Influence of gait training and prosthetic foot category on external work symmetry during unilateral transtibial amputee gait

Effects of a Powered Ankle-Foot Prosthesis and Physical Therapy on Function for Individuals With Transfemoral Limb Loss: Rationale, Design, and Protocol for a Multisite Clinical Trial

BACKGROUND

Powered ankle-foot prosthetic devices can generate net positive mechanical work during gait, which mimics the physiological ankle. However, gait deviations can persist in individuals with transfemoral limb loss because of habit or lack of rehabilitation. Prosthetic research efforts favor the design or evaluation of prosthetic componentry and rarely incorporate any type of rehabilitation, despite evidence suggesting that it is critical for minimizing gait imbalances. Given the accelerated rate of innovation in prosthetics, there is a fundamental knowledge gap concerning how individuals with transfemoral limb loss should learn to correctly use powered ankle-foot devices for maximum functional benefit. Because of the recent advances in prosthetic technology, there is also a critical unmet need to develop guidelines for the prescription of advanced prosthetic devices that incorporate both physical and psychological components to identify appropriate candidates for advanced technology.

OBJECTIVE

The primary goal of this investigation is to examine the roles of advanced prosthetic technology and a device-specific rehabilitative intervention on gait biomechanics, functional efficacy, and pain in individuals with transfemoral limb loss. The secondary goal is to develop preliminary rehabilitation guidelines for advanced lower limb prosthetic devices to minimize gait imbalances and maximize function and to establish preliminary guidelines for powered ankle-foot prosthetic prescription.

METHODS

This prospective, multisite study will enroll 30 individuals with unilateral transfemoral limb loss. At baseline, participants will undergo a full gait analysis and assessment of function, neurocognition, cognitive load, subjective preferences, and pain using their current passive prosthesis. The participants will then be fitted with a powered ankle-foot device and randomized into 2 equal groups: a powered device with a device-specific rehabilitation intervention (group A) or a powered device with the current standard of practice (group B). Group A will undergo 4 weeks of device-specific rehabilitation. Group B will receive the current standard of practice, which includes basic device education but no further device-specific rehabilitation. Data collection procedures will then be repeated after 4 weeks and 8 weeks of powered ankle use.

RESULTS

This study was funded in September 2017. Enrollment began in September 2018. Data collection will conclude by March 2024. The initial dissemination of results is expected in August 2024.

CONCLUSIONS

The projected trends indicate that the number of individuals with limb loss will dramatically increase in the United States. The absence of effective, evidence-based interventions may make individuals with transfemoral limb loss more susceptible to increased secondary physical conditions and degenerative changes. With this expected growth, considerable resources will be required for prosthetic and rehabilitation services. Identifying potential mechanisms for correcting gait asymmetries, either through advanced prosthetic technology or rehabilitative interventions, can provide a benchmark for understanding the optimal treatment strategies for individuals with transfemoral limb loss.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03625921; https://clinicaltrials.gov/study/NCT03625921.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/53412.

Clinimetrics of performance-based functional outcome measures for vascular amputees: A systematic review

BACKGROUND

Objective physical performance-based outcome measures (PerBOMs) are essential tools for the holistic management of people who have had an amputation due to vascular disease. These people are often non-ambulatory, however it is currently unclear which PerBOMs are high quality and appropriate for those who are either ambulatory or non-ambulatory.

RESEARCH QUESTION

Which PerBOMs have appropriate clinimetric properties to be recommended for those who have had amputations due to vascular disease ('vascular amputee')?

DATA SOURCES

MEDLINE, CINAHL, EMBASE, EMCARE, the Cochrane Library, Cochrane Central Register of Controlled Trials (CENTRAL) and Scopus databases were searched for the terms: "physical performance" or "function", "clinimetric properties", "reliability", "validity", "amputee" and "peripheral vascular disease" or "diabetes".

REVIEW METHODS

A systematic review of PerBOMs for vascular amputees was performed following COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology and PRISMA guidelines. The quality of studies and individual PerBOMs was assessed using COSMIN risk of bias and good measurement properties. Overall PerBOM quality was evaluated with a modified GRADE rating. Key clinimetric properties evaluated were reliability, validity, predictive validity and responsiveness.

RESULTS

A total of 15,259 records were screened. Forty-eight studies (2650 participants) were included: 7 exclusively included vascular amputees only, 35 investigated validity, 20 studied predictive validity, 23 investigated reliability or internal consistency and 7 assessed responsiveness. Meta-analysis was neither possible nor appropriate for this systematic review in accordance with COSMIN guidelines, due to heterogeneity of the data. Thirty-four different PerBOMs were identified of which only 4 are suitable for non-ambulatory vascular amputees. The Amputee Mobility Predictor no Prosthesis (AMPnoPro) and Transfemoral Fitting Predictor (TFP) predict prosthesis use only. PerBOMs available for assessing physical performance are the One-Leg Balance Test (OLBT) and Basic Amputee Mobility Score (BAMS).

CONCLUSION

At present, few PerBOMs can be recommended for vascular amputees. Only 4 are available for non-ambulatory individuals: AMPnoPro, TFP, OLBT and BAMS.

Longitudinal Gait Analysis of a Transfemoral Amputee Patient: Single-Case Report from Socket-Type to Osseointegrated Prosthesis

The aim of the present case report was to provide a longitudinal functional assessment of a patient with transfemoral amputation from the preoperative status with socket-type prosthesis to one year after the osseointegration surgery. A 44 years-old male patient was scheduled for osseointegration surgery 17 years after transfemoral amputation. Gait analysis was performed through 15 wearable inertial sensors (MTw Awinda, Xsens) before surgery (patient wearing his standard socket-type prosthesis) and at 3-, 6-, and 12-month follow-ups after osseointegration. ANOVA in Statistical Parametric Mapping was used to assess the changes in amputee and sound limb hip and pelvis kinematics. The gait symmetry index progressively improved from the pre-op with socket-type (1.14) to the last follow-up (1.04). Step width after osseointegration surgery was half of the pre-op. Hip flexion-extension range significantly improved at follow-ups while frontal and transverse plane rotations decreased (p < 0.001). Pelvis anteversion, obliquity, and rotation also decreased over time (p < 0.001). Spatiotemporal and gait kinematics improved after osseointegration surgery. One year after surgery, symmetry indices were close to non-pathological gait and gait compensation was sensibly decreased. From a functional point of view, osseointegration surgery could be a valid solution in patients with transfemoral amputation facing issues with traditional socket-type prosthesis.

Comparison of prosthetic mobility and balance in transfemoral amputees with bone-anchored prosthesis vs. socket prosthesis

BACKGROUND

The literature comparing bone-anchored prosthesis (BAP) with socket prosthesis (SP) consistently reports improvement in physical health and quality of life using primarily patient-reported outcome measures (PROMs).

OBJECTIVE

To determine the differences in mobility and balance using performance-based outcome measures and PROMs in people with transfemoral amputations (TFAs) fitted with BAP vs. SP.

STUDY DESIGN

Causal comparative.

METHODS

Two groups of people with TFAs were recruited: one using a BAP (N = 11; mean age ± standard deviation, 44 ± 14.9 years; mean residual limb length as a percentage of the intact femur, 68% ± 15.9) and another group using a SP (N = 11; mean age ± standard deviation, 49.6 ± 16.0 years; mean residual limb length as a percentage of the intact femur, 81% ± 13.9), and completed the 10-meter walk test, component timed-up-and-go, Prosthetic Limb Users Survey of Mobility™ 12-item, and Activities-specific Balance Confidence Scale.

RESULTS

There were no statistically significant differences between the BAP and SP groups in temporal spatial gait parameters and prosthetic mobility as measured by the 10-meter walk test and component timed-up-and-go, yet large effect sizes were found for several variables. In addition, Activities-specific Balance Confidence Scale and Prosthetic Limb Users Survey of Mobility™ scores were not statistically different between the BAP and SP groups, yet a large effect sizes were found for both variables.

CONCLUSIONS

This study found that people with TFA who use a BAP can demonstrate similar temporal spatial gait parameters and prosthetic mobility, as well as self-perceived balance confidence and prosthetic mobility as SP users. Therefore, suggesting that the osseointegration reconstruction surgical procedure provides an alternative option for a specific population with TFA who cannot wear nor have limitations with a SP. Future research with a larger sample and other performance-based outcome measures and PROMs of prosthetic mobility and balance would further determine the differences between the prosthetic options.

Microprocessor feet improve prosthetic mobility and physical function relative to non-microprocessor feet

Introduction: The clinical benefits associated with the microprocessor regulation of prosthetic ankle position and resistance have largely been reported through manufacturer conducted research in controlled laboratory environments. Measures with greater ecological validity are needed. This study aimed to understand if there are differences in physical function and mobility outcomes as patients transitioned from a non-Microprocessor to Microprocessor Feet. Method: A retrospective analysis of patient outcomes was performed. Patient-reported benefits associated with the adoption of such prosthetic foot-ankle mechanisms were collected from 23 individuals through the longitudinal use of a custom short form of the Patient-Reported Outcomes Measurement Information System-Physical Function and individual items from the Prosthesis Evaluation Questionnaire. Results: The impact of Microprocessor Feet upon physical function and mobility were observed in a significant increase in physical function (mean increase in t-score of 5.4 ± 1.25; p = .0004) and significant improvements in several mobility items. Conclusions: Collectively, these measures support the beneficial impact of Microprocessor Feet on improving socket comfort, reducing back pain, improving sit to stand transfers and enhancing hill ascent and descent as well as stair negotiation.

Error-Manipulation Gait Training for Veterans With Nontraumatic Lower Limb Amputation: A Randomized Controlled Trial Protocol

OBJECTIVE

he purpose of this study will be to determine the efficacy of error-manipulation gait training (error-augmentation or error-correction) to improve step length symmetry and secondary health outcomes in veterans with unilateral nontraumatic transtibial amputation (TTA).

METHODS

This will be a 3-arm, parallel, assessor-blinded, randomized controlled trial, with baseline, postintervention, and 3-month follow-up assessments in a VA Geriatric Research Education and Clinical Center. Participants are 54 US military veterans ranging in age from 50 to 85 years with a unilateral transtibial nontraumatic amputation. Participants will be randomized into 1 of 3 groups: error-augmentation training (EAT), error-correction training (ECT), or supervised walking (CTL). Each group will complete 8 split-belt treadmill walking training sessions of 25 minutes each over 4 weeks. The EAT group will walk with belts moving at asymmetrical speeds. The ECT group will walk to the cadence of a metronome and the split belts moving at symmetrical speeds. The CTL group will walk with symmetrical belt speeds and without feedback. Step length symmetry is the primary outcome and will be assessed using an asymmetry index during overground walking. Secondary outcomes include lower extremity joint work during treadmill walking, 6-Minute Walk Test performance, daily step count, participant-perceived disability, and residual-limb integumentary health. Outcomes will be assessed at preintervention, 1-week postintervention (primary endpoint), and 13 weeks postintervention.

IMPACT

This study protocol focuses on an understudied area of rehabilitation for patients with nontraumatic unilateral TTA who have high levels of spatiotemporal gait asymmetry and mobility impairment. The results of this study will inform future implementation of clinical gait training interventions to improve spatiotemporal gait symmetry and long-term health and disability outcomes in patients with nontraumatic unilateral TTA.

Symmetry function - An effective tool for evaluating the gait symmetry of trans-femoral amputees

BACKGROUND

Prostheses can help persons with trans-femoral amputation (TFA) regain normal function, but such individuals still exhibit gait deviations expressed in gait asymmetries. We apply a specialised tool, the Symmetry Function (SF), to evaluate the symmetry of walking in terms of kinematic and dynamic variables and to identify areas with large side deviations (exceeding defined ±5% threshold) in the movement cycle.

RESEARCH QUESTION

Which movements and joints or GRF components revealed the most significant side deviations in the movement cycle? When exactly are they located in the gate cycle?

METHODS

In this retrospective observational study, an instrumented motion analysis system was used to register the gait of fourteen patients after unilateral TFA. Measurements involved evaluating the time series of gait variables characterising a range of motion and the ground reaction force components. Comparison of the prosthetic (involved) limb with the sound (uninvolved) limb in TFA patients was carried out on the basis of the Symmetry Function values.

RESULTS

The Symmetry Function proved to be an effective tool to localise the regions of asymmetry and limb dominance in the full gait cycle. The difference between sides revealed by the Symmetry Function was the highest for the pelvis and the hip. In the sagittal plane, the pelvis was asymmetrically tilted, reaching the highest SF value of more than 25 % at 60 % cycle time. In the transverse plane, the pelvis was even more asymmetrically positioned throughout the entire gait cycle (50 % difference). The hip in the frontal plane reached a 60 % difference throughout the single support phase for the involved and then for the uninvolved limb.

SIGNIFICANCE

The Symmetry Function allows for the detection of gait asymmetries, temporal shifts in the gait phases and may assess the precise in time adaptation of prostheses and rehabilitation monitoring, especially in unilateral impairments.

Usability Assessment of the Rehabilitation Lower-limb Orthopedic Assistive Device by Service Members and Veterans With Lower Limb Loss

INTRODUCTION

Telehealth is an increasingly common approach to improve healthcare delivery, especially within the Veterans Health Administration and Department of Defense (DoD). Telehealth has diminished many challenges to direct access for clinical follow-up; however, the use of mobile telehealth for specialty rehabilitative care is emerging and is referred to as telerehabilitation. As early adopters of telehealth, the Veterans Affairs and DoD have supported collaborated efforts for programs designed to increase the access and quality of rehabilitative care while improving the functional ability of our service members (SMs) and veterans with lower limb amputation (LLA). The DoD and Veterans Health Administration collaborated on a Mobile Device Outcomes-based Rehabilitation Program (MDORP) to help injured SMs and veterans with LLA. The MDORP project utilized a mobile health system called the Rehabilitative Lower Limb Orthopedic Accommodating Device (ReLOAD) to assess walking quality. The ReLOAD system includes real-time auditory biofeedback to notify the user of their most prominent gait deviation and then recommends exercises that address specific balance and strength impairments. The purpose of this study was to describe the responses to a postintervention survey evaluating the feasibility and usability of ReLOAD completed by SMs and veterans with LLA who used the system for 5 months.

MATERIALS AND METHODS

A link to an anonymous usability survey was emailed to all participants who completed MDORP. The survey was modeled after the System Usability Scale, with agreeableness to items rated on a 5-point Likert-style questionnaire in addition to open feedback. Data visualization of Likert-style questionnaires was conducted using ggplot2 and reshape2 statistical packages and was analyzed using R. We obtained institutional review board approval through both Miami Veterans Affairs Healthcare System and Walter Reed National Military Medical Center.

RESULTS

The majority of participants reported that they would use the system again for home rehabilitation (65%) and that auditory biofeedback helped them walk better (59%). Participants also suggested that future work should include a greater variety of exercise options and the use of smart phones for the ReLOAD application in addition to the iPad tablet.

CONCLUSIONS

The participants provided positive and constructive feedback that will enhance the value and usability of telerehabilitation interventions like the ReLOAD system for future users.

Physical sciences

In the original edition of Prosthetics and Orthotics International, Dr Sidney Fishman identified what he anticipated as foundational educational needs for the emerging field of clinical prosthetics and orthotics. Within the broader construct of the physical sciences, this included mathematics, physics, chemistry, biomechanics, and material sciences. The clinical application of these disciplines to expanding the collective understanding within the field is described, including the biomechanics of able-bodied and prosthetic gait, the material science of socket construction, the physics of suspension and load distribution, and the engineering of prosthetic components to mimic human biomechanics. Additional applications of the physical sciences to upper limb prosthetics and lower limb orthotics are also described. In contemplating the continued growth and maturation of the field in the years to come, mechatronics and statistics are suggested as future areas where clinical proficiency will be required.

Differences in Gait Patterns of Unilateral Transtibial Amputees With Two Types of Energy Storing Prosthetic Feet

OBJECTIVE

To evaluate if there is a difference in gait pattern when applying two different shapes of energy storing prosthetic feet for trainstibial amputation we conducted a comparative study. Energy storing prosthetic feet for transtibial amputation are increasing in use, but there are few studies that evaluate the effects of the shape of energy storing feet on gait patterns.

METHODS

Ten unilateral transtibial amputees were recruited. Two different shapes of dynamic response feet were applied to each subject either 1C30 Trias or 1C60 Triton. The main differences between the two are a split forefoot and the presence of a heel wedge. Spatiotemporal, kinematic, and kinetic data was obtained through gait analysis. Differences between intact and prosthetic side and differences between the two prosthetics were assessed.

RESULTS

On a side to side comparison, cadence asymmetry with 1C30 Trias was observed. Ankle plantarflexion at the end of stance and ankle supination at the onset of preswing was smaller with both prosthetic feet compared to the intact side. Other spatiotemporal, kinematic, and kinetic data showed no significant differences in a side to side comparison. In a comparison between the two prosthetics, stance and swing ratio and ankle dorsiflexion through mid-stance was closer to normal with 1C60 Triton than 1C30 Trias. Other spatiotemporal, kinematic, and kinetic data showed no statistically significant differences between prosthetics.

CONCLUSION

Both energy storing feet implants showed symmetric gait in unilateral transtibial amputees who are functionally independent in daily living. And 1C60 Triton showed closer to normal gait patterns than 1C30 Trias in our study.

Energy storing and return prosthetic feet improve step length symmetry while preserving margins of stability in persons with transtibial amputation

Background

Energy storing and return (ESAR) feet are generally preferred over solid ankle cushioned heel (SACH) feet by people with a lower limb amputation. While ESAR feet have been shown to have only limited effect on gait economy, other functional benefits should account for this preference. A simple biomechanical model suggests that enhanced gait stability and gait symmetry could prove to explain part of the difference in the subjective preference between both feet.

Aim

To investigate whether increased push-off power with ESAR feet increases center of mass velocity at push off and enhance intact step length and step length symmetry while preserving the margin of stability during walking in people with a transtibial prosthesis.

Methods

Fifteen people with a unilateral transtibial amputation walked with their prescribed ESAR foot and a SACH foot at a fixed walking speed (1.2 m/s) over a level walkway while kinematic and kinetic data were collected. Push-off work generated by the foot, center of mass velocity, step length, step length symmetry and backward margin of stability were assessed and compared between feet.

Results

Push-off work was significantly higher when using the ESAR foot compared to the SACH foot. Simultaneously, center of mass velocity at toe-off was higher with ESAR compared to SACH, and intact step length and step length symmetry increased without reducing the backward margin of stability.

Conclusion

Compared to the SACH foot, the ESAR foot allowed an improvement of step length symmetry while preserving the backward margin of stability at community ambulation speed. These benefits may possibly contribute to the subjective preference for ESAR feet in people with a lower limb amputation.

Is symmetry of loading improved for injured runners during novice barefoot running?

BACKGROUND

As barefoot (BF) running provides important sensory information that influence landing patterns, it may also affect loading symmetry.

RESEARCH QUESTION

The purpose of this investigation was to examine whether symmetry of loading in a group of injured runners would be improved in a novice, barefoot condition.

METHODS

Cross-sectional design evaluating 67 injured RFS runners. Each subject ran on an instrumented treadmill, first with their habitual shod pattern and then in a BF condition with a FFS pattern, both at the same self-selected speed. Data were averaged over 10 footstrikes. Variables of interest included vertical average load rate, vertical instantaneous load rate, and resultant instantaneous load rate. Symmetry indices (SI) for full population and within quartiles were compared for each loadrate variable (P ≤ 0.05) to evaluate changes between conditions.

RESULTS

On average, symmetry of loading was similar in a novice BF condition of injured runners compared with their habitual RFS shod condition. However, a subanalysis of quartiles revealed that the injured runners with the highest asymmetry (greatest SI values) displayed significantly lower asymmetry when running BF for all three loadrate measures.

SIGNIFICANCE

The addition of sensory input during barefoot running only improves symmetry of loading when habitual loading is highly asymmetric.

Comparison between three types of prosthetic feet: a randomized double-blind single-subject multiple-rater trial

There are many prosthetic feet (Pfeet) on the market, and those in the same category do not necessarily have the same properties. We assessed three different Pfeet in terms of gait patterns on various terrains, balance and walking speed in a randomized double-blind controlled single-subject multiple-rater clinical trial. The patient was a 43-year old man who was an active prosthesis user and was amputated at transtibial level because of injury 17 years ago. One Solid Ankle Cushion Heel and two Dynamic Elastic Response (DER) Pfeet were tried six times in random order. The patient walked on flat, uneven, sloped terrain and stairs. Gait pattern was rated in comparison with the patient's previous prosthetic foot (Pfoot) by a physiatrist, physiotherapist, prosthetist and the patient; one-leg standing test on the prosthesis and 10-m walking test were also performed. The ratings differed significantly between the raters on each terrain, and there was no agreement among the raters regarding the ranking order of the Pfeet. All the Pfeet were generally rated as worse than the patient's previous one. The patient gave lower ratings on average than the professionals and recognized the order of the tested Pfeet. The results of one-leg standing test with one DER and the Solid Ankle Cushion Heel Pfoot were statistically significant better than with the other DER and the patient's previous Pfoot. Our study therefore indicates that rehabilitation professionals, when blinded, cannot always reliably observe differences in walking on different terrains with different Pfeet. The patient may feel the differences, but those may not match what the manufacturers declare.

Prosthetic energy return during walking increases after 3 weeks of adaptation to a new device

Background

There are many studies that have investigated biomechanical differences among prosthetic feet, but not changes due to adaptation over time. There is a need for objective measures to quantify the process of adaptation for individuals with a transtibial amputation. Mechanical power and work profiles are a primary focus for modern energy-storage-and-return type prostheses, which strive to increase energy return from the prosthesis. The amount of energy a prosthesis stores and returns (i.e., negative and positive work) during stance is directly influenced by the user’s loading strategy, which may be sensitive to alterations during the course of an adaptation period. The purpose of this study was to examine changes in lower limb mechanical work profiles during walking following a three-week adaptation to a new prosthesis.

Methods

A retrospective analysis was performed on 22 individuals with a unilateral transtibial amputation. Individuals were given a new prosthesis at their current mobility level (K3 or above) and wore it for three weeks. Kinematic and kinetic measures were recorded from overground walking at 0, 1.5, and 3 weeks into the adaptation period at a self-selected pace. Positive and negative work done by the prosthesis and sound ankle-foot were calculated using a unified deformable segment model and a six-degrees-of-freedom model for the knee and hip.

Results

Positive work from the prosthesis ankle-foot increased by 6.1% and sound ankle-foot by 5.7% after 3 weeks (p = 0.041, 0.036). No significant changes were seen in negative work from prosthesis or sound ankle-foot (p = 0.115, 0.192). There was also a 4.1% increase in self-selected walking speed after 3 weeks (p = 0.038). Our data exhibited large inter-subject variations, in which some individuals followed group trends in work profiles while others had opposite trends in outcome variables.

Conclusions

After a 3-week adaptation, 14 out of 22 individuals with a transtibial amputation increased energy return from the prosthesis. Such findings could indicate that individuals may better utilize the spring-like function of the prosthesis after an adaptation period.

Electronic supplementary material

The online version of this article (10.1186/s12984-018-0347-1) contains supplementary material, which is available to authorized users.

When to biomechanically examine a lower-limb amputee: A systematic review of accommodation times

BACKGROUND

Hundreds of investigations examining biomechanical outcomes of various prostheses have been completed, but one question remains unanswered: how much time should an amputee be given to accommodate to a new prosthesis prior to biomechanical testing?

OBJECTIVE

To examine the literature for accommodation time given during biomechanical investigations to determine whether consensus exists.

STUDY DESIGN

Systematic review.

METHODS

A systematic search was completed on 7 January 2016 using PubMed and Scopus.

RESULTS

The search resulted in 156 investigations. Twenty-eight studies did not provide an accommodation or were unclear (e.g. provided a "break in period"), 5 studies tested their participants more than once, 25 tested only once and on the same day participants received a new prosthesis (median (range): above-knee: 60 (10-300) min; below-knee: 18 (5-300) min), and 98 tested once and gave a minimum of 1 day for accommodation (hip: 77 (60-180) days; above-knee: 42 (1-540) days; below-knee: 21 (1-475) days).

CONCLUSION

The lack of research specifically examining accommodation and the high variability in this review's results indicates that it remains undecided how much accommodation is necessary. There is a need for longitudinal biomechanical investigations to determine how outcomes change as amputees accommodate to a new prosthesis. Clinical relevance The results of this review indicate that little research has been done regarding lower-limb amputees accommodating to a new prosthesis. Improper accommodation could lead to increased variability in results, results that are not reflective of long-term use, and could cause clinicians to make inappropriate decisions regarding a prosthesis.

Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses

Many studies have reported the effects of different foot prostheses on gait, but most results cannot be generalized because the prostheses' properties are seldom reported. We varied hindfoot and forefoot stiffness in an experimental foot prosthesis, in increments of 15N/mm, and tested the parametric effects of these variations on treadmill walking in unilateral transtibial amputees, at speeds from 0.7 to 1.5m/s. We computed outcomes such as prosthesis energy return, center of mass (COM) mechanics, ground reaction forces, and joint mechanics, and computed their sensitivity to component stiffness. A stiffer hindfoot led to reduced prosthesis energy return, increased ground reaction force (GRF) loading rate, and greater stance-phase knee flexion and knee extensor moment. A stiffer forefoot resulted in reduced prosthetic-side ankle push-off and COM push-off work, and increased knee extension and knee flexor moment in late stance. The sensitivity parameters obtained from these tests may be useful in clinical prescription and further research into compensatory mechanisms of joint function.

Considering passive mechanical properties and patient user motor performance in lower limb prosthesis design optimization to enhance rehabilitation outcomes

Background

Selection of prosthesis mechanical characteristics to restore function of persons with lower-limb loss can be framed as an optimization problem to satisfy a given performance objective. However, the choice of a particular objective is critical, and considering only device and generalizable outcomes across users without accounting for inherent motor performance likely restricts a given patient from fully realizing the benefits of a prosthetic intervention.

Objectives

This review presents methods for optimizing passive below-knee prosthesis designs to maximize rehabilitation outcomes and how considerations on patient motor performance may enhance these outcomes.

Major Findings

Available literature supports that considering patient-specific variables pertaining to motor performance permits a multidimensional landscape relating device characteristics and user function, which may yield more accurate predictions of rehabilitation outcomes for individual patients. Moreover, the addition of targeted physical therapeutic interventions that encourage user self-organization may further improve these outcomes. We note the potential of existing paradigms to address these additional dimensions, and we encourage investigators to consider the many different performance objectives available for prosthesis optimization.

Conclusions

By considering user motor performance in combination with prosthesis mechanical characteristics, a staged optimization approach can be formulated which acknowledges that device modifications may only improve outcomes to a certain extent and user self-organization is a critical component to complete rehabilitation. An iterative process that can be integrated within existing rehabilitative practices accounts for changes in patient status through combined targeted prosthetic solutions and physical therapeutic techniques, and embodies the concept of personalized intervention for patients with lower limb-loss.

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.

Comparison of four different categories of prosthetic feet during ramp ambulation in unilateral transtibial amputees

BACKGROUND

Comparative effectiveness of prosthetic feet during ramp ambulation in unilateral transtibial amputees, who function at different Medicare Functional Classification Levels, has not been published.

OBJECTIVE

To determine differences in symmetry in external work between four categories of prosthetic feet in K-Level-2 and K-Level-3 unilateral transtibial amputees during ramp ascent and descent.

STUDY DESIGN

Randomized repeated-measures trial.

METHODS

Ten subjects completed six testing sessions during which symmetry in external work was calculated using F-scan in-sole sensors. Between testing sessions 1 and 2, subjects received standardized functional prosthetic training. In Sessions 3-6, subjects tested four feet--solid ankle cushion heel, stationary attachment flexible endoskeleton, Talux (categories K1, K2, and K3, respectively), and Proprio-Foot (microprocessor ankle)--using a study socket and had a 10- to 14-day accommodation period with each foot.

RESULTS

During ramp descent, K-Level-2 subjects demonstrated higher symmetry in external work values with Talux and Proprio-Foot compared to the solid ankle cushion heel foot. K-Level-3 subjects also had higher symmetry in external work values with the Talux foot than the solid ankle cushion heel foot. Ramp ascent symmetry in external work values were not significantly different between feet.

CONCLUSIONS

Prosthetic foot category appears to influence symmetry in external work more during decline walking than incline walking. K-Level-2 unilateral transtibial amputees achieve greater symmetry from K3 dynamic response prosthetic feet with J-shaped ankle and microprocessor ankles while descending ramps.

CLINICAL RELEVANCE

The findings suggest that K-Level-2 unilateral transtibial amputees benefit from K3 dynamic response prosthetic feet with J-shaped ankle. These results support the prescription of K3 feet for K-Level-2 amputees who frequently negotiate ramps.

Analysis of weight distribution strategies in unilateral transtibial amputees during the stand-to-sit activity

Current methods of quantifying the stand-to-sit activity (StTS) are resource intensive and have not been applied to unilateral transtibial amputees (TTAs). The purpose of this study is to define five phases of arm-rest assisted and unassisted StTS using simple instrumentation and implement this method for assessing TTA movement patterns. Twelve TTAs and 12 age-matched non-amputees performed StTS with and without arm-rest support. Symmetry of weight distribution between lower limbs was calculated for five StTS phases: Descent Initiation; Descent Deceleration; Seat-Contact; Stabilisation and Sitting. TTAs demonstrated an asymmetrical weight distribution pattern and a tendency to transfer weight to the intact limb during the course of the activity. Non-amputees had relatively higher symmetry and did not exhibit substantial weight shifts during the activity. Symmetry indices were similar for assisted and unassisted sitting in both subject groups. These results highlight a need for therapeutic interventions in TTAs for reducing loading asymmetries and associated co-morbidities.

PRACTITIONER SUMMARY

This study defines a novel method for quantifying stand-to-sit movements using clinically friendly equipment and is the first to investigate the stand-to-sit activity of unilateral transtibial amputees. The observed differences in inter-limb weight distribution strategies between amputees and non-amputees could provide insights for clinical assessment and intervention.

The effects of prosthetic foot type and visual alteration on postural steadiness in below-knee amputees

Background

Achieving independent upright posture has known to be one of the main goals in rehabilitation following lower limb amputation. The purpose of this study was to compare postural steadiness of below knee amputees with visual alterations while wearing three different prosthetic feet.

Methods

Ten male below-knee amputees were instructed to stand quietly on the Biodex® balance platform while wearing solid ankle cushion heel (SACH), single axis (SA) and energy storage and release (ESAR) prosthetic foot under different visual input conditions (eyes-opened and eyes-closed). The overall stability index (OSI), anterior- posterior stability index (APSI), and medial-lateral stability index (MLSI) were computed. Perceived balance assessment of each foot was evaluated using Activities-specific Balance Confidence (ABC) score.

Results

The findings highlights that SACH showed lowest overall stability index (indicating less body sway) during eyes-opened (OSI: SACH = 1.09, SA = 1.58, ESAR = 1.59) and SA showed lowest overall stability index during eyes-closed (OSI: SACH = 2.52, SA = 2.30, ESAR = 2.76) condition. However, overall stability indexes between foot types did not differ significantly during eyes-opened or eyes-closed (p = 0.651). There was a trend of instability which occurred more in medial-lateral compared to anterior-posterior direction for all foot types, with significant result in ESAR foot(eyes-opened: MLSI = 1.59, APSI = 0.65, p = 0.034; eyes-closed: MLSI = 2.76, APSI = 1.80, p = 0.017, respectively). When comparing between visual conditions, stability score was significantly higher during eyes-closed compared to eyes-opened situations for SACH and ESAR foot (eyes-closed vs opened; SACH OSI: 3.43 vs 1.71, p = 0.018 and MLSI: 3.43 vs 1.71, p = 0.018; ESAR OSI: 3.58 vs 1.86, p = 0.043 and APSI: 1.80 vs 0.65, p = 0.027).

Conclusions

The results of this study suggested postural steadiness in below-knee amputees was not affected by the types of prosthetic foot during quiet upright standing, but was significantly affected when visual cues was absent.