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Development of a gait analysis driven finite element model of the diabetic foot
Full text linkDiabetic foot is an invalidating complication of diabetes mellitus, a chronic disease increasingly frequently encountered in the aging population. The global prevalence of diabetes is predicted to double by the year 2030 from 2.8% to 4.4%. The prevalence of foot ulceration among patients with diabetes mellitus ranges from 1.3% to 4.8%.
Several studies have highlighted that biomechanical factors play a crucial role in the aetiology, treatment and prevention of diabetic foot ulcers. Recent literature on the diabetic foot indicates that mechanical stresses, high plantar pressures or/and high tangential stresses, acting within the soft tissues of the foot can contribute to the formation of neuropathic ulcers. While it is important to study the in-vivo diabetic foot-to-floor interactions during gait, models for simulations of deformations and stresses in the diabetic plantar pad are required to predict high risk areas or to investigate the performance of different insoles design for optimal pressure relief.
The finite elements (FE) models allow taking into account the critical aspects of the diabetic foot, namely the movement, the morphology, the tissue properties and the loads.
Several 2-dimensional (2D) and 3-dimensional (3D) foot models were developed recently to study the biomechanical behavior of the human foot and ankle. However, to the author knowledge, a geometrically detailed and subject specific 3D FE model of the diabetic neuropathic foot and ankle has not been reported. Furthermore 2D and 3D state-of-the-art FE foot models are rarely combined with subject specific gait analysis data both in term of ground reaction forces and kinematics as input parameters and plantar pressure for validation purposes.
The purpose of the study herein presented was to simulate the biomechanical behavior of both an healthy and a diabetic neuropathic foot in order to predict the area characterized by excessive stresses on the plantar surface. To achieve this, it has been developed an FE model of the foot by means of applying the loading and boundary conditions given by subject-specific integrated and synchronized kinematic-kinetic data acquired during gait analysis trials to a subject specific FE model (geometry was obtained through subject specific magnetic resonance images - MRI). Thus, an integrated kinematic-kinetic protocol for gait analysis which evaluates 3D kinematics and kinetics of foot subsegments together with two comprehensive FE models of an healthy and a diabetic neuropathic foot and ankle were described herein.
In order to establish the feasibility of the former approach, a 2D FE model of the hindfoot was first developed, taking into account the bone and plantar pad geometry, the soft tissues material properties, the kinematics and the kinetics of both an healthy and a diabetic neuropathic foot acquired during three different phases of the stance phase of gait. Once demonstrated the advantage of such an approach in developing 2D FE foot models, 3D FE models of the whole foot of the same subjects were developed and the simulations were run in several phases of the stance phase of gait
The validation of the FE simulations were assessed by means of comparison between the simulated plantar pressure and the subject-specific experimental ones acquired during gait with respect to different phases of the stance phase of gait.
A secondary aim of the study was to drive the healthy and the diabetic neuropathic FE foot models with the gait analysis data respectively of 10 healthy and 10 diabetic neuropathic subjects, in order to verify the possibility of extending the results of the subject specific FE model to a wider population. The validity of this approach was also established by comparison between the simulated plantar pressures and the subject-specific experimental ones acquired during gait with respect to different phases of the stance phase of gait. Comparison was also made between the errors evaluated when the FE models simulations was run with the subject specific geometry (obtained from MRI data) and the errors estimated when the FE simulations were run with the data of the 20 subjectsIl diabete mellito è una malattia cronica sempre più frequente. Fra le complicanze ad esso associate vi è il cosiddetto “piede diabetico”. L’incidenza del diabete a livello mondiale è destinata a raddoppiare entro il 2030 passando dal 2.8% al 4.4% della popolazione ed il numero di pazienti affetti da diabete mellito che sviluppano ulcera podalica oscilla tra l’1.3% ed il 4.8%.
Numerosi studi hanno evidenziato come i fattori biomeccanici giochino un ruolo fondamentale nell’eziologia, nel trattamento e nella prevenzione delle ulcere del piede diabetico. La letteratura recente sul piede diabetico indica che le sollecitazioni meccaniche, ossia le elevate pressioni plantari e/o gli elevati sforzi tangenziali, che agiscono all’interno dei tessuti molli del piede possono contribuire alla formazione di ulcere. È quindi importante studiare le interazioni piede-suolo durante il cammino nei pazienti diabetici, ma si rendono anche necessari dei modelli per la simulazione di sollecitazioni e deformazioni nel tessuto plantare del piede diabetico che permettano di predire le aree ad alto rischio di ulcerazione o di valutare l’efficacia di ortesi plantari nel ridistribuire in modo ottimale le pressioni plantari.
I modelli agli elementi finiti consentono di tenere conto degli aspetti critici del piede diabetico, vale a dire il movimento, la morfologia, le proprietà dei tessuti e le sollecitazioni meccaniche.
Di recente sono stati sviluppati diversi modelli bidimensionali (2D) e tridimensionali (3D) del piede con lo scopo di studiare il comportamento biomeccanico di piede e caviglia. Tuttavia, per quanto appurato dall’autore, in letteratura non è stato riportato un modello 3D agli elementi finiti del piede diabetico neuropatico con geometria dettagliata e specifica di un soggetto. Inoltre, i modelli 2D e 3D agli elementi finiti del piede presenti in letteratura sono stati raramente combinati con i dati del cammino specifici dei soggetti, sia in termini di forze di reazione al suolo e cinematica (come parametri di input) che in termini di pressioni plantari per la validazione.
L’obiettivo dello studio qui presentato è stato quello di simulare il comportamento biomeccanico sia del piede di un soggetto sano che del piede di un soggetto diabetico neuropatico per prevedere l'area della superficie plantare caratterizzata da eccessive sollecitazioni. A tal scopo, sono stati sviluppati due modelli agli elementi finiti di piede e caviglia, utilizzando le geometrie specifiche dei piedi dei due soggetti (uno sano ed uno diabetico neuropatico) ottenute attraverso immagini di risonanza magnetica (MRI). Quindi sono state effettuate delle simulazioni mediante l'applicazione di carichi e di condizioni al contorno, ottenuti da dati di cinematica e cinetica, integrati e sincronizzati, acquisiti durante il cammino, specifici dei due soggetti sui rispettivi modelli agli elementi finiti. Pertanto in questa tesi sono stati descritti un protocollo integrato di cinematica-cinetica per l'analisi del cammino che permette di valutare la cinematica e la cinetica 3D dei sottosegmenti del piede e due modelli completi agli elementi finiti di un piede sano e di un piede diabetico neuropatico.
Per stabilire la fattibilità di tale approccio, sono stati inizialmente sviluppati due modelli 2D agli elementi finiti del retropiede di un soggetto sano e di un soggetto diabetico neuropatico, tenendo conto della geometria ossea e del cuscinetto plantare, delle proprietà dei materiali dei tessuti molli, della cinematica e della cinetica. Questi ultimi sono stati acquisiti durante tre istanti della fase di appoggio del ciclo del passo. Una volta dimostrato il vantaggio di un simile approccio nello sviluppo di modelli 2D agli elementi finiti del piede, sono stati sviluppati i modelli 3D agli elementi finiti del piede intero degli stessi soggetti e sono state eseguite le simulazioni in vari istanti della fase di appoggio.
La validazione delle simulazioni è stata effettuata attraverso il confronto tra le pressioni plantari simulate e quelle acquisite sperimentalmente durante il cammino degli stessi soggetti, nei corrispondenti istanti della fase di appoggio.
Un secondo scopo dello studio qui presentato è stato quello di effettuare simulazioni del modello del piede del soggetto sano e di quello del soggetto neuropatico con dati di analisi del cammino rispettivamente di 10 soggetti sani e 10 diabetici neuropatici, al fine di verificare la possibilità di estendere i risultati dei modelli specifici dei due soggetti ad una popolazione più ampia. La validità di questo approccio è stata valutata tramite il confronto tra le pressioni plantari simulate e quelle sperimentali specifiche di ogni soggetto, acquisite durante il cammino. Inoltre gli errori delle simulazioni eseguite con i dati dei 20 soggetti sono stati confrontati con gli errori effettuati quando le simulazioni dei modelli avevano previsto l’utilizzo di dati di cammino specifici dei due soggetti la cui geometria podalica era stata ottenuta da MR
A multi-scale framework for the prevention of plantar ulcers in diabetic subjects: a multidisciplinary approach combining gait analysis, musculkoskeletal and finite element foot modelling.
Full text linkThis study aims to evaluate the accuracy of a multiscale workflow applicable in clinical practice aiming to prevent ulceration by detecting excessive external and internal stresses preceding overloading and breakdown in diabetic subjects
PREDICTING DIABETIC SUBJECTS AT RISK FOR PLANTAR ULCERS USING HIERARCHICAL CLUSTER ANALYSIS.
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Different foot kinematics, kinetics and plantar pressure patterns within the gait of diabetic subjects: cluster analysis
No full textCould foot kinematics be used to predict the distribution of vertical force in multisegment foot models?
No full text3D finite element model of the diabetic neuropathic foot: A gait analysis driven approach
No full textDiabetic foot is an invalidating complication of diabetes that can lead to foot ulcers. Three-dimensional (3D) finite element analysis (FEA) allows characterizing the loads developed in the different anatomical structures of the foot in dynamic conditions. The aim of this study was to develop a subject specific 3D foot FE model (FEM) of a diabetic neuropathic (DNS) and a healthy (HS) subject, whose subject specificity can be found in term of foot geometry and boundary conditions. Kinematics, kinetics and plantar pressure (PP) data were extracted from the gait analysis trials of the two subjects with this purpose. The FEM were developed segmenting bones, cartilage and skin from MRI and drawing a horizontal plate as ground support. Materials properties were adopted from previous literature. FE simulations were run with the kinematics and kinetics data of four different phases of the stance phase of gait (heel strike, loading response, midstance and push off). FEMs were then driven by group gait data of 10 neuropathic and 10 healthy subjects. Model validation focused on agreement between FEM-simulated and experimental PP.The peak values and the total distribution of the pressures were compared for this purpose. Results showed that the models were less robust when driven from group data and underestimated the PP in each foot subarea. In particular in the case of the neuropathic subject[U+05F3]s model the mean errors between experimental and simulated data were around the 20% of the peak values. This knowledge is crucial in understanding the aetiology of diabetic foo
Subject-specific modelling of the foot integrating finite element modelling, gait analysis and opensim: proof of concept in diabetic neuropathic subjects
No full textEffects of a proprioceptive focal stimulation (Equistasi®) on reducing the biomechanical risk factors associated with ACL injury in female footballers
Full text linkIntroductionFootball presents a high rate of lower limb injuries and high incidence of Anterior Cruciate Ligament (ACL) rupture, especially in women. Due to this there is the need to optimize current prevention programs. This study aims to verify the possibility to reduce the biomechanical risk factors associated with ACL injury, through the application of proprioceptive stimulation by means of the Equistasi & REG; device. MethodsTen elite female footballers were enrolled and received the device for 4 weeks (5 days/week, 1h/day). Athletes were assessed directly on-field at four time points: T0 and T1 (evaluation without and with the device), T2 (after 2 weeks), T4 (after 4 weeks) while performing two different tasks: Romberg Test, and four sidestep cutting maneuvers bilaterally. Seven video cameras synchronized with a plantar pressure system were used, thirty double colored tapes were applied on anatomical landmarks, and three dimensional coordinates reconstructed. Vertical ground reaction forces and center of pressure data were extracted from the plantar pressure insoles. Hip, knee, and ankle flexion-extension angles and moments were computed as well as abd-adduction joint torques. From the Romberg Test both center of pressure descriptive variables and frequency analysis parameters were extracted. Each variable was compared among the different time frames, T1, T2 and T4, through Friedman Test for non-parametric repeated measures (p<0.05); Wilcoxon Signed Rank Test was used for comparing variables between T0 and T1 (p<0.05) and across the different time frames as follows: T1-T2, T2-T4 and T1-T4. ResultsStatistically significant differences in both posturographic and biomechanical variables between the assessment at T0 and T1 were detected. Reduced hip and knee abduction torques were revealed in association with reduced both ground reaction forces and ankle dorsiflexion torque from T1 up to T4. DiscussionThe proprioceptive stimuli showed to have the potential to improve cutting biomechanics mainly with respect to the ligament and quadriceps dominance theories. Results of the present study, even if preliminary and on a small sample size, could be considered promising towards the inclusion of proprioceptive training in injury prevention programs
The Effect of Custom Insoles on Muscle Activity in Diabetic Individuals with Neuropathy
Full text linkFoot ulcers are amongst the most serious complications of diabetes. Guidelines recommend that people with diabetes wear appropriate footwear or insoles to reduce repetitive stresses. Excessive plantar pressure has been recognized as the major risk factor for plantar ulcers in diabetic individuals; custom insoles are indicated as the gold standard treatment to unload the foot structure. The aim of this study was to investigate the effect of custom insoles on biomechanical and neuromuscular functions in diabetic neuropathic individuals. Ten diabetic subjects walked with and without custom insoles at their preferred speed; ten controls were assessed for comparison. Data were captured through seven video cameras, plantar pressure insoles, and surface electromyography. The electrical activity of Rectus Femoris, Tibialis Anterior, Medius Gluteus and Gastrocnemius Lateralis were acquired bilaterally. The plantar pressure and surface electromyographic variables were determined, while videos were used to detect the gait cycle. The following comparisons were made across the variables through the non-parametric SPM1D test (p < 0.05): condition with vs. without insoles vs. controls. Custom insoles provided a reduction in plantar pressure through contact surface redistribution in association with a reduced electromyographic activity. Our results suggest optimizing the prevention approach by including personalized foot and ankle exercises
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