1,721,066 research outputs found
Biomeccanica del piede
No full textIl piede, segmento distale dell’arto inferiore, rappresenta l’espressione di un processo evolutivo che lo ha reso sempre più adatto allo svolgimento delle sue funzioni fondamentali di sostegno e di spostamento del corpo. Il piede si trova in un continuo stato di variabilità, sia durante gli spostamenti, tipici della deambulazione, sia durante la semplice stazione eretta.
La scarpa ideale dovrebbe permettere al piede di mantenere il più possibile la sua fisiologica funzione biomeccanica: il piede si comporta alternativamente ed in modo più o meno ritmico, come una struttura flessibile nella fase di adattamento al terreno e come una struttura rigida nella fase di distacco e spinta, divenendo l’effettore di una risposta motoria, modulata e finalizzata alla realizzazione cinetica di equilibrio e spostamento del corpo.
Questa attività del piede può essere sintetizzata mediante due movimenti complessi triplanari: la pronazione corrispondente allo stato di rilasciamento e la supinazione corrispondente allo stato di irrigidimento. Le singole articolazioni e i muscoli del piede partecipano al movimento complesso di pronazione e supinazione in modo armonico e concatenato, così da costituire nel loro insieme un’unità funzionale che può essere definita come la catena cinetica del piede. La catena cinetica del piede è una parte integrante della catena cinetica dell’arto inferiore e dell’intero corpo.
Durante la deambulazione è importante studiare come avviene l’alternanza dei due stati di rilasciamento e irrigidimento del piede: il rilasciamento del piede è necessario ai fini dell’adattamento al terreno nella fase di risposta al carico, mentre il piede deve diventare una leva rigida nel momento successivo della fase propulsiva del passo.
E’ utile analizzare non solo la catena cinetica del piede ma tutto l’assetto posturale del tronco e dell’arto inferiore, per verificare gli eventuali effetti agli altri distretti superiori, essendo la probabile causa di sovraccarichi articolari e dolore
Author Correction: 3D measurement techniques for the hindfoot alignment angle from weight-bearing CT in a clinical population
Full text linkCone-beam CT (CBCT) scans now enable accurate measurements on foot skeletal structures with
the advantage of observing these in 3D and in weight-bearing. Among the most common skeletal
deformities, the varus/valgus of the hindfoot is the most complex to be represented, and a number
of measure proposals have been published. This study aims to analyze and to compare these
measurements from CBCT scans in a real clinical population with large such deformity. Ten patients
with severe acquired adult fatfoot and indication for surgery underwent CBCT scans (Carestream,
USA) while standing on that leg, before and after surgical correction. Corresponding 3D shape of each
bone of the distal shank and hindfoot were defned (Materialise, Belgium). Six diferent techniques
from the literature were used to calculate the varus/valgus deformity, i.e. the inclination of the
hindfoot in the frontal plane of the shank. Standard clinical measurements by goniometers were taken
for comparison. According to these techniques, and starting from a careful 3D reconstruction of the
relevant foot skeletal structures, a large spectrum of measurements was found to represent the same
hindfoot alignment angle. Most of them were very diferent from the traditional clinical measures. The
assessment of the pre-operative valgus deformity and of the corresponding post-operative correction
varied considerably. CBCT fnally allows 3D assessment of foot deformities in weight-bearing.
Measurements from the diferent available techniques do not compare well, as they are based on
very diferent approaches. It is recommended to be aware of the anatomical and functional concepts
behind these techniques before clinical and surgical conclusions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Functional evaluation of bilateral subtalar arthroereisis for the correction of flexible flatfoot in children: 1-year follow-up
No full textBackground: Flexible flatfoot (FFF) is a common alteration of the foot diagnosed in the pediatric population causing pain and decreased quality of life. Surgical treatment via arthroereisis of the subtalar joint can be recommended when non-invasive options do not result in sufficient pain relief. While clinical outcome of subtalar joint arthroereisis is generally positive, no functional evaluation has thus far been reported following surgery. Research question: The aim of this study was to assess the effects of two arthroereisis implants for the correction of bilateral FFF on foot and lower limb biomechanics during gait. Methods: This is a prospective study following 13 children affected by bilateral symptomatic FFF. The patients underwent bilateral subtalar arthroereisis during the same surgery using two types of poly-L-lactide bioabsorbable implants: an expanding endo-orthotic implant, and a calcaneo-stop screw. Radiological parameters and gait analysis were performed preoperatively and at 1 year follow-up and compared to those from an age-matched normal-arched control population. Lower limb and multisegment foot kinematic analysis, along with EMG of the main ankle flexor/extensor muscles, were performed during level walking at comfortable speed. Paired non-parametric Wilcoxon signed-rank test was used to assess differences in radiological and kinematic parameters between pre-op and post-op assessments. Results: All radiological parameters, and frontal-plane orientation of the rearfoot in double-leg standing were improved at 1-year follow-up in both implant groups (e.g calcaneo-stop: pre-op = 15 ± 7 deg; post-op = 6 ± 9 deg; p < 0.01). The endo-orthotic implant group showed significantly lower pronation/supination at the ankle and midtarsal joint. Activation of the tibialis anterior muscle was more physiological after surgery in both groups. Significance: According to the present analysis, both implants appear effective in restoring physiological alignment of the rearfoot, however the endo-orthotic implant appeared more effective in restoring a more correct frontal-plane mobility of foot joints
Pedobarographic and kinematic analysis in the functional evaluation of two post-operative forefoot offloading shoes
Full text linkBackground: Forefoot offloading shoes are special orthopaedic footwear designed to protect and unload the injured part of the foot after surgery and for conservative treatments. The offloading action is often achieved by transferring plantar load to the rearfoot via rocker shoes with reduced contact area between shoe and ground. While these shoes are intended to be worn only for short periods, a compromise must be found between functionality and the risk of alterations in gait patterns at the lower limb joints. In this study, the pedobarographic, kinematic and kinetic effects of a traditional half-shoe and a double-rocker full-outsole shoe were compared to those of a comfortable shoe (control). Methods: Ten healthy female participants (28.2±10.0 years) were asked to walk in three different footwear conditions for the left/right foot: control/half-shoe, control/full-outsole, and control/control. Full gait analysis was obtained in three walking trials for each participant in each condition. Simultaneously a sensor insole system recorded plantar pressure in different foot regions. Normalized root-mean-square error, coefficient of determination, and frame-by-frame statistical analysis were used to assess differences in time-histories of kinematic and kinetic parameters between shoes. Results: The half -shoe group showed the slowest walking speed and the shortest stride length. Forefoot plantar load was significantly reduced in the half-shoe (maximum force as % of Body Weight: half-shoe=62.1; full-outsole=86.9; control=93.5; p<0.001). At the rearfoot, mean pressure was the highest in the full-outsole shoe. At the ankle, sagittal-plane kinematics in the full-outsole shoe had a pattern more similar to control. Conclusions: The half-shoe appears significantly more effective in reducing plantar load at the forefoot than a double-rocker full-outsole shoe, which is designed to reduce forefoot loading by using an insole with a thicker profile anteriorly as to maintain the foot in slight dorsiflexion. However, the half-shoe is also associated with altered gait spatio-temporal parameters, more kinematic modifications at the proximal lower limb joints and reduced propulsion in late stance
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