Transfemoral interfaces with vacuum assisted suspension comparison of gait, balance, and subjective analysis: ischial containment versus brimless

Is the subischial socket better than others in subjects with transfemoral amputation? A systematic review of randomized and controlled clinical trials

Rehabilitation is often complex for persons with transfemoral amputation, and poor socket fit is one of the main factors affecting gait re-education, rehabilitation, and quality of life. The present study systematically reviewed the literature to test whether the subischial socket provides better outcomes in comfort, quality of life, and mobility than other transfemoral sockets. Systematic review and meta-analysis. We searched MEDLINE, Physical Therapy Evidence Database Scale, Epistemonikos, Cochrane, BIREME, Web of Science, and Scopus from inception to January 2024 to identify randomized and controlled trials. Two authors independently screened records and assessed the risk of bias. We performed a narrative synthesis of the evidence and used the standardized mean difference and mean difference for meta-analyses and the Grading of Recommendations, Assessment, Development, and Evaluation approach for recommendations. We identified 7 randomized and controlled clinical trials. Five studies compared the subischial socket with the ischial containment socket (IC), 1 study compared the IC with the Marlo anatomical socket, and 1 study compared the IC with the quadrilateral. Very low certainty showed a difference in comfort (1 study: mean difference = 1.4 [95% CI 0.61, 2.19]), but no in quality of life (2 studies: standardized mean difference = 1.28 (95% CI -1.04, 3.59), and mobility (2 studies: mean difference = 0.11 (95% CI -1.08, 1.29). We observed differences between the subischial socket and the IC in comfort but not in quality of life, mobility, and stability. Furthermore, we found a very low certainty that the subischial socket provides better outcomes than the IC in comfort, quality of life, and mobility.

Effect of pregnancy on anthropometrics, comfort, and functional performance for women living with transfemoral limb loss: Case report

Women living with limb loss (amputees) have unique needs that increase during pregnancy. Comfort, pain, and activity are exponentially compromised. Changes in mass and altered center of gravity increase the likelihood of falls and compromise safety for the mother and unborn baby. Subjective and physical functional performance measures data was collected through 2 separate pregnancies on a 36-year-old woman with a right transfemoral amputation. Physiological changes during pregnancy effected comfort, pain, and functional performance. Clinical practice guidelines for prosthetic management should be established to include protocols such as adjustment schedules, specialized socket design, and necessary component changes throughout the course of pregnancy.

The influence of prosthetic suspension on gait and cortical modulations is persons with a transfemoral amputation: socket-suspended versus bone-anchored prosthesis

BACKGROUND

Persons with a transfemoral amputation (TFA) often experience difficulties in daily-life ambulation, including an asymmetrical and less stable gait pattern and a greater cognitive demand of walking. However, it remains unclear whether this is effected by the prosthetic suspension, as eliminating the non-rigid prosthetic connection may influence stability and cortical activity during walking. Spatiotemporal and stability-related gait parameters, as well as cortical activity during walking, were evaluated between highly active individuals (MFC-level K3-4) with a TFA and able-bodied (AB) persons, and between persons with a bone-anchored prosthesis (BAP) and those with a socket-suspended prosthesis (SSP).

METHODS

18 AB persons and 20 persons with a unilateral TFA (10 BAP-users, 10 SSP-users) walked on a treadmill at their preferred speed. Spatiotemporal and margin of stability parameters were extracted from three-dimensional movement recordings. In addition, 126-channel electroencephalogram (EEG) was recorded. Brain-related activity from several cortical areas was isolated using independent component analysis. Source-level data were divided into gait cycles and subjected to time-frequency analysis to determine gait-cycle dependent modulations of cortical activity.

RESULTS

Persons with TFA walked with smaller and wider steps and with greater variability in mediolateral foot placement than AB subjects; no significant differences were found between BAP- and SSP-users. The EEG analysis yielded four cortical clusters in frontal, central (both hemispheres), and parietal areas. No statistically significant between-group differences were found in the mean power over the entire gait cycle. The event-related spectral perturbation maps revealed differences in power modulations (theta, alpha, and beta bands) between TFA and AB groups, and between BAP- and SSP-users, with largest differences observed around heel strike of either leg.

CONCLUSIONS

The anticipated differences in gait parameters in persons with TFA were confirmed, however no significant effect of the fixed suspension of a BAP was found. The preliminary EEG findings may indicate more active monitoring and control of stability in persons with TFA, which appeared to be timed differently in SSP than in BAP-users. Future studies may focus on walking tasks that challenge stability to further investigate differences related to prosthetic suspension.

Quantitative methods used to evaluate balance, postural control, and the fear of falling in lower limb prosthesis users: A systematic review

Problems with balance, postural control, and fear of falling are highly prevalent in lower limb prosthesis users, with much research conducted to understand these issues. The variety of tools used to assess these concepts presents a challenge when interpreting research outcomes. This systematic review aimed to provide a synthesis of quantifiable methods used in the evaluation of balance, postural control, and fear of falling in lower limb prosthesis users with an amputation level at or proximal to the ankle joint. A systematic search was conducted in CINAHL, Medline, AMED, Cochrane, AgeLine, Scopus, Web of Science, Proquest, PsycINFO, PsycArticles, and PubPsych databases followed by additional manual searching via reference lists in the reviewed articles databases. Included articles used quantitative measure of balance or postural control as one of the dependent variables, lower limb prosthesis users as a sample group, and were published in a peer-reviewed journal in English. Relevant assessment questions were created by the investigators to rate the assessment methods used in the individual studies. Descriptive and summary statistics are used to synthesize the results. The search yielded (n = 187) articles assessing balance or postural control (n = 5487 persons in total) and (n = 66) articles assessing fear of falling or balance confidence (n = 7325 persons in total). The most used test to measure balance was the Berg Balance Scale and the most used test to measure fear of falling was the Activities-specific Balance Confidence scale. A large number of studies did not present if the chosen methods were valid and reliable for the lower limb prosthesis users. Among study limitations, small sample size was common.

Investigation of the correlation between knee joint position sense and physical functional performance in individuals with transtibial amputation

INTRODUCTION

In individuals with transtibial amputation, the distal part of the lower extremity is lost. Therefore, the knee joint is of greater importance to be able to provide physical performance. The aim of this study was to evaluate the correlation between knee joint position sense and physical functional performance in individuals with transtibial amputation.

METHODS

The study included 21 subjects with transtibial amputation. A digital inclinometer was used to evaluate the joint position sense of the amputated side knee joint. The timed up and go test, the 4-square step test, and 10-m walk test were used to evaluate physical functional performance. Linear regression analysis was used to investigate the associations between independent variables and functional performance tests.

RESULTS

The mean age of the participants was 52.52 ± 15.68 years. The mean of the error in knee joint position sense was 5.33 degree (standard deviation = 3.08 degree). The error in knee joint position sense of the amputated limb predicted 45% of the variance in the 4-square step test and 22% of the variance in the 10-m walk test ( P < 0.05).

CONCLUSIONS

The knee joint position sense on the amputated side was found to be associated with physical functional performance in individuals with transtibial amputation. Residual limb knee joint position sense should be considered when prescribing prostheses and planning rehabilitation programs.

Amputation and prosthetics of the lower extremity: The 2020 Dutch evidence-based multidisciplinary guideline

BACKGROUND

Lower-limb amputations are rare but debilitating events in the lives of affected persons. Treatment of persons with amputation inherently involves many different health care professions at different stages leading to and after an amputation. There are prevailing clinical questions within the work field related to different facets of care including peri/postoperative aspects, prosthetic components, rehabilitation treatment, and health care processes.

OBJECTIVES

To provide an up-to-date multidisciplinary evidence-based guideline for health care professionals involved in the treatment of persons with lower-limb amputation in the Netherlands.

METHODS

Identification of key questions in a focus group, systematic review of the evidence (up to March 2019, using Embase and MEDLINE databases), and weighing considerations, culminating in clinical recommendations.

RESULTS

Twelve key questions were formulated. Recommendations of two key questions were upheld in line with the previous 2012 guideline. Ten systematic literature searches were performed, leading to the inclusion of 59 studies.

CONCLUSION

A summary of evidence-based conclusions, considerations, and recommendations of the 2020 guideline is presented.

Normalized kinematic walking symmetry data for individuals who use lower-limb prostheses: considerations for clinical practice and future research

Introduction

Individuals who use unilateral transtibial or transfemoral prostheses have negative secondary health effects associated with decreased kinematic (e.g., spatiotemporal and joint angle) walking symmetry between prosthetic and intact limbs. Research studies have quantified kinematic walking symmetry, but studies can be difficult to compare owing to the inclusion of small sample sizes and differences in participant demographics, biomechanical parameters, and mathematical analysis of symmetry. This review aims to normalize kinematic walking symmetry research data across studies by level of limb loss and prosthetic factors to inform considerations in clinical practice and future research.

Methods

A search was performed on March 18, 2020, in PubMed, Scopus, and Google Scholar to encompass kinematic walking symmetry literature from the year 2000. First, the most common participant demographics, kinematic parameters, and mathematical analysis of symmetry were identified across studies. Then, the most common mathematical analysis of symmetry was used to recalculate symmetry data across studies for the five most common kinematic parameters.

Results

Forty-four studies were included in this review. The most common participant demographics were younger adults with traumatic etiology who used componentry intended for higher activity levels. The most common kinematic parameters were step length, stance time, and sagittal plane ankle, knee, and hip range of motion. The most common mathematical analysis was a particular symmetry index equation.

Conclusions

Normalization of data showed that symmetry tended to decrease as level of limb loss became more proximal and to increase with prosthetic componentry intended for higher activity levels. However, most studies included 10 or fewer individuals who were active younger adults with traumatic etiologies.

Clinical Relevance

Data summarized in this review could be used as reference values for rehabilitation and payer justification. Specifically, these data can help guide expectations for magnitudes of walking symmetry throughout rehabilitation or to justify advanced prosthetic componentry for active younger adults under 65 years of age with traumatic etiologies to payers.

Analyzing Dynamic Operational Conditions of Limb Prosthetic Sockets with a Mechatronics-Twin Framework

Lower limb prostheses offer a solution to restore the ambulation and self-esteem of amputees. One key component is the prosthetic socket that serves as the interface between prosthetic device and amputee stump and thereby has a wide range of impacts on efficient fitting, appropriate load transmission, operational stability, and control. For the design and optimization of a prosthetic socket, an understanding of the actual intra-socket operational conditions becomes therefore necessary. This is however a difficult task due to the inherent complexity and restricted observability of socket operation. In this study, an innovative mechatronics-twin framework that integrates advanced biomechanical models and simulations with physical prototyping and dynamic operation testing for effective exploration of operational behaviors of prosthetic sockets with amputees is proposed. Within this framework, a specific Stewart manipulator is developed to enable dynamic operation testing, in particular for a well-managed generation of dynamic intra-socket loads and behaviors that are otherwise difficult to observe or realize with the real amputees. A combination of deep learning and Bayesian Inference algorithms is then employed for analyzing the intra-socket load conditions and revealing possible anomalous.

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

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.

Effect of transfemoral prosthetic socket interface design on gait, balance, mobility, and preference: A randomized clinical trial

BACKGROUND

There are alternative transfemoral (TF) socket interface designs that have not been compared with the standard of care, ischial ramus containment (IRC). The interface directly affects performance.

OBJECTIVES

To compare 3 TF interface designs, IRC, dynamic socket (DS), and subischial (Sub-I), regarding gait, balance, mobility, and preference. The authors hypothesized that these more active users may experience gait, mobility, and preference benefits from the less intrusive DS and Sub-I interface designs.

STUDY DESIGN

Single-blind, repeated-measures, 3-period randomized controlled crossover clinical trial.

METHODS

People with unilateral TF amputation with 1 year or longer prosthesis use experience, independent community ambulatory status, 18 to 60 years of age, of any race or ethnicity, with a body mass of 45 to 125 kg, and with a self-reported ability to walk for 20 minutes continuously were included in the study. Each participant was fit in all 3 interface designs.

RESULTS

Thirteen participants completed the clinical trial. Velocity, cadence, mobility, and balance were not statistically different between the 3 socket conditions. The DS demonstrated significantly greater symmetry in swing, stance, single support percentage, and toe angle compared with IRC and Sub-I. Sixty days after study completion, 7 participants changed interfaces, trending away from IRC.

CONCLUSIONS

Large differences were not observed. Small differences in spatiotemporal gait measures combined with patient preference may make a meaningful difference to individual patients and should be considered.

Comparison of Ischial Containment and Subischial Sockets on Comfort, Function, Quality of Life, and Satisfaction With Device in Persons With Unilateral Transfemoral Amputation: A Randomized Crossover Trial

OBJECTIVE

To compare comfort and functional performance of the Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket with the ischial containment (IC) socket in persons with unilateral transfemoral amputation.

DESIGN

Randomized crossover trial with two 7-week periods.

SETTING

Private prosthetic clinics and university research laboratory.

PARTICIPANTS

A total of 30 enrolled (N=30); 25 participants completed the study with full (n=18) or partial data (n=7).

INTERVENTIONS

Two custom-fabricated sockets (IC and NU-FlexSIV), worn full-time for 7 weeks, with testing at 1, 4, and 7 weeks after socket delivery.

MAIN OUTCOME MEASURES

The primary outcome was change in Socket Comfort Score (SCS) at 7 weeks. Secondary outcomes at 7 weeks included the Orthotic and Prosthetic Users' Survey (OPUS) to assess lower extremity functional status, health-related quality of life, and satisfaction with device, as well as the 5-Times Rapid Sit-to-Stand Test, Four Square Step Test, and T-Test of Agility to assess functional performance.

RESULTS

At 7 weeks, the mean SCS for IC (7.0±1.7) and NU-FlexSIV (8.4±1.1) Sockets were significantly different (P<.001; 95% confidence interval, 0.8-2.3). Results from a linear mixed-effects model, accounting for data from all time points, indicated that the SCS was 1.7 (SE=0.45) points higher for the NU-FlexSIV Socket (P<.001). For the secondary outcomes, only OPUS satisfaction with device was significantly better in the NU-FlexSIV Socket after accounting for all data points.

CONCLUSIONS

The results suggest that after 7 weeks' accommodation, the NU-FlexSIV Socket was more comfortable and led to greater satisfaction with device than the IC socket in persons with unilateral transfemoral amputation and K3/K4 mobility. Other patient-reported outcomes and function were no different between sockets.

Lower limb prosthetic interfaces: Clinical and technological advancement and potential future direction

The human-prosthesis interface is one of the most complicated challenges facing the field of prosthetics, despite substantive investments in research and development by researchers and clinicians around the world. The journal of the International Society for Prosthetics and Orthotics, Prosthetics and Orthotics International, has contributed substantively to the growing body of knowledge on this topic. In celebrating the 50th anniversary of the International Society for Prosthetics and Orthotics, this narrative review aims to explore how human-prosthesis interfaces have changed over the last five decades; how research has contributed to an understanding of interface mechanics; how clinical practice has been informed as a result; and what might be potential future directions. Studies reporting on comparison, design, manufacturing and evaluation of lower limb prosthetic sockets, and osseointegration were considered. This review demonstrates that, over the last 50 years, clinical research has improved our understanding of socket designs and their effects; however, high-quality research is still needed. In particular, there have been advances in the development of volume and thermal control mechanisms with a few designs having the potential for clinical application. Similarly, advances in sensing technology, soft tissue quantification techniques, computing technology, and additive manufacturing are moving towards enabling automated, data-driven manufacturing of sockets. In people who are unable to use a prosthetic socket, osseointegration provides a functional solution not available 50 years ago. Furthermore, osseointegration has the potential to facilitate neuromuscular integration. Despite these advances, further improvement in mechanical features of implants, and infection control and prevention are needed.

The effect of the transfemoral prosthetic socket interface designs on skeletal motion and socket comfort: A randomized clinical trial

BACKGROUND

The most crucial aspect of a prosthesis is the socket, as it will directly determine gait stability and quality. The current standard of care ischial ramus containment socket is reported to increase coronal stability through gait; however, socket discomfort is the primary complaint among prosthetic users.

OBJECTIVES

The purpose of this study is to compare ischial ramus containment to alternatives in the transfemoral amputee population. All subjects were fit with three different sockets: traditional ischial ramus containment, a dynamic socket, and a sub-ischial. In this study, authors hypothesized socket skeletal motion would be equivalent across interventions.

STUDY DESIGN

Single-blind, repeated-measures, three-period randomized crossover clinical trial.

METHODS

Outcome measures were socket comfort score and skeletal motion, viewed coronally with X-ray measuring the position of the skeleton in relationship to the socket in full weight-bearing and full un-loading.

RESULTS

The mean age was 38.2 and mean Amputee Mobility Predictor score was 40. Mean vertical movement, horizontal movement, single limb prosthetic stance, mean femoral adduction in swing and stance, and median socket comfort score were not statistically different.

CONCLUSION

The socket design did not significantly effect skeletal motion and socket comfort. All socket designs are suitable depending on the patient-centric preferences and prosthetist skill set.

CLINICAL RELEVANCE

The comfort of the standard of care transfemoral amputation socket has been widely reported as problematic. A comparison of alternative designs in a controlled clinical trial environment will assist the clinician in understanding the impact of design regarding skeletal motion and comfort. Users could benefit from alternatives applied in clinical practice.

The influence of a microprocessor-controlled hydraulic ankle on the kinetic symmetry of trans-tibial amputees during ramp walking: A case series

Introduction

Asymmetrical limb loading is believed to cause health problems for lower limb amputees and is exacerbated when walking on slopes. Hydraulically damped ankle-feet improve ground compliance on slopes compared to conventional prosthetic feet. Microprocessor-controlled hydraulic ankle-feet provide further adaptation by dynamically adjusting viscoelastic damping properties.

Method

Using a case series design, gait analysis was performed with four trans-tibial amputees. There were two walking conditions (ramp ascent and descent) and two prosthetic foot conditions (microprocessor-control on and off – MPF-on and MPF-off). Total support moment integral (MIsup) and degree-of-asymmetry were compared across foot conditions.

Results

During ramp descent, the transition of prosthetic ankle moment from dorsiflexion to plantarflexion occurred earlier in stance phase with MPF-on, slowing the angular velocity of the shank. During ramp ascent, the MPF-on dorsiflexion/plantarflexion moment transition occurred later, meaning less resistance to shank rotation in early stance and increasing walking speed by up to 6%. For both slope conditions, sound limb MIsup was universally decreased with MPF-on (4–13% descent, 3–11% ascent).

Discussion

Microprocessor-control of hydraulic ankle-feet reduced the total loading of the sound limb joints, for both walking conditions, for all participants. This may have beneficial consequences for long-term joint health and walking efficiency.

The development and internal consistency of the comprehensive lower limb amputee socket survey in active lower limb amputees

BACKGROUND:

Prosthetic socket fit is an important element associated with successful ambulation and use of a prosthesis. Prosthetists and rehabilitation clinicians would benefit from an assessment tool that discriminates between and quantifies the multiple determinants that influence the lower limb amputee's performance and satisfaction of a prosthetic socket.

OBJECTIVES:

To determine the internal consistency of the comprehensive lower limb amputee socket survey, a new self-report measure of prosthetic socket satisfaction that quantifies suspension, stability, comfort, and appearance.

STUDY DESIGN:

Cross-sectional sample of active amputees.

METHODS:

Interviews were conducted with prosthetists, physical therapists, and lower limb amputees to identify clinical concerns and common activities influencing socket fit. An expert panel of five clinicians reviewed the items and constructed the original version of the comprehensive lower limb amputee socket survey which was then administered to a convenience sample of 47 active lower limb amputees. Item analysis and Cronbach's alpha were used to determine the final version of the comprehensive lower limb amputee socket survey.

RESULTS:

Following item raw score-to-total score correlation with Cronbach's alpha for comprehensive lower limb amputee socket survey determinants, internal consistency improved when nine questions were eliminated.

CONCLUSION:

The comprehensive lower limb amputee socket survey is a self-report measure of prosthetic socket satisfaction with very good internal consistency.

CLINICAL RELEVANCE

When socket problems occur, the ability to determine the specific cause can reduce modification time, enhance socket fit, and promote patient satisfaction. A standardized multi-dimensional assessment measure of socket satisfaction enables prosthetists to quantify the multiple determinants of socket satisfaction, improve patient communication, and demonstrate the value of socket interventions.

Residual Limb Revision Surgery Alters Velocity-Curvature Coupling During Stepping and Turning of a Transfemoral Amputee

Two-Thirds Power Law is a frequently observed relationship in human movement, relating velocity and curvature of movement trajectory. These movements span handwriting, larvae crawling, and human-robot interaction. Despite vast acceptance as a common principle of biology, it is unknown if the power law applies to interaction between amputees and prostheses, and if interventions to augment the physical connection between amputees and prostheses influence this speed-curvature coupling during demanding forms of human locomotion. The purpose of this study was to determine if individuals with transfemoral amputation exhibit a biologically-appropriate power law relationship during non-steady-state locomotion, and if a surgical intervention to reduce residual limb soft tissue would influence the observed coupling. We hypothesized that a power regression would well characterize amputee locomotion, and that limb revision surgery would result in a non-linear power coupling close to one-third and overall increased speed (i.e., higher linear coupling) in each non-steady-state movement. The subject performed repeated trials of left and right 90° turns during walking, as well as Foursquare Step Test (FSST), while whole-body kinematics were captured. After fitting center-of-mass velocity and curvature to the power law, the power coupling in FSST was similar to the Two-Thirds Power Law, while turning was not. Finally, the intervention was shown to increase linear coupling suggesting an overall improvement in movement tempo characterized by modest changes in velocity, enabling tasks to be achieved more quickly.

Elevated vacuum suspension preserves residual-limb skin health in people with lower-limb amputation: Randomized clinical trial

A growing number of clinical trials and case reports support qualitative claims that use of an elevated vacuum suspension (EVS) prosthesis improves residual-limb health on the basis of self-reported questionnaires, clinical outcomes scales, and wound closure studies. Here, we report first efforts to quantitatively assess residual-limb circulation in response to EVS. Residual-limb skin health and perfusion of people with lower-limb amputation (N = 10) were assessed during a randomized crossover study comparing EVS with nonelevated vacuum suspension (control) over a 32 wk period using noninvasive probes (transepidermal water loss, laser speckle imaging, transcutaneous oxygen measurement) and functional hyperspectral imaging approaches. Regardless of the suspension system, prosthesis donning decreased perfusion in the residual limb under resting conditions. After 16 wk of use, EVS improved residual-limb oxygenation during treadmill walking. Likewise, prosthesis-induced reactive hyperemia was attenuated with EVS following 16 wk of use. Skin barrier function was preserved with EVS but disrupted after control socket use. Taken together, outcomes suggest chronic EVS use improves perfusion and preserves skin barrier function in people with lower-limb amputation.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; "Evaluation of limb health associated with a prosthetic vacuum socket system": NCT01839123; https://clinicaltrials.gov/ct2/show/NCT01839123?term=NCT01839123&rank=1.

Sockets for Limb Prostheses: A Review of Existing Technologies and Open Challenges

In the prosthetics field, one of the most important bottlenecks is still the human-machine interface, namely the socket. Indeed, a large number of amputees still rejects prostheses or points out a low satisfaction level, due to a sub-optimal interaction between the socket and the residual limb tissues. The aim of this paper is to describe the main parameters (displacements, stress, volume fluctuations and temperature) affecting the stump-socket interface and reducing the comfort/stability of limb prostheses. In this review, a classification of the different socket types proposed in the literature is reported, together with an analysis of advantages and disadvantages of the different solutions, from multiple viewpoints. The paper then describes the technological solutions available to face an altered distribution of stresses on the residual limb tissues, volume fluctuations affecting the stump overtime and temperature variations affecting the residual tissues within the socket. The open challenges in this research field are highlighted and the possible future routes are discussed, towards the ambitious objective of achieving an advanced socket able to self-adapt in real-time to the complex interplay of factors affecting the stump, during both static and dynamic tasks.

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

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 relevance Rectification 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.

Northwestern University Flexible Subischial Vacuum Socket for persons with transfemoral amputation: Part 2 Description and Preliminary evaluation

BACKGROUND

Current transfemoral prosthetic sockets are problematic as they restrict function, lack comfort, and cause residual limb problems. Development of a subischial socket with lower proximal trim lines is an appealing way to address this problem and may contribute to improving quality of life of persons with transfemoral amputation.

OBJECTIVES

The purpose of this study was to illustrate the use of a new subischial socket in two subjects.

STUDY DESIGN

Case series.

METHODS

Two unilateral transfemoral prosthesis users participated in preliminary socket evaluations comparing functional performance of the new subischial socket to ischial containment sockets. Testing included gait analysis, socket comfort score, and performance-based clinical outcome measures (Rapid-Sit-To-Stand, Four-Square-Step-Test, and Agility T-Test).

RESULTS

For both subjects, comfort was better in the subischial socket, while gait and clinical outcomes were generally comparable between sockets.

CONCLUSION

While these evaluations are promising regarding the ability to function in this new socket design, more definitive evaluation is needed. Clinical relevance Using gait analysis, socket comfort score and performance-based outcome measures, use of the Northwestern University Flexible Subischial Vaccum Socket was evaluated in two transfemoral prosthesis users. Socket comfort improved for both subjects with comparable function compared to ischial containment sockets.

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

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 relevance We 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.

RADIOGRAPHIC ASSESSMENT OF EXTREMITY OSSEOINTEGRATION FOR THE AMPUTEE

Osseointegration (OI) is a bone-anchoring procedure that allows the direct skeletal attachment of a prosthesis through the use of an implant. Transcutaneous OI implants are similar to subcutaneous intramedullary joint implants with some exceptions. Particularly, OI implants are inserted at the distal aspect of the femur, while intramedullary implants are inserted at the proximal aspect of the femur. In this report, an additional adaptation of the radiographic zonal analysis used for intramedullary implants, known as Gruen zones, is introduced to include OI implants of extremity prosthetics. Radiographic zonal analyses and interpretations are proposed. Gruen zones are used for intramedullary implants, which are generally inserted from the proximal aspect of the bone. OI extremity implants are inserted from the distal end of the bone. Therefore, the zonal analysis is inverted. A radiographic zonal analysis has been introduced by the Osseointegration Group of Australia (OGA). This analysis is needed specifically for the clinical evaluation of extremity OI, as significant changes to the bone and OI implant have been reported and need to be clinically described. A classification technique is necessary for establishing treatment guidelines for the extremity osseointegrated implant. The OGA Zonal analysis addresses this need by adapting a common reference standard to osseointegration of the extremity amputee.

THE EFFECT OF TRANSFEMORAL INTERFACE DESIGN ON GAIT SPEED AND RISK OF FALLS

Falls and diminished walking capacity are impairments common in persons with transfemoral amputation (TFA). Reducing falls and optimizing walking capacity through such means as achieving a more normal gait speed and community ambulation should be considered when formulating the prosthetic prescription. Because walking capacity and balance confidence are compromised with TFA, these outcomes should be considered when evaluating interfaces for transfemoral prosthetic users. The purpose of this study was to compare the effect of TFA interface design on walking capacity and balance confidence A retrospective cohort design was utilized involving unilateral TFA patients who used ischial ramus containment (IRC) and High-Fidelity (HiFi) interfaces (independent variables). Dependent variables included the Activity-specific Balance Scale (ABC) and the two-minute walk test (2MWT). Complete records were available for 13 patients (n = 13). The age range was 26 to 58 years. Three patients functioned at the K4 activity level, whereas all others functioned at the K3 level. Mean ABC scores were significantly different (p ≤ 0.05) at 77.2 (±16.8; 35.6 to 96.9) for IRC and 90.7 (±5.7; 77.5 to 98.7) for HiFi. The mean distance walked on the 2MWT was 91.8 m (±22.0, 58.3 to 124.7) for IRC compared to 110.4 m (±28.7; 64.7 to 171.1) for the HiFi socket (p ≤ 0.05). Alternative transfemoral interface design, such as the HiFi socket, can improve walking capacity and balance confidence in higher-functioning TFA patients.

Gait Training Interventions for Lower Extremity Amputees: A Systematic Literature Review

Lower extremity (LE) amputation patients who use prostheses have gait asymmetries and altered limb loading and movement strategies when ambulating. Subsequent secondary conditions are believed to be associated with gait deviations and lead to long-term complications that impact function and quality of life as a result. The purpose of this study was to systematically review the literature to determine the strength of evidence supporting gait training interventions and to formulate evidence statements to guide practice and research related to therapeutic gait training for lower extremity amputees. A systematic review of three databases was conducted followed by evaluation of evidence and synthesis of empirical evidence statements (EES). Eighteen manuscripts were included in the review, which covered two areas of gait training interventions: 1) overground and 2) treadmill-based. Eight EESs were synthesized. Four addressed overground gait training, one covered treadmill training, and three statements addressed both forms of therapy. Due to the gait asymmetries, altered biomechanics, and related secondary consequences associated with LE amputation, gait training interventions are needed along with study of their efficacy. Overground training with verbal or other auditory, manual, and psychological awareness interventions was found to be effective at improving gait. Similarly, treadmill-based training was found to be effective: 1) as a supplement to overground training; 2) independently when augmented with visual feedback and/or body weight support; or 3) as part of a home exercise plan. Gait training approaches studied improved multiple areas of gait, including sagittal and coronal biomechanics, spatiotemporal measures, and distance walked.

Parkinsonian Balance Deficits Quantified Using a Game Industry Board and a Specific Battery of Four Paradigms

This study describes a cost-effective screening protocol for parkinsonism based on combined objective and subjective monitoring of balance function. Objective evaluation of balance function was performed using a game industry balance board and an automated analyses of the dynamic of the center of pressure in time, frequency, and non-linear domains collected during short series of stand up tests with different modalities and severity of sensorial deprivation. The subjective measurement of balance function was performed using the Dizziness Handicap Inventory questionnaire. Principal component analyses on both objective and subjective measurements of balance function allowed to obtained a specificity and selectivity for parkinsonian patients (vs. healthy subjects) of 0.67 and 0.71 respectively. The findings are discussed regarding the relevance of cost-effective balance-based screening system as strategy to meet the needs of broader and earlier screening for parkinsonism in communities with limited access to healthcare.

The evidence-base for elevated vacuum in lower limb prosthetics: Literature review and professional feedback

BACKGROUND

An optimal suspension system can improve comfort and quality of life in people with limb loss. To guide practice on prosthetic vacuum suspension systems, assessment of the current evidence and professional opinion are required.

METHODS

PubMed, Web of Science, and Google Scholar databases were explored to find related articles. Search terms were amputees, artificial limb, prosthetic suspension, prosthetic liner, vacuum, and prosthesis. The results were refined by vacuum socket or vacuum assisted suspension or sub-atmospheric suspension. Study design, research instrument, sample size, and outcome measures were reviewed. An online questionnaire was also designed and distributed worldwide among professionals and prosthetists (www.ispoint.org, OANDP-L, LinkedIn, personal email).

FINDINGS

26 articles were published from 2001 to March 2016. The number of participants averaged 7 (SD=4) for transtibial and 6 (SD=6) for transfemoral amputees. Most studies evaluated the short-term effects of vacuum systems by measuring stump volume changes, gait parameters, pistoning, interface pressures, satisfaction, balance, and wound healing. 155 professionals replied to the questionnaire and supported results from the literature. Elevated vacuum systems may have some advantages over the other suspension systems, but may not be appropriate for all people with limb loss.

INTERPRETATION

Elevated vacuum suspension could improve comfort and quality of life for people with limb loss. However, future investigations with larger sample sizes are needed to provide strong statistical conclusions and to evaluate long-term effects of these systems.

Evaluation of a Prototype Hybrid Vacuum Pump to Provide Vacuum-Assisted Suspension for Above-Knee Prostheses

Vacuum-assisted suspension (VAS) of prosthetic sockets utilizes a pump to evacuate air from between the prosthetic liner and socket, and are available as mechanical or electric systems. This technical note describes a hybrid pump that benefits from the advantages of mechanical and electric systems, and evaluates a prototype as proof-of-concept. Cyclical bench testing of the hybrid pump mechanical system was performed using a materials testing system to assess the relationship between compression cycles and vacuum pressure. Phase 1 in vivo testing of the hybrid pump was performed by an able-bodied individual using prosthesis simulator boots walking on a treadmill, and phase 2 involved an above-knee prosthesis user walking with the hybrid pump and a commercial electric pump for comparison. Bench testing of 300 compression cycles produced a maximum vacuum of 24 in-Hg. In vivo testing demonstrated that the hybrid pump continued to pull vacuum during walking, and as opposed to the commercial electric pump, did not require reactivation of the electric system during phase 2 testing. The novelty of the hybrid pump is that while the electric system provides rapid, initial vacuum suspension, the mechanical system provides continuous air evacuation while walking to maintain suspension without reactivation of the electric system, thereby allowing battery power to be reserved for monitoring vacuum levels.