A comprehensive methodology to assess human bone transversal toughness based on macroscopic specimens, the compliance method, and 3D bio-faithful numerical simulations.

This study proposes a method for assessing the transverse toughness of human long-bone cortical tissue. The method is based on a three-point bending test of pre-notched femur diaphysis segments, post-processed using the compliance method coupled with numerical simulations. Given the cracking nature of bone and if cracking processes remain confined to the crack tip, it is assumed that the compliance method can be used.

Traumatic axonal injury: Clinic, forensic and biomechanics perspectives.

Identification of Traumatic axonal injury (TAI) is critical in clinical practice, particularly in terms of long-term prognosis, but also for medico-legal issues, to verify whether the death or the after-effects were attributable to trauma. Multidisciplinary approaches are an undeniable asset when it comes to solving these problems. The aim of this work is therefore to list the different techniques needed to identify axonal lesions and to understand the lesion mechanisms involved in their formation.

Head injury: Importance of the deep brain nuclei in force transmission to the brain.

Finite element modeling provides a digital representation of the human body. It is currently the most pertinent method to study the mechanisms of head injury, and is becoming a scientific reference in forensic expert reports. Improved biofidelity is a recurrent aim of research studies in biomechanics in order to improve earlier models whose mechanical properties conformed to simplified elastic behavior and mechanic laws.

Assessment of the tolerance angle for pedicle screw insertion.

Cannulation process intervenes before implantation of pedicle screw and depends on the surgeon's experience. A reliable experimental protocol has been developed for the characterization of the slipping behavior of the surgical tool on the cortical shell simulated by synthetic materials. Three types of synthetic foam samples with three different densities were tested using an MTS Acumen 3 A/T electrodynamic device with a tri-axis 3 kN Kistler load cell mounted on a surgical tool, moving at a constant rotational speed of 10° mm and performing a three-step cannulation test.

Sliding on cortical shell: Biomechanical characterization of the vertebral cannulation for pedicle screw insertion.

Background: Pedicular screws pull-out has been well studied unlike their insertion. A need for characterizing cannulation before pedicle screw implantation is highlighted in literature and offers promising prospects for future intra-operation instrumentation. A reliable cannulation protocol for ex-vivo testing in swine and cadaver vertebrae is presented in this work to predict extra pedicular perforation.

Mandibular Titanium Miniplates Change the Biomechanical Behaviour of the Mandible in the Case of Facial Trauma: A Three-Dimensional Finite Element Analysis.

Our study aimed to compare the biomechanical behaviour of mandibles with or without titanium miniplates when subjected to an impact after bone healing using a finite element model (FEM) of the human mandible. We simulated mandibular trauma on an FEM of a human mandible carrying or not two parasymphyseal miniplates and applying a concentrated force of 2000 N to four different areas, including the insertion area, the area straddling the edge of the miniplates and the adjacent bone, at a distance from the miniplates on the symphysis, and on the basilar border of the mandible below the miniplates. Then, we compared the Von Mises stress distributions between the two models.

Method for Evaluating Cortical Bone Young's Modulus: Numerical Twin Reconstruction, Finite Element Calculation, and Microstructure Analysis.

The determination of bone mechanical properties remains crucial, especially to feed up numerical models. An original methodology of inverse analysis has been developed to determine the longitudinal elastic modulus of femoral cortical bone. The method is based on a numerical twin of a specific three-point bending test.

Characterisation of the very young child's palatal vault growth pattern: how do its size and shape evolve?

Aim: This study aimed to characterise the palatal vault evolution during the first years of life, both in terms of shape and size.

Materials: The study sample was composed of 168 healthy children aged less than 4 years. Twenty-one measurements of distances and 6 angles were taken from 7 fixed landmarks set on the palatal vaults 3D surfaces reconstructed from CT-scans.

Traction mechanical characterization of porcine mitral valve annulus.

The Mitral Annulus (MA) is an anisotropic, fibrous, flexible and dynamical structure. While MA dynamics are well documented, its passive mechanical properties remain poorly investigated to complete the design of adequate prostheses. Mechanical properties in traction on four sections of the MA (aortic, left, posterior and right segments) were assessed using a traction test system with a 30 N load cell and pulling jaws for sample fixation.

Macrocrack propagation in a notched shaft segment of human long bone: Experimental results and mechanical aspects.

Experimenting with crack propagation in human cortical tissue is a necessary prerequisite for developing a cracking model. A three-point bending test on a shaft section of a notched human long bone is presented. A procedure for carrying out the experimental test, including unloading/reloading cycles, is implemented.

Do mandibular titanium miniplates affect the biomechanical behaviour of the mandible? A preliminary experimental study.

Introduction: Whether to conserve or remove titanium miniplates after rigid internal fixation of mandibular fractures still remains controversial. Miniplates could affect the biomechanical behaviour of the mandible in case of trauma, and therefore cause more complex fractures.

Materials And Methods: An experimental study, consisting in simulating a mandibular trauma, was designed in order to compare the fractures caused by an impact on the mandible in the presence or absence of an internal fixation.

Management of the pediatric OSAS: what about simultaneously expand the maxilla and advance the mandible? A retrospective non-randomized controlled cohort study.

Objective/background: This retrospective non-randomized controlled cohort study aimed to evaluate the efficiency of simultaneous maxillary expansion and mandibular advancement for the management of pediatric OSAS.

Patients/methods: The sample was composed of 94 children treated with an innovative orthopedic device to correct a Class II malocclusion associated with an OSAS. Polysomnographic recordings were performed before and after the treatment.

Experimental Bi-axial tensile tests of spinal meningeal tissues and constitutive models comparison.

Introduction This study aims at identifying mechanical characteristics under bi-axial loading conditions of extracted swine pia mater (PM) and dura and arachnoid complex (DAC). Methods 59 porcine spinal samples have been tested on a bi-axial experimental device with a pre-load of 0.01 N and a displacement rate of 0.

Modeling one-handed grip strangulation: Intentionality of the gesture and age influence.

Strangulation is a violent act which can be lethal and is often studied in forensic context. The neck includes several anatomical elements that can evolve with aging. We therefore created a numerical human neck model including the main anatomical elements and simulated one-handed grip strangulation cases.

Sudden death after facial impacts: Is the brainstem involved?

Three deaths following facial impacts in the presence of witnesses and resulting in brain lesions that were visualized only on pathological examination were studied at the forensic medicine institute of Marseille. Craniofacial impacts, even of low intensity, received during brawls may be associated with brain lesions ranging from a simple knock-out to fatal injuries. In criminal cases that are brought to court, even by autopsy it is still difficult to establish a direct link between the violence of the impact and the injuries that resulted in death.

Leaflet stress quantification of porcine vs bovine surgical bioprostheses: an study.

Calcified aortic stenoses are among the most prevalent form of cardiovascular diseases in the industrialized countries. This progressive disease, with no effective medical therapy, ultimately requires aortic valve replacement - either a surgical or very recently transcatheter aortic valve implantation. Increase leaflet mechanical stress is one of the main determinants of the structural deterioration of bioprosthetic aortic valves.

Impact of the Craniofacial Surgery Simulation in Anterior Plagiocephaly on Orbits and Oculomotor Muscles: Biomechanical Analysis With a Finite Element Model.

Purpose: The aim of this study was to show the displacements and strain induced by the supraorbital band advancement during a craniofacial surgery for an anterior plagiocephaly on the orbital bones and the orbital content thanks to a numerical surgical simulation using the finite element method.

Methods: A three-dimensional (3D) finite element model of a child with an anterior plagiocephaly was entirely created from a tomodensitometry of a patient followed by our Craniofacial Pediatric team. Data of the tomodensitometry were computed with Slicer 3D to re-create the orbit geometry.

The Hypoplasic Mandible: What Makes it Different From the Healthy Child?

Objective: This study aimed to analyze the morphology of the hypoplasic mandible and its evolution during the growth period to better understand how it differs from the pediatric healthy mandible.

Method: Three-dimensional mandibular models of hypoplasic and healthy children aged from 39 gestational weeks to 7 years old were analyzed with a morphometric method including data clustering. Morphological distinctions between pathological and healthy mandibles were highlighted.

The association of Le Fort midfacial fractures with frontobasal injuries: a 17-year review of 125 cases, reflections on biomechanics, classifications and treatment.

The frequency of midface and frontobasal fractures has increased over the past 40 years despite the improvement and stringent regulation implemented on modern safety equipment (belts, helmets…). This observation might be correlated with the progress of radiodiagnosis tools. Literature was reviewed according to Prisma guidelines.

Preliminary results on the impact of simultaneous palatal expansion and mandibular advancement on the respiratory status recorded during sleep in OSAS children.

Introduction: The study aimed to evaluate the evolution of the respiratory status during sleep of OSAS children treated with a custom-made device combining maxillary expansion and mandibular advancement.

Material And Methods: Sleep studies were performed before and after the treatment for 103 children presenting an initial OSAS and Class II malocclusion. Sleep questionnaires were also addressed to parents several years after the end of the treatment to evaluate its long-term effects.

Salivary side effects after radioiodine treatment for differentiated papillary thyroid carcinoma: Long-term study.

Background: Although many studies focus on short-term side effects of radioiodine therapy, almost none studied long-term side effects. We assessed radioiodine long-term salivary side effects after radioiodine treatment for differentiated papillary thyroid carcinoma and compared it to short-term morbidity within the same population.

Methods: A standardized self-administrated questionnaire was submitted in 2019 by patients treated with radioiodine between January 2011 and December 2012.

Biomechanical analysis of two insertion sites for the fixation of the sacroiliac joint via an oblique lateral approach.

Background: The sacroiliac joint is an important source of low back pain. In severe cases, sacroiliac joint fusion is used to reduce pain, but revision rates can reach 30%. The lack of initial mechanical stability may lead to pseudarthrosis, thus not alleviating the patient's symptoms.

Study of cerebrospinal injuries by force transmission secondary to mandibular impacts using a finite element model.

Brain and cervical injuries are often described after major facial impacts but rarely after low-intensity mandibular impacts. Force transmission to the brain and spinal cord from a mandibular impact such as a punch was evaluated by the creation and validation of a complete finite element model of the head and neck. Anteroposterior uppercut impacts on the jaw were associated with considerable extension and strong stresses at the junction of the brainstem and spinal cord.

Morphometric characterization of the very young child mandibular growth pattern: What happen before and after the deciduous dentition development?

Objectives: Numerous tools have been developed to characterize the morphometry of 3D models. The aim of this study was to apply these techniques to better understand the morphometric growth pattern of healthy children's mandibles.

Material And Methods: The study sample was composed of 480 very young children aged from 36 gestational weeks to 7 years old.