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Uterine artery projection relative to anatomical bony landmarks in CT-angiographies
No full textInternational audiencePurpose The aim was to find bony landmarks of the pelvis for the origins and routes of uterine arteries, hoping to improve speed and safety of embolization procedures (leiomyoma, post-partum bleedings…). Methods We carried out a study based on the analysis of CT-angiographies in arterial phases of whole-body scans. Two measurements were done per artery, one from the origin of uterine arteries to a first perpendicular line passing through the lowest part of the sacroiliac joint, another one from the beginning of the parametrial segment from a second parallel line passing by the acetabular roof. Mean distances across all these measurements were calculated, as were potential associations with known variables such as anatomical variants, age, parity and any pelvic surgical history. Results Two hundred uterine arteries were analyzed. Concerning the origin, 83.5% of uterine arteries were located approximately one centimeter around the first line defined above, with a mean distance of + 4.8 mm. Concerning parametrial segment beginning, 88% were located approximately one centimeter around the second line defined, with a mean distance of only + 3.9 mm above the acetabular roof. Some significant differences were observed in subgroups, notably with a small trend to higher arising of uterine arteries in patients who had at least one childbirth, and expectedly lower arising in distal anatomical variants. Conclusion Clear pelvic anatomic landmarks exist and could help the guidance of arteries catheterization, and therefore indirectly lead to faster embolization and optimize procedures safety
Canalicular Intrinsic Permeability in Human Femoral Cortical Bone assessed by 3D Synchrotron Nano-CT
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Effects of short circuit applications on PEM fuel cell performance and degradation
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Development of an automatic method for quantifying the performance of a bicycle path-following task using computer vision
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Illustration of the use of adhesively bonded Carbon Fiber Reinforced Polymer reinforcement to increase fatigue life of steel bridges
No full textInternational audienceThere is a great concern regarding the steel bridges stock management in North America and Western Europe. Structures are indeed ageing and may face fatigue issues as this was not taken into account during design before the 70s. The use of adhesively bonded Carbon Fiber Reinforced Polymer may provide a solution to extend their service life either when crack has occurred or as a preventive step before crack initiation. This article intends at illustrating the use of this technique for old steel structures in both cases. The application of the technique to cracked steel elements is developed for the specific case of old riveted elements (both in mild steel and wrought iron). While the preventive case is illustrated through the presentation of a methodology developed during an international project called FASSTBridge and applied on part of a real bridge in Spain. Both studies show the interest of the technique and highlights key choices. A conclusion gives some insights of additional needed developments for a wider use of the technique on real site
Inferior outcome of stand-alone short versus long tibial stem in revision total knee arthroplasty. A retrospective comparative study with minimum 2 year follow-up
No full textInternational audienceIntroduction: Revision Total Knee Arthroplasty (RTKA) is complex, and induced bone loss might endanger implant fixation and joint stability. Intramedullary stems improve fixation throughout stress redistribution. The current study aims to compare the performance of short tibial stems with long tibial stems, investigating their intermediate-term radiographic and survival outcomes in RTKA. The main hypothesis is that the two types of tibial stems would exhibit similar complication and revision rates in mid-term follow-up. Methods: Patients who underwent RTKA for all causes in a specialized arthroplasty center from 2010 to 2022 with minimum 2-year follow-up were included in this study. Patients receiving mega prosthesis or implants associated with sleeves or cones were excluded. The final groups consisted of 234 knees: 110 patients with short stems (SS) and 124 with long stems (LS). The mean age at surgery was 65.96 ± 8.73 years in SS and 67.07 ± 8.64 years in LS. The mean Body Mass Index (BMI) was 28.95 is SS and 30.88 in LS (p 0.05). Pathological radiolucency was present in 20.91% in SS group and 33.87% in LS group (p < 0.02). Time-to-re-revision was shorter in SS group and occurred at a mean of 3.1 years, while LS failed at a mean of 5.1 years (p < 0.001). Conclusions: The SS and LS may be comparable in terms of complications and re-revision. SS significantly fails almost 2 years earlier than long stem (p < 0.001). Additionally, there is a higher tendency for re-revision due to loosening in patients who present pathological radiolucency in SS group. To obtain the benefits of short stem and improve the longevity of the construct; adjuvant zone II (metaphyseal) fixation might be the clue
Redefining the Concept of Patellofemoral Stuffing in Total Knee Arthroplasty
No full textInternational audienceIntroductionBalancing the patellofemoral joint (PFJ) in total knee arthroplasty (TKA) involves avoiding over-stuffing. The purpose of this study was to assess how often a strategy of recreating the anterior space of the trochlea (full extension) led to the trochlea depth being recreated in both mid-flexion (30–40°) and deep flexion (80–90°).MethodsOne hundred and twenty two consecutive patients undergoing robotic-assisted TKA had femoral components placed according to functional alignment principals and were assessed. The femoral component was sized and positioned in order to ensure that the anterior flange was within 2 mm of the native anatomy, corresponding to a patella position of full extension (0° flexion). Trochlea depth restoration in 3 positions along the floor of the trochlea groove was compared and measured. The trochlea was defined as balanced if the prosthesis was within 2 mm of the native anatomy. Patients were divided into over-stuffed (prosthesis >2 mm above the native anatomy) or under-stuffed (prosthesis >2 mm beneath the native anatomy).ResultsAll patients 122/122 (100%) had a balanced trochlea in full extension. In total 54 TKA were over or under-stuffed at either mid-flexion or deep flexion. In mid-flexion, 3/122 (2.5%) trochlea were over-stuffed and 39/122 (32%) trochlea were under-stuffed. In deep flexion, 25/122 (20.5%) of trochlea’s were overstuffed and 30/122 (24.6%) were under-stuffed. In mid-flexion, balanced trochlea components were more externally rotated relative to the posterior condylar axis compared to unbalanced components (2.35° external rotation vs 1.21°, p=0.004). There were no other significant differences observed between the balanced and unbalanced trochlea groups in mid or deep flexion.ConclusionOver 40% of TKA over or under-stuff the trochlea in deeper flexion despite the anterior flange being positioned within 2 mm of the native anatomy in full extension. The rate of over or under-stuffing in mid and deep flexion was similar (>40%); however, in mid-flexion, under-stuffing of the native trochlea was more common. The concept of PFJ over or under-stuffing in TKA needs to be redefined to consider the full arc of flexion of the trochlea groove, and the biomechanical and clinical consequences of under-stuffing the trochlea investigated further.EvidenceLevel IV
Identifying Critical Commuters: A Machine Learning Approach to Flexible Work Hours and Urban Congestion
No full textInternational audienceCongestion remains one of the most prevalent transport problems in major cities. Recent approaches to managing demand aim to make working hours flexible to reduce congestion during peak periods. However, these approaches must also address synchronization needs at the employer, household, and individual levels. This study presents a framework to identify critical commuters who can adjust their arrival times, benefiting individual motivations, and managing arrival time demands. We explore multiple machine learning approaches to model and predict an individual's ability to shift their workplace arrival times. Ultimately, we choose gradient boosting due to its superior performance. Utilizing this ensemble approach on an employee survey data from Rennes Metropole in France, we analyze the factors that influence individual's flexibility in their arrival times. Key determinants identified include regular school drop-offs, theoretical arrival time contract with employer, and, to a lesser extent, age and income. Our findings demonstrate the need for a bi-level framework that incorporates both arrival time demand management and social justice analyses to ensure effective and equitable outcomes
A Machine Learning Approach for Network Equilibrium Estimation
No full textInternational audienceThe Traffic Assignment Problem (TAP) is essential for traffic flow analysis, traditionally solved using mathematical programs under the User Equilibrium (UE) principle. These methods become computationally prohibitive for large-scale networks due to non-linear growth in complexity with the number of origin-destination (OD) pairs. This study introduces a novel data-driven approach using Deep Neural Networks (DNNs), specifically leveraging Transformer architecture, to predict equilibrium path flows directly. By focusing on path-level traffic distribution, the proposed model captures intricate correlations between OD pairs, offering a more detailed and flexible analysis compared to traditional link-level approaches. The Transformer-based model significantly reduces computation time and adapts to changes in both demand and network structure, predicting optimal solutions without the need for recalculating from scratch. Numerical experiments are conducted on the Manhattan-like synthetic network and the Sioux Falls network. The results demonstrate that the proposed model efficiently estimates optimal traffic flow distribution at the path level, saving computational resources, enhancing traffic flow prediction accuracy by capturing detailed trip usage and flow information, and offering flexibility to adapt to varying demand and network changes, thus supporting traffic management, and enabling "what-if" analyses for improved transportation planning and policy-making
On the use of Vision for the Weighting of GNSS observation: comparisons
No full textInternational audiencePositioning is a critical function in every intelligent vehicle application. Most applied system is a GNSS (Global Navigation Satellite System)-based receiver, cheap and offering a continuous meter-level accuracy. However accuracy strongly depends on the satellite signal reception state: LOS (Line of sight), that is direct, optimal signal or NLOS (Non LOS), i.e received without direct visibilty and after one or more reflections of the signal. Based on previous work, this paper summarizes different weighting schemes applied to mitigate these local effects on GNSS signals and enhance position accuracy in land transport environment. A database collected by ISAE is used for application and comparison of the different schemes. One of them not only relies on GNSS signals but also on satellite state identification thanks to the use of a fisheye camera. This state allows us to deweight degraded measurements without excluding them, in order to keep availability. The paper shows that considering this additional information allows the WLS (Weighting Least Square) to significantly increase accuracy in every types of environments. If state of the art weighting schemes already improve accuracy by 65 and 77% over ordinary least squares in the 2D plan, our weight further improves accuracy by 40% compared to the classical elevation-based weight