scholarly journals An Optoelectronics-Based Sensor For Measuring Multi-Axial Shear Stresses

2021 ◽  
Author(s):  
Michael McGeehan
Keyword(s):  
Shear Force ◽  
Light Emitting Diode ◽  
Color Pattern ◽  
Motion Artifacts ◽  
Force Sensors ◽  
Shear Stresses ◽  
Residual Limb ◽  
Prosthetic Socket ◽  
Axial Shear ◽  
Orthopedic Rehabilitation

Tactile shear force sensors are increasingly popular for medical applications especially for orthopedic rehabilitation such as measuring interfacial shear stresses between a residual limb and prosthetic socket to manage socket fit and residual limb tissue health, or measuring shearing between a foot sole and shoe for assessing performance in athletes. However, there are considerable challenges in implementing shear force sensors for orthopedic applications due to the requirements for noninvasiveness, light weight, low power, and robustness against motion artifacts, normal force, or electromagnetic fields. To address these challenges, this paper describes the design, fabrication, and characterization of a simple, low-cost, optoelectronic sensor that can measure multi-axial shear stresses. The sensor is based on a red, green, and blue (RGB) light-emitting diode (LED) cycling among red, green, and blue lights onto a color pattern surface. As shear strain causes a displacement between the LED and the color pattern, the relative intensities of reflected lights among the different colors change. A photodiode is used to capture the reflected light intensity at each color illumination, allowing the determination of the color pattern surface displacement, and in turn the shear, along two axes. In this paper, the efficacy of the sensor under benchtop testing conditions is reported, confirming the potential of this technology for shear monitoring at orthopedic devices such as protheses or shoes. Future efforts will focus on miniaturization and packaging of the sensors, and characterizing their performance for more medical and other types of applications.

scholarly journals A Simulation-Based Analysis of The Effects of Variable Prosthesis Stiffness On Interface Dynamics Between The Prosthetic Socket and Residual Limb

2021 ◽  
Author(s):  
Michael McGeehan
Keyword(s):  
Computational Models ◽  
External Rotation ◽  
Experimental Studies ◽  
Design Parameters ◽  
Shear Stresses ◽  
Residual Limb ◽  
Interface Dynamics ◽  
Prosthetic Socket ◽  
Subject Specific ◽  
Socket Interface

Introduction: Loading of a residual limb within a prosthetic socket can cause tissue damage such as ulceration. Computational models and simulations may be useful tools for estimating tissue loading within the socket and thus provide insights into how interventions (e.g. prosthesis designs or rehabilitation techniques) affect residual limb-socket interface dynamics. The purpose of this study was to model and simulate residual limb-socket interface dynamics and evaluate the effects of varied prosthesis stiffness on interface dynamics during gait. Methods: A spatial contact model of a residual limb-socket interface was developed and integrated into a gait model with a below-knee amputation. Gait trials were simulated for four subjects walking with low, medium, and high prosthesis stiffness settings. The effects of prosthesis stiffness on interface kinematics, normal pressure, and shear stresses were evaluated. Mean group responses and a subject-specific case study were analyzed. Results: Model-predicted outcome values were similar to those reported previously in sensor-based experiments; however, there were no discernable effects of prosthesis stiffness on interface dynamics among the group data (p>0.05). Subject-specific data showed decreased external rotation in the low stiffness trials, though high variability was present in the data. Conclusions: These methods may be useful to aid experimental studies by providing insights into the effects of varied prosthesis design parameters or gait conditions on residual limb-socket interface dynamics. Data suggest that these effects may be subject-specific.

scholarly journals Key considerations for finite element modelling of the residuum–prosthetic socket interface

2020 ◽  
pp. 030936462096778
Author(s):  
JW Steer ◽  
PR Worsley ◽  
M Browne ◽  
Alex Dickinson
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Modelling ◽  
Soft Tissues ◽  
Shear Stresses ◽  
Material Models ◽  
Element Modelling ◽  
Prosthetic Socket ◽  
Highly Nonlinear ◽  
Socket Interface

Background: Finite element modelling has long been proposed to support prosthetic socket design. However, there is minimal detail in the literature to inform practice in developing and interpreting these complex, highly nonlinear models. Objectives: To identify best practice recommendations for finite element modelling of lower limb prosthetics, considering key modelling approaches and inputs. Study design: Computational modelling. Methods: This study developed a parametric finite element model using magnetic resonance imaging data from a person with transtibial amputation. Comparative analyses were performed considering socket loading methods, socket–residuum interface parameters and soft tissue material models from the literature, to quantify their effect on the residuum’s biomechanical response to a range of parameterised socket designs. Results: These variables had a marked impact on the finite element model’s predictions for limb–socket interface pressure and soft tissue shear distribution. Conclusions: All modelling decisions should be justified biomechanically and clinically. In order to represent the prosthetic loading scenario in silico, researchers should (1) consider the effects of donning and interface friction to capture the generated soft tissue shear stresses, (2) use representative stiffness hyperelastic material models for soft tissues when using strain to predict injury and (3) interrogate models comparatively, against a clinically-used control.

scholarly journals Within-subjects Effects of Standardized Prosthetic Socket Modifications on Physical Function and Patient-Reported Outcomes

2021 ◽  
Author(s):  
William Anderst ◽  
Goeran Fiedler ◽  
Kentaro Onishi ◽  
Gina McKernan ◽  
Tom Gale ◽  
...  
Keyword(s):  
Physical Function ◽  
Patient Reported Outcomes ◽  
Design Method ◽  
Pressure Sensors ◽  
Residual Limb ◽  
Prosthetic Socket ◽  
Large Patient ◽  
Increased Risk ◽  
Patient Reported ◽  
And Function

Abstract • Background: Among the challenges of living with lower limb loss is the increased risk of long-term health problems that can be either attributed directly to the amputation surgery and/or prosthetic rehabilitation or indirectly to a disability-induced sedentary lifestyle. These problems are exacerbated by poorly fit prosthetic sockets. There is a knowledge gap regarding how the socket design affects in-socket mechanics, and how in-socket mechanics affect patient-reported comfort and function. The objectives of this study are: 1) to gain a better understanding of how in-socket mechanics of the residual limb in transfemoral amputees are related to patient-reported comfort and function, 2) to identify clinical tests that can streamline the socket design process, and 3) to evaluate the efficacy and cost of a novel, quantitatively informed socket optimization process.• Methods: Users of transfemoral prostheses will be asked to walk on a treadmill wearing their current socket plus 8 different check sockets with designed changes in different structural measurements that are likely to induce changes in residual limb motion, skin strain, and pressure distribution within the socket. Dynamic biplane radiography and pressure sensors will be used to measure in-socket residual limb mechanics. Patient-reported outcomes will also be collected after wearing each socket. The effects of in-socket mechanics on both physical function and patient-reported outcomes (aim 1) will be assessed using a generalized linear model. Partial correlation analysis will be used to examine the association between research grade measurements and readily available clinical measurements (aim 2). In order to compare the new quantitative design method to the Standard of Care, patient reported outcomes and cost will be compared between the two methods, utilizing the Wilcoxon Mann-Whitney non-parametric test (aim 3).• Discussion: Knowledge on how prosthetic socket modifications affect residual bone and skin biomechanics itself can be applied to devise future socket designs, and the methodology can be used to investigate and improve such designs, past and present. Apart from saving time and costs, this may result in better prosthetic socket fit for a large patient population, thus increasing their mobility, participation, and overall health-related quality of life. • Trial registration: clinicaltrials.gov: NCT05041998

scholarly journals Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

2018 ◽  
Vol 147 ◽  
pp. 01005
Author(s):  
Jonie Tanijaya
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Shear Force ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Web Openings ◽  
The Right ◽  
Lower Corner ◽  
T Beam

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.

Three-dimensional printing in prosthetics: Method for managing rapid limb volume change

2020 ◽  
Vol 44 (5) ◽  
pp. 355-358 ◽  
Author(s):  
Eric Nickel ◽  
Kyle Barrons ◽  
Barry Hand ◽  
Alana Cataldo ◽  
Andrew Hansen
Keyword(s):  
Service Life ◽  
Three Dimensional ◽  
Residual Limb ◽  
Volume Loss ◽  
Limb Volume ◽  
Three Dimensional Printing ◽  
Body Mass Change ◽  
Prosthetic Socket ◽  
Test Distance ◽  
Gain Loss

Background and Aim: During post-amputation recovery or rapid body mass change, residual limb volume can change quickly, requiring frequent adjustments or replacement of the socket to maintain fit. The aim of this pilot test was to evaluate the feasibility of using a three-dimensional-printed insert to extend the service life of a prosthetic socket after substantial residual limb volume loss. Technique: One research subject with a well-fitting transtibial prosthetic socket had an oversized socket fabricated to simulate substantial limb volume loss. The digital shapes of the oversized and well-fitting sockets were used to create a three-dimensional-printed insert to restore fit. Discussion: Two-minute walk test distance decreased when using the oversized socket without the insert, but not when using the socket with the insert. Socket comfort score was 8+ under all conditions. These results suggest that three-dimensional-printed inserts may be an effective method of extending the service life of prosthetic sockets when rapid limb volume loss occurs. Clinical relevance Three-dimensional (3D) printing gives prosthetists a new tool to manage large volume changes without refabricating entire sockets. Sockets can be fabricated in anticipation of volume gain/loss, using replaceable 3D-printed inserts to maintain fit and comfort.

scholarly journals Accuracy Verification of Magnetic Resonance Imaging (MRI) Technology for Lower-Limb Prosthetic Research: Utilising Animal Soft Tissue Specimen and Common Socket Casting Materials

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Mohammad Reza Safari ◽  
Philip Rowe ◽  
Arjan Buis
Keyword(s):  
Surface Area ◽  
Cross Sections ◽  
Lower Limb ◽  
Residual Limb ◽  
Cross Sectional ◽  
Prosthetic Socket ◽  
Semiautomatic Segmentation ◽  
Segmented Images ◽  
Cad Cam ◽  
Volume Measurements

Lower limb prosthetic socket shape and volume consistency can be quantified using MRI technology. Additionally, MRI images of the residual limb could be used as an input data for CAD-CAM technology and finite element studies. However, the accuracy of MRI when socket casting materials are used has to be defined. A number of six, 46 mm thick, cross-sections of an animal leg were used. Three specimens were wrapped with Plaster of Paris (POP) and the other three with commercially available silicone interface liner. Data was obtained by utilising MRI technology and then the segmented images compared to corresponding calliper measurement, photographic imaging, and water suspension techniques. The MRI measurement results were strongly correlated with actual diameter, surface area, and volume measurements. The results show that the selected scanning parameters and the semiautomatic segmentation method are adequate enough, considering the limit of clinical meaningful shape and volume fluctuation, for residual limb volume and the cross-sectional surface area measurements.

Measurement of Motion Between the Residual Limb and the Prosthetic Socket During Cycling

2012 ◽  
Vol 24 (1) ◽  
pp. 19-24 ◽  
Author(s):  
W. Lee Childers ◽  
Karen L. Perell-Gerson ◽  
Robert J. Gregor
Keyword(s):  
Residual Limb ◽  
Prosthetic Socket

Fluctuating residual limb volume accommodated with an adjustable, modular socket design: A novel case report

2016 ◽  
Vol 41 (5) ◽  
pp. 527-531 ◽  
Author(s):  
Kay Mitton ◽  
Jai Kulkarni ◽  
Kenneth William Dunn ◽  
Anthony Hoang Ung
Keyword(s):  
Case Report ◽  
Complex Regional Pain Syndrome ◽  
Patellofemoral Instability ◽  
Pain Syndrome ◽  
Successful Outcome ◽  
Residual Limb ◽  
Case Description ◽  
Limb Volume ◽  
Prosthetic Socket ◽  
Volume Fluctuations

Background: This novel case report describes the problems of prescribing a prosthetic socket in a left transfemoral amputee secondary to chronic patellofemoral instability compounded by complex regional pain syndrome. Case Description and Methods: Following the amputation, complex regional pain syndrome symptoms recurred in the residual limb, presenting mainly with oedema. Due to extreme daily volume fluctuations of the residual limb, a conventional, laminated thermoplastic socket fitting was not feasible. Findings and Outcomes: An adjustable, modular socket design was trialled. The residual limb volume fluctuations were accommodated within the socket. Amputee rehabilitation could be continued, and the rehabilitation goals were achieved. The patient was able to wear the prosthesis for 8 h daily and to walk unaided indoors and outdoors. Conclusion: An adjustable, modular socket design accommodated the daily residual limb volume fluctuations and provided a successful outcome in this case. It demonstrates the complexities of socket fitting and design with volume fluctuations. Clinical relevance Ongoing complex regional pain syndrome symptoms within the residual limb can lead to fitting difficulties in a conventional, laminated thermoplastic socket due to volume fluctuations. An adjustable, modular socket design can accommodate this and provide a successful outcome.

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