Managing periprosthetic fractures: perspectives on periprosthetic pelvic fractures

Periacetabular periprosthetic fractures are rare but potentially disastrous for the longevity of the adjacent implants, leading to multiple revision surgeries. It is of paramount importance to identify and treat intraoperative fractures, which will lead to satisfactory results. Postoperative fractures may be managed operatively or nonoperatively depending on the patient's pain and function, the fracture pattern, and the stability of the acetabular component

Virtual reduction of complex fractures of the pelvis using the first patient-specific biomechanical simulation

The aim of this work was to develop and validate a new pre-operative planning in acetabular surgery based on a patient-specific biomechal model. During the first part of this work we brought enhancement in each step of the planning process for acetabular fracture surgery. The first step was to generate 3D models of several acetabular fracture patterns using semi-automatic segmentation methods. In the same time, we showed that the segmented fragments bone could be usefull to correctly classify acetabular fracture by unexperimented residents. The second step was to generate a patient-specific model, in a very simple way, that could be used in clinical practice by surgeons. A literature review of acetabular planning models was performed to identify that a new paradigm was required because of the limitations of the existing models. Once the objectives of patient-specific modelling was identified, a literature review of hips models was performed to record biomechanical properties of the elements that we had to modelize. A compromise between simplicity and realistic behaviour was found to generate patient-specifics biomechanical models, in a limited time, that could be used in clinical practice. Clinical studies on 14 operated cases, then 29 operated cases and finally 39 operated cases, were performed to validate retrospectively the simulations. The results were quite promising. Only open-source softwares with their own weaknesses were used because validity and feasability of the procedure was required before bigger investissment. The proof of concept was done. A prospective clinical study has shown the efficiency of the patient-specific biomechanical simulation and its feasibility in a daily clinical practice. This work opens a door for new approaches in surgical planning and patient-specific modelling.L’objectif de cette thèse est de développer et valider une nouvelle méthode de planification pré-opératoire en chirurgie traumatique de l’acetabulum reposant sur un modèle biomécanique patient-spécifique. La première partie de ce travail a consisté en l’élaboration et l’amélioration progressive de ce nouvel outil de planification. La première étape était de générer des modèles tri-dimensionnels de plusieurs fractures acétabulaires à l’aide d’une méthode de segmentation semi-automatique. Dans le même temps, nous avons démontré que les fragments osseux segmentés pouvaient être utile pour classer correctement les fractures acétabulaires par des internes non expérimentés. La seconde étape était de générer un modèle biomécanique patient-spécifique, le plus simplement possible pour pouvoir être compatible avec une pratique clinique régulière. Une revue de la littérature à propos des différentes méthodes de planifications péri-opératoire en traumatologie de l’acetabulum a été réalisée afin d’identifier qu’un nouveau paradigme était nécessaire du fait des limites des méthodes existantes. Une fois les objectifs d’une modélisation biomécanique patient-spécifique définis, une revue de la littérature des différents modèles biomécanique de la hanche a été réalisée pour définir les propriétés biomécaniques des différents éléments à modéliser. Un compromis entre simplicité et comportement réaliste du modèle a été trouvé pour générer un modèle biomécanique patient-spécifique, dans un temps limité, compatible avec une utilisation courante en pratique clinique. Des études cliniques portant sur 14 cas de fractures acétabulaires opérées, puis 29 et finalement 39 cas ont été réalisées pour valider rétrospectivement les simulations biomécaniques. Les résultats montraient une parfaite adéquation avec la réalité. Seuls des logiciels en libre accès, avec leurs faiblesses, étaient utilisés car la fiabilité et la validité de la simulation étaient nécessaires avant d’envisager plus d’investissements. La preuve de concept était donnée. Enfin, une étude clinique prospective a démontré l’efficacité de la simulation biomécanique patient-spécifique et sa faisabilité en pratique clinique quotidienne. Ce travail ouvre la porte à de nouvelles approches en matière de planification chirurgicale et de modélisation patient-spécifique

Aide à la classification des fractures du cotyle par segmentation des fragments osseux

International audienceThe classification of acetabular fractures proposed by Letournel and Judet in 1961 is currently the most widely used system although its complexity and a wide variation in the interpretation. Development of CT scans with 2D then 3D reconstructions allow a better comprehension of fracture patterns. We thought that the exopelvic and endopelvic views of a 3D model reconstruction of acetabular fracture which separates each bone fragments by semi-automatic segmentation are sufficient to get a correct classification according to Letournel descriptions

Planning acetabular fracture reduction using patient-specific multibody simulation of the hip

International audienceAcetabular fractures are a challenge in orthopedic surgery. Computer-aided solutions were proposed to segment bone fragments, simulate the fracture reduction or design the osteosynthesis fixation plates. This paper addresses the simulation part, which is usually carried out by freely moving bone fragments with six degrees of freedom to reproduce the pre-fracture state. Instead we propose a different paradigm, closer to actual surgeon's requirements: to simulate the surgical procedure itself rather than the desired result. A simple, patient-specific, biomechanical multibody model is proposed, integrating the main ligaments and muscles of the hip joint while accounting for contacts between bone fragments. Main surgical tools and actions can be simulated, such as clamps, Schanz screws or traction of the femur. Simulations are computed interactively, which enables clinicians to evaluate different strategies for an optimal surgical planning. Six retrospective cases were studied, with simple and complex fracture patterns. After interactively building the models from preoperative CT, gestures from the surgical reports were reproduced. Results of the simulations could then be compared with postoperative CT data. A qualitative study shows the model behavior is excellent and the simulated reductions fit the observed data. A more quantitative analysis is currently being completed. Two cases are particularly significant, for which the surgical reduction actually failed. Simulations show it was indeed not possible to reduce these fractures with the chosen approach. Had our simulator being used, a better planning may have avoided a second surgery to these patients

Chirurgie assistée par ordinateur dans les fractures de l’acétabulum : réduction virtuelle des fractures de l’acétabulum utilisant le premier simulateur biomécanique patient-spécifique

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Virtual fracture reduction of the acetabulum using a rigid body biomechanical model

International audienceAbout computer-assisted surgery in acetabular fractures, several preoperative planning tools have been proposed to simulate the desired reduction based on geometrical constraints. The main contribution of this work is an intuitive simulation of the surgical procedure itself, to evaluate different strategies until thebest reduction is achieved

Computer assisted surgery in preoperative planning of acetabular fracture surgery: state of the art

International audienceThe development of imaging modalities and computer technology provides a new approach in acetabular surgery. Areas covered: This review describes the role of computer-assisted surgery (CAS) in understanding of the fracture patterns, in the virtual preoperative planning of the surgery and in the use of custom-made plates in acetabular fractures with or without 3D printing technologies. A Pubmed internet research of the English literature of the last 20 years was carried out about studies concerning computer-assisted surgery in acetabular fractures. The several steps for CAS in acetabular fracture surgery are presented and commented by the main author regarding to his personal experience. Expert commentary: Computer-assisted surgery in acetabular fractures is still initial experiences with promising results. Patient-specific biomechanical models considering soft tissues should be developed to allow a more realistic planning

Towards a learning-based CT segmentation of acetabular fractures

International audienceFractures of the acetabulum, the cavity of the hip that hosts the femoral head, are complex to understand, plan, and surgically reduce. Segmenting bone fragments in CT scans is fundamental for assisting surgeons in their therapeutically process, and can benefit from recent learning-based advances. In this paper, we extended a learning-based network for the semantic segmentation of 6 pelvic bones: left and right hip, left and right femur, sacrum, and lumbar spine. This semantic segmentation is then process by a surgeon to separate fracture fragments, similarly to an existing baseline process. Results on 6 fracture cases show a qualitative improvement of the final fragment segmentation quality. Mostly, the segmentation time is statistically significantly reduced from 94 min to 18 min, in mean, which is a promising step towards using such learning-based method in preoperative clinical routine