Prostheses and orthoses enable people with physical impairments or functional limitations to live healthy, productive, independent, dignified lives and to participate in education, the labour market and social life. The current design and manufacture of Prosthetic and Orthotic device interfaces is dominated by hand-forming of thermoplastic materials on the plaster obtained via subtraction manufacturing techniques to allow for adaptation of the geometry to every user. This manual and iterative process is necessary to target optimal load transfer and ensure a good socket fit. At the same time, the process is highly dependent on the skill and experience of the prosthetist, as well as patient feedback with no quantitative prediction of fit prior to the manufacture of the socket. The current approach also hinders the automatization of the manufacturing chain and the use of mechanically based model for the optimization of shape and material properties. Additive Manufacturing processes are now mature enough to be used to create Orthopaedic/medical devices which are functional and in their end-use state. However, challenges remain to integrate it in a fully digitalized procedure that can take into account personalized and user-oriented design. Biomechanical modelling has been identified as a potential tool to assist the prosthetist in their design process, by providing a prediction of fit prior to manufacture. Integrating such modeling in the manufacturing process would therefore be a major innovation. However, model validation is difficult due to the large inter- and intra-individual loading and anatomic variability including accurate description of the material properties, geometrical data, loading characteristics, and boundary and interface interaction conditions. The IMPRINT project will be a timely contribution to the scientific and technological breakthroughs required for disrupting the Orthotics and Prosthetics market with digital processes and AM. To achieve this ambitious goal, IMPRINT will pursue four research objectives: 1/ Develop and evaluate an efficient modelling-simulation framework combining Gait Analysis, MusculoSKeletal simulations and Finite Element Analysis to investigate stump-socket interaction and quantify the impact of rectifications on biomechanical metrics used as surrogates for the goodness-of-fit of the prosthetic socket 2/ Collect experimental data on the inter- and intra-individual variability including accurate description of the material properties, geometrical data, loading characteristics, and boundary and interface interaction conditions 3/ Perform a mixed experimental-numerical parametric analysis to determine what model input parameters account for variability in the model output (interface pressure) 4/ Develop and integrate a 100% digitalized and waste-free manufacturing of all the orthoses and prostheses manufactured by PROTEOR. This includes all tasks required for an effective implementation of digital manufacturing cycle within 3D printing clusters and the development of a computer framework allowing to assist the prosthetist/orthotist in their design process, by providing a prediction of fit prior to manufacture. Beyond the very positive ecological impact, this will also have a social and economic impact: improving the comfort and function of the prosthetic limb interface are substantial to improve quality of life of the Orthopaedic device user. This will pave the way for human-centered and flexible Digital Processes to meet the demand for innovative, personalized and optimized products in waste-free processes. From a more general scope, the underlying challenge addressed by the IMPRINT project extends to all the man-machine mechanical interfaces.

The human body is daily exposed to vibrations of different nature. In the case of Manual Wheelchair (MWC) users, these vibrations are even present at the core of one's locomotion and, according to literature, have detrimental effect on their anatomical structures. Various parameters are likely to affect the vibration exposure for MWC users: ground irregularities, user’s characteristics, MWC settings and defects such as micro-cracks and mechanical fatigue. Further, the 2020-circular-economy law pushes for the second-hand use of refurbished, thus maybe defective, MWC. These evidence highlight the need to finely address the vibration exposure of the interacting User/MWC couple for a better MWC user care. Under this framework, the objectives of HandiVib are to quantify the vibration exposure of the User/MWC couple to understand the incurred risk of injury and subsequently propose new procedures to evaluate the MWC suitability. To fulfill these objectives, HandiVib lies on three hypotheses. The vibration exposure of MWC users (H1) conveys to a raise in the musculoskeletal loads, increasing the risk of injury; (H2) has consequences that depend on the user’s level of disability (H3) is expected to rise using a MWC with degraded mechanical conditions (e.g. microcracks, mechanical fatigue). To reach these aims, the overall goal of this project will be to investigate the vibration exposure for a wide number of User/MWC couples and situations. Proven methods in the field of human body exposure to vibration will be implemented. An experimental framework will be designed associating an MWC ergometer and electrodynamic shakers able to simulate the ground excitation a MWC is exposed to under real conditions. This setup, combined to biomechanical models will be helpful to determine vibration transmission and intervertebral forces affecting the user under various levels of disability and MWC mechanical states. The project’s originality lies in the simultaneous evaluation of vibration transmission through the body and musculoskeletal loads. HandiVib will proceed into three technical work packages: one will aim at designing a dedicated experimental setup and two others will address the project’s hypotheses based on experimentation and biomechanical modeling. HandiVib will be led by D. Chadefaux, associate professor at the Université Sorbonne Paris Nord (USPN) since 2018. D. Chadefaux conducts her research activities about the optimization of the human-equipment interactions under shock and vibrations at the Institut de Biomécanique Humaine Georges Charpak (Arts et Métiers - Sciences et Technologie). Regarding the project’s execution, the team will be composed of senior researchers from the IBHGC, the INI-CERAH, the Hopital Raymond Poincaré (Garches), and Politecnico di Milano. Given its potential to improve MWC users care and to promote innovation for MWC evaluation, Handivib meets the intentions of the research theme 8.7 “Technologies pour la santé”. Experimental outcomes will provide a tool to the clinician to evaluate the risk of injury incurred for a given MWC mechanical condition. Findings will also contribute to innovating procedures of interest to determine whether a MWC complies with safety standards. Through a simple lumped-element model, a physical model could be developed to enhance the design of test dummies reproducing faithfully the user effect on a MWC. Findings will also contribute to detect mechanical defects in a MWC: a testing platform will be developed to evaluate the suitability of a refurbished MWC for further use. The experimental database collected will favour understanding the specificity of each pathology with respect to vibration exposure. HandiVib will contribute to guide MWC user in their MWC choice and tuning in accordance with rehabilitation therapists’ recommendations to minimize the risk of injury induced by the vibration exposure.

The aim of this research project is to explore the neuro-mechanical coupling between the postural and respiratory systems, focusing on the essential role of the diaphragm. It focuses in particular on patients suffering from chronic obstructive pulmonary disease (COPD), a respiratory disease that progressively alters lung function and posture. The underlying hypothesis of this project is that this coupling between postural and ventilatory systems significantly influences the health of COPD patients. In particular, it is hypothesized that alterations in the geometry and dual function of the diaphragm are responsible for postural dysfunctions in these patients. The project's methodology is multidisciplinary. It includes the use of biplane radiographs to create three-dimensional models of the diaphragm in the upright position, observing variations in lung volume during inspiration and expiration. In addition, ultrasound elastography is used to characterize diaphragm thickness and mechanical properties throughout the respiratory cycle. The postural adaptations resulting from these variations will be analyzed by examining the entire skeleton, while the data will be correlated with indices of neuro-mechanical balance/respiration coupling and respiratory function. The originality of this research lies in the creation of a three-dimensional model of the diaphragm in the standing position, a breakthrough that has not yet been achieved. This model will provide a better understanding of the mechanisms responsible for postural dysfunctions in COPD patients, by identifying early indicators. The ultimate aim is to contribute to the prevention of disability and falls in these patients, which is of great importance in public health terms, given the considerable number of people affected by chronic respiratory diseases in France.

Locomotion with a manual wheelchair (MWC) submits the upper-limbs of the manual wheelchair users (MWU) to an important stress, which varies according to the environment. To assist MWU in selecting the paths that preserve their upper limbs, a cost reflecting the physical demand of the successive situations along the possible paths must be attributed. In the current state of knowledge and accessibility standards, an obstacle has no graduation and can only be marked as crossable or not, which cannot reflect, neither the heterogeneity of the situations, nor the link between their accessibility and the physical and technical abilities of the MWU. To go beyond these limitations, this project aims at defining biomechanical costs that can be attributed to the environmental situations, and that could be implemented in future optimal path selection algorithms. This will make it possible to provide MWU with individualized paths taking into account their individual capacities. To do so, a musculoskeletal model will be developed to quantify various biomechanical quantities that will serve as input data for the definition of the biomechanical costs. These costs will be computed for various situations, reproduced in a realistic MWC locomotion simulator developed in the framework of this proposal. Such a project will provide original and useful data for accessibility evaluation, planning of urban development services and assistance adaptation. It will also be the basis for further work on MWU evaluation and paths characterization to provide personalized cost-optimal paths.

The recovery of a correct dynamic balance is at the heart of gait rehabilitation. However, no real consensus exists about an indicator that could be used to monitor the balance during walking either for humans or humanoid robots that share similar issue in this context. The ambition of the project if to propose concrete metrics that could be used to monitor instability during the locomotion by combining complementary approaches of biomechanics and robotics. These metrics computed from real-time capture of mechanical signals are the prerequisite for effective implementation in dedicated clinical tools to adapt the rhythm of rehabilitation to each individual. The three main objectives are to: 1/ develop a complete theoretical mechanical analysis of bipedal locomotion to quantify the instability from the equations of the dynamics of motion, 2/ classify different indicators defined from the theoretical analysis according to two criteria: i/ their performance on caricatural experiments on robots and humans ii/ their accuracy when computed from wearable technologies 3/ make a proof of concept of a wearable solution from existing sensors integrated in a prototype device able to compute the indicator in real time. The consortium gathers the complementary skills required for the project in biomechanics, health and rehabilitation, instrumentation, motion control and humanoid robotics. The impact of the project will be major for both the understanding of mechanical balance during gait from a theoretical approach and the proof of concept that dynamic based indicator can be made available in the clinical context.