]. From selected landmarks, 15 facial angles were calculated and averaged for gender and age: upper, middle, and lower facial, and mandibular corpus convexities in the horizontal plane; relative position of the exocanthia and nasion; facial convexity in the sagittal plane; midfacial to mandibular plane, nasal convexity, nasolabial, mentolabial, interlabial, maxillary prominence, and left and right gonial angles. Comparisons were performed by factorial analysis of variance. On average men had larger facial and mandibular corpus convexities in the horizontal plane than women (ANOVA, p, Italian Journal of Anatomy and Embryology, Vol 119, No 1 (Supplement) 2014

The study aimed to provide quantitative information about the facial soft-tissues of Italian and Northern Sudanese subjects with Down’s syndrome (DS) by using summary anthropometric measurements representative of facial size and harmony. The 3D coordinates of soft-tissue facial landmarks were obtained by a computerized digitizer in 54 Italian subjects with DS (20 females, 34 males, aged 13-52 years), in 64 Northern Sudanese subjects with DS (18 females, 46 males, aged 5-34 years), in 578 healthy Italian, and 653 healthy Northern Sudanese reference subjects, matched for sex and age. From the landmarks, 16 facial dimensions were calculated. Data from subjects with DS were compared to those collected in reference individuals by computing z-scores. Two summary anthropometric measurements for quantifying craniofacial variations were obtained: the mean z-score (an index of overall facial size), and its standard deviation, or the craniofacial variability index (an index of facial harmony) [1]. In subjects with DS, facial size was significantly smaller, and craniofacial variability was significantly larger than in normal individuals; 93% of Italian and 81% of Northern Sudanese subjects with DS had one or both values outside the normal interval. Overall, Italian subjects with DS differed more from the norm than Northern Sudanese ones. In the Northern Sudanese subjects, the mean z-scores and the CVI decreased significantly with age. The facial soft-tissue structures of subjects with DS differed from those of normal controls of the same age, sex and ethnic group: a reduced facial size was coupled with a global anomalous relationship between individual measurements. The alterations in soft-tissue facial dimensions were different in the two ethnic groups and partially influenced by age., Italian Journal of Anatomy and Embryology, Vol 119, No 1 (Supplement) 2014

Objective: To investigate dimensions and ratios of soft-tissue facial volumes of adult Northern Sudanese subjects with Down syndrome by using computerized anthropometric measurements. Design, Setting, and Patients: The 3D coordinates of soft-tissue facial landmarks were obtained by a computerized digitizer in 26 Northern Sudanese adult subjects with Down syndrome (18 men, 8 women, aged 17-34 years), and in 99 healthy Northern Sudanese controls (48 women, 51 men) of the same age range. From the landmarks, several facial volumes and volume ratios were calculated. Data were compared to those collected in healthy individuals by computing z-scores. Results: In subjects with Down syndrome, facial volumes were significantly smaller than in control subjects (Student’s t, p < 0.05). The patterns of deviation from the norm were similar in men and women. When compared to controls, subjects with Down syndrome had no differences in nose volume as a fraction of total facial volume and a larger total lip volume as a fraction of total facial volume; within the facial middle third, they had relatively larger upper lip volumes and relatively smaller nose volumes. Conclusions: The facial soft-tissue structures of subjects with Down syndrome differed from those of normal controls of the same age, sex and ethnic group: a reduced facial size was coupled with specific variations in the nasal and labial regions., Italian Journal of Anatomy and Embryology, Vol 119, No 3 (2014)

The aim of this study was to evaluate the feasibility of using a two-stage implant system in a single-stage procedure and to study the impact of the microgap at crestal level and to monitor the microflora in the peri-implant area. Forty edentulous patients (Cawood & Howell class V-VI) participated in this study. After randomisation, 20 patients received two IMZ implants inserted in a single-stage procedure and 20 patients received two ITI implants. After 3 months, overdentures were fabricated, supported by a bar and clip attachment. A standardised clinical and radiographic evaluation was performed immediately after denture insertion and 6 and 12 months later. Twelve months after loading, peri-implant samples were collected with sterile paper points and analysed for the presence of putative periodontal pathogens using culture techniques. One IMZ implant was lost due to insufficient osseointegration. With regard to the clinical parameters at the 12 months evaluation, significant differences for plaque score and probing pocket depth (IMZ: mean 3.3 mm, ITI: mean 2.9 mm) were found between the two groups. The mean bone loss in the first year of functioning was 0.6 mm for both groups. Prevotella intermedia was detected more often in the ITI group (12 implants) than in the IMZ group (three implants). Porphyromonas gingivalis was found in three patients. In one of these patients an implant showed bone loss of 1.6 mm between T0 and T12. Some associations were found between clinical parameters and the target microorganisms in the ITI group. These associations were not present in the IMZ group. The short-term results indicate that two-stage implants inserted in a single-stage procedure may be as predictable as one-stage implants. The microgap at crestal level in nonsubmerged IMZ implants seems to have no adverse influence on the peri-implant microbiological colonisation and of crestal bone loss in the first year of functioning. The peri-implant sulcus can and does harbour potential periodontal pathogens without signs of peri-implantitis during the evaluation period of 1 year.

Aim: To assess the effect of platform switching on peri-implant bone remodeling around short implants (8.5mm) placed in the resorbed posterior mandibular and maxillary region of partially edentulous patients. Materials and Methods: Seventeen patients with one or more missing teeth at both sides in the posterior region were, according to a split-mouth design, randomly assigned to be treated with a platform-matched (control) implant on the one side and a platform-switched implant (test) on the other side. A total of 62 short implants (8.5mm) with a dual-acid etched surface with nanometer-sized calcium phosphate particles was placed. Follow-up visits were conducted one month and one year after placing the implant crown. Outcome measures were interproximal bone level changes, implant survival and clinical parameters. Results: One year after loading, peri-implant bone remodeling around test implants (0.530.54mm) was significant less than around control implants (0.85 +/- 0.65mm; p=.003). With regard to implant survival and clinical parameters no significant differences were observed between test and control implants. Conclusions: This study suggested that peri-implant bone remodeling is affected by platform switching. One year after loading, interproximal bone levels were better maintained at implants restored according to the platform switching concept.

The research work presented for the habilitation thesis aim to provide new simulation tools for medical and surgical interventions.These tools have many applications including training of physicians, planning of interventions (for rehearsal and for the validation of a therapy) or providing assistance during a real intervention. However, to obtain a realistic or even predictive simulation of the procedure, we must take into account the deformation of anatomical structures and the mechanical interactions between devices and tissues. At the same time, the simulation must be interactive and computed in real-time to keep the gesture of the physician in the loop of the simulation. The major challenge of our work is to guarantee a certain level of accuracy in the simulation while keeping a very short computation time, consistent with the real-time. First, we present an optimized formulation of the finite element method (FEM) for the deformable models and new numerical tools (preconditionner, coupling between models...) dedicated to real-time FEM computation. This approach is used to compute the biomechanics of anatomical soft-tissues, as well as flexible instruments. The second key point is the boundary conditions: the mechanical interactions between organs and/or with surgical devices are often difficult to account for. Yet, a bad modeling of these interaction can lead to a large source of errors. Our approach builds on non-smooth mechanics for modeling contact and friction between solids but also extends to other models of interaction (like needle insertion for instance). In this context, we also address the difficult problem of computing the compliance of deformable structures in real-time. Third, during some procedures, the visual feedback is far from perfect and the physician uses haptic feedback for guidance. In such case it is important to provide haptic rendering using dedicated haptic devices and simulation algorithms. In this domain, we provide a new asynchronous approach that is centered on the mechanical interactions between devices and human tissues. The method addresses the problem of high-refresh rates (1kHz) needed in the haptic loop. Finally, we present some research results on concrete application examples that we are currently developing. We present the remaining challenges to allow a large diffusion of the simulation as a clinical tool, used by physicians in the future.; Les travaux de recherche présentés pour l'habilitation à diriger des recherches, visent à proposer de nouveaux outils pour simuler des interventions médicales et chirurgicales. Ces outils ont plusieurs applications dont l'amélioration de la formation des praticiens, la planification d'interventions pour la préparation et la validation d'une thérapie ou encore l'assistance au geste médical durant une intervention. Or, pour simuler ces interventions de manière réaliste voire prédictive, il faut tenir compte de la déformation des structures anatomiques et des interactions mécaniques entre les outils et les organes. En même temps, la simulation doit être interactive et calculée en temps-réel pour garder le geste du praticien dans la boucle de la simulation. Le défi majeur de notre travail est donc de garantir un calcul précis au niveau de la simulation tout en gardant un temps de calcul très court, qui soit compatible avec le temps-réel. D'abord, nous proposons une formulation optimisée de la méthode par éléments finis (FEM) et de nouveaux outils numériques (pré-conditionneurs, couplage entre modèles...) dédiés à au calcul FEM temps-réel. Cette approche est utilisée pour calculer la biomécanique des déformations des tissus anatomiques et les instruments flexibles. Nous abordons ensuite un autre point clé de ces simulations que sont les conditions aux limites. Les interactions mécaniques entre organes et/ou entre les outils chirurgicaux et les tissus sont souvent complexes à modéliser. Or, une mauvaise prise en compte de ces interactions peut aboutir à des erreurs importantes. Notre approche suit les bases de la mécanique non-régulière pour gérer, notamment, le contact et le frottement entre solides. Nous étendons l'approche à d'autres modèles d'interaction (comme l'insertion d'aiguille par exemple). Dans ce contexte, nous mettons l'accent sur le calcul de la compliance des structures en temps-réel. Par ailleurs, pour certaines interventions où le retour visuel n'est pas parfait, le praticien se guide aussi avec le sens du toucher. Il est donc important de reproduire au moins partiellement cette sensation - dite haptique - avec des interfaces à retour d'effort, pilotée à partir des données de la simulation. Dans ce domaine, nous proposons une approche centrée sur le rendu haptique des interactions mécaniques entre outil chirurgical et tissus humain. Cette approche se base notamment sur une désynchronisation du calcul de la boucle de simulation et de la boucle de retour d'effort qui demande un rafraichissement à haute fréquence (1kHz). Finalement, nous présentons ces résultats de recherche sur des exemples concrets d'application et nous présentons les défis à venir pour permettre à la simulation de devenir un outil utilisé par les praticiens à l'avenir. Le manuscrit est en anglais.

The research work presented for the habilitation thesis aim to provide new simulation tools for medical and surgical interventions.These tools have many applications including training of physicians, planning of interventions (for rehearsal and for the validation of a therapy) or providing assistance during a real intervention. However, to obtain a realistic or even predictive simulation of the procedure, we must take into account the deformation of anatomical structures and the mechanical interactions between devices and tissues. At the same time, the simulation must be interactive and computed in real-time to keep the gesture of the physician in the loop of the simulation. The major challenge of our work is to guarantee a certain level of accuracy in the simulation while keeping a very short computation time, consistent with the real-time. First, we present an optimized formulation of the finite element method (FEM) for the deformable models and new numerical tools (preconditionner, coupling between models...) dedicated to real-time FEM computation. This approach is used to compute the biomechanics of anatomical soft-tissues, as well as flexible instruments. The second key point is the boundary conditions: the mechanical interactions between organs and/or with surgical devices are often difficult to account for. Yet, a bad modeling of these interaction can lead to a large source of errors. Our approach builds on non-smooth mechanics for modeling contact and friction between solids but also extends to other models of interaction (like needle insertion for instance). In this context, we also address the difficult problem of computing the compliance of deformable structures in real-time. Third, during some procedures, the visual feedback is far from perfect and the physician uses haptic feedback for guidance. In such case it is important to provide haptic rendering using dedicated haptic devices and simulation algorithms. In this domain, we provide a new asynchronous approach that is centered on the mechanical interactions between devices and human tissues. The method addresses the problem of high-refresh rates (1kHz) needed in the haptic loop. Finally, we present some research results on concrete application examples that we are currently developing. We present the remaining challenges to allow a large diffusion of the simulation as a clinical tool, used by physicians in the future.; Les travaux de recherche présentés pour l'habilitation à diriger des recherches, visent à proposer de nouveaux outils pour simuler des interventions médicales et chirurgicales. Ces outils ont plusieurs applications dont l'amélioration de la formation des praticiens, la planification d'interventions pour la préparation et la validation d'une thérapie ou encore l'assistance au geste médical durant une intervention. Or, pour simuler ces interventions de manière réaliste voire prédictive, il faut tenir compte de la déformation des structures anatomiques et des interactions mécaniques entre les outils et les organes. En même temps, la simulation doit être interactive et calculée en temps-réel pour garder le geste du praticien dans la boucle de la simulation. Le défi majeur de notre travail est donc de garantir un calcul précis au niveau de la simulation tout en gardant un temps de calcul très court, qui soit compatible avec le temps-réel. D'abord, nous proposons une formulation optimisée de la méthode par éléments finis (FEM) et de nouveaux outils numériques (pré-conditionneurs, couplage entre modèles...) dédiés à au calcul FEM temps-réel. Cette approche est utilisée pour calculer la biomécanique des déformations des tissus anatomiques et les instruments flexibles. Nous abordons ensuite un autre point clé de ces simulations que sont les conditions aux limites. Les interactions mécaniques entre organes et/ou entre les outils chirurgicaux et les tissus sont souvent complexes à modéliser. Or, une mauvaise prise en compte de ces interactions peut aboutir à des erreurs importantes. Notre approche suit les bases de la mécanique non-régulière pour gérer, notamment, le contact et le frottement entre solides. Nous étendons l'approche à d'autres modèles d'interaction (comme l'insertion d'aiguille par exemple). Dans ce contexte, nous mettons l'accent sur le calcul de la compliance des structures en temps-réel. Par ailleurs, pour certaines interventions où le retour visuel n'est pas parfait, le praticien se guide aussi avec le sens du toucher. Il est donc important de reproduire au moins partiellement cette sensation - dite haptique - avec des interfaces à retour d'effort, pilotée à partir des données de la simulation. Dans ce domaine, nous proposons une approche centrée sur le rendu haptique des interactions mécaniques entre outil chirurgical et tissus humain. Cette approche se base notamment sur une désynchronisation du calcul de la boucle de simulation et de la boucle de retour d'effort qui demande un rafraichissement à haute fréquence (1kHz). Finalement, nous présentons ces résultats de recherche sur des exemples concrets d'application et nous présentons les défis à venir pour permettre à la simulation de devenir un outil utilisé par les praticiens à l'avenir. Le manuscrit est en anglais.

Aim To assess the medium-term results of 8.5 mm implants supplied with a conventional platform-matched implant-abutment connection or a platform-switched design. Materials & methods Eighty patients with 1 or more missing teeth in the maxillary or mandibular posterior zone were randomly assigned for treatment with implants with a conventional (control group) or platform-switched (test group) implant-abutment connection. Follow-up visits were conducted 1 month, 1 year and 5 years after functional loading. Interproximal bone loss, assessed with standardized peri-apical radiographs, clinical parameters, survival of implants and satisfaction of patients were the outcome parameters studied. Results After 5 years of loading, 5 of the 80 patients were lost to follow-up. The interproximal bone loss in the test group (0.38±0.61 mm) was comparable to the bone loss in the control group (0.41±0.47 mm; p=0.201). Remarkably, bone loss has not progressed compared to the 1-year results. Implant survival, clinical parameters and satisfaction of the patients were favourable and comparable for the test and control group. Conclusion The 5-years results showed that interproximal bone resorption was minor and comparable around platform-matched and platform-switched implants, and implant survival, peri-implant health and patients’ satisfaction were favourable. This article is protected by copyright. All rights reserved.

Traumatic brain injury (TBI) occurs when local mechanical load exceeds certain tolerance levels for brain tissue. Extensive research has been done previously for brain matter experiencing compression at quasistatic loading; however, limited data is available to model TBI under dynamic impact conditions. In this research, an experimental setup was developed to perform unconfined compression tests and stress relaxation tests at strain rates < 90/s. The brain tissue showed a stiffer response with increasing strain rates, showing that hyperelastic models are not adequate. Specifically, the compressive nominal stress at 30% strain was 8.83 +/- 1.94, 12.8 +/- 3.10 and 16.0 +/- 1.41 kPa (mean +/- SD) at strain rates of 30, 60 and 90/s, respectively. Relaxation tests were also conducted at 10%-50% strain with the average rise time of 10 ms, which can be used to derive time dependent parameters. Numerical simulations were performed using one-term Ogden model with initial shear modulus mu_0 = 6.06 +/- 1.44, 9.44 +/- 2.427 and 12.64 +/- 1.227 kPa (mean +/- SD) at strain rates of 30, 60 and 90/s, respectively. A separate set of bonded and lubricated tests were also performed under the same test conditions to estimate the friction coefficient mu, by adopting combined experimental - computational approach. The values of mu were 0.1 +/- 0.03 and 0.15 +/- 0.07 (mean +/- SD) at 30 and 90/s strain rates, respectively, indicating that pure slip conditions cannot be achieved in unconfined compression tests even under fully lubricated test conditions. The material parameters obtained in this study will help to develop biofidelic human brain finite element models, which can subsequently be used to predict brain injuries under impact conditions., 31 pages

Made available in DSpace on 2019-09-12T16:53:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2011 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study examined the clinical, histological, and immunohistochemical features as well as the differential diagnoses of oral intravascular papillary endothelial hyperplasia (IPEH) to aid clinicians and pathologists in its diagnosis. Clinical features of five oral IPEH cases were obtained from medical records, and all histopathological diagnoses were reviewed. Immunohistochemical reactions, including anti-CD-34, laminin, vimentin, estrogen receptor alpha, and Ki-67, were assessed. Microscopically, a reactive proliferation of vascular cells composed of small papillary structures with hypocellular and hyalinized cores arising in an organized thrombus was seen. CD-34, vimentin, and laminin staining were strongly positive, while estrogen receptor alpha was negative in all cases. A low percentage of cells were positive for Ki-67 in four of five lesions, but one case was strongly positive. A diagnosis of angiosarcoma was investigated and rejected. IPEH presents specific microscopic characteristics that along with clinical data lead to an accurate diagnosis. The general dentist, the first to participate in the diagnostic process, must share the responsibility for diagnosis with the pathologist, and they must work together to determine the correct diagnosis and management. Oral lesions of IPEH are uncommon. Their main significance is that they show a microscopic resemblance to angiosarcoma. Thus, clinicians should have more information regarding this benign entity. Finally, we suggest that in recurrent cases exhibiting strong immunolabeling of proliferative markers the possibility of angiosarcoma should be investigated. [Campos, Marcia Sampaio] Universidade de Taubaté (Unitau), Dent Grad Program, Dept Dent, BR-12020330 Taubate, SP, Brazil [Fontes, Alexandra; Campos, Marcia Sampaio; de Sousa, Suzana C. O. M.; Martins, Marilia Trierveiler; Nunes, Fabio Daumas] Univ Sao Paulo, Dept Oral Pathol, Sch Dent, Sao Paulo, Brazil