Tratamiento de las complicaciones vasculares tras aplicación del método de Ilizarov: Aportación de tres casos

Entre 1987 y 1991 fueron intervenidos 209 pacientes mediante el método de Ilizarov en nuestra institución. Tres de los pacientes presentaron complicaciones vasculares durante el tratamiento. Todos ellos eran adultos y habían sido tratados por pseudoartrosis de un hueso largo. La lesión vascular ocurrió en la arteria femoral superficial en un caso, la arteria poplítea en otro y la arteria tibial posterior en el último de ellos. El signo clínico del problema vascular fue la presencia de la hemorragia en el punto de salida cutánea de las agujas de Kirschner de transfixión. Se realizó exploración arteriográfica en todos los casos, pero su interpretación fue difícil debido a la presencia del fijador externo. El tratamiento de la complicación vascular fue: en el caso de la lesión de la arteria femoral fue retirado el fijador y realizado un by-pass con un injerto invertido obtenido de la vena safena; en el caso de lesión de la arteria poplítea, se realizó la misma técnica pero sin retirar el fijador. En el último caso la lesión de la arteria tibial posterior se trató mediante ligadura de la misma. En todos los casos, la evolución del tratamiento vascular fue excelente, siendo posible finalizar el tratamiento ortopédico.From 1987 to 1991, 209 patients were operated on by the Ilizarov method in our institution. Among them, 3 patients presented vascular complications during the treatment. All were adults and have been treated for long bone pseudoarthrosis. The vascular lesion ocurred at the femoral superficial artery in one case, at the popliteal artery in other case, and at the posterior tibial artery in the third case. The clinical sign of vascular damage was bleeding through the cutaneous point of the Kirschnner transfixion wires in all cases. Arteriography was done in all cases but its interpretation was very difficult because of the presence of the external fixator. In the case of femoral artery, injury the external fixator was removed and a vascular by-pass was performed with an inverted graft of the saphenous vein. The same procedure was done in the case with a popliteal artery injury but without removal of the external fixator. The case with lesion of the posterior tibial artery was treated by arterial hgature. In all cases, outcome was satisfactory, allowing completion of the orthopaedic treatment

Upper limbs cranking for post-stroke rehabilitation: A pilot study on healthy subjects

Since one of the major consequences of stroke is hemiparesis, the rehabilitation of upper limbs is necessary to improve the quality of life. Arm cranking gesture represents an alternative rehabilitation tool, especially if accompanied by a biofeedback involving and motivating patients. The aim of this pilot study was twofold: (1) to evaluate the effect of a visual and virtual biofeedback on arm cranking gesture and (2) to estimate the duration of pull and push phases of the crank cycle. Nine healthy and young subjects were involved in the test and were asked to perform the arm cranking gesture in different conditions. A stereophotogrammetric system was adopted to create a virtual, visual and real time biofeedback of cadence, to measure the real cadence of participants and to estimate push and pull phases durations. Results showed that the biofeedback helped subjects to follow an externally imposed cadence. Furthermore, the pull phase resulted to be slightly longer than the push one, although the angular amplitude of the two phases suggested they were the same

Intraseasonal Drainage Network Dynamics in a Headwater Catchment of the Italian Alps

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Intraseasonal Drainage Network Dynamics in a Headwater Catchment of the Italian Alps

In the majority of existing studies, streams are conceived as static objects that occupy predefined regions of the landscape. However, empirical observations suggest that stream networks are systematically and ubiquitously featured by significant expansion/retraction dynamics produced by hydrologic and climatic variability. This contribution presents novel empirical data about the active drainage network dynamics of a 5 km2 headwater catchment in the Italian Alps. The stream network has been extensively monitored with a biweekly temporal resolution during a field campaign conducted from July to November 2018. Our results reveal that, in spite of the wet climate typical of the study area, more than 70% of the observed river network is temporary, with a significant presence of disconnected reaches during wet periods. Available observations have been used to develop a set of simple statistical models that were able to properly reconstruct the dynamics of the active stream length as a function of antecedent precipitation. The models suggest that rainfall timing and intensity represent major controls on the stream network length, while evapotranspiration has a minor effect on the observed intraseasonal changes of drainage density. Our results also indicate the presence of multiple network expansion and retraction cycles that simultaneously operate at different time scales, in response to distinct hydrological processes. Furthermore, we found that observed spatial patterns of network dynamics and unchanneled lengths are related to the underlying heterogeneity of geological attributes. The study offers novel insights on the physical mechanisms driving stream network dynamics in low-order alpine catchments

Upper Limbs Musculoskeletal OpenSim Model: Customization and Assessment

Computational modelling is a powerful tool in biomechanical studies. Open-source software OpenSim provides different musculoskeletal models. However, existing upper body models consider only one limb, which could be a limitation in reproducing two-handed tasks. The purpose of this research was to develop a two upper limbs model that can be customized with subject’s anthropometry and muscles properties. The proposed model was composed of thorax, left and right upper limbs. Each limb presents 3 degrees of freedom (shoulder flexion-extension, elbow flexion-extension and prono-supination), 4 flexor and 3 extensor muscles. A preliminary model assessment was done. A subject was asked to execute isometric tests at three elbow angles, holding different loads, while EMG muscle activation was recorded. Simulated and experimental muscles activation were compared considering the right upper limb. Very good results were obtained without external load, whereas differences were observed when increasing the load; but, overall, model performance remained acceptable

Electrodes' Configuration Influences the Agreement between Surface EMG and B-Mode Ultrasound Detection of Motor Unit Fasciculation

Muscle fasciculations, resulting from the spontaneous activation of motor neurons, may be associated with neurological disorders, and are often assessed with intramuscular electromyography (EMG). Recently, however, both ultrasound (US) imaging and multichannel surface EMG have been shown to be more sensitive to fasciculations. In this study we combined these two techniques to compare their detection sensitivity to fasciculations occurring in different muscle regions and to investigate the effect of EMG electrodes' configuration on their agreement. Monopolar surface EMGs were collected from medial gastrocnemius and soleus with an array of 32 electrodes (10 mm Inter-Electrode Distance, IED) simultaneously with b-mode US images detected alongside either proximal, central or distal electrodes groups. Fasciculation potentials (FP) were identified from single differential EMGs with 10 mm (SD1), 20 mm (SD2) and 30 mm (SD3) IEDs, and fasciculation events (FE) from US image sequences. The number, location, and size of FEs and FPs in 10 healthy participants were analyzed. Overall, the two techniques showed similar sensitivities to muscle fasciculations. US was equally sensitive to FE occurring in the proximal and distal calf regions, while the number of FP revealed by EMG increased significantly with the IED and was larger distally, where the depth of FE decreased. The agreement between the two techniques was relatively low, with a percentage of fasciculation classified as common ranging from 22% for the smallest IED to 68% for the largest IED. The relevant number of events uniquely detected by the two techniques is discussed in terms of different spatial sensitivities of EMG and US, which suggest that a combination of US-EMG is likely to maximise the sensitivity to muscle fasciculations

Dynamic spatio-temporal patterns of metapopulation occupancy in patchy habitats

Spatio-temporal dynamics in habitat suitability and connectivity among mosaics of heterogeneous wetlands are critical for biological diversity and species persistence in aquatic patchy landscapes. Despite the recognized importance of stochastic hydroclimatic forcing in driving wetlandscape hydrological dynamics, linking such effects to emergent dynamics of metapopulation poses significant challenges. To fill this gap, we propose here a dynamic stochastic patch occupancy model (SPOM), which links parsimonious hydrological and ecological models to simulate spatio-temporal patterns in species occupancy in wetlandscapes. Our work aims to place ecological studies of patchy habitats into a proper hydrologic and climatic framework to improve the knowledge about metapopulation shifts in response to climate-driven changes in wetlandscapes. We applied the dynamic version of the SPOM (D-SPOM) framework in two wetlandscapes in the US with contrasting landscape and climate properties. Our results illustrate that explicit consideration of the temporal dimension proposed in the D-SPOM is important to interpret local- A nd landscape-scale patterns of habitat suitability and metapopulation occupancy. Our analyses show that spatio-temporal dynamics of patch suitability and accessibility, driven by the stochasticity in hydroclimatic forcing, influence metapopulation occupancy and the topological metrics of the emergent wetlandscape dispersal network. D-SPOM simulations also reveal that the extinction risk in dynamic wetlandscapes is exacerbated by extended dry periods when suitable habitat decreases, hence limiting successful patch colonization and exacerbating metapopulation extinction risks. The proposed framework is not restricted only to wetland studies but could also be applied to examine metapopulation dynamics in other types of patchy habitats subjected to stochastic external disturbances

How typhoons trigger turbidity currents in submarine canyons

Intense turbidity currents occur in the Malaylay Submarine Canyon off the northern coast of Mindoro Island in the Philippines. They start in very shallow waters at the shelf break and reach deeper waters where a gas pipeline is located. The pipeline was displaced by a turbidity current in 2006 and its rock berm damaged by another 10 years later. Here we propose that they are triggered near the mouth of the Malaylay and Baco rivers by direct sediment resuspension in the shallow shelf and transport to the canyon heads by typhoon-induced waves and currents. We show these rivers are unlikely to generate hyperpycnal flows and trigger turbidity currents by themselves. Characteristic signatures of turbidity currents, in the form of bed shear stress obtained by numerical simulations, match observed erosion/deposition and rock berm damage patterns recorded by repeat bathymetric surveys before and after typhoon Nock-ten in December 2016. Our analysis predicts a larger turbidity current triggered by typhoon Durian in 2006; and reveals the reason for the lack of any significant turbidity current associated with typhoon Melor in December 2015. Key factors to assess turbidity current initiation are typhoon proximity, strength, and synchronicity of typhoon induced waves and currents. Using data from a 66-year hindcast we estimate a ~8-year return period of typhoons with capacity to trigger large turbidity currents

Transport at basin scales: 1. Theoretical framework

The paper describes the theoretical framework for a class of general continuous models of the hydrologic response including both flow and transport of reactive solutes. The approach orders theoretical results appeared in disparate fields into a coherent theoretical framework for both hydrologic flow and transport. In this paper we focus on the Lagrangian description of the carrier hydrologic runoff and of the processes embedding catchment-scale generation and transport of matter carried by runoff. The former defines travel time distributions, while the latter defines lifetime distributions, here thought of as contact times between mobile and immobile phases. Contact times are assumed to control mass transfer in a well-mixed approximation, appropriate in cases, like in basin-scale transport phenomena, where the characteristic size of the injection areas is much larger than that of heterogeneous features. As a result, we define general mass-response functions of catchments which extend to transport of matter geomorphologic theories of the hydrologic response. A set of examples is provided to clarify the theoretical results towards a computational framework for generalized applications, described in a companion paper. © 2006 Author(s). This work is licensed under a Creative Commons License