Chapter Towards a Realistic and Self-Contained Biomechanical Model of the Hand

Computer modelling & simulatio

Defective HNF4alpha-dependent gene expression as a driver of hepatocellular failure in alcoholic hepatitis

Alcoholic hepatitis (AH) is a life-threatening condition characterized by profound hepatocellular dysfunction for which targeted treatments are urgently needed. Identification of molecular drivers is hampered by the lack of suitable animal models. By performing RNA sequencing in livers from patients with different phenotypes of alcohol-related liver disease (ALD), we show that development of AH is characterized by defective activity of liver-enriched transcription factors (LETFs). TGFβ1 is a key upstream transcriptome regulator in AH and induces the use of HNF4α P2 promoter in hepatocytes, which results in defective metabolic and synthetic functions. Gene polymorphisms in LETFs including HNF4α are not associated with the development of AH. In contrast, epigenetic studies show that AH livers have profound changes in DNA methylation state and chromatin remodeling, affecting HNF4α-dependent gene expression. We conclude that targeting TGFβ1 and epigenetic drivers that modulate HNF4α-dependent gene expression could be beneficial to improve hepatocellular function in patients with AH

Model biomecànic de la mà orientat al disseny d'eines manuals

En aquesta tesi es presenta un model biomecànic de la mà orientat al disseny d'eines manuals.S'ha comprovat que una correcta adaptació del disseny de l'eina al treballador i a la tasca a realitzar (disseny ergonòmic) suposa una millora dels processos de producció i una reducció de les baixes laborals derivades de l'ús de les eines, i per tant un benefici per a la salut dels treballadors i per a la millora de les condicions de treball.En l'actualitat l'avaluació i el disseny ergonòmic d'eines manuals es realitza únicament en base a una sèrie de recomanacions experimentals de vegades poc realistes o amb una avaluació pràctica insuficient.En aquest sentit, es proposa com a objectiu d'aquesta tesi el desenvolupament d'un model biomecànic de la mà amb la finalitat última d'ajudar en el procés de disseny d'eines manuals, des del punt de vista ergonòmic.Després d'analitzar els models biomecànics existents a la literatura, i d'acord amb l'anatomia funcional de la mà i l'objectiu perseguit, s'ha desenvolupat un model biomecànic de la mà escalable que permet estimar la distribució d'esforços musculars durant la realització tant d'agarrades estàtiques com dinàmiques. El model permet, així mateix, predir màximes forces de prensió per als distints tipus d'agarrada. L'escalabilitat del model permet analitzar distints percentils i grups de població.El model biomecànic desenvolupat ha estat convenientment validat quant a la predicció de màximes forces d'agarrada i a l'estimació d'esforços musculars, la qual cosa permet assegurar la bondat de les aproximacions considerades durant el procés del seu desenvolupament d'acord amb els objectius perseguits.El model ha estat utilitzat amb una sèrie d'aplicacions senzilles orientades a investigar les seues possibilitats i limitacions. En particular el model pot utilitzar-se per estudiar l'espai disponible d'agarrada per a distints grups de població, per estimar màximes forces d'agarrada, pot ajudar a triar la forma d'agarrada més idònia i per tant a definir la forma i zona d'agarrada, permet comparar la qualitat de dos dissenys distints, i pot emprar-se per generar noves recomanacions de disseny.Així mateix es presenta una classificació sistemàtica d'agarrades desenvolupada com pas previ a l'estudi i aplicació del model a l'agarrada d'eines manuals, així com una tècnica fotogramètrica desenvolupada per mesurar la postura sense entorpir el comportament normal dels subjectes en situacions reals d'ús de les eines

Model biomecànic de la mà orientat al disseny d'eines manuals

En aquesta tesi es presenta un model biomecànic de la mà orientat al disseny d'eines manuals.S'ha comprovat que una correcta adaptació del disseny de l'eina al treballador i a la tasca a realitzar (disseny ergonòmic) suposa una millora dels processos de producció i una reducció de les baixes laborals derivades de l'ús de les eines, i per tant un benefici per a la salut dels treballadors i per a la millora de les condicions de treball.En l'actualitat l'avaluació i el disseny ergonòmic d'eines manuals es realitza únicament en base a una sèrie de recomanacions experimentals de vegades poc realistes o amb una avaluació pràctica insuficient.En aquest sentit, es proposa com a objectiu d'aquesta tesi el desenvolupament d'un model biomecànic de la mà amb la finalitat última d'ajudar en el procés de disseny d'eines manuals, des del punt de vista ergonòmic.Després d'analitzar els models biomecànics existents a la literatura, i d'acord amb l'anatomia funcional de la mà i l'objectiu perseguit, s'ha desenvolupat un model biomecànic de la mà escalable que permet estimar la distribució d'esforços musculars durant la realització tant d'agarrades estàtiques com dinàmiques. El model permet, així mateix, predir màximes forces de prensió per als distints tipus d'agarrada. L'escalabilitat del model permet analitzar distints percentils i grups de població.El model biomecànic desenvolupat ha estat convenientment validat quant a la predicció de màximes forces d'agarrada i a l'estimació d'esforços musculars, la qual cosa permet assegurar la bondat de les aproximacions considerades durant el procés del seu desenvolupament d'acord amb els objectius perseguits.El model ha estat utilitzat amb una sèrie d'aplicacions senzilles orientades a investigar les seues possibilitats i limitacions. En particular el model pot utilitzar-se per estudiar l'espai disponible d'agarrada per a distints grups de població, per estimar màximes forces d'agarrada, pot ajudar a triar la forma d'agarrada més idònia i per tant a definir la forma i zona d'agarrada, permet comparar la qualitat de dos dissenys distints, i pot emprar-se per generar noves recomanacions de disseny.Així mateix es presenta una classificació sistemàtica d'agarrades desenvolupada com pas previ a l'estudi i aplicació del model a l'agarrada d'eines manuals, així com una tècnica fotogramètrica desenvolupada per mesurar la postura sense entorpir el comportament normal dels subjectes en situacions reals d'ús de les eines

Problems Using Data Gloves with Strain Gauges to Measure Distal Interphalangeal Joints’ Kinematics

Data gloves with strain gauges are a widely used technology to record hand kinematics. Several researchers have experienced problems when using data glove models to record distal interphalangeal (DIP) joints, mainly in relation to bad glove fitting. The aim of this work is to report the problems that arise when using one of these gloves (CyberGlove) and to determine an appropriate hand size to avoid these problems. First, static controlled postures of DIP joints and dynamic recordings while closing/opening the fist were taken using the data gloves on participants with different hand sizes, in order to establish the minimum hand length that does not pose recording problems. The minimum obtained hand length that allowed proper recording was 184 mm. Then, validation was performed, which consisted of recording the functional range of motion of the DIP joints in a sample of eight healthy participants with hand lengths longer than the minimum obtained one. These results were then compared to the results found in the literature. Although the glove fit properly, some problems remained: difficulty to record small flexion angles or a diminished touch sensitivity. Its usability would improve if two or three different glove sizes were commercially available

Foot sole contact forces vs. ground contact forces to obtain foot joint moments for in-shoe gait-A preliminary study

In-shoe models are required to extend the clinical application of current multisegment kinetic models of the bare foot to study the effect of foot orthoses. Work to date has only addressed marker placement for reliable kinematic analyses. The purpose of this study is to address the difficulties of recording contact forces with available sensors. Ten participants walked 5 times wearing two different types of footwear by stepping on a pressure platform (ground contact forces) while wearing in-shoe pressure sensors (foot sole contact forces). Pressure data were segmented by considering contact cells' anteroposterior location, and were used to compute 3D moments at foot joints. The mean values and 95% confidence intervals were plotted for each device per shoe condition. The peak values and times of forces and moments were computed per participant and trial under each condition, and were compared using mixed-effect tests. Test-retest reliability was analyzed by means of intraclass correlation coefficients. The curve profiles from both devices were similar, with higher joint moments for the instrumented insoles at the metatarsophalangeal joint (~26%), which were lower at the ankle (~8%) and midtarsal (~15%) joints, although the differences were nonsignificant. Not considering frictional forces resulted in ~20% lower peaks at the ankle moments compared to previous studies, which employed force plates. The device affected both shoe conditions in the same way, which suggests the interchangeability of measuring joint moments with one or the other device. This hypothesis was reinforced by the intraclass correlation coefficients, which were higher for the peak values, although only moderate-to-good. In short, both considered alternatives have drawbacks. Only the instrumented in-soles provided direct information about foot contact forces, but it was incomplete (evidenced by the difference in ankle moments between devices). However, recording ground reaction forces offers the advantage of enabling the consideration of contact friction forces (using force plates in series, or combining a pressure platform and a force plate to estimate friction forces and torque), which are less invasive than instrumented insoles (which may affect subjects' gait)

Evaluation of Human Prehension Using Grasp Quality Measures

One of the main features of the human hand is its grasping ability. Robot grasping has been studied for years and different quality measures have been proposed to evaluate the stability and manipulability of grasps. Although the human hand is obviously more complex than robot hands, the methods used in robotics might be adopted to study the human grasp. The purpose of this work is to propose a set of measures that allow the evaluation of different aspects of the human grasp. The most common robotic grasp quality measures have been adapted to the evaluation of the human hand and a new quality measure  ‐ the fatigue index  ‐  is proposed in order to incorporate the biomechanical aspect into the evaluation. The minimum set of indices that allows the evaluation of the different aspects of the grasp is obtained from the analysis of a human prehension experiment

Electromyography and kinematics data of the hand in activities of daily living with special interest for ergonomics

Abstract This work presents a dataset of human hand kinematics and forearm muscle activation collected during the performance of a wide variety of activities of daily living (ADLs), with tagged characteristics of products and tasks. A total of 26 participants performed 161 ADLs selected to be representative of common elementary tasks, grasp types, product orientations and performance heights. 105 products were used, being varied regarding shape, dimensions, weight and type (common products and assistive devices). The data were recorded using CyberGlove instrumented gloves on both hands measuring 18 degrees of freedom on each and seven surface EMG sensors per arm recording muscle activity. Data of more than 4100 ADLs is presented in this dataset as MATLAB structures with full continuous recordings, which may be used in applications such as machine learning or to characterize healthy human hand behaviour. The dataset is accompanied with a custom data visualization application (ERGOMOVMUS) as a tool for ergonomics applications, allowing visualization and calculation of aggregated data from specific task, product and/or participants’ characteristics

Impact of hand osteoarthritis in women on maximal forces in six different grasp types

Abstract This work aims to: (1) Provide maximal hand force data on six different grasp types for healthy subjects; (2) detect grasp types with maximal force significantly affected by hand osteoarthritis (HOA) in women; (3) look for predictors to detect HOA from the maximal forces using discriminant analyses. Thirty-three healthy subjects (37 ± 17 years, 17 women, 16 men) and 30 HOA patients (72 ± 9 years, all women) participated in the experiment. Participants were asked to exert their maximal force while performing six different grasp types 3 times. Two MANOVAs were conducted to detect if force depended on gender in healthy participants and if force significantly diminished in women with HOA. Finally, a linear discriminant analysis for detecting HOA was performed using forces of the grasp types that were significantly affected by HOA. Gender-disaggregated statistics are provided for healthy participants. Significant differences are obtained for all grasp types per gender. The women with HOA exerted significantly lower force values (p < 0.001) for all the grasp types than healthy ones. The discriminant analysis revealed that oblique grasp was the most significant one for detecting HOA. A discrimination equation was obtained with a specificity of 88.2% and a sensitivity of 83.3%. This work provides grip force data on six grasp types for healthy participants and for women with HOA. HOA women present reduced strength in all grasps due to pathology. Three of these grasps are a novelty. Oblique grasp strength may suffice to discriminate a patient with HOA, which might help non-invasive HOA detection