The effects of suction and pin/lock suspension systems on transtibial amputees' gait performance

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.

The Clinical History and Basic Science Origins of Transcutaneous Osseointegration for Amputees

Transcutaneous osseointegration for amputees (TOFA) refers to an intramedullary metal endoprosthesis which passes transcutaneously to connect with a limb exoprosthesis. The first recognizably modern experiments and attempts occurred in the 1940s. Multiple researchers using a plethora of materials and techniques over the following 50 years identified principles and obstacles which informed the first long-term successful surgery in 1990. Unfortunately, the current mainstream TOFA literature presents almost exclusively subsequent developments, generally omitting prior research, leading to some historical mistakes being repeated. Given the increasing interest and surgical volume of TOFA, this literature review was performed to delineate TOFA's basic science and surgical origins and to integrate these early efforts within the contemporary understanding. Studying this research could protect and benefit future patients, surgeons, and implant developers as TOFA is entering a phase of increased attention and innovation. The aim of this article is to provide a focused reference of foundational research, much of which is difficult to identify and retrieve, for clinicians and researchers.

Self-reported socket comfort, mobility, and balance-confidence of individuals with transtibial amputation using pinlock vs suction suspension

BACKGROUND

Improper suspension between the residual limb and prosthesis can result in pistoning, which may compromise skin integrity and reduce overall user comfort. In addition to objective measures of limb pistoning, user perspective may provide insight into suspension system effectiveness.

OBJECTIVES

The primary objective of this analysis was to explore differences in self-reported measures among adults with transtibial amputation (TTA) using pinlock vs suction suspension systems.

STUDY DESIGN

This is a secondary analysis of cross-sectional data.

METHODS

Participants (n = 48) were included if they (1) were ≥18 years of age, (2) were community-dwelling, (3) had a unilateral TTA of ≥6 months, and (4) were prescribed a prosthesis with either pinlock or suction suspension. Participants completed self-reported measures evaluating socket comfort (Socket Comfort Score [SCS]), prosthesis-enabled mobility (Prosthesis Evaluation Questionnaire-Mobility Section [PEQ-MS]; Locomotor Capabilities Index [LCI]), and balance-confidence (Activities-Specific Balance Confidence Scale [ABC]).

RESULTS

Participants using suction suspension reported significantly higher SCS as compared with participants using pinlock suspension (P ≤ .001). No differences were observed between groups for PEQ-MS, LCI, and/or ABC.

CONCLUSIONS

Individuals with TTA using suction suspension may report greater socket comfort than peers using pinlock suspension, but prosthesis-enabled mobility and balance-confidence may be similar. Future research is warranted to confirm these preliminary findings using a prospective, crossover study design that controls for all suspected factors that might influence socket comfort.

Vibration Suppression of a Composite Prosthetic Foot Using Piezoelectric Shunt Damping: Implications to Vibration-Induced Cumulative Trauma

OBJECTIVE

Energy-storage-and-return (ESAR) prosthetic feet have improved amputee mobility due to their efficient conversion of strain energy to mechanical work. However, this efficiency is typically achieved using light-weight, high-stiffness materials, which generate high-frequency vibrations that are potentially injurious if transmitted to biological tissues. To reduce the vibration which may cause cumulative tissue trauma, high-frequency vibration suppression by piezoelectric shunt damping patches on a commercial ESAR foot was evaluated.

METHODS

Two patches with either passive or active shunt circuits were placed on the foot to investigate vibration suppression during experimental tests where a plastic hammer was used to hit a clamped ESAR foot on the free end. Prosthesis bending moments at each modal frequency were obtained by finite element methods to identify piezoelectric patch placement.

RESULTS

Both shunt circuits decreased vibration amplitudes at specific modes better than the no shunt case, but also increased the amplitude at specific frequencies. The vibration suppression performance of the active shunt circuit deteriorated at the second mode, while the vibration suppression performance of the passive shunt circuit deteriorated at all frequencies above the third mode.

CONCLUSIONS

These results indicate piezoelectric shunt patches may be a viable strategy for decreasing vibrations of an ESAR foot, with active methods more efficient at suppressing high-frequency vibrations. Additional research is necessary to fine-tune the method for maximal vibration suppression.

SIGNIFICANCE

Overall, this study indicates that high-frequency vibration suppression is possible using piezoelectric patches, possibly decreasing the cumulative tissue damage that may occur with repetitive exposure to vibration.

Mechanical Evaluation Of Unity Elevated Vacuum Suspension System

BACKGROUND

Small residual limb-socket displacement is a good indicator of prosthetic suspension system quality. Active vacuum suspension systems can decrease vertical movement inside the socket, compared to non-active suction systems. This study mechanically evaluated limb-socket displacement with the Össur Unity active vacuum system.

METHOD

Forty-eight conditions were evaluated: four cylindrical and four conical sockets (polypropylene, polyethylene terephthalate glycol-modified (PETG), thermoset resin (acrylic), Thermolyn soft materials); two Iceross Seal-In V liners (standard, high profile); three vacuum conditions (active vacuum, inactive vacuum, no suction with valve open). An Instron 4428 test machine applied 0-100N linear ramped tensile loads to each positive mold, with the socket secured in place, while displacement between the mold and socket was recorded. Following the displacement tests, the load before failure (i.e., 10 mm displacement) was measured.

RESULTS

Average and standard deviations for movement between the mold and sockets were small. The displacement average for all conditions was 0.30±0.16mm for active vacuum, 0.32±0.16mm for inactive vacuum, and 0.39±0.22mm for no suction. Across all trials, active vacuum systems tolerated significantly (p<0.001) more load before failure (812±221N) compared to inactive vacuum (727±213N), and no suction (401±184N). The maximum load before failure (1142±53N) was for the cylindrical polypropylene socket and high-profile liner.

CONCLUSION

The Unity system successfully controlled pistoning inside the socket for regular activity loads and also controlled the greatest traction loads. While relative movement was smallest for Unity, all conditions (inactive vacuum, no suction) were viable for loads less than 100N. Furthermore, similar results can be achieved when using different socket fabrication materials.

A Practical Approach for Evaluation of Socket Pistoning for Lower Limb Amputees

Although fit of the socket-suspension system is critical to lower limb amputees, monitoring of the fit is largely based on user feedback, which is subjective and often unreliable. Pistoning, defined as the relative displacement between the socket and the residual limb, is a well-accepted indicator of the fit of the socket-suspension system. However, opacity and rigidity of everyday prosthetic sockets make measurement of pistoning a challenging task. In this paper, we describe the development of a pistoning evaluation procedure that relies on two motion capture systems: a magnetic motion capture system used to measure the motion of the residual limb and an optical motion capture system used to measure the motion of the socket. Through synchronization of the two motion capture systems, the motion of the residual limb relative to the socket can be determined to derive the amplitude of pistoning. Here, we evaluated the performance of our approach through repeated calibration and a treadmill walking task with an amputee. Results demonstrate that this procedure, which does not rely on radiography unlike some existing methods, can be used to evaluate the fit of amputees' everyday sockets.

A Prospective Assessment of an Adjustable, Immediate Fit, Transtibial Prosthesis

BACKGROUND

There exists a need for an adjustable socket to accommodate residual limb volume and shape changes. Further, limb loss rates globally are rising and there is a large unmet need for affordable and accessible prosthetic systems.

OBJECTIVE

To assess the utility of an immediate fit modular prosthetic system (iFIT Prosthetics, LLC).

DESIGN

Prospective feasibility study involving a 2-week single-group pre-post intervention study.

SETTING

Physical Medicine and Rehabilitation gait laboratory.

PARTICIPANTS

Participants were at least 6 months post amputation and walking with a conventional prosthesis. They were free of skin wounds, other neurological disorders, and severe pain conditions.

METHODS

Participants were fit with an immediate fit prosthesis and instructed to wear it for a 2-week evaluation period. They were given a progressive wearing schedule and they completed outcome measurements at the 2-week follow-up.

MAIN OUTCOME MEASUREMENTS

Self-reported satisfaction, gait biomechanics, and intrasocket peak pressures.

RESULTS

Twenty-six participants entered the study, with 22 completing the single group pre-post study. They averaged 50 years (SD ±10.2) of age; four were female. Sixteen were dysvascular and 10 were traumatic in etiology. Significant differences (P = .03) in self-reported satisfaction were found in favor of the iFIT device 29.33 (SD ± 4.51) versus the conventional device 25.52 (SD ± 6.8). No falls or limb ischemia were reported. Gait biomechanics revealed no differences across any temporal characteristics. Intrasocket peak pressures were significantly lower for the iFIT prostheses overall (P = .0014), at the anterior tibia (P = .0002), and the lateral side of the residual limb (P = .013).

CONCLUSIONS

The iFIT transtibial prosthetic system appears to be safe in this short-term single-group pre-post study. This study provided preliminary evidence to support the feasibility of the iFIT system. It compared favorably to participants' conventional prostheses across all outcome measures. With its cost, adjustability, and accessibility advantages, this device may prove useful for persons with transtibial amputations. A larger multicenter study is needed to confirm these results.

LEVEL OF EVIDENCE

III.

Prosthesis satisfaction in lower limb amputees: A systematic review of associated factors and questionnaires

BACKGROUND

Factors influencing patient satisfaction with a transtibial prosthesis have been studied fragmentarily. The aims of this systematic review were to review the literature regarding factors of influence on patient satisfaction with a transtibial prosthesis, to report satisfaction scores, to present an overview of questionnaires used to assess satisfaction and examine how these questionnaires operationalize satisfaction.

METHODS

A literature search was performed in PubMed, Embase, PsycInfo, CINAHL, Cochrane, and Web of Knowledge databases up to February 2018 to identify relevant studies.

RESULTS

Twelve of 1832 studies met the inclusion criteria. Sample sizes ranged from 14 to 581 participants, mean age ranged from 18 to 70 years, and time since amputation ranged from 3 to 39 years. Seven questionnaires assessed different aspects of satisfaction. Patient satisfaction was influenced by appearance, properties, fit, and use of the prosthesis, as well as aspects of the residual limb. These influencing factors were not relevant for all amputee patients and were related to gender, etiology, liner use, and level of amputation. No single factor was found to significantly influence satisfaction or dissatisfaction. Significant associations were found between satisfaction and gender, etiology, liner use, and level of amputation.

CONCLUSION

Relevance of certain factors for satisfaction was related to specific amputee patient groups. Questionnaires assessing satisfaction use different operationalizations, making comparisons between studies difficult.

Standardized Approach to Quantitatively Measure Residual Limb Skin Health in Individuals with Lower Limb Amputation

Objective: (1) Develop a standardized approach to quantitatively measure residual limb skin health. (2) Report reference residual limb skin health values in people with transtibial and transfemoral amputation. Approach: Residual limb health outcomes in individuals with transtibial (n = 5) and transfemoral (n = 5) amputation were compared to able-limb controls (n = 4) using noninvasive imaging (hyperspectral imaging and laser speckle flowmetry) and probe-based approaches (laser doppler flowmetry, transcutaneous oxygen, transepidermal water loss, surface electrical capacitance). Results: A standardized methodology that employs noninvasive imaging and probe-based approaches to measure residual limb skin health are described. Compared to able-limb controls, individuals with transtibial and transfemoral amputation have significantly lower transcutaneous oxygen tension, higher transepidermal water loss, and higher surface electrical capacitance in the residual limb. Innovation: Residual limb health as a critical component of prosthesis rehabilitation for individuals with lower limb amputation is understudied in part due to a lack of clinical measures. Here, we present a standardized approach to measure residual limb health in people with transtibial and transfemoral amputation. Conclusion: Technology advances in noninvasive imaging and probe-based measures are leveraged to develop a standardized approach to quantitatively measure residual limb health in individuals with lower limb loss. Compared to able-limb controls, resting residual limb physiology in people that have had transfemoral or transtibial amputation is characterized by lower transcutaneous oxygen tension and poorer skin barrier function.

User experience of transtibial prosthetic liners: A systematic review

BACKGROUND

The liner is an integral part of a transtibial prosthesis designed to protect the residual limb, enhance comfort and provide suspension. Literature is difficult to interpret and use given the variety of interventions, outcome measures and method designs. Critical appraisal and synthesis of the evidence is needed to help inform decisions about liner prescription based on the user experience.

OBJECTIVES

To critically appraise and synthesise research describing the user experience of transtibial prosthetic liners.

STUDY DESIGN

Systematic review.

METHODS

A comprehensive suite of databases were searched using terms related to amputation level, liner type and user experience. Included studies were in English and measured the first-person experience of using a transtibial liner. Studies were appraised using the McMaster University Critical Review Forms.

RESULTS

A total of 18 articles met the inclusion criteria. While the quality of the evidence has improved over time, a number of common issues (e.g. sampling bias, validity of outcome measures, incorrect inferential analysis) reduce our ability to differentiate between the user experience of different transtibial liners.

CONCLUSION

There is insufficient research to differentiate between the user experience of different transtibial liners. High-quality research is needed to inform decisions about liner prescription based on the user experience. Clinical relevance The available evidence suggests that the user experience of commonly reported problems (e.g. sweating) may be very similar between different liners. Aspects of the user experience that differ most between liners (e.g. unwanted noises, rotation within the socket) can help focus attention on what matters most when discussing prescription.

A comparison of vacuum and KBM prosthetic fitting for unilateral transtibial amputees using the Gait Profile Score

The purpose of this study was to compare gait deviations between Kondylen Bettung Münster (KBM) and vacuum prosthetic fitting using the Gait Profile Score (GPS), the Movement Analysis Profile (MAP) and temporal-spatial parameters. Seventeen transtibial amputees that received their prosthesis from the Brazilian governmental health system participated in this study. Twelve of them used KBM prosthetic fitting on their prosthesis and five used vacuum prosthetic fitting. Kinematic and temporal-spatial parameters data were captured by a six-camera Motion Analysis system (Santa Rosa, CA). The results showed that the vacuum group walked faster than the KBM group but the differences in temporal-spatial parameters between them were not significant. The GPS for the intact limb (IL) and the overall GPS differentiated between the groups of prosthetic fitting. Hip flexion/extension and knee flexion/extension were higher in KBM group than in the vacuum group, although only knee flexion/extension for the intact limb revealed significant difference between the groups. In KBM group, the major deviations were in hip flexion/extension for both limbs, knee flexion/extension for both limbs and ankle dorsi/plantar flexion for the prosthetic limb. The vacuum group showed deviations especially in ankle dorsi/plantar flexion for both limbs, knee flexion/extension for the prosthetic limb and hip rotation for the prosthetic limb. Besides, the vacuum group was more symmetrical than the KBM group. This study concluded that subjects who used vacuum prosthetic fitting presented smaller gait deviations and a more symmetrical gait than those who used KBM prosthetic fitting.

Biomedical and psychosocial factors influencing transtibial prosthesis fit: a Delphi survey among health care professionals

PURPOSE

We aimed to reach consensus among professionals caring for prosthesis users, on definitions of biomedical and psychosocial factors, to assess their influence on fit of transtibial prosthesis and to identify new factors.

METHOD

A three-round, internet-based, Delphi survey was conducted among experts recruited via the Dutch National Amputee and Prosthesis Work Group. The main outcome measure was consensus among care professionals on statements concerning new and presented biomechanical and psychosocial factors that influence transtibial prosthesis fit.

RESULTS

Fifty-four experts participated in the survey, and consensus was reached on 67% (46/69) of all statements. Consensus on statements relevant for good prosthesis fit was reached in most of the statements concerning psychosocial factors and on statements concerning the biomedical factors "prosthesis support and suspension". Least consensus was reached on statements concerning the biomedical factor "skin problems and pain in the residual limb".

CONCLUSIONS

Biomedical and psychosocial factors influence transtibial prosthesis fit. Consensus was reached among care professionals in a majority of the presented statements concerning these factors. Implications for Rehabilitation Prosthesis fit and comfort is suboptimal in many prosthesis users. Both biomedical and psychosocial factors influence fit. Biomedical and psychosocial factors should be checked during transtibial prosthesis prescription to achieve and maintain an optimal fit. Consensus on many factors influencing prosthesis fit is achieved among care professionals. Consensus was largest regarding prosthesis support and suspension and least regarding skin problems and pain in the residual limb. This consensus contributes to systematic assessment of prosthesis fit.