L’effet de la prothèse totale du genou sur la cinématique 3D : vers le développement de biomarqueurs mécaniques de la douleur

La prothèse totale du genou (PTG) est une chirurgie couramment pratiquée pour traiter les patients souffrant d’arthrose sévère du genou. Bien que cette technique chirurgicale soit efficace pour diminuer la douleur, améliorer la fonction du genou et rentable d’un point de vue socio-économique, un pourcentage non négligeable de patients n’est pas satisfait suite à la chirurgie, principalement due à une douleur persistante ou due à une perception d’avoir une mauvaise fonction articulaire, sans cause identifiée. Cependant, l’impact de cette chirurgie sur la cinématique tridimensionnelle (3D) du genou demeure mal compris. Dans le but de mieux comprendre pourquoi certains patients ressentent toujours de la douleur suite à cette chirurgie, cette étude analysera, dans un premier temps, l’effet prospectif de la chirurgie sur la cinématique 3D du genou. Puis dans un second temps, comparera la cinématique 3D de sujet souffrant de douleur à celle de sujets asymptomatiques suite à la prothèse. Pour parvenir à ces deux objectifs, deux études distinctes ont été entreprises. Une première étude prospective a porté sur l’évolution de la cinématique 3D du genou d’un groupe de 19 sujets, recrutés sur la liste d’attente pour prothèse totale du genou de deux chirurgiens du CHUM, hôpital Notre-Dame, puis la cinématique a été comparée avec un groupe contrôle de 17 sujets avec des genoux sains. Une seconde étude a comparé la cinématique 3D de 20 sujets souffrant de douleur post-PTG avec 20 sujets avec des genoux asymptomatiques suite à leur chirurgie. La première étude a permis de montrer que la cinématique dans le plan frontal suite à la prothèse totale du genou était corrigée vers celle des sujets sains. Contrairement à celle mesurée dans les autres plans (sagittal et axial) qui, malgré de petites corrections, demeure différente de la cinématique des sujets sains. La seconde étude a permis d’identifier un marqueur biomécanique de la douleur chez les sujets souffrant de douleur post-PTG. Effectivement, contrairement aux sujets asymptomatiques, suite à leur chirurgie, les patients souffrants de douleur marchent avec une contracture en flexion plus importante tout au long de la phase d’appui. Les résultats de ces deux études tendent à montrer que la prothèse totale du genou modifie la cinématique 3D du genou, sans toutefois redevenir semblable à celle d’un genou normal. De plus, certains marqueurs biomécaniques peuvent être associés à de la douleur suite à la chirurgie. Une meilleure compréhension de l’impact de la PTG sur la cinématique 3D du genou permettra d’offrir de meilleurs traitements en préparation et après la chirurgie et pourrait mener à de nouveaux designs de prothèses.The total knee arthroplasty (TKA) is a common procedure in patients with severe knee osteoarthritis. This surgery has been proved to reduce pain, to improve knee function, and to be cost-effective. However, an important proportion of patients report insatisfaction, pain, and low articular function following the surgery. Moreover, even with this problem, the impact of the TKA on the tridimensional (3D) kinematics is not well understood. Therefore, two studies have been undertaken with the purpose of using the 3D kinematics to understand the post-TKA pain syndrome. During the first study, 19 subjects, recruited on a TKA waiting list of two surgeons of the CHUM, Hôpital Notre-Dame, were prospectively followed to measure the evolution of their 3D knee kinematics. A control group of 17 subjects with normal knees has also been recruited. The second study has compared 20 subjects with knee pain post-TKA with 20 subjects without pain post-TKA. The results of the first study tend to show an improvement in the frontal plan kinematics after the TKA toward the control group. However, the kinematics in the others plans still different of the control group. When the 3D kinematics of a group with pain is compared to a group without pain (second study), a biomechanical marker associated with pain was identified. The group with pain walk with a higher flexion contracture during the stance phase than the group without pain. Those results show that the total knee arthroplasty has an impact on the 3D kinematics; however, this impact is not necessarily toward the control group. Moreover, some biomechanical markers can be associated with the knee pain following the TKA. This show that we still doesn’t really understand the impact of the TKA on the kinematics, and that a better understanding of this impact could allow the surgeons to improve their care to their patients before and after the surgery

The Evolution of Reverse Total Shoulder Arthroplasty and Its Current Use in the Treatment of Proximal Humerus Fractures in the Older Population

Proximal humerus fracture (PHF) is a common injury in the older population. While the majority of these fractures are treated non-operatively, a small subset of patients may benefit from surgical treatment. However, there continues to be an ongoing debate regarding the indications and ideal surgical treatment strategy. The use of reverse total shoulder arthroplasty (RTSA) has resulted in a paradigm shift in the treatment of PHFs in the older population. Unique biomechanical principles and design features of RTSA make it a suitable treatment option for PHFs in the older population. RTSA has distinct advantages over hemiarthroplasty and internal fixation and provides good pain relief and a reliable and reproducible improvement in functional outcomes. As a result, there has been an exponential increase in the volume of RTSA in the older population in last decade. The aim of this paper is to review the current concepts, outcomes and controversies regarding the use of RTSA for the treatment of PHFs in the older population

Passive imaging of localized reflectors and interfaces in open media

International audiencePrevious experiments in open media showed the possibility of reconstructing the direct (ballistic) wave between two passive sensors from the time correlations of elastic or acoustic scattered wave fields. Here we illustrate how the passive imaging technique can also retrieve detailed features of the Green's function, beyond the ballistic wave. Two ultrasonic experiments are presented. In the first one we reconstruct the complete signature of two well-separated scatterers with a perfect distribution of distant sources. In the second experiment we image an aluminum/water interface with only a few sources. The lack of sources is compensated for by taking advantage of a multiple scattering slab

MRI endoscopy using intrinsically localized probes

Magnetic resonance imaging (MRI) is traditionally performed with fixed externally applied gradient magnetic fields and is hence intrinsically locked to the laboratory frame of reference (FoR). Here a method for high-resolution MRI that employs active, catheter-based, tiny internal probes that utilize the spatial properties of the probe itself for localization is proposed and demonstrated at 3 T. Because these properties are intrinsic to the probe, they move with it, transforming MRI from the laboratory FoR to the FoR of the device itself, analogous to an endoscope. The “MRI endoscope” can utilize loop coils and loopless antennas with modified sensitivity, in combination with adiabatic excitation by the device itself, to restrict the MRI sensitivity to a disk-shaped plane a few mm thick. Excitation with the MRI endoscope limits the eddy currents induced in the sample to an excited volume whose size is orders of magnitude below that excited by a conventional body MRI coil. Heat testing shows maximum local temperature increases of <1 °C during MRI, within regulatory guidelines. The method is demonstrated in a kiwifruit, in intact porcine and rabbit aortas, and in an atherosclerotic human iliac artery specimen, with in-plane resolution as small as 80 μm and 1.5–5 mm slice thickness