Energy Storing Prosthetic Feet Research Articles

High-Level Mobility of Trans-Tibial Prosthesis Users Wearing Commercial and sPace Energy-Storing Prosthetic Feet.

Outcomes of users provided with a commercial ESR Vari-Flex foot (Össur, Reykjavik, Iceland) and a locally designed sPace foot were investigated. Step activity with users’ own prosthetic foot compared to the sPace foot was explored. Methods: Eleven individuals with unilateral trans-tibial amputation participated and were provided with an sPace and Vari-Flex foot. Ten- and twenty-meter walk tests (10/20MWT) at comfortable and fast walking speeds (CWS/FWS), the two-minute walk test (2-MWT) and Comprehensive High-Level Activity Mobility Predictor (CHAMP) were administered. A subgroup was provided a pedometer to record their steps over a 7-day period in their own foot and later the sPace. Results: The sPace foot performed well in a battery of high-level mobility outcome measures. On CHAMP, participants scored 16.94 ± 5.41 and 16.72 ± 6.09 with the sPace and Vari-Flex feet, respectively. Subgroup testing of step activity showed 4490 ± 3444 steps in users’ own feet and 3115 ± 1967 in the sPace foot, p = 0.176. Conclusions: Participants using the sPace foot were capable of performing walking, high-level mobility and activity outcome measures.

Evaluation of a quasi-passive biarticular prosthesis to replicate gastrocnemius function in transtibial amputee gait

Lower limb amputees experience gait impairments, in part due to limitations of prosthetic limbs and the lack of a functioning biarticular gastrocnemius (GAS) muscle. Energy storing prosthetic feet restore the function of the soleus, but not GAS. We propose a transtibial prosthesis that implements a spring mechanism to replicate the GAS. A prototype Biarticular Prosthesis (BP) was tested on seven participants with unilateral transtibial amputation. Participants walked on an instrumented treadmill with motion capture, first using their prescribed prosthesis, then with the BP in four different spring stiffness conditions. A custom OpenSim musculoskeletal model, including the BP, was used to estimate kinematics, joint torques, and muscle forces. Kinematic symmetry was evaluated by comparing the amputated and intact angles of the ankle, knee, and hip. The BP knee and ankle torques were compared to the intact GAS. Finally, work done by the BP spring was calculated at the ankle and knee. There were no significant differences between conditions in kinematic symmetry, indicating that the BP performs similarly to prescribed prostheses. When comparing the BP torques to intact GAS, higher spring stiffness better approximated peak GAS torques, but those peaks occurred earlier in the gait cycle. The BP spring did positive work on the knee joint and negative work on the ankle joint, and this work increased as BP spring stiffness increased. The BP has the potential to improve amputee gait compensations associated with the lack of biarticular GAS function, which may reduce their walking effort and improve quality of life.

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

ObjectiveTo 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.MethodsTen 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.ResultsOn 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.ConclusionBoth 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.

하지절단자용 에너지저장형 인공발의 사용성 평가

재활공학연구소에서는 산재환자의 원활한 직무활동을 위하여 직무활동의 특성에 부합하는 다양한 재활보조기구를 보급하고 있다. 이 중 재활공학연구소에서 개발된 직무지원용 인공발은 탄소복합소재의 에너지 저장 및 방출 특성을 활용하여 장시간의 보행 및 업무 시에 신체 에너지 소모를 절감할 수 있도록 고안되었다. 본 연구에서는 공급된 인공발의 사용현황 파악 및 향후 인공발 개발에 반영하기 위한 개선 요소를 도출하기 위하여 사용중인 인공발에 대한 사용성 평가를 수행하였다. 사용성 평가 방법은 35문항의 우편 설문방법을 사용하였으며, 총 89명을 대상으로 하여 50명으로부터 설문 결과를 획득하였다. 기능성 평가 결과, 전체 응답자의 78%의 응답자들이 이전에 사용했던 인공발과 비교하여 공급받은 인공발을 긍정적으로 평가하였다. 발의 탄력을 평가한 결과, 보행 시 발이 딱딱하다는 평가가 나타났다. 사용성 평가 결과, 실제 사용자들이 제품의 주요 기능뿐만 아니라 소음, 외관 등 부가적인 요소에 민감한 것을 확인하였다. 공급 시 발의 강성을 선택할 때에는 단순히 체중에 비례한 선택보다는 대상자의 보행 특성 등과 같은 실질적 요소에 따라 적합한 강성을 선택하는 것이 중요함을 확인하였다.

Passive Prosthetic Foot Shape and Size Optimization Using Lower Leg Trajectory Error

A method is presented to optimize the shape and size of a passive, energy-storing prosthetic foot using the lower leg trajectory error (LLTE) as the design objective. The LLTE is defined as the root-mean-square error between the lower leg trajectory calculated for a given prosthetic foot's deformed shape under typical ground reaction forces (GRFs), and a target physiological lower leg trajectory obtained from published gait data for able-bodied walking. Using the LLTE as a design objective creates a quantitative connection between the mechanical design of a prosthetic foot (stiffness and geometry) and its anticipated biomechanical performance. The authors' prior work has shown that feet with optimized, low LLTE values can accurately replicate physiological kinematics and kinetics. The size and shape of a single-part compliant prosthetic foot made out of nylon 6/6 were optimized for minimum LLTE using a wide Bezier curve to describe its geometry, with constraints to produce only shapes that could fit within a physiological foot's geometric envelope. Given its single part architecture, the foot could be cost effectively manufactured with injection molding, extrusion, or three-dimensional printing. Load testing of the foot showed that its maximum deflection was within 0.3 cm (9%) of finite element analysis (FEA) predictions, ensuring the constitutive behavior was accurately characterized. Prototypes were tested on six below-knee amputees in India—the target users for this technology—to obtain qualitative feedback, which was overall positive and confirmed the foot is ready for extended field trials.

Assessment of low- and high-level task performance in people with transtibial amputation using crossover and energy-storing prosthetic feet: A pilot study.

Crossover feet incorporate features of energy-storing feet and running-specific feet. As such, crossover feet may be suitable for both daily ambulation and participation in physically demanding activities. To compare crossover feet and energy-storing feet on performance-based tests including a range of low-level (e.g. sit-to-stand) and high-level (e.g. jogging) activities. Cross-sectional, repeated measures. Participants with transtibial amputation completed a battery of performance-based outcome measures, including the Five Times Sit-to-Stand, Timed-Up-and-Go, Four Square Step Test, and the Comprehensive High-level Activity Mobility Predictor. Participants wore duplicate prostheses fit with crossover feet and energy-storing feet to perform the tests; the order of foot conditions was randomized. Paired t tests were used to evaluate differences between feet and order of testing. Data from seven participants showed improvements in all measures while using crossover feet. Improvements in the second foot condition were also observed, indicating a practice effect for all measures. However, differences between feet and order of conditions were not statistically significant ( p > 0.05). Results of this study suggest that crossover feet may improve low- and high-level mobility outcomes. However, intervention effects are small and practice effects were observed in all outcomes. Future research is needed to evaluate the influence of practice effects on performance-based mobility measures. Crossover feet may improve transtibial prosthesis users' performance compared to energy-storing feet across a range of activities, but additional research is needed. Practice effects may be an influential factor in the measurement of performance-based mobility outcomes and should be considered when performing a clinical assessment.

Functional Outcomes in People with Transtibial Amputation Using Crossover and Energy-Storing Prosthetic Feet: A Pilot Study

ABSTRACT Introduction Contemporary prosthetic feet are purposefully designed to address the many functional limitations experienced by people with transtibial amputation (TTA). Choice of materials, geometry, and fabrication techniques contribute to the overall performance of the foot, and ultimately to the functional outcomes achieved by the user. The crossover foot is a novel foot design that integrates features from traditional energy-storing feet and modern, running-specific feet in an effort to maximize performance and energy return. Although initial user feedback is promising, research is needed to determine whether the crossover foot is capable of improving user outcomes relative to other types of contemporary prosthetic feet. Materials and Methods A cross-sectional pilot study was conducted to evaluate mobility, endurance, perceived exertion, and walking performance attained by participants wearing prostheses with crossover and energy-storing feet. Participants with unilateral TTA were administered a short battery of performance-based tests while wearing a prosthesis with a crossover foot and a prosthesis with a traditional energy-storing foot. The order of prostheses worn was randomly assigned. Tests included the Timed Up and Go (TUG) performed at comfortable speed, the TUG performed at fast speed, and the 6-minute walk test (6MWT). Spatiotemporal measures (speed, cadence, step length, step width, and step time) were assessed during the 6MWT using a GAITRite electronic walkway. Participants were asked to report their perceived exertion following the 6MWT using the Borg rating of perceived exertion (CR100). Results Seven participants completed all pilot study procedures. On average, participants exhibited better mobility at comfortable and fast speeds (0.83 second and 0.63 second faster during the TUG-comfortable and TUG-fast, respectively), improved endurance (19.7 m farther in the 6MWT), reduced perceived exertion (12.9 points less on the Borg CR100), increased speed (0.05 m/s), faster cadence (2 steps/min), and longer sound side steps (3.3 cm) while wearing the crossover foot than when wearing the energy-storing foot. However, not all participants exhibited the same functional benefits from using the crossover foot. Conclusions The crossover foot is a promising prosthetic foot design that appears to provide modest functional benefits to transtibial prosthesis users. Given the pilot nature of this study, additional research is needed to assess benefits across a larger and more diverse range of users to inform prescription practices.

Energy expenditure in people with transtibial amputation walking with crossover and energy storing prosthetic feet: A randomized within-subject study

BackgroundEnergy storing feet are unable to reduce the energy required for normal locomotion among people with transtibial amputation. Crossover feet, which incorporate aspects of energy storing and running specific feet, are designed to maximize energy return while providing stability for everyday activities. Research questionDo crossover prosthetic feet reduce the energy expenditure of walking across a range of speeds, when compared with energy storing feet among people with transtibial amputation due to non-dysvascular causes? MethodsA randomized within-subject study was conducted with a volunteer sample of twenty-seven adults with unilateral transtibial amputation due to non-dysvascular causes. Participants were fit with two prostheses. One had an energy storing foot (Össur Variflex) and the other a crossover foot (Össur Cheetah Xplore). Other components, including sockets, suspension, and interface were standardized. Energy expenditure was measured with a portable respirometer (Cosmed K4b2) while participants walked on a treadmill at self-selected slow, comfortable, and fast speeds with each prosthesis. Gross oxygen consumption rates (VO2 ml/min) were compared between foot conditions. Energy storing feet were used as the baseline condition because they are used by most people with a lower limb prosthesis. Analyses were performed to identify people who may benefit from transition to crossover feet. ResultsOn average, participants had lower oxygen consumption in the crossover foot condition compared to the energy storing foot condition at each self-selected walking speed, but this difference was not statistically significant. Participants with farther six-minute walk test distances, higher daily step counts, and higher Medicare Functional Classification Levels at baseline were more likely to use less energy in the crossover foot. SignificanceCrossover feet may be most beneficial for people with higher activity levels and physical fitness. Further research is needed to examine the effect of crossover feet on energy expenditure during high-level activities.

Laboratory- and community-based health outcomes in people with transtibial amputation using crossover and energy-storing prosthetic feet: A randomized crossover trial.

Contemporary prosthetic feet are generally optimized for either daily or high-level activities. Prosthesis users, therefore, often require multiple prostheses to participate in activities that span a range of mobility. Crossover feet (XF) are designed to increase the range of activities that can be performed with a single prosthesis. However, little evidence exists to guide clinical prescription of XF relative to traditional energy storing feet (ESF). The objective of this study was to assess the effects of XF and ESF on health outcomes in people with transtibial amputation. A randomized crossover study was conducted to assess changes in laboratory-based (endurance, perceived exertion, walking performance) and community-based (step activity and self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction) outcomes. Twenty-seven participants were fit with XF and ESF prostheses with standardized sockets, interfaces, and suspensions. Participants were not blinded to the intervention, and wore each prosthesis for one month while their steps were counted with an activity monitor. After each accommodation period, participants returned for data collection. Endurance and perceived exertion were measured with the Six-Minute Walk Test and Borg-CR100, respectively. Walking performance was measured using an electronic walkway. Self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction were measured with survey instruments. Participants also reported foot preferences upon conclusion of the study. Differences between feet were assessed with a crossover analysis. While using XF, users experienced improvements in most community-based outcomes, including mobility (p = .001), fatigue (p = .001), balance confidence (p = .005), activity restrictions (p = .002), and functional satisfaction (p < .001). Participants also exhibited longer sound side steps in XF compared to ESF (p < .001). Most participants (89%) reported an overall preference for XF; others (11%) reported no preference. Results indicate that XF may be a promising alternative to ESF for people with transtibial amputation who engage in a range of mobility activities.Trial registration: ClinicalTrials.gov NCT02440711

Differences in Military Obstacle Course Performance Between Three Energy-Storing and Shock-Adapting Prosthetic Feet in High-Functioning Transtibial Amputees: A Double-Blind, Randomized Control Trial.

Approximately 683 persons engaged in military service experienced transtibial amputation (TTA) related to recent war in Iraq and Afghanistan. Military TTAs function at a level beyond basic ambulation. No empirical data demonstrate which higher functioning prosthetic feet maximize injured service personnel's ability to continue performing at a level commensurate with return to duty. This study's purpose was to determine which of three high-functioning, energy-storing prosthetic feet maximize performance and preference in a field obstacle course (OC) and to quantify physical performance differences between TTAs and high-functioning nonamputees. A randomized, double-blind, repeated measures experimental design compared three prosthetic feet (Ossur Variflex, Endolite Elite Blade, and Ossur Re-Flex Rotate) during performance on a field OC. TTAs accommodated with study feet and the OC before assessment. 14 TTAs and 14 nonamputee controls completed the course. Subjective and objective performance differences were compared across feet conditions and between groups. Total OC completion times were similar between prosthetic feet: Elite-Blade (419 seconds ± 130), Variflex (425 seconds ± 144), and Re-Flex Rotate (444 seconds ± 220). Controls' OC completion time (287.2 seconds ± 58) was less (p ≤ 0.05) than TTA times. In total, controls had faster completion times (p ≤ 0.05) compared to all prosthetic feet conditions in 13/17 obstacles. Re-Flex Rotate had 2 additional obstacles different (p ≤ 0.05) than controls and required more time to complete. Median RPE values were lower (p ≤ 0.05) for controls than TTA regardless of foot. Regarding foot preference for OC completion, 7/14 (50%) preferred Elite Blade, 5/14 (36%) preferred Re-Flex Rotate, and the remaining 2/14 (14%) preferred Variflex. Controls completed the OC faster and with less effort than TTAs regardless of prosthetic foot. No clear differences in prosthetic feet emerged during OC completion; however, individual task performance, perceived effort, and preference resulted in trends of slight performance improvement with and preference for Elite Blade, a dual function energy-storing and return foot combined with vertical shock absorption. Understanding how to maximally improve performance in such functional tasks may allow service members to best sustain physical fitness, return to their military occupational specialty and possibly in-theater duty.

ANALYSIS OF DYNAMIC BALANCE CONTROL IN TRANSTIBIAL AMPUTEES WITH USE OF A POWERED PROSTHETIC FOOT

Powered prosthetic feet (PPF) are designed to provide transtibial amputees (TTA) with active propulsion and range of motion similar to that of the biological limb. Previous studies have demonstrated the PPF’s ability to increase TTA walking speeds while reducing the energetic costs, however, little is known about its effects on dynamic balance control. The purpose of this pilot study was to assess dynamic balance control in TTA subjects during level ground walking and obstacle-crossing tasks. Control subjects ([Formula: see text]) and TTA subjects ([Formula: see text]) were instructed to complete a series of functional walking tasks. The TTA subjects completed the walking protocol twice, first in their passive energy-storing prosthetic foot (ESPF) and again in the prescribed PPF after two weeks of acclimation. Motion data were collected via a 10-camera system with a 53-marker and 15-segment body model. Whole body medial-lateral center of mass motion (displacement and peak velocity) was analyzed and used as a functional indicator of dynamic balance control. Findings indicate no difference in the dynamic balance control of TTA wearing the PPF compared to the ESPF. However, there was an observed trend of walking speed and obstacle height affecting balance control within the groups.

Case Study of Energy Expenditure for a BKA Using SACH vs. Energy Storing Prosthetic Foot

Case Study of Energy Expenditure for a BKA Using SACH vs. Energy Storing Prosthetic Foot

Finite element modelling of an energy–storing prosthetic foot during the stance phase of transtibial amputee gait

Energy-storing prosthetic feet are designed to store energy during mid-stance motion and to recover it during late-stance motion. Gait analysis is the most commonly used method to characterize prosthetic foot behaviour during walking. In using this method, however, the foot is generally modelled as a rigid body. Therefore, it does not take into account the ability of the foot to deform. However, the way this deformation occurs is a key parameter of various foot properties under gait conditions. The purpose of this study is to combine finite element modelling and gait analysis in order to calculate the strain, stress and energy stored in the foot along the stance phase for self-selected and fast walking speeds. A finite element model, validated using mechanical testing, is used with boundary conditions collected experimentally from the gait analysis of a single transtibial amputee. The stress, strain and energy stored in the foot are assessed throughout the stance phase for two walking speed conditions: a self-selected walking speed (SSWS), and a fast walking speed (FWS). The first maximum in the strain energy occurs during heel loading and reaches 3J for SSWS and 7J for FWS at the end of the first double support phase. The second maximum appears at the end of the single support phase, reaching 15J for SSWS and 18J for FWS. Finite element modelling combined with gait analysis allows the calculation of parameters that are not obtainable using gait analysis alone. This modelling can be used in the process of prosthetic feet design to assess the behaviour of a prosthetic foot under specific gait conditions.

Comments on Point:Counterpoint: Artificial limbs do/do not make artificially fast running speeds possible

Comments on Point:Counterpoint: Artificial limbs do/do not make artificially fast running speeds possible

片側大腿切断者による対称動作のスプリント走行の可能性について

When a unilateral transfemoral amputee performs sprinting, alternation between the sound limb and the prosthetic limb causes asymmetrical motion. One of the causes of the asymmetrical sprinting performance is that the knee joint of the prosthetic limb does not flex easily due to strong flexion resistance in order to prevent giving way during the landing by extension delay of the shank after flexion in the swing phase. This study examined whether the prosthetic limb performs the same motion as the sound limb working with the movements of the hip joint and other areas by setting the knee joint to allow easier flexion when relaxing the flexion-and-extension resistance of the knee joint in the swing phase. Moreover, when possible, we also examined whether this allows more rational motion than during sprinting when the flexion resistance of the knee joint is set strongly. The composition of the prosthetic limb used for the trial was an IRC (Ischial Ramal Containment) suction socket, high-activity hydraulic knee joint (model 3R55; Otto Bock, Duderstadt, Germany) in which the flexion-and-extension resistance was relaxed, in combination with an energy-storing prosthetic foot for running (model Sprinter; Otto Bock, Duderstadt, Germany). Sprinting was performed by a unilateral transfemoral amputee using this prosthetic limb after the subject had learned how to sprint while using it. Sprinting performance was filmed (30 fps) with a video tape recorder (DCR-PC101 NTSC, Sony Corporation, Tokyo, Japan), and we compared the motion of the prosthetic foot and the knee joint angle with the motion of the sound limb. Moreover, the motion was also compared with that during sprinting when the flexion-and-extension resistance of the knee joint was set strongly. As a result of the relaxed setting of the prosthetic knee joint, it was shown that the prosthetic limb performed the same motion as a sound limb without giving way at landing by extension delay of the shank of the prosthetic limb during the swing phase. Moreover, it was shown that this setting facilitates more rational motion than that during sprinting with a stronger setting for the flexion resistance of the knee joint.

A comparative study of oxygen consumption for conventional and energy-storing prosthetic feet in transfemoral amputees

Objective: To compare oxygen consumption for traumatic high-functioning transfemoral amputees wearing initially a conventional prosthetic foot (Multiflex) and then an energy-storing prosthetic foot (Vari-Flex). Setting: A regional prosthetic and amputee rehabilitation tertiary referral centre in a teaching hospital. Study design: Experimental crossover trial. Subjects: Six established unilateral transfemoral prosthetic users. Interventions: Oxygen consumption breath-by-breath analysis at multiple speeds on a treadmill for each amputee wearing initially the Multiflex foot and then repeated wearing the Vari-Flex foot. Results: Mean oxygen consumption across all subjects was lower for the Vari-Flex foot than for the Multiflex foot at all speeds, although the differences were only significant at speeds of 0.83 and 1.1 m/s (P<0.05). ANCOVA analysis across all speeds showed that oxygen consumption with the Vari-Flex foot was significantly lower (P<0.001). The estimated difference across all speeds was 3.54 mL/kg.min. Conclusion: A high functioning transfemoral amputee who wears an energy-storing prosthetic foot may have significantly reduced oxygen consumption at normal walking speeds.

A Comparative Study of Conventional and Energy-Storing Prosthetic Feet in High-Functioning Transfemoral Amputees

A Comparative Study of Conventional and Energy-Storing Prosthetic Feet in High-Functioning Transfemoral Amputees

A Comparative Study of Conventional and Energy-Storing Prosthetic Feet in High-Functioning Transfemoral Amputees

Graham LE, Datta D, Heller B, Howitt J. A comparative study of conventional and energy-storing prosthetic feet in high-functioning transfemoral amputees. Objective To compare the results of gait analysis, timed walking tests, and socket comfort for transfemoral amputees wearing initially a Multiflex conventional prosthetic foot and then a Vari-Flex energy-storing prosthetic foot. Design Experimental crossover trial. Setting A regional prosthetic and amputee rehabilitation tertiary referral center in a teaching hospital. Participants Six established unilateral transfemoral prosthetic users. Interventions Not applicable. Main Outcome Measures Gait analysis, a timed walking test, and a Prosthetic Socket Fit Comfort Score for each amputee wearing the Multiflex foot and then repeated wearing the Vari-Flex foot. Results Wearing the Vari-Flex foot, our subjects walked faster in the gait lab (1.38±0.13m/s, P<.001) and took more equal step lengths at fast speed (1.063±0.05, P<.05). They also had greater peak ankle dorsiflexion at push-off on the prosthetic side (18.3°±4.73°, P<.001) and 3 times as much power from the prosthetic ankle at push-off (1.13±0.22W/kg, P<.001). There were no significant changes in temporal symmetry or loading of the prosthetic limb, in the timed walking test with each foot, or in the comfort score. Conclusions A transfemoral amputee who wears an energy-storing foot can have a more symmetric gait with regard to some measures of spatial symmetry, kinetics, and kinematics than one who wears a conventional foot. However, in this study important aspects such as more symmetric loading and comfort did not differ significantly between the 2 foot types.

Design of Joint Angle Profiles for a Planar Five-Link Bipedal System

A set of joint angle profiles for a five-link bipedal model walking on level ground is designed. One feature of the joint angle profiles is that after an impulsive energy injection at an early stage of each step, the mechanical energy of the bipedal system remains constant for the rest of the step. This feature is of special interest in the studies of energetics of bipedal walking and can be beneficial to the design of modern energy-storing prosthetic feet. The joint angle profiles also satisfy four kinematic constraints, i.e., the walking speed, stance knee bias, upright posture of the trunk and motion coordination. To obtain acceptable gait patterns, a set of parameters is carefully tuned to satisfy extra conditions (repeatable gait, no hyperextension, and no scuffing at the swing knee). This work can provide some insight into the mechanics of bipedal walking and has potential to establish a framework for estimating the optimal energy storage of modern prosthetic feet.

Évolution des prothèses des sprinters amputés de membre inférieur

For about 15 years, technical advances in prosthetic treatment have been the main factor in the increased performance of athletes with lower-limb amputation. For trans-tibial amputation, the prosthesis for sprinting is composed of a gel liner and a socket joined by a locking or virtual vacuum liner. Because of these dynamic properties, the carbon prosthetic foot equipped with tacks ensures outstanding performance. For trans-femoral amputation, a hydraulic swing and a stance control unit are added to the same prosthesis. In comparison with the able-bodied runner, athletes with amputation have smaller loading times in the prosthetic limb and larger ones in the sound limb. The length of the energy-storing prosthetic foot is determined by the “up-on-the-toes” running gait. The sprinting gait with trans-tibial amputation is almost symmetrical. The hip extensor effort is the main compensation of propulsion reduction with lower-limb amputation. With trans-femoral amputation, the lack of knee increases the asymmetry. The total prosthetic knee extension (early in late-swing phase and lasting during total stance phase) compensates with extension of both hips, especially the opposite one. The amputation and sound limb load transfer with lumbar hyperlordosis concern the pelvis, trunk and shoulders. Because of athletes with amputation, research in prosthetic treatment has progressed. The development of orthotics and prostheses for such athletes has benefited non-athletes with amputation.