Search

Orienting properly the prosthetic cup in total hip arthroplasty is key to ensure the postoperative stability. Several navigation solutions have been developed to assist surgeons in orienting the cup regarding the anterior pelvic plane (APP), defined by both anterior superior iliac spines (ASIS) and the pubic symphysis. However acquiring the APP when the patient is ready for surgery, i.e., mainly in lateral decubitus, is difficult due to the contralateral ASIS being against the operating table. We propose a method to determine the APP from both (1) alternative anatomical landmarks which are easy to acquire with a navigated ultrasound probe and (2) a Statistical Shape Model (SSM) of the pelvis. After creating a pelvic SSM from 40 data, a SSM-based morphometric analysis has been carried out to identify the best anatomical landmarks allowing the easy determination of the APP. The proposed method has then been assessed with both in silico and in vivo experiments on respectively forty synthetic data, and five healthy volunteers. The in silico experiment shows the feasibility to determine the APP with an average error of 4.7

The usual safe zone for cup orientation in THA is not suitable for all patients, as the pelvic tilt varies with the movements of daily activities. A new Functional Safe Zone (FSZ) is proposed that considers the pelvic tilt in different positions. The aims of this study were to validate the proposed FSZ and to evaluate how the pelvic mobility impact it.We measured the pelvic tilts of 30 patients when standing, sitting and supine, using our ultrasound-based device and computed their FSZs. The FSZs accuracy was assessed using a Computer-Aided-Design (CAD) software. The pelvic mobility influence onto the FSZ was assessed by jointly analysing the patients’ FSZs and their pelvic tilt difference between positions.The true FSZ provided by the CAD software and the estimated FSZ were similar by 92% and differed by less than 0.5◦ at borders and at the mean orientation. Patients with stiff pelvic mobility obtained small FSZs, and conversely, patients with large pelvic tilt variations between positions obtained large FSZs.The proposed method allows the computation of a patient-specific FSZ without requir- ing additional X-ray or CT images. Patients having a low pelvic mobility with a higher risk of postoperative instability could be better managed using this FSZ.

Limiting the risk of dislocation is one of the main aims of both dual mobility and Lefevre retentive cups. However, these devices have never been compared. The goal of our study was to compare these devices in total hip arthroplasty revisions for instability. The judgement criterion was non-recurrence of dislocation in a follow-up period of eight years. This retrospective case-control study compared two continuous paired series of total hip arthroplasty revisions for instability. These series included 63 patients and 159 patients with implantation of a Lefevre retentive cup and a dual mobility cup, respectively. The success rate at eight years (i.e., no recurrence) was 91 ± 0.05% and 95 ± 0.02% in the Lefevre retentive cup and dual mobility groups, respectively. The difference was not statistically significant (p = 0.6). It seems that the Lefevre retentive cup provides comparable outcomes with the dual mobility cup in the total hip arthroplasty revisions for instability, avoiding recurrence in long term.

Resume Introduction Le brochage-cerclage (ou brochage-haubanage) est considere comme le traitement standard des fractures transversales de l’olecrane. Ses principales complications sont la migration des broches et la gene engendree par le materiel. Nous avons concu et utilise des broches anti-expulsion (BAE), dont le design previent la migration et reduit la gene sur materiel. Cette etude comparait les taux de migration et des autres complications entre ces broches anti-expulsion et les classiques broches de Kirschner (groupe controle). Hypotheses Les BAE presenteraient des taux de migration et de complications plus faibles que les broches de Kirschner standards. Materiel et methodes Etude des donnees patients, retrospective, monocentrique, multi-operateur, observationnelle, de janvier 1996 a decembre 2014. Le critere de jugement principal etait la survenue de migration de broche. Les criteres de jugement secondaires etaient la survenue d’une ou plusieurs autres complications et le taux d’ablation du materiel. Resultas Ont ete inclus 101 patients : 53 (52,4 %) dans le groupe avec broches anti-expulsion (BAE) et 48 (47,6 %) dans le groupe controle. Aucun cas de migration n’a ete retrouve dans le groupe BAE, contre 21 cas (43,7 %) dans le groupe controle (p Conclusion Les broches anti-expulsion ont toute leur place dans le traitement des fractures de l’olecrane par brochage-cerclage : elles ne migrent pas, et reduisent les taux de complications, de gene, de deplacement secondaire et d’ablation du materiel. Niveau de preuve III, Etude comparative retrospective.

Tension band wiring is considered the standard treatment for transverse olecranon fractures. Its main complications are pin migration and discomfort caused by the hardware. We have designed and used "expulsion-proof" pins (EPP) that are shaped to prevent migration and reduce discomfort. This study compared the complication rate between our device and Kirschner pins (controls).We hypothesised that EPP would have lower migration rates and fewer complications than standard Kirschner pins.This retrospective, single-center, multi-operator, observational, study examined data from January 1996 to December 2014. The primary outcome was the occurrence of pin migration. Secondary outcomes were the occurrence of one or more additional complications and the hardware removal rate.The study enrolled 101 patients: 53 (52.4%) with expulsion-proof pins and 48 (47.6%) controls. The mean follow-up was 240.6days in the EPP group and 268.9days in the control group. No cases of migration (0%) were found in the EPP group versus 21 (43.7%) cases in the controls (p0.05). One or more complications occurred in 18 (33.9%) patients in the EPP group versus 46 (95.8%) controls (p0.05). There was material discomfort in 13 (24.5%) cases and 1 (1.9%) case of secondary displacement in the EPP group, compared with 38 (79.2%) and 7 (14.6%) cases, respectively, in the controls (p0.05). The rate of delayed consolidation was statistically identical in the two groups (p=0.103). The hardware was removed in 13 (24.5%) cases in the EPP group compared with 36 (75%) controls (p0.05).EPPs are useful for management of olecranon fractures treated via TBW: the pins do not migrate and can reduce complications, discomfort, secondary displacement, and the hardware removal rate.Level III, retrospective comparative study.

Objectives A new ultrasound-based device is proposed to measure the patient-specific pelvic tilt in different daily positions. The aim of this study was to assess the accuracy of this device as well as the intraobserver and interobserver precisions. Methods The accuracy was assessed by performing several tilt measurements with the device on a testing mechanical bench. The error was defined as the difference between the tilt measured with the device and the tilt provided by this test bench. Three physicians, a novice, an intermediate, and an expert user, were also asked to perform 10 measurements on 3 healthy volunteers with low, medium, and high body mass indices to analyze the intraobserver and interobserver precisions. These 10 measurements were performed in the standing, sitting, and supine positions. Results The mean accuracy of the device ± SD was 1.1° ± 0.7° (range, 0°-4.0°). The interobserver and intraobserver precisions were excellent whatever the body mass index and good to excellent according to the positions. There was no learning curve, and the time required to complete the measurements was approximately 5 minutes. Conclusions This study presents an accurate and precise noninvasive device for measurement of the pelvic tilt in different positions.

In computer-assisted orthopedic surgery, the hip center (HC) can be determined by calculating the center of rotation of the femur in relation to the pelvis. Several methods are available: Gamage, Halvorsen, Pivot or Least-Moving Point (LMP). To our knowledge, no studies have compared these four methods. We therefore conducted in silico and in vitro experiments to assess whether their accuracy and precision in locating the HC and calculating the hip-knee-ankle (HKA) angle were equivalent.The four methods show similar accuracy and precision.The in silico experiment assessed the independent influence of four parameters (camera noise, acetabular noise, movement amplitude, and number of circumductions) on accuracy. The accuracy and precision of the four methods and the impact on HKA ankle calculation were assessed in an in vitro study on six cadaver limbs.In the in silico experiment, all differences according to method were significant (p0.0002). The Pivot method was the most accurate for acetabular and camera noise, number of circumductions, and movement amplitude. With the LMP, Pivot, Gamage and Halvorsen methods, error was respectively 23.07±8.40 (range 2.10-54.67) mm, 1.98±081 (0.15-4.89) mm, 28.18±3.42 (18.57-37.60) mm and 2.84±1.46 (0.11-9.44) mm depending on camera noise, 1.65±0.72 (0.13-4.80) mm, 0.52±0.22 (0.05-1.23) mm, 3.02±0.57 (0.60-4.78) mm and 0.61±0.27 (0.04-1.82) mm depending on movement amplitude, 0.50±0.20 (0.05-1.34) mm, 0.18±0.08 (0.01-0.44) mm, 0.36±0.14 (0.03-0.80) mm and 0.21±0.09 (0.01-0.55) mm depending on number of circumductions, and 11.30±5.77 (0.56-37.87) mm, 2.78±1.47 (0.10-8.77) mm, 88.08±8.85 (60.59-117.79) mm and 24.33±9.82 (1.40-66.17) mm depending on acetabular noise. In the in vitro experiment, differences were non-significant between the Pivot and LMP methods (p0.98) and between the Gamage and Halvorsen methods (p0.65). With the LMP, Pivot, Gamage and Halvorsen methods, precision was respectively 8.2±4.6 (3.3-23.6) mm, 7.3±3.6 (3.4-14.1) mm, 33.6±19.1 (4.7-111.4) mm and 35.0±25.0 (4.7-132.5) mm. Accuracy was 13.5±8.2 (3.2-40.7) mm. 12.3±6.4 (3.2-23.6) mm, 47.0±33.3 (6.2-176.6) mm and 40.3±27.8 (6.1-130.3) mm. The LMP and Pivot methods were thus more accurate and more precise than the Gamage and Halvorsen methods. HKA angle error was 1.1±0.9° (0.1-3.7) and 0.9±0.8° (0.0-2.5) with the LMP and Pivot methods, and 3.2±2.7° (0.0-12.7) and 3.8±3.5° (0.0-13.3) with the Gamage and Halvorsen methods.The study highlighted differences between the four methods of HC location in computer-assisted surgery; the Pivot method was the most accurate and precise, thus falsifying the study hypothesis.III, prospective comparative in silico and in vitro study.

Resume L’interet pour les voies d’abord permettant la pose d’une prothese totale de hanche reste eleve, mais sans veritable consensus. Plusieurs artifices techniques recents ont permis de diminuer les risques de luxation et d’ameliorer ainsi l’efficacite de la voie d’abord postero-laterale. Depuis 2003, nous utilisons une voie d’abord postero-laterale mini-invasive modifiee dite SPARTAQUUS (« Spare the Piriformis And Respect The Active QUadratus femoris and gluteus mediUS ») qui respecte le tendon du muscle piriforme (piriformis), le muscle carre femoral (quadratus femoris), le muscle moyen fessier (gluteus medius) et qui implique une suture capsulaire directe. Ainsi l’effet « hamac postero-superieur actif » du tendon du muscle piriforme est couple a l’effet « hamac postero-superieur passif » de la suture capsulaire, limitant ainsi les risques de luxation posterieure de l’articulation prothetique.

Cup orientation is a challenging step in total hip arthroplasty (THA), to ensure comfort of the patient and durability of the prosthesis. The safe zone defined by Lewinnek is commonly used for cup orientation, but it is nowadays being questioned because it is not patient-specific.We propose to define a new safe zone for cup orientation, that considers patient-specific parameters such as the pelvic tilt and the range of motion (ROM) of the leg.We developed a software that easily computes a unique safe zone from these param- eters in different daily positions, ensuring a cup orientation without risks of prosthetic impingement.

The anterior pelvic plane (APP) defined by both anterior superior iliac spines (ASIS) and the pubic symphysis (PS), is used as reference for cup orientation during total hip arthroplasty (THA). However, acquiring the PS and the contralateral ASIS during the intervention with the patient in lateral decubitus position, can be challenging due to the medical devices and the patient abdominal apron. The goal of this study is to find more easily accessible anatomical landmarks, useful for the APP acquisition. Thus we propose to study the variability of the pelvis anatomy in order to identify which landmarks vary with the APP. We built a statistical shape model (SSM) of the pelvis and studied the variability of APP orientation when deforming the SSM along its variation modes. We computed the APP inclination for each deformation and modeled linear relations between the APP inclination and the deformation along the variation modes. We found that the variability in APP inclination is mainly due to 3 variation modes that deform the iliac crest (IC), the posterior superior and anterior inferior iliac spines (PSIS, AIIS). Acquiring those three anatomical landmarks (IC, PSIS and AIIS) with the ipsilateral ASIS, could be a solution to determine more easily the APP for THA in lateral decubitus.

International audience

International audience; The anterior pelvic plane (APP) defined by both iliac spines and the pubic symphysis, is essential in total hip arthroplasty (THA) for the orientation of the prosthetic cup. However, the APP is nowadays still difficult to determine in computer assisted orthopedic surgery (CAOS). We propose to use a statistical shape model (SSM) of the pelvis to estimate the APP from ipsilateral anatomical landmarks, more easily accessible during surgery in computer assisted THA with the patient in lateral decubitus position. A SSM of the pelvis has been built from 40 male pelvises. Various ipsilateral anatomical landmarks have been extracted from these data and used to deform the SSM. Fitting the SSM to several combinations of these landmarks, we were able to reconstruct the pelvis with an accuracy between 2.8mm and 4.4mm, and estimate the APP inclination with an angular error between 1.3° and 2.8°, depending on the landmarks fitted. Results are promising and show that the APP could be acquired during the intervention from ipsilateral landmarks only.

Hip dysplasia is nowadays certainly less frequent than it used to be due to better and widely development of screening techniques in childhood. Quality of early care and therapeutic have also subsequently improved the prognosis in pathology development. Nevertheless, hip dysplasia remains a current issue. In pediatric and adult care, orthopaedic surgeons still deal with this pathology. If conservative medical management in childhood can avoid early surgery, a symptomatic hip dysplasia at adult age will always require surgical management., Les dysplasies de hanche sont une pathologie manifestement en voie de régression, grâce au développement des techniques de dépistage mises en pratique chez l’enfant depuis de nombreuses années, mais aussi à la précocité et à la qualité de leur prise en charge thérapeutique sitôt le début d’une dysplasie diagnostiquée. On voit ainsi de moins en moins actuellement de situations avancées pouvant mettre en jeu l’avenir fonctionnel de l’enfant et donc du futur adulte. Néanmoins, il apparaît nécessaire de rester vigilant, car cette affection n’a pas complètement disparu. Tant dans le domaine pédiatrique que chez l’adulte, les orthopédistes restent aujourd’hui confrontés à cette pathologie de la hanche ; si le recours à des solutions médicales permet parfois d’éviter à l’enfant une chirurgie, la dysplasie de hanche résiduelle devenue symptomatique de l’adulte ne trouvera, elle, que des solutions chirurgicales.

The Lefèvre retentive cup is a salvage solution for total hip replacement at high risk of dislocation. Only a few studies have reported the medium or long-term survival; most often, only a small number of patients were included in these studies. This led us to conduct a retrospective analysis of a large population to determine: 1) the 10-year survival rate after primary or revision arthroplasty, 2) the complication rate.The dislocation rate is5% for revision arthroplasty and2% for primary arthroplasty.This single-center retrospective study included 466 consecutive total hip replacements performed with the Lefèvre retentive cup with a 12-year theoretical minimum follow-up (1/1/1998 to 31/8/2006). There were 257 indications for primary arthroplasty and 209 for revision arthroplasty. The cohort had 316 women and the mean age at surgery was 72.9years (30.2-89.9). The mean follow-up was 10.2±5 years (0.1-19.3). A statistical analysis was done based on the Kaplan-Meier survival curves in two subsets of patients: primary and revision surgery.At the final review, 264 patients had died because of reasons unrelated to the procedures (mean 7.8±4.7years after the procedure), 48 were lost to follow-up (mean 3.0±3.3years after the procedure), and 39 patients (8%) had undergone acetabular revision of which 12 were for infection (2.5%), 25 were for loosening (5.4%) (5 femoral loosening only) and 2 were for dislocation (0.4%). In all, there were 10/466 dislocations (2.1%) of which 5/257 (1.9%) were in the primary group and 5/209 (2.4%) were in the revision group: 2 had a cup exchange and 8 were reduced by closed procedures. The probability of survival free of mechanical complications at 10years was estimated at 94.8%±1.6% (95% CI: 91.6%-98.0%) for the primary group and 87.8%±2.7% (95% CI: 82.4%-93.2%) for the revision groups (p=0.0017). There were 39 re-operations in the overall cohort: 1/257 (0.4%) for dislocation, 7/257 (2.7%) for aseptic loosening and 3/257 (1.2%) for infection in the primary group, while in the revision group, 1/209 (0.5%) was for dislocation, 18/209 (8.6%) for aseptic loosening and 9/209 (4.3%) for infection.The Lefèvre retentive cup has good long-term survival with a low mechanical complication rate, both in primary and revision surgery. To us, this implant appears to be a reliable salvage procedure for total hip replacement in patients at high risk for dislocation.IV; retrospective study without control group.

Introduction Les tumeurs orbitaires entrainent des risques fonctionnels eleves du fait de l’etroitesse [1] de la region [2] , que ce soit dans l’evolution spontanee ou lors du traitement chirurgical. L’abord endoscopique se developpe du fait d’une morbidite moindre en comparaison aux techniques ouvertes, la classique voie laterale de Kronlein. L’objectif de cette etude est de definir les principaux reperes anatomiques necessaires pour realiser cet abord afin de limiter sa iatrogenie. Materiel et methode L’etude s’appuie sur 11 sujets, dont 8 (4 injectees et 4 non injectees) ont ete utilises pour un abord endoscopique, 2 pour des coupes sagittales paramedianes, et un dernier a fait l’objet d’une dissection de la face pour aborder les sinus. Un endoscope KARL STORZ 30° a ete utilise par la fosse nasale droite pour decrire l’abord chirurgical. Resultats Differents reperes ont pu etre mis en evidence. Dans les fosses nasales, le cornet moyen qui etait luxe (ou reseque) permet de reperer le processus unciforme et la bulle ethmoidale. La paroi infero-mediale de l’orbite etait ensuite exposee lors de l’acces au sinus maxillaire. L’ouverture de la bulle ethmoidale decouvre le toit de l’ethmoide et l’artere ethmoidale anterieure [3] . Apres ethmoidectomie, les reliefs de la paroi antero-laterale du sphenoide (reliefs de l’artere carotide interne, du recessus opto-carotidien et le canal optique) etaient visualises. Enfin, l’ouverture du canal optique et de la paroi mediale de la fissure orbitaire superieure, permettait, apres incision de la periorbite, l’exposition de la graisse orbitaire extra conique, puis le muscle droit medial et inferieur. L’exposition de l’espace intra conique etait possible une fois ces muscles franchis, permettant l’acces au nerf optique. Conclusion Cette etude permet une visualisation de rapports specifiques a l’utilisation de l’endoscope, au cours d’un abord orbitaire endonasal et de definir la localisation des tumeurs accessibles par cette voie.

Case-report La vascularisation pulmonaire est formee de deux systemes. L’un est un systeme fonctionnel, constituant la circulation pulmonaire, forme des arteres et veines pulmonaires, et assurant l’hematose. L’autre est un systeme nourricier, comprenant les arteres et veines bronchiques et apportant du sang oxygene, riche en nutriments aux poumons [1] , [2] . Des anastomoses preexistantes entre ces deux systemes peuvent, de maniere acquise ou congenitale, devenir fonctionnelles [3] , [4] . Nous rapportons le cas d’un patient ayant un shunt entre les deux vascularisations pulmonaires et ayant abouti a un mauvais diagnostic d’embolie pulmonaire. Discussion L’embolie pulmonaire est une pathologie thromboembolique affectant la circulation pulmonaire, en lien avec un thrombus obstruant une branche arterielle a destinee pulmonaire. L’angioscanner thoracique permet de confirmer une suspicion clinique d’embolie pulmonaire [5] . Il repose sur une analyse morphologique en identifiant un defect endoluminal au sein du reseau arteriel pulmonaire opacifie a l’aide de produit de contraste iode. Nous rapportons le cas d’un patient pour lequel, il a ete porte, a tort, le diagnostic d’embolie pulmonaire. En effet, un shunt entre le reseau arteriel bronchique et le reseau arteriel pulmonaire secondaire a une neoplasie bronchique adjacente, aboutissait a un remplissage a « retro » du reseau arteriel pulmonaire alors opacifie par le produit de contraste iode, par du sang non opacifie provenant du reseau arteriel bronchique et creant un defect endoluminal mimant une embolie pulmonaire. Le diagnostic fut redresse a l’aide d’une scintigraphie pulmonaire de ventilation/perfusion et d’une imagerie morphologique scanographique thoracique dediee a l’etude du reseau arteriel bronchique. Conclusion Les shunts entre les deux circulations pulmonaires peuvent exister et entrainer des faux-positifs de l’angioscanner thoracique dans le cadre d’une suspicion clinique d’embolie pulmonaire.

Lower-limb discrepancy following total hip arthroplasty is the third-most common reason for patient dissatisfaction in orthopaedic surgery. Therefore, accurate planning and evaluation methods are mandatory. The main aim of this study was to evaluate the reliability of the EOS™ system by establishing and comparing the reproducibility of lower-limb automatic and manual 3D measurements. We hypothesized that the reproducibility of the lower-limb measurements is similar regardless of the method used and with an agreement higher than 0.95 for the length parameters. This study utilized an EOS radiological database of 112 patients. Two independent observers performed two rounds of lower-limb measurements twice, either in manual 3D or automatic 3D mode. The intra- and inter-observer reproducibility was evaluated by the calculation of the intra-class coefficient for each measurement method. The methods were then compared. The intra- and inter-observer reproducibility for length measurements found with the manual and automatic 3D methods was always > 0.98. There was no significant difference in the reproducibility between the two measurement modes, with the exception of the offset, hip–knee–shaft, and neck–shaft angles. Our results indicate a very good reproducibility of EOS™ length measurement, regardless of the method used. Automated 3D mode is preferred for the collection of angular and offset measurements. Furthermore, manual mode measurements are not affected by surgical history. Level of evidence IV.

In the debate on governance in city regions, the role of the state is currently an open question. Drawing on our own and secondary research on governance of large city regions across the world, we argue that nation-states (in unitary systems) and federate states (in federalist systems) are crucial protagonists of governance in megacities – defined as city regions of 10 million or more. Megacity governance thus provides a stark contrast to the prominent narrative of a retreating state conveyed in some of the new regionalist literature. It is concluded that megacities are a category of urban settlements in which the state is not withering away but continues to play a leading role in addressing urban policy problems.

SterEOS is a software developed by EOS Imaging® allowing the measurement of 3D orthopaedic parameters on two bi-planar radiographs. The goal of this preliminary study was to assess the reliability of the pelvic measurements. Two observers, a novice and an intermediate user, measured three times these parameters on pre and postoperative EOS images coming from ten patients. Intra- and inter-observer precision have been evaluated with intra-class coefficient (ICC) and Bland-Altman graphs. On preoperative EOS images, a high intra- and inter-observer precision (ICC>0.8) was obtained for the measurement of the femoral head diameter, the femur length, the pelvic version and the pelvic obliquity. The offset, the femoral neck length, the pelvic incidence and the sacral slope measurement had a high intra-observer precision but a lower inter-observer precision. The measurement of the acetabulum inclination and anteversion, the CCD angle, the femur torsion, the pelvic rotation and the anterior pelvic plane inclination had a low intra- and inter-observer precision. Similar results were found on postoperative EOS images. Our results are partially consistent with the literature since authors found high intra- and inter-observer precision for all pelvic parameters. Further studies are therefore needed to evaluate the impact of the observer experience on the reliability of those measurements.

Background Constrained liners are used as part of a salvage procedure to provide stability for patients at high risk for dislocation after a total hip arthroplasty. However, no recent studies exist highlighting their effectiveness and/or limitations. Method This prospective review included 166 consecutive hip arthroplasties, either primary (27%) or revision (73%), with a unique design of a constrained liner: Lefevre retentive cup. There were 113 females (69%), and the average age at index surgery was 75.9 years (range, 35-94). The mean follow-up was 6.2 years (range, 0.3-11). Results Twenty patients had a reoperation; 10 for infection (4 acute and 6 chronic joint infection) and 10 for cup failure (5 fixation failure, 3 aseptic loosening, and 2 dislocation). Ten-year survivals for cup revision were 89% (CI, 83-94) and 92% (CI, 89-97) for all revision and revision for noninfectious reasons, respectively. When solely evaluating for dislocation, the survival at 10 years was 99% (CI, 97-100). Considering primary and revision cases, 10-year survivals cup revision for aseptic reasons were 92.4% (CI, 84-100) and 92.5% (CI, 87-98), respectively. Conclusions The Lefevre retentive cup demonstrated excellent 10-year’s survivorship. With the rate of aseptic loosening around 2% and a dislocation rate around 1%, the cup is as effective as other available devices and is therefore a cost-effective tool to reduce the risk of dislocation in at-risk patients undergoing hip arthroplasty.

This chapter tells the story of the difficult and contested efforts to construct Paris as a metropolitan space. Covering the period of 2000 to the present, it focuses on the search for a collective actor and the production of collective action through the quest for alliances between players, be they the central State, local governments or business associations. More specifically, the chapter concentrates on the relationships between core metropolitan stakeholders through the analysis of four political initiatives aiming at building collective action and territorial leadership at the metropolitan scale. In the Ile-de-France region, many competing conceptions of metropolitan space are co-present and are conflicting. First the regional council, whatever its political leaning, has always considered the Metropolis to be the Ile-de-France region. In that perspective the construction of metropolitan space is understood to mean the strengthening of the powers and resources of the regional authority. Second, the city of Paris considers the core area to be the most relevant space to address the important problems of the metropolis. Third, the State maintains an ambiguous position as regards its conception of the metropolitan space, identifying it as the city region in the period 2007–2012 when the State was controlled by the conservative parties, but restricting it to the core area in the period 2012–2017 by the new Socialist government. In this context, the most important business associations have been ready to accommodate any initiative, provided that the treatment of the most important issues of economic competitiveness, transport and housing, was taken care of. This story clearly indicates the importance of politics in the construction of metropolitan space and shows the critical role that politics plays in shaping scalar conflicts. In this context, decentralization and globalization can be understood to be both structuring forces and elements which are instrumentalized. First, there is the issue of territorial leadership which has consistently led to a stalemate, because of a governance system whose main feature, unregulated competitive decentralization, prevents any leader from being accepted as legitimate at a regional scale. Second, the building of a coalition at the metropolitan level, to ensure capacity to act at that scale, has proved impossible, first, because of a relative balance of powers between local governments and, second, because of the incapacity of the State to successfully act as the leader of a coalition because of its political instability and its lack of resources. Third, players also conflict about the vision they have of the future of the metropolitan area. Two clearly opposed visions coexist, one in which priorities are to fight against social and territorial inequalities and to initiate an alternative mode of development based on ecological transition, another one in which economic competitiveness is the top priority to which social, territorial and environmental issues must be subordinated. Since these two visions are supported by alliances of players which are roughly equal in strength, the not surprising result is conflict and the blockage of the governance system.

The orientation of the cup in Total Hip Arthroplasty plays a major role on the post- operative results. It has been considered for several decades that the cup should be oriented according to the safe zone defined by Lewinnek. However, this safe zone is not always suitable because of the inter-individual variability of the pelvic tilt during daily activities. We propose in this paper a non-invasive ultrasound based solution which can easily measure this patient specific parameter in order to thereafter otimise the cup orientation. The accuracy of this system was assessed with a specific pelvic phantom. A clinical pilot study was also performed on ten patients. The pelvic tilt was measured in three daily positions: the supine, sitting and standing positions. The average error was 1.15°±0.82°. The average pelvic tilt was -97.1°±28.6°, -46.3°±12.8° and -9.0°±8.3° for respectively the supine, the sitting and the standing positions. The high inter-individual variability of the pelvic tilt in different daily positions highlight the need to have a suitable device for the measurement of this patient specific parameter for THA. The proposed system is easy-to-use, portable and allows the pelvic tilt measurement in different positions without any additional x-ray radiation.

To study the white matter tracts connecting the different stereoscopic visual areas of the brain by diffusion tensor imaging. In a previous study, we identified the cortical activations to a visual 3D stimulation in 12 subjects using functional MRI (fMRI). These areas of cortical activations [V5, V6, lateral occipital complex (LOC) and intra parietal sulcus areas (IPS)] in addition to the lateral geniculate nucleus (LGN) and the primary visual area V1 were chosen as regions of interest (ROIs). We studied by deterministic tractography the connections existing between these ROIs. Found connections were divided into three groups. The first group entails the geniculo-extrastriate connections. LGN was connected to V5, V6, IPS and LOC. These fibers course in the inferior longitudinal fascicule. The second group comprises the associative fibers. V1 was connected to V5 and LOC through the transverse occipital fascicule on one hand, and, to V6 and IPS through the stratum proprium cuni on the other hand. Connections between V5 and LOC, and V6 and IPS course within the vertical occipital fascicule. The third group contains commissural fibers. Forceps major entailed the connections between both V1, both V6, both IPS and IPS and contralateral V6. LGN was connected to contralateral LGN, V1, V6, IPS and LOC. We have elucidated numerous connections between the visual areas and the LGN. Generalization of these results to the remainder of the population must remain prudent due to the limited number of subjects in this study.

Functional approaches for the localization of the hip center (HC) are widely used in Computer Assisted Orthopedic Surgery (CAOS). These methods aim to compute the HC defined as the center of rotation (CoR) of the femur with respect to the pelvis. The Least-Moving-Point (LMP) method is one approach which consists in detecting the point that moves the least during the circumduction motion. The goal of this paper is to highlight the limits of the native LMP (nLMP) and to propose a modified version (mLMP). A software application has been developed allowing the simulation of a circumduction motion of a hip in order to generate the required data for the computation of the HC. Two tests have been defined in order to assess and compare both LMP methods with respect to (1) the camera noise (CN) and (2) the acetabular noise (AN). The mLMP and nLMP error is respectively: (1) 0.5±0.2mm and 9.3±1.4mm for a low CN, 21.7±3.6mm and 184.7±13.1mm for a high CN, and (2) 2.2±1.2mm and 0.5±0.3mm for a low AN, 35.2±18.5mm and 13.0±8.2mm for a high AN. In conclusion, mLMP is more robust and accurate than the nLMP algorithm.

The hip center (HC) in Computer Assisted Orthopedic Surgery (CAOS) can be determined either with anatomical (AA) or functional approaches (FA). AA is considered as the reference while FA compute the hip center of rotation (CoR). Four main FA can be used in CAOS: the Gammage, Halvorsen, pivot, and least-moving point (LMP) methods. The goal of this paper is to evaluate and compare with an in-vitro experiment (a) the four main FA for the HC determination, and (b) the impact on the HKA. The experiment has been performed on six cadavers. A CAOS software application has been developed for the acquisitions of (a) the hip rotation motion, (b) the anatomical HC, and (c) the HKA angle. Two studies have been defined allowing (a) the evaluation of the precision and the accuracy of the four FA with respect to the AA, and (b) the impact on the HKA angle. For the pivot, LMP, Gammage and Halvorsen methods respectively: (1) the maximum precision reach 14.2, 22.8, 111.4 and 132.5 mm; (2) the maximum accuracy reach 23.6, 40.7, 176.6 and 130.3 mm; (3) the maximum error of the frontal HKA is 2.5°, 3.7°, 12.7° and 13.3°; and (4) the maximum error of the sagittal HKA is 2.3°, 4.3°, 5.9°, 6.1°. The pivot method is the most precise and accurate approach for the HC localization and the HKA computation.

Introduction Le nerf median est affecte par de nombreuses neuropathies peripheriques, tel que le syndrome du canal carpien. Ce diagnostic repose principalement sur l’examen clinique et electromyographique. Certains auteurs suggerent que l’echographie pourrait egalement etre un outil diagnostique interessant, la morphologie et la vascularisation intraneurale du nerf median etant modifiees en cas de syndrome compressif. Les publications decrivant la vascularisation intrinseque du nerf median non pathologique sont cependant peu nombreuses et anciennes. L’objectif de ce travail est donc d’etudier la vascularisation intrinseque du nerf median. Materiel et methode L’etude a ete realisee sur 15 membres superieurs de sujets frais congeles. Chaque membre a ete injecte avec une solution de latex rouge diluee a 5 % au niveau de l’artere brachiale. La dissection intraneurale a ete realisee sous une loupe chirurgicale (×3) pour 10 des membres et sous un microscope chirurgical a grossissement × 36 pour les 5 autres. La description de la vascularisation intra neurale du nerf median a ete faite par rapport a un point fixe, le tubercule du scaphoide. Resultats L’etude met en evidence une vascularisation intraneurale du nerf median qui provient d’arterioles epineurales sur la face ventrale du nerf et dans certains cas sur ses faces laterale ou mediale. Ces arterioles sont issues de branches nourricieres provenant des gros troncs arteriels adjacents. Nous avons constate que les rameaux des arterioles epineurales forment un reseau arteriel intraneural compose d’une artere intraneurale principale s’anastomosant avec les rameaux situe en amont ou en aval. L’artere intraneurale principale peut etre accompagnee par d’autres arteres de plus petits calibres naissant du reseau intraneural ou extraneural. Conclusion Ce travail a permis d’etudier la vascularisation intrinseque du nerf median, qui est probablement impliquee dans la physiopathologie du syndrome du canal carpien.

Introduction La classe inversee est un modele de cours qui fait partie des innovations pedagogiques. Elle est de plus en plus utilisee dans les facultes de medecine mais encore peu en anatomie. La classe inversee est une technique utilisee en 2e annee de medecine pour l’enseignement de l’anatomie de l’appareil digestif. Nous avons mene une etude sociologique que nous presentons. Materiel et methode L’anatomie de l’appareil digestif est enseignee en 12 heures au second semestre de la 2e annee des etudes medicales. La promotion de DFGSM2 concernee, est composee de 180 etudiants. L’enseignement comporte 12 heures en amphitheâtre. Des groupes ont ete constitues sur la base du volontariat afin de « faire la classe » aux autres etudiants et a l’enseignant. Des elements de cours ont ete definis, un support de cours etait propose aux etudiants au prealable. Une sociologue a interroge des etudiants en entretiens individuels. Tous les etudiants presents en cours ont repondu a un questionnaire en ligne. Resultats Les entretiens mettent en evidence une plus grande motivation des etudiants et un investissement dans la preparation des cours. Les enseignants sont consideres comme des referents qui apportent, outre la correction, les connaissances d’expert. Les questionnaires ont mis en evidence la valeur de la discipline, le controle de l’apprentissage. Un apprentissage par les critiques de l’enseignant. Outre la valeur ajoutee de la discipline, des competences transversales sont mises en exergue, comme le partage de l’information, l’organisation, la presentation face a un public. Conclusion Le systeme de classe inversee peut-etre realise dans le cadre de l’enseignement d’anatomie. Les etudiants ont largement participe a cet enseignement et ont porte un interet a cette technique d’enseignement. Leur investissement est le reflet de l’interet qu’ils portent a la discipline. La classe inversee est une technique complementaire des autres modalites d’apprentissage.

The cup orientation plays a major role in the long-term implant stability following Total Hip Arthroplasty (THA). Because of the patient specific spine-hip kinematics, the safe zone introduced by Lewinnek is more and more controversial. Several solutions have been recently developed to take into account such parameter for THA but are all either invasive, difficult to use or expensive. A non-invasive ultrasound (US) based device has been recently proposed which allows the acquisition of the pelvic tilt in different daily positions. The goal of this study is to analyze the in-vivo intra and inter-observer precision of this device. Measurements were realized by three physicians on three healthy subjects having a low, medium and high Body Mass Index (BMI). Among the three physicians, there were an expert, an intermediate, and a novice user. For each subject, the pelvic tilt was measured ten times by the three physicians in the supine, standing and sitting positions. The inter and intra-observer precisions have been analyzed using the intraclass correlation coefficient (ICC) and according to the BMI, the positions and the user expertise level. The inter-observer precision was therefore excellent whatever the BMI. It was also excellent regarding the supine and the sitting positions and good concerning the standing position. The in-vivo intra-observer precision was excellent for all measurements and whatever the user’s expertise, the BMI and the positions. This study shows therefore that the precision of our system meets the clinical requirement. Introduction