Lucile Tuchtan

Etablir le lien de causalité entre des violences physiques et le décès d’un individu est une problématique récurrente de la pratique médico-légale. Une grande partie des situations de violence ne pose pas de difficulté au médecin légiste. Toutefois, cette causalité n’est parfois que supposée sans démontrer le mécanisme lésionnel. Cette situation peut provenir de l’absence de traduction anatomique de ce mécanisme lésionnel, illustrée par des cas de décès secondaires à des impacts faciaux, observés à l’institut médico legal où seules des lésions histologiques étaient objectivées.Pour répondre à cette problématique, un premier modèle de tête a été réalisé afin d’étudier la transmission des forces au crâne à partir d’un impact mandibulaire. Nous avons observé une diminution des transmissions des efforts à la base du crâne ainsi que des contraintes de Von Mises au niveau du tronc cérébral notamment. Ce modèle a été amélioré par l’ajout d’un cou et de la moelle épinière cervicale afin d’étudier plus précisément les contraintes au niveau du tronc cérébral, lors d’impacts mandibulaires type uppercut ou antéro posterieur, des contraintes au niveau de la jonction cérébro spinale ainsi qu’une hyperextension de la moelle sont observées.Ces mécanismes lésionnels mettant en jeu des contraintes dans la zone des pédoncules cérébraux, sont en accord avec nos résultats de simulations numériques par éléments finis. Ce niveau de contrainte observé, très proche de la valeur seuil traduisant des lésions cérébrales, laisse présager de possibles lésions axonales.

Background and Clinical Significance: Traumatic brain injuries (TBI), most frequently caused by falls, represent a major source of morbidity and mortality and pose significant challenges in forensic investigations, especially when events are unwitnessed or testimonies conflict. Despite advances in imaging and autopsy, reconstructing the mechanism of head trauma often remains impossible. The objective of this study is to assess how biomechanical modeling can support forensic practitioners by narrowing the range of plausible scenarios and strengthening evidence-based interpretation in complex medico-legal contexts, without seeking to establish legal causality or certainty. Case Presentation: This case report investigates forensic biomechanics as a decision-support tool using a combined multibody and finite element (FE) modeling approach. An initial set of twenty-five scenarios, derived from witness statements and investigative data, was reconstructed to simulate potential fall- and assault-related mechanisms. Multibody simulations with the human facet model were first performed to estimate head impact velocities and orientations. These parameters were then applied to an FE head model to evaluate tissue response. Conclusions: Skull fracture patterns and intracerebral von Mises stress distributions were analyzed and systematically compared with clinical, radiological, and autopsy findings. Although simulated stress magnitudes were generally lower than injury thresholds reported in the literature, several scenarios reproduced fracture propagation and intracerebral stress patterns consistent with the documented lesions, including corpus callosum involvement. This multidisciplinary approach highlights the growing role of biomechanics in forensic investigations and forensic anthropology.

Background: Cardiac injury caused by a sharp object is a medical and surgical therapeutic challenge. Mortality risk factors have been identified but there are major discrepancies in the literature. The aim of this study was to analyse the management of victims of penetrating cardiac injuries before and after admission to hospital and the anatomical characteristics of these injuries in order to facilitate diagnosis of the most critical patients. Methods: To carry out this study, we conducted a retrospective analytical study with epidemiological data on victims of penetrating cardiac injuries. We included two types of patients, with those who underwent autopsy in our institution after death from sharp injury to the heart or great vessels and those who survived with treatment in the emergency department or intensive care unit between January 2015 and February 2022. Results: We included 30 autopsied patients and 12 survivors aged between 18 and 73 years. Higher mortality was associated with prehospital or in-hospital cardiorespiratory arrest (OR = 4, CI [1.71–9.35]), preoperative mechanical ventilation (OR = 10, CI [1.53–65.41]), preoperative catecholamines (OR = 7, CI [1.12–6.29]), preoperative and perioperative adrenaline (OR = 13, CI [1.98–85.46] and [1.98–85.46]), penetrating cardiac injury (OR = 14, CI [2.10–93.22]), multiple cardiac injuries (OR = 1.5, CI [1.05–2.22]) and an Organ Injury Scaling of the American Association for the Surgery of Trauma (AAST-OIS) score of 5 (OR = 2.9, CI [1.04–8.54]; p = 0.0329) with an AUC-ROC curve value of 0.708 (CI [0.543–0.841]). Conclusions: This study identified risk mortality factors in penetrating cardiac injury patients. These findings can help improve the diagnosis and management of these patients. The AAST-OIS score may be a good tool to diagnose critical patients.