Optimisation of the prescription for trans-tibial (TT) amputees

The Functionality Verification through Pilot Human Subject Testing of MyFlex-δ: An ESR Foot Prosthesis with Spherical Ankle Joint

Most biomechanical research has focused on level-ground walking giving less attention to other conditions. As a result, most lower limb prosthesis studies have focused on sagittal plane movements. In this paper, an ESR foot is presented, of which five different stiffnesses were optimized for as many weight categories of users. It is characterized by a spherical ankle joint, with which, combined with the elastic elements, the authors wanted to create a prosthesis that gives the desired stiffness in the sagittal plane but at the same time, gives flexibility in the other planes to allow the adaptation of the foot prosthesis to the ground conditions. The ESR foot was preliminarily tested by participants with transfemoral amputation. After a brief familiarization with the device, each participant was asked to wear markers and to walk on a sensorized treadmill to measure their kinematics and kinetics. Then, each participant was asked to leave feedback via an evaluation questionnaire. The measurements and feedback allowed us to evaluate the performance of the prosthesis quantitatively and qualitatively. Although there were no significant improvements on the symmetry of the gait, due also to very limited familiarization time, the participants perceived an improvement brought by the spherical ankle joint.

Effects of women’s footwear on the mechanical function of heel-height accommodating prosthetic feet

The loaded mechanical function of transtibial prostheses that result from the clinical assembly, tuning, and alignment of modular prosthetic components can directly influence an end user’s biomechanics and overall mobility. Footwear is known to affect prosthesis mechanical properties, and while the options of footwear are limited for most commercial feet due to their fixed geometry, there exists a selection of commercial prosthetic feet that can accommodate a moderate rise in heel height. These feet are particularly relevant to women prosthesis users who often desire to don footwear spanning a range of heel heights. The aim of this study was to assess the effects of adding women’s footwear (flat, trainer, 5.08 cm heel) on the mechanical properties (deformation and energy efficiency) of four models of heel-height accommodating prosthetic feet. Properties were measured through loading-unloading at simulated initial contact, midstance and terminal stance orientations with a universal materials test system, and statistically compared to a barefoot condition. Results suggest that the addition of footwear can alter the level of foot deformation under load, which may be a function of the shoe and alignment. Moreover, while each foot displayed different amounts of energy storage and return, the addition of footwear yielded similar levels of energy efficiency across foot models. Overall, prosthesis users who don shoes of varying heel heights onto adjustable prosthetic feet and their treating clinicians should be aware of the potential changes in mechanical function that could affect the user experience.

A systematic review on design technology and application of polycentric prosthetic knee in amputee rehabilitation

The objective of this paper is to conduct a systematic review on design technology and clinical application of polycentric prosthetic knee joint in the rehabilitation of trans-femoral amputees. Relevant studies were identified using electronic database such as PubMed, EMBASE, SCOPUS and the Cochrane Controlled Trials Register (Rehabilitation and Related Therapies) up to February 2020. Screening of abstracts and application of inclusion and exclusion criteria were made. Design, modeling, material use, kinematic study, simulation technique and clinical application of polycentric knee models used in many developed and developing countries have been reviewed. Out of 516 potentially relevant studies, 43 articles were included. Specific variables on technical and clinical aspects were extracted and added to summary tables. The results reveal that polycentric knees have a variety of geometries but the methods for comparing their performances are rare. The data of structural analysis using different simulation techniques are validated with experimental results for determining model accuracy. Gait analysis using the polycentric knee components provides a valid tool to correlate with experimental results. There are well-designed studies on the technological development of polycentric knees, however, high-quality clinical researches are scarce. Conventional clinical knowledge had considerable gaps concerning the effects of polycentric knee and their mechanical characteristics on human functioning with a lower-limb prosthesis. Still, further research is needed to develop and implement standardized measures on prosthetic knee joints for their effective use, function, durability, and cost-effectiveness.

Stiffness and energy storage characteristics of energy storage and return prosthetic feet

BACKGROUND

Mechanical properties of prosthetic feet can significantly influence amputee gait, but how they vary with respect to limb loading and orientation is infrequently reported.

OBJECTIVE

The objective of this study is to measure stiffness and energy storage characteristics of prosthetic feet across limb loading and a range of orientations experienced in typical gait.

STUDY DESIGN

This study included mechanical testing.

METHODS

Force-displacement data were collected at combinations of 15 sagittal and 5 coronal orientations and used to calculate stiffness and energy storage across prosthetic feet, stiffness categories, and heel wedge conditions.

RESULTS

Stiffness and energy storage were highly non-linear in both the sagittal and coronal planes. Across all prosthetic feet, stiffness decreased with greater heel, forefoot, medial, and lateral orientations, while energy storage increased with forefoot, medial, and lateral loading orientations. Stiffness category was proportional to stiffness and inversely proportional to energy storage. Heel wedge effects were prosthetic foot dependent.

CONCLUSION

Orientation, manufacturer, stiffness category, and heel wedge inclusion greatly influenced stiffness and energy storage characteristics.

CLINICAL RELEVANCE

These results and an available graphical user interface tool may help improve clinical prescriptions by providing prosthetists with quantitative measures to compare prosthetic feet.

Instantaneous stiffness and hysteresis of dynamic elastic response prosthetic feet

BACKGROUND

Dynamic elastic response prosthetic feet are designed to mimic the functional characteristics of the native foot/ankle joint. Numerous designs of dynamic elastic response feet exist which make the prescription process difficult, especially because of the lack of empirical evidence describing the objective performance characteristics of the feet.

OBJECTIVES

To quantify the mechanical properties of available dynamic elastic response prosthetic feet, specifically the stiffness and hysteresis.

STUDY DESIGN

Mechanical testing of dynamic elastic response prosthetic feet.

METHODS

Static Proof Testing in accordance with ISO 10328 was conducted on seven dynamic elastic response prosthetic feet. Load-displacement data were used to calculate the instantaneous stiffness in both the heel and forefoot regions, as well as hysteresis associated with each foot.

RESULTS

Heel stiffness was greater than forefoot stiffness for all feet. The heel of the glass composite prosthetic foot was stiffer than the carbon fiber feet and it exhibited less hysteresis. Two different carbon fiber feet had the stiffest forefoot regions.

CONCLUSION

Mechanical testing is a reproducible method that can be used to provide objective evidence about dynamic elastic response prosthetic foot performance and aid in the prescription process. Clinical relevance The quantitative stiffness and hysteresis data from this study can be used by prosthetists to aid the prescription process and make it more objective.

Biomechanics and physiological parameters during gait in lower-limb amputees: a systematic review

OBJECTIVE

The purpose of this systematic review was to identify which biomechanical and physiological parameters are the most relevant, commonly used, able to discriminate and/or have specific clinical relevance for the gait analysis of lower-limb amputees (LLA).

METHODS

We performed an electronic search via the PubMed, EMBASE and ISI Web of Knowledge databases from 1979 to May 2009. Two independent reviewers assessed the title and abstract of each identified study. The quality assessment of the full text was undertaken using a 13-item checklist divided into three levels: A, B, and C.

RESULTS

The literature search identified 584 abstracts to be considered. After applying the inclusion criteria, we reviewed the full text of a total of 89 articles. The mean article quality was 8±2. No A-level article was found; the primary reason was a negative score in blinded outcome assessment. Sixty-six articles (74%) corresponded to a B-level, and two articles (2%) corresponded to a C-level. Twenty-one articles (24%) did not acquire enough points to be assigned to any level. In this study, we present and discuss the most commonly used and most relevant 32 parameters. Many of the parameters found were not reported in enough studies or in enough detail to allow a useful evaluation.

CONCLUSION

This systematic review can help researchers compare, choose and develop the most appropriate gait evaluation protocol for their field of study, based on the articles with best scores on the criteria list and the relevance of specific biomechanical and physiological parameters.

A new methodology to measure the running biomechanics of amputees

We present a new methodology to measure the running biomechanics of amputees. This methodology combines the use of a spring-mass model and symmetry index, two standard techniques in biomechanics literature, but not yet used in concert to evaluate amputee biomechanics. The methodology was examined in the context of a pilot study to examine two transtibial amputee sprinters and showed biomechanically quantifiable changes for small adjustments in prosthetic prescription. Vertical ground reaction forces were measured in several trials for two transtibial amputees running at constant speed. A spring-mass model was used in conjunction with a symmetry index to observe the effect of varying prosthetic height and stiffness on running biomechanics. All spring-mass variables were significantly affected by changes in prosthetic prescription among the two subjects tested (p < 0.05). When prosthetic height was changed, both subjects showed significant differences, in Deltay(max), Deltal and contact time (t(c)) on the prosthetic limb and in k(vert) and k(leg) on the sound limb. The symmetry indices calculated for spring-mass variables were all significantly affected due to changes in prosthetic prescription for the male subject and all but the peak force (F(peak)) for the female subject. This methodology is a straight-forward tool for evaluating the effect of changes to prosthetic prescription.

The Effect of Foot and Ankle Prosthetic Components on Braking and Propulsive Impulses During Transtibial Amputee Gait

OBJECTIVE

To assess the influence of energy storage and return (ESAR) prosthetic feet and multi-axis ankles on ground reaction forces and loading asymmetry between lower limbs in transtibial amputees.

DESIGN

Subjects wore 2 different prosthetic feet with and without a multi-axis ankle and were analyzed using a blind repeated-measures multivariate analysis-of-variance design.

SETTING

Gait analysis laboratory.

PARTICIPANTS

Fifteen healthy unilateral transtibial amputees (>55 y) who had an amputation at least 1 year before testing because of vascular disorders.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The anteroposterior ground reaction force impulse, peak ground reaction forces, and braking and propulsion impulse duration were analyzed as subjects walked at a self-selected speed while wearing each of the 4 foot-ankle prosthesis combinations. Statistical analyses were used to determine if there was a significant foot, ankle, or foot-ankle interaction effect on the outcome measures for each foot (P<.05).

RESULTS

Amputees generated a significantly greater propulsive impulse with the residual leg when wearing a multi-axis ankle with the ESAR and non-ESAR foot, which improved the propulsive symmetry between the residual and intact legs. There was no prosthetic foot effect on these measures. There were no significant differences in the peak residual-leg braking or propulsive ground reaction forces or the impulse durations due to the prosthetic foot, ankle, or foot-ankle interactions, although an increase in the propulsive impulse duration approached significance (P=.062) with a multi-axis ankle.

CONCLUSIONS

These results suggest that amputee gait may improve with the prescription of multi-axis ankles that allow for greater propulsive impulses by the residual leg, which improve the loading symmetry between legs.

A functional evaluation of prosthetic foot kinematics during lower-limb amputee gait

This paper reports on a functional evaluation of prosthetic feet based on gait analysis. The aim is to analyse prosthetic feet behaviour under loads applied during gait in order to quantify user benefits for each foot. Ten traumatic amputees (six trans-tibial and four trans-femoral) were tested using their own prosthetic foot. An original protocol is presented to calculate the forefoot kinematics together with the overall body kinematics and ground reaction forces during gait. In this work, sagittal motion of the prosthetic ankle and the forefoot, time-distance parameters and ground reaction forces were examined. It is shown that an analysis of not only trans-tibial but also trans-femoral amputees provides an insight in the performance of prosthetic feet. Symmetry and prosthetic propulsive force were proved to be mainly dependant on amputation level. In contrast, the flexion of the prosthetic forefoot and several time-distance parameters are highly influenced by foot design. Correlations show influential of foot and ankle kinematics on other parameters. These results suggest that prosthetic foot efficiency depends simultaneously on foot design and gait style. The evaluation, proposed in this article, associated to clinical examination should help to achieve the best prosthetic foot match to a patient.

Componentry for lower extremity prostheses

Prosthetic components for both transtibial and transfemoral amputations are available for patients of every level of ambulation. Most current suspension systems, knees, foot/ankle assemblies, and shock absorbers use endoskeletal construction that emphasizes total contact and weight distribution between bony structures and soft tissues. Different components offer varying benefits to energy expenditure, activity level, balance, and proprioception. Less dynamic ambulators may use fixed-cadence knees and non-dynamic response feet; higher functioning walkers benefit from dynamic response feet and variable-cadence knees. In addition, specific considerations must be kept in mind when fitting a patient with peripheral vascular disease or diabetes.

Claimed walking distance of lower limb amputees

PURPOSE

Walking ability in general and specifically for lower limb amputees is of major importance for social mobility and ADL independence. Walking determines prosthesis prescription. The aim of this study was to mathematically analyse factors influencing claimed walking distance of lower limb amputees of 500 m or more.

METHOD

A total of 437 patients returned two questionnaires: the Groningen Questionnaire Problems after Leg Amputation, in which walking distance was assessed, and the RAND 36.

RESULTS

The chance of walking 500 m or more reduced when a transfemoral amputation was performed. The chance reduced even more when phantom pain or stump pains were present. If the amputation was performed because of vascular disease or because of vascular problems because of diabetes the chance reduced again. Independently of these factors, age reduced the chance of walking 500 m or more.

CONCLUSION

The chance of walking 500 m or more reduces with increase in age and a more proximal amputation. The chance reduces even further when the amputation is performed because of diabetes or vascular disease and also if phantom pain and or stump pain is present.

Prescription of prosthetic ankle-foot mechanisms after lower limb amputation

BACKGROUND

A correct prosthetic prescription can be derived from adapting the functional benefits of a prosthesis to the functional needs of the prosthetic user. For adequate matching, the functional abilities of the amputees are of value, as well as the technical and functional aspects of the various prosthetic ankle-foot mechanisms. There seems to be no clear clinical consensus on the precise prescription criteria for the various prosthetic ankle-foot mechanisms related to the functional abilities of amputees.

OBJECTIVES

To obtain information about aspects of prosthetic ankle-foot mechanisms and daily functioning of amputees with a prosthesis, for appropriate prosthetic prescription criteria.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Injuries Group specialised register of trials (April 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (1966 to April 2003), EMBASE (1983 to April 2003), CINAHL (1982 to April 2003) and reference lists of articles. No language restrictions were applied.

SELECTION CRITERIA

All randomised controlled trials and quasi-randomised controlled trials comparing different prosthetic devices for lower limb amputation in adults. No language restrictions were applied.

DATA COLLECTION AND ANALYSIS

Two reviewers independently identified potential articles from the literature search. Methodological quality was assessed using a checklist comprising 13 criteria. The reviewers extracted data using pre-defined extraction forms.

MAIN RESULTS

Twenty-three trials were included, with a total of 217 participants. The methodological quality was moderate. Only one study was of high quality. No classical RCT's were identified, yet, all included studies used cross-over designs allowing sufficient control for confounding. In high activity transfemoral amputees, there is limited evidence for the superiority of the Flex foot during level walking compared with the SACH foot in respect of energy cost and, gait efficiency. This benefit has only been confirmed in transtibial amputees during decline and incline walking and increased walking speeds.

REVIEWER'S CONCLUSIONS

There is insufficient evidence from high quality comparative studies for the overall superiority of any individual type of prosthetic ankle-foot mechanism. In high activity transfemoral amputees, there is limited evidence for the superiority of the Flex foot during level walking compared with the SACH foot in respect of energy cost and, gait efficiency. This benefit has only been confirmed in transtibial amputees during decline and incline walking and increased walking speeds. In prescribing prosthetic-ankle foot mechanisms for lower-limb amputees, practitioners should take into account availability, patient functional needs, and cost.

Prosthetic prescription in the Netherlands: an observational study

Prosthetic prescription for lower limb amputees and the methodology used are primarily based on empirical knowledge. Clinical expertise plays an important role that can lead to an adequate prescription; however, a clear evidence based motivation for the choices made cannot be given. This can lead to local prescription variations with regard to overuse or underuse of prosthetic care and a lack of transparency for consumers and health insurance companies. Hence a clinical guideline may lead to a more consistent and efficient clinical practice and thus more uniformly high quality care. The purpose of this study was to get insight into potential similarities in prescription criteria in clinical practice in the Netherlands. Secondly, the authors were interested to know if prosthetic prescription was primarily based on the level of activity or intended use of the prosthesis. As part of the development of a consensus-based clinical guideline a multi-centred, cross-sectional study was carried out in order to observe the prosthetic prescription for a group of lower limb amputees. Therefore prescription data were collected from 151 amputees with trans-femoral amputation, knee disarticulation or trans-tibial amputation. Results of the multiple logistic regression show no relationship between the activity level and any of the variables included in the equation such as the hospital or medical doctor in Physical and Rehabilitation Medicine (MD in P&RM), prosthetic components, age of the amputee or reason of amputation. The criteria used are merely based on the clinical expertise and local experience whereas the actual prescriptions differ from location to location. In conclusion the development of a clinical guideline for prosthetic prescription in lower limb amputation is recommended. The information gained from this observational study will be used in a clinical guideline procedure for prosthetic prescription in the Netherlands.

Gait analysis in prosthetics: opinions, ideas and conclusions

A review was performed of the literature of the last eleven years (1990-2000) with the topic: "clinical use of instrumented gait analysis in patients wearing a prosthesis of the lower limb". To this end a literature search was performed in Embase, Medline and Recal. Forty-five (45) articles were identified for study from which 34 were reviewed. The reviews were divided into five subtopics: 1) adaptive strategies in gait (12 studies); 2) the influence of different parts of the prosthesis on gait (12 studies); 3) pressure measurements in the socket in gait studies (4 studies); 4) the influence of the mass of the prostheses on gait (5 studies); 5) energy considerations in gait (2 studies). A considerable part of the studies concerned the adaptive strategies of the amputee in walking and running and the evaluation of different prosthetic feet. All aspects and outcomes were reviewed concerning the clinical relevance.

Specialized prostheses for activities. An update

The ideal prosthetic foot would imitate perfectly the human foot in form and function. This is not possible given current technology. Foot designs must use the most appropriate materials organized in such a way as to functionally optimize ground reaction forces generated as the patient stands or walks. The incorporation of materials from the aerospace industry allows designers to create lightweight feet, which are capable of controlled deformation under load and the memory to return to their original shape when the load is removed. These dynamic elastic response prosthetic feet have revolutionized the functional properties of the prosthesis and the functional capabilities of the patient. Patients presently are limited less by their prosthesis than ever before, allowing them to pursue most activities. An increasing number of designs are available to enhance most activities, making appropriate selection of a specific component a difficult task. A simple functional categorization of dynamic prosthetic feet is presented to assist in selection.