Technique modifications for a suction suspension version of the Northwestern University Flexible Sub-Ischial Vacuum socket: The Northwestern University Flexible Sub-Ischial Suction socket

2018 ◽  
Vol 43 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Ryan Caldwell ◽  
Stefania Fatone
Keyword(s):  
Relative Motion ◽  
Clinical Relevance ◽  
Technical Note ◽  
Residual Limb ◽  
Transfemoral Amputation ◽  
Prosthetic Socket ◽  
Northwestern University

Background and Aim: Development of a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket would expand application of sub-ischial sockets to a larger proportion of persons with transfemoral amputation. While active vacuum suspension provides more positive coupling of the residual limb to the prosthetic socket, there are circumstances when use of active vacuum is not appropriate or feasible. Therefore, this technical note describes the technique modifications required to cast, fabricate, and fit a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket (i.e. the Northwestern University Flexible Sub-Ischial Suction socket). Technique: Most technique modifications stem from the use of an internal seal with the Northwestern University Flexible Sub-Ischial Suction socket and the need to account for the greater relative motion occurring between the residual limb and socket with passive suction compared to active vacuum suspension. Discussion: Between January 2015 and March 2018, 266 Northwestern University Flexible Sub-Ischial Suction sockets were fit successfully using the described technique modifications. Clinical relevance A passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket—the Northwestern University Flexible Sub-Ischial Suction socket—broadens the application of sub-ischial sockets to a larger proportion of the population with transfemoral amputation.

scholarly journals Northwestern University Flexible Subischial Vacuum Socket for persons with transfemoral amputation-Part 1: Description of technique

2017 ◽  
Vol 41 (3) ◽  
pp. 237-245 ◽  
Author(s):  
Stefania Fatone ◽  
Ryan Caldwell
Keyword(s):  
Quality Of Life ◽  
Range Of Motion ◽  
Study Design ◽  
Clinical Relevance ◽  
Development Project ◽  
Residual Limb ◽  
Transfemoral Amputation ◽  
Hands On ◽  
Northwestern University

Background:Current transfemoral prosthetic sockets restrict function, lack comfort, and cause residual limb problems. Lower proximal trim lines are an appealing way to address this problem. Development of a more comfortable and possibly functional subischial socket may contribute to improving quality of life of persons with transfemoral amputation.Objectives:The purpose of this study was to (1) describe the design and fabrication of a new subischial socket and (2) describe efforts to teach this technique.Study design:Development project.Methods:Socket development involved defining the following: subject and liner selection, residual limb evaluation, casting, positive mold rectification, check socket fitting, definitive socket fabrication, and troubleshooting of socket fit. Three hands-on workshops to teach the socket were piloted and attended by 30 certified prosthetists and their patient models.Results:Patient models responded positively to the comfort, range of motion, and stability of the new socket while prosthetists described the technique as “straight forward, reproducible.”Conclusion:To our knowledge, this is the first attempt to create a teachable subischial socket, and while it appears promising, more definitive evaluation is needed.Clinical relevanceWe developed the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket as a more comfortable alternative to current transfemoral sockets and demonstrated that it could be taught successfully to prosthetists.

scholarly journals A Sensor Array for the Measurement of Relative Motion in Lower Limb Prosthetic Sockets

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2658
Author(s):  
Veronika Noll ◽  
Sigrid Whitmore ◽  
Philipp Beckerle ◽  
Stephan Rinderknecht
Keyword(s):  
Pilot Study ◽  
Relative Motion ◽  
Lower Limb ◽  
Sagittal Plane ◽  
Functional Model ◽  
Transverse Plane ◽  
Residual Limb ◽  
Test Rig ◽  
Prosthetic Socket ◽  
Dynamic Gait

The relative motion between residual limb and prosthetic socket could be a relevant factor in quantifying socket fit. The measurement of these movements, particularly in dynamic gait situations, poses a challenging task. This paper presents the realization of a measurement concept based on multiple optical 2D-motion sensors. The performance of the system was evaluated on a test rig considering accuracy and precision as well as accomplished measurement frequency and reliability of the system. Additionally, results of a pilot study measuring the relative motion between residual limb and prosthetic socket at seven specific locations of one individual with transtibial amputation during straight level walking are presented. The sensor functionality of the array was confirmed and the test rig experiments were comparable to the previously tested functional model ( e r r rel = 0.52 ± 1.87 %). With a sampling frequency of 1.3 kHz to be distributed among the number of sensor units, the developed system is suitable for investigating the relative movement between residual limb and prosthetic socket in dynamic gait situations. Results of the pilot study show the majority of relative motion occurring during the second half of the gait cycle. The measured relative motions show the residual limb sinking deeper into the socket, extending in the Sagittal plane and rotating internally in the Transverse plane during stance phase. Data captured during swing phase indicate a lower limb extension in the Sagittal plane as well as an external rotation in the Transverse plane.

scholarly journals Effects of Prosthetic Socket Design on Residual Femur Motion Using Dynamic Stereo X-Ray - A Preliminary Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Jason T. Maikos ◽  
John M. Chomack ◽  
J. Peter Loan ◽  
Kathryn M. Bradley ◽  
Susan E. D’Andrea
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Residual Limb ◽  
Transfemoral Amputation ◽  
X Ray ◽  
Prosthetic Socket ◽  
Rotational Degrees Of Freedom ◽  
Socket Technology ◽  
Effectiveness Studies ◽  
Analytical Tools

Individuals with transfemoral amputation experience relative motion between their residual limb and prosthetic socket, which can cause inefficient dynamic load transmission and secondary comorbidities that limit mobility. Accurately measuring the relative position and orientation of the residual limb relative to the prosthetic socket during dynamic activities can provide great insight into the complex mechanics of the socket/limb interface. Five participants with transfemoral amputation were recruited for this study. All participants had a well-fitting, ischial containment socket and were also fit with a compression/release stabilization socket. Participants underwent an 8-wk, randomized crossover trial to compare differences between socket types. Dynamic stereo x-ray was used to quantify three-dimensional residual bone kinematics relative to the prosthetic socket during treadmill walking at self-selected speed. Comfort, satisfaction, and utility were also assessed. There were no significant differences in relative femur kinematics between socket types in the three rotational degrees of freedom, as well as anterior-posterior and medial-lateral translation (p > 0.05). The ischial containment socket demonstrated significantly less proximal-distal translation (pistoning) of the femur compared to the compression/release stabilization socket during the gait cycle (p < 0.05), suggesting that the compression/release stabilization socket provided less control of the residual femur during distal translation. No significant differences in comfort and utility were found between socket types (p > 0.05). The quantitative, dynamic analytical tools used in the study were sensitive to distinguish differences in three-dimensional residual femur motion between two socket types, which can serve as a platform for future comparative effectiveness studies of socket technology.

Quantification of rectifications for the Northwestern University Flexible Sub-Ischial Vacuum Socket

2017 ◽  
Vol 41 (3) ◽  
pp. 251-257 ◽  
Author(s):  
Stefania Fatone ◽  
William Brett Johnson ◽  
Lilly Tran ◽  
Kerice Tucker ◽  
Christofer Mowrer ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Shape Change ◽  
Tissue Type ◽  
Transfemoral Amputation ◽  
Computer Aided Manufacturing ◽  
Prosthetic Socket ◽  
Northwestern University ◽  
Computer Aided ◽  
Aided Design

Background:The fit and function of a prosthetic socket depend on the prosthetist’s ability to design the socket’s shape to distribute load comfortably over the residual limb. We recently developed a sub-ischial socket for persons with transfemoral amputation: the Northwestern University Flexible Sub-Ischial Vacuum Socket.Objective:This study aimed to quantify the rectifications required to fit the Northwestern University Flexible Sub-Ischial Vacuum Socket to teach the technique to prosthetists as well as provide a computer-aided design–computer-aided manufacturing option.Study Design:Development project.Methods:A program was used to align scans of unrectified and rectified negative molds and calculate shape change as a result of rectification. Averaged rectifications were used to create a socket template, which was shared with a central fabrication facility engaged in provision of Northwestern University Flexible Sub-Ischial Vacuum Sockets to early clinical adopters. Feedback regarding quality of fitting was obtained.Results:Rectification maps created from 30 cast pairs of successfully fit Northwestern University Flexible Sub-Ischial Vacuum Sockets confirmed that material was primarily removed from the positive mold in the proximal-lateral and posterior regions. The template was used to fabricate check sockets for 15 persons with transfemoral amputation. Feedback suggested that the template provided a reasonable initial fit with only minor adjustments.Conclusion:Rectification maps and template were used to facilitate teaching and central fabrication of the Northwestern University Flexible Sub-Ischial Vacuum Socket. Minor issues with quality of initial fit achieved with the template may be due to inability to adjust the template to patient characteristics (e.g. tissue type, limb shape) and/or the degree to which it represented a fully mature version of the technique.Clinical relevanceRectification maps help communicate an important step in the fabrication of the Northwestern University Flexible Sub-Ischial Vacuum Socket facilitating dissemination of the technique, while the average template provides an alternative fabrication option via computer-aided design–computer-aided manufacturing and central fabrication.

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

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.

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