Biomechanical evaluation of SACH and uniaxial feet. Interlimb symmetry of traumatic unilateral transtibial amputees wearing two different prosthetic feet in the early rehabilitation stage. Comparative biomechanical analysis of energy-storing prosthetic feet. The effect of five prosthetic feet on the gait and loading of the sound limb in dysvascular below-knee amputees. Physiological measurements of walking and running in people with transtibial amputations with 3 different prostheses. Prosthetic weight acceptance mechanics in transtibial amputees wearing the Single Axis, Seattle Lite, and Flex Foot. Below-knee amputee gait with dynamic elastic response prosthetic feet: a pilot study. Optimisation of the prescription for trans-tibial (TT) amputees. Energy expenditure during ambulation in dysvascular and traumatic below-knee amputees: a comparison of five prosthetic feet. Comparison of gait using a Multiflex foot versus a Quantum foot in knee disarticulation amputees. A comparison of the SACH and single axis foot in the gait of unilateral below-knee amputees. Gait analysis and energy consumption of below-knee amputees wearing three different prosthetic feet. Bioenergetic comparison of a new energy-storing foot and SACH foot in traumatic below-knee vascular amputations. Influence of prosthetic foot design on sound limb loading in adults with unilateral below-knee amputations. The effects of prosthetic foot design on physiologic measurements, self-selected walking velocity, and physical activity in people with transtibial amputation. A comparison of two prosthetic feet on the multi-joint and multi-plane kinetic gait compensations in individuals with a unilateral trans-tibial amputation. Comprehensive analysis of energy storing prosthetic feet: Flex Foot and Seattle Foot Versus Standard SACH foot. Comprehensive analysis of dynamic elastic response feet: Seattle Ankle/Lite Foot versus SACH foot. Segment velocities in normal and transtibial amputees: prosthetic design implications. Energy expenditure and biomechanical characteristics of lower limb amputee gait: the influence of prosthetic alignment and different prosthetic components.
A review of prosthetic prescription practice reveals that in the United Kingdom about 85% of below and above-knee amputees are fitted with uniaxial feet, whereas in the United States about 80% are fitted with SACH feet. An evaluation method was developed to assess the performance of these two different types of feet. This included a subjective assessment procedure and a biomechanical evaluation of the function of the two feet and their effects on whole body gait kinematics and lower limb kinetics. Data were acquired by three Bolex H16 cine cameras and two Kistler force plates. This set-up allowed three-dimensional analysis on the prosthetic and contralateral sides of the subject. Investigations were undertaken in which an experimental prosthesis permitted the interchange of the ankle/foot while keeping the rest of the components the same. Altogether, six below knee and five above knee amputees were tested. No clear trend for preference for either type of foot was evident from the subjective survey; in general the patients showed a preference for the foot that they were accustomed to. Kinematic and kinetic analysis showed some differences in the function between the two prosthetic feet. It is the purpose of this paper to discuss these differences and their significance. This study evaluated the SACH and the Greissinger Plus prosthetic feet, in terms of the symmetry provided between the lower limbs, in the case of unilateral transtibial amputees 16.3 weeks from the time of limb fitting and 38.9 weeks from surgery. Sagittal plane gait analysis was carried out for nine right-limb traumatic amputees. In all examined cases, the spatial and temporal parameters measured were significantly improved. When the symmetry indexes of the same parameters calculated with three different methods were considered, significant improvement was observed for the hip and ankle ranges of motion and the stance phase period. However, no significant differences were found for the symmetry indexes of the knee range of motion, cadence, and walking speed. In addition, for most spatial parameters, the statistical significance varied considerably among the three methods used for the analysis of symmetry. Gait analysis was performed on eight men who had unilateral traumatic below-knee amputation and on nine control subjects. Each subject was given two prostheses--the Seattle Foot and the Flex Foot--which differed only in the energy-storing foot component. Analysis of subjects consisted of clinical gait observation, forceplate analysis of the ground reaction force (GRF) while using each prosthesis during level walking at the natural cadence, and evaluation of subject preference between the two prosthetic feet. In the control subjects, there was no significant asymmetry in any averaged GRF patterns or parameters. In the subjects with amputations, the amputated limb had a weaker propulsion and the nonamputated limb had a stronger propulsion than controls. This was true for both prostheses. During ambulation with the Flex Foot, there was a pattern of larger late vertical forces but smaller late anteroposterior and mediolateral forces. This is consistent with a medial heel whip, and it was observed when the Flex Foot was used. Three months after the biomechanical studies, four subjects used the Flex Foot exclusively, two used the Seattle Foot exclusively, and two used both, ie, the Flex Foot for sports and the Seattle Foot for work. Application of these results to the choice of prosthetic components is discussed. The purpose of this study was to determine the effects of prosthetic foot design on the vertical ground reaction forces experienced by the sound and amputated limbs in a group of persons with dysvascular below-knee amputations. Stride characteristics, joint motion, and ground reaction forces were recorded simultaneously during a self-selected free walking velocity in seven subjects wearing five different prosthetic feet (SACH, Flex-Foot, Carbon Copy II, Seattle, Quantum). Subjects used each foot for one month prior to testing. Results indicated that the sound limb was exposed to higher vertical ground reaction forces than normal despite a reduced walking velocity. Use of the Flex-Foot resulted in the lowest sound limb vertical forces, which appears to be related to its large arc of dorsiflexion motion. In addition, there was increased loading response knee flexion of the sound limb indicating an attempt by these subjects to modulate floor impact. These results suggest that the intact lower extremity is susceptible to excessive floor impact, and that prosthetic foot design can have an effect on the magnitude of the vertical forces experienced by the limb. A 3-factor (foot type, speed, and mode of ambulation) repeated-measures experimental design was used.
                To compare the differences in energy expenditure, gait efficiency, and relative exercise intensity in persons with transtibial amputations with various prostheses.
                There is a need for improved prosthetic designs to accommodate physically active persons with lower-extremity amputations.
                We used progressive speeds of treadmill walking (53.64, 67.05, 80.46, 93.87, and 107.28 m/min) and running (120.69, 134.1, and 147.51 m/min) with 3 different types of prostheses: the Solid Ankle Cushion Heel (SACH) foot, the Flex-Foot (FF), and the Re-Flex Vertical Shock Pylon (VSP) prosthesis. Five physically active men with unilateral transtibial amputations served as subjects (aged 31.6 +/- 4.28 years).
                The following statistically significant differences (improvements) between the Re-Flex VSP versus the FF and the SACH foot were found. Energy cost: walking (5%), running (11%); gait efficiency: walking (6%), running (9%); relative exercise intensity: walking (4%), running (5%). However, we found no significant differences between the FF and the SACH.
                The Re-Flex VSP appears to have a positive effect on energy cost, efficiency, and relative exercise intensity compared with the other prosthetic foot types during walking and running. Loading response challenges the limb with the dual demands of accepting rapidly moving body weight to both absorb the shock of floor contact and create a stable limb over which the body can advance. Delay in achieving foot flat contact with the floor causes a prolonged period of heel only support and results in an unstable base of support for those persons with transtibial amputations. The purpose of this study was to identify mechanical causes of instability during weight acceptance with three different prosthetic foot designs, Single Axis, Seattle Lightfoot, and Flex Foot. Ten male individuals with transtibial amputations were tested on three separate occasions wearing each prosthetic foot. A comparison group of ten individuals without transtibial amputations was also examined. Mean free walking speed was significantly slower for those with transtibial amputations regardless of the prosthetic foot worn (p < 0.05). Contralateral toe off times were significantly later for each prosthetic foot (p < 0.01). The timing of peak knee flexion was found to be significantly later than normal for each prosthetic foot (p < 0.01). To minimize the impact of initial floor contact, persons with an intact limb used rapid plantar flexion, followed by a slower lowering of the foot to the floor. Dorsiflexion then stimulated knee flexion and foot flat. Two altered functions were found for all three prosthetic feet, reduced knee flexion and prolonged heel only support. Diminished knee flexion reflected delayed dorsiflexion and tibial advancement as a result of the cushioned heel. Lateness in reaching foot flat was also found. To improve the walking abilities of those persons with transtibial amputations, prosthetic foot designs need to incorporate mechanisms which promote early foot flat while preserving limb stability. The purpose of this pilot study was to investigate some of the new dynamic elastic response (DER) prosthetic feet compared to the SACH foot and determine if any demonstrated trends of producing the most optimum gait. We investigated the gait of five below-knee amputees while wearing four different DER feet (Flex-Foot, Carbon Copy II, SEATTLE, STEN) and a standard SACH foot. Each subject used each foot for 1 month prior to in-depth gait analysis and energy expenditure testing at the Pathokinesiology Laboratory. Minimal differences in either free or fast walking were noted between the five feet. The Flex-Foot resulted in significantly different gait kinematics at the "ankle" compared to the other four feet, however, this foot did not produce an increased velocity nor an improved energy cost. The results of this pilot study indicated that during free or fast-paced walking on level ground there were no clinically significant advantages of any one of the feet tested. Based on this pilot data, recommendations are made for future studies including appropriate sample size. The great diversity of prosthetic mechanisms available nowadays leads to the question of which type of artificial foot would be the most advisable for a particular person. To answer correctly, it is necessary to establish, in an objective way, the performance of each type of prosthetic mechanism. This knowledge is obtained by means of the study of the subject-prosthesis interaction, both in static and dynamic conditions. This paper, based on the analysis of 8 trans-tibial (TT) amputees, presents a quantitative method for the study of human gait which allows the determination of the influence of four different prosthetic ankle-foot mechanisms (SACH, Single-axis, Greissinger and Dynamic) on gait. To do this, 1341 gait trials at different cadences were analysed (383 with normal subjects and 958 with amputees, using the four prosthetic feet under study). From all the variables available for study only those which offered interpretable clinical information were chosen for analysis. A total of 18 variables (kinetic, kinematic and time-related) were selected. A covariance analysis (ANOVA) of these variables was made, which showed that the factors influencing TT amputee gait were, in order of importance, cadence and leg studied (sound or prosthetic), inter-individual variability and, finally, the prosthetic mechanism used. When looking at the performance during gait of the 4 prosthetic mechanisms studied it can be observed that there are similarities in the kinetic study between SACH and Dynamic feet on one hand and Single-axis and Greissinger feet on the other. These results seem to support the classification criteria of articulated and non-articulated prosthetic mechanisms. Recent advancement in prosthetic technology has led to the development of dynamic elastic response feet (DER), which are reported to store and release energy to facilitate gait. To date, there has been no objective evidence to suggest energy conservation while using these foot designs. The purpose of this study was to compare the energy expenditure of five commercially available prosthetic feet (SACH and four DER feet) in both the traumatic and dysvascular populations during level walking. Seventeen male subjects with below-knee amputation (nine traumatic and seven dysvascular) were tested for energy expenditure (Douglas Bag technique) during a 20-min walk while wearing each of the prosthetic feet. The DER prosthetic foot designs were not shown to reduce the energy cost (ml O2/kg-m) or rate of energy expenditure (ml O2/kg-min) compared to the SACH foot. Overall, the traumatic amputees had a similar oxygen consumption per meter traveled compared to the dysvascular amputees; however, the rate of energy consumption was much higher in the traumatic group. This increased rate was a function of the greater walking velocity employed by the traumatic subjects, made possible by their better physical fitness. The subjective responses and gait patterns of unilateral knee disarticulation amputees wearing prostheses fitted first with the Multiflex foot and then with the Quantum foot were studied. Nine amputees were included in the trial. A questionnaire asked the amputees about their preference for one of the feet. Gait analysis was performed measuring temporal parameters and goniometry of hips, knees and ankles in the sagittal and frontal planes. There was a slight preference for the Quantum foot. Preference seemed not to be related to physical characteristics of the amputees nor to gait parameters. There were no differences in gait as far as the temporal factors were concerned. The main differences in the range of motion of the joints were in the frontal plane: the eversion-inversion movement of the ankle and the adduction-abduction movement of the hip. During walking at comfortable speed with the Multiflex foot the ankle and hip range of motion averaged 2.1 and 3.1 degrees respectively, less than during walking with the Quantum foot. nan This study scientifically measures the dynamic gait characteristics and energy consumption of 16 male below-knee amputees, eight vascular and eight traumatic, while wearing solid ankle cushion heel (SACH), single axis and multiple axis prosthetic feet via six-camera motion analysis, metabolic measurement cart and heavy-duty treadmill. Subjective results are additionally determined via questionnaire after testing. Motion analysis showed statistically significant differences at P<0.05 between the SACH, single axis and multiple axis foot in the velocity, cadence, stride length and single limb stance. Significant differences were found in energy consumption between the traumatic and vascular groups, and significant changes in walking under different speeds and different inclines. Results provide quantitative and qualitative information about the dynamic performance of the various feet, which can be helpful in prescribing the optimal prosthetic foot for individual amputees. In this study, the metabolic performances of a new energy-storing foot (Proteor) and of the solid-ankle cushion heel (SACH) are compared. Twelve patients with traumatic below-knee amputations (mean age: 50.0 +/- 19.9 years) and 12 patients with vascular below-knee amputations (mean age: 73 +/- 7 years) were studied. Oxygen uptake (VO2) was measured in all the subjects on a walkway at a self-selected velocity; only the subjects with traumatic amputation were tested on a level treadmill (progressive speed: 2.4-4 and 6 km/h), and then in two randomized trials: incline (+5%) and decline walking treadmill test at 4 km/h. Vascular explorations were done in the vascular patients: distal pressure measurements, pulse plethysmography, transcutaneous oxygen tension. Free walking was improved in subjects with traumatic amputation using the energy-storing foot (+6%), with a better bioenergetic efficiency (0.24 +/- 0.4mL/kg.m vs 0.22 +/- 0.04mL/kg.m). However, in subjects with vascular amputation, this foot did not produce an increased free velocity nor an improved energy cost. During the level treadmill test, the traumatic amputee subjects showed a decrease of energy expenditure with the new prosthetic foot, more significant at sufficient speed (4 km/h): 17.00 +/- 3.42 vs 14.67 +/- 2.05 mL/kg/min (p < .05). The same effect is shown during the incline (19.31 +/- 2.80 vs 16.79 +/- 2.32 mL/kg/min-p < .02) and decline walking tests (14.13 +/- 3.64 vs 11.81 +/- 1.54mL/kg/min-p < .02). There is no significant difference in cardiocirculatory effects between the two types of prosthetic foot. Despite a lower velocity, the subjects with vascular amputation exceed 70% of the maximal heart rate, with the cardiocirculatory factor being the main cause of walking restriction. The energy-storing foot should be reserved for active and fast walkers, whereas the SACH foot seems more suitable for elderly patients with amputation with a slow walk. Altered gait patterns resulting from amputation has been implicated as a possible mechanism for early degenerative changes in the sound limb of unilateral amputees. The purpose of this study was to examine the ground reaction force characteristics and joint motion in this population. Ground reaction forces, joint motion, and stride characteristics of 10 traumatic below-knee amputees were analyzed while wearing five different prosthetic feet (SACH, Flex-foot, Carbon Copy II, Seattle, and Quantum). Subjects used each foot for 1 month prior to testing. Results indicated that the Flex-foot significantly reduced the initial peak of the vertical ground reaction force on the sound limb compared to all other feet tested (p < .0001). The SACH foot consistently produced the greatest ground reaction forces on the sound limb; however, this was not statistically significant. The effective factor of the Flex-foot appears to be minimization of the center of gravity elevation, which was accomplished through a significant increase in terminal stance dorsiflexion compared to the other feet tested (p < .0001). To investigate the physiologic differences during multispeed treadmill walking and physical activity profiles for the Otto Bock C-Walk foot (C-Walk), Flex-Foot, and solid ankle cushion heel (SACH) foot in people with transtibial amputation.
                A repeated-measures design with 3 prostheses.
                Research laboratory.
                Eight men with unilateral transtibial amputation.
                Not applicable.
                Physiologic responses (energy expenditure, gait efficiency, exercise intensity, rating of perceived exertion [RPE]) during multispeed treadmill walking (53.64, 67.05, 80.46, 93.87, 107.28 m/min) test were analyzed with 2-way repeated-measures analysis of variance (ANOVA). One-way ANOVA was employed to analyze foot-type differences for self-selected walking velocity (SSWV), and steps per day (daily activity). Analysis of covariance was used to analyze foot-type differences with SSWV as the covariable for the physiologic measurements.
                The C-Walk had a trend of improved physiologic responses compared with the SACH; however, no foot-type differences were statistically significant. Compared with the C-Walk and SACH, the Flex-Foot showed no significant differences in energy expenditure and gait efficiency, but significantly lower percentage of age-predicted maximum heart rate and RPE values.
                The energy storing-releasing feet appeared to have certain trends of improved gait performance compared with the SACH; however, not many objective foot-type differences were significantly noted. Further studies with a larger sample size are suggested. To determine the effects of two different prosthetic feet on the three-dimensional kinetic patterns of both the prosthetic and sound limbs during unilateral trans-tibial amputee gait.
                Eleven individuals with a unilateral trans-tibial amputation participated in two walking sessions: once while using the conventional SAFE foot, the other while using the dynamic Flex foot.
                Despite the wide variation in the design of prosthetic feet, the benefits of these prostheses remain unclear.
                During each test session, peak joint moments and powers in the sagittal, transverse and frontal planes were examined, as subjects walked at a comfortable speed.
                The majority of the kinetic differences that occurred due to the changing of prosthetic foot type were limited to ankle joint variables in the sagittal plane with greater peak moments and power during propulsion for the Flex foot compared to the SAFE foot. However, effects were also found at joints proximal to the prosthesis (e.g. knee) and differences were also found in the kinetics of the sound limb.
                The dynamic Flex foot allowed subjects to rely more heavily on the prosthetic foot for propulsion and stability during walking with minimal compensations at the remaining joints.
                Determining the biomechanical differences between the conventional and dynamic prosthetic feet may advocate the use of one prosthetic foot type over another. This information, when used in conjunction with subjective preferences, may contribute to higher functioning and greater satisfaction for individuals with a lower limb amputation.
                Copyright 2004 Elsevier Ltd. This study compared the mechanical and biomechanical functions, metabolic demand, and shock absorption of two dynamic elastic response (DER) prosthetic foot designs with the SACH foot. Nine individuals who had undergone unilateral below knee amputation were studied. Mechanical properties of the feet were related to gait biomechanics. Forefoot compliance is greatest for the Flex Foot and least for the SACH foot, hence, Flex Foot demonstrates (1) the longest midstance phase, (2) the greatest ankle angle range, and (3) greater forward movement of the center of pressure. There was some evidence that the DER feet produced a better push-off. However, neither the self-selected walking speed nor the metabolic rate or efficiency over a spectrum of walking speeds (73 to 120m/min) and running speeds (140 to 200m/min) was significantly different. Because no energy savings resulted for the DER feet, the release of stored energy in the flexible feet may not occur at the proper time to assist in ambulation as a result of the natural frequency of oscillation. This study evaluated biomechanical and metabolic performance differences between two prosthetic foot designs in light of their mechanical properties. Ten unilateral below-knee amputee subjects, at least 1 year after amputation, capable of walking and running, were studied. Differences in heel and forefoot compliance explained differences in gait events and alignment. Increased efficiency of pushoff in the Seattle Ankle/Lite Foot exists as evidenced by the decrease loading on the opposite limb during double support and a less shortened step length on the sound side compared to the SACH foot. The natural frequency of oscillation for the prosthetic feet was determined to be too high to provide energy storage and release synchronized with kinematic requirements because neither metabolic cost savings nor differences in metabolic efficiency were found. Comfortable walking speed and the nadir of metabolic rate and efficiency are not different. Via accelerometer measurement, it was found that the more compliant and lossy SACH foot heel was less likely to transmit high frequency vibration. Dynamic elastic response foot and ankle prostheses (Seattle-Lite, Flex Foot, etc.) used by transtibial amputees feature substantial design improvements over conventional designs (SACH, Single Axis, etc.). Despite this progress, transtibial amputees continue to expend greater energy than normals. Increased residual limb EMG data and altered gait patterns suggest that impaired mobility may be the cause of overactive muscles in early stance. Prosthetic mobility was therefore quantified by measuring foot, shank and thigh velocities in nine transtibial amputees, wearing three different foot designs: Single Axis (SA), Seattle Lite (SL) and Flex Foot (FF). The magnitude, timing and rate of segment velocities for each prosthetic design, characterizing early stance mobility, were compared with corresponding measures in normal, nonamputee (NA) controls using Dunnett's test. Regardless of foot type, transtibial (TT) amputees walked slower than non amputee controls (63.3-65.8 m/min versus 78.5 m/min, p < 0.05) and their stride length was shorter (1.21-1.26 m versus 1.41 m, p < 0.01). In early stance, peak foot and shank velocities were lower (p < 0.01) for both the SL and FF while only shank velocity was lower (p < 0.01) with the SA compared to NA controls. Significant delays in the timing of early stance events such as peak shank velocity, peak ankle plantarflexion and peak knee flexion compromised shank and knee stability in TT amputees. Foot and shank mobility was uncontrolled with the SA design while ankle mobility was restricted by the FF and SL feet. In NA controls on the other hand, appropriate timing and rate of segment velocity changes preserved dynamic stability and forward progression in early stance. This was evidenced by rapid decreases in foot and shank velocity as the thigh velocity increased during weight acceptance. Future prosthetic designs should provide TT amputees with improved ankle mobility that attempt to capture the dynamic characteristics of a normal articulation between the foot and shank segments during the early stance weight acceptance period. In this study, the influence of different prosthetic alignments and components on oxygen consumption and the important biomechanical characteristics of the normal gait pattern of leg amputees was investigated. With 15 transtibial and 12 transfemoral amputees, the oxygen consumption during walking on a treadmill was analyzed and biomechanical parameters during walking on even ground at a self-selected speed were defined. The amputation of all patients was caused by trauma. Variations of the prosthetic alignment affect the energy consumption of transfemoral amputees more significantly than that of transtibial amputees. Comparison of different prosthetic feet worn by transtibial amputees did not show significant differences regarding metabolic parameters. Compared with conventional hydraulic knee controls, the oxygen consumption of transfemoral amputees provided with an electronically controlled hydraulic knee joint is reduced. All investigated variations can be clearly characterized by the sagittal moments acting on the joints of the prosthetic limb during gait.