Research on Feet

Read the available clinical studies on Össur feet.

Fradet, L. et al., 2010. Biomechanical analysis of ramp ambulation of transtibial amputees with an adaptive ankle foot system. Gait & Posture, 32(2), 191 - 198.

Sixteen transtibial amputees [TTAs] were compared to non-amputees when walking up and down a ramp. Conventional 3D gait analysis was carried out when walking with a neutral ankle and with the ankle adapted. When participants walked up a ramp with a dorsiflexed ankle, the kinematics and kinetics were closer to physiological normal gait and the compensation mechanism was reduced. When walking down a ramp, the kinematics and kinetics were less physiological. However, patients reported feeling safer when walking with the adapted ankle, suggesting that PROPRIO also brings about improvements in ramp descent although it does not appear in the gait analysis.

“According to these results [ramp ascent], the increased dorsiflexion was beneficial to the TTAs by improving the kinematics and the kinetics of the lower limb, particularly on the involved side”
“..patients reported benefits by the plantarflexed ankle during ramp descent. They mentioned they felt safer and had a better support during roll over with reduced stress at the knee joint”

View the full article here.

Wolf, S.I. et al., 2009. Pressure characteristics at the stump/socket interface in transtibial amputees using an adaptive prosthetic foot. Clinical Biomechanics, 24(10), 860-5.

The socket pressures for 12 PROPRIO FOOT wearing, unilateral amputees were measured and synchronised with 3D gait analysis in level, stair and incline walking. The measurements taken on the stairs and incline were done both with the ankle set in neutral and in adaptation mode (dorsi/plantar flexion according to the walking condition). Analysis of the data showed that for incline and stair walking the pressure was more evenly distributed when the foot was used in adaptation mode. Furthermore the socket pressures were closer to that of level ground walking when using the adaptation mode.

“Adapting the prosthetic ankle is a valuable means of modifying joint kinetics and thereby the pressure distribution at the stump”

To view the full article click here.

Alimusaj, M. et al., 2009. Kinematics and kinetics with an adaptive ankle foot system during stair ambulation of transtibial amputees. Gait & Posture, 30(3), 356 - 363.

Sixteen transtibial amputees were compared to non-amputees when walking on stairs. For the amputees measurements were taking when walking with a neutral ankle and with the ankle adapted to 4 deg dorsiflexion. Analysis showed that gait biomechanics on the stairs were closer to normal when the amputees were using the adapted ankle. In particular, the knee flexion and knee moment on the involved side was improved by the adapted PROPRIO ankle.

“This improved knee function which partially compensates for the absence of ankle motion and proprioception can be regarded as a substantial benefit in the patient group investigated"

“Prosthetic ankles such as the PROPRIO FOOT ® constitute a good alternative for active patients whose life induces a lot of stair ambulation”

To view the full article click here.

Heiðrun Gigja Ragnarsdóttir M.Sc., Hjordís Thorhallsdóttir, M.Sc., Knut Lechler, CPO-D Comparison study: Symmetric versus asymmetric foot design

Synopsis: This comparison study objectifiesthe effect of symmetric versus asymmetric foot desing on the progression of center of pressure in the medio-lateral directions. A design with variable medio-lateral characteristics was compared to the conventional symmetric foot design. Objective measurement equipment shows that the use of an asymmetric foot design results in a more natural roll-over of the foot module.

Click here for full version(330Kb pdf).

Hafner, B. J., Sanders, J. E., Czerniecki, J. and Fergason, J. Energy storage and return prostheses: does patient perception correlate with biomechanical analysis? Clin Biomech (Bristol, Avon), 17, 325-44, 2002.

Synopsis: This is a literature review evaluating energy storage and return and conventional prosthetic feet presented in various studies. Results suggest that while experimental methodologies may limit the statistical significance of objective gait analysis results, consistent trends in temporal, kinetic, and kinematic parameters correlate well with perceptive impressions of DER feet. These correlations provide insight to subtle changes in gait parameters that are deemed neither clinically nor statistically significant, yet are perceived by amputees to affect their preference for and performance of prosthetic feet during locomotion. It is suggested how to design studies revealing more statistical significant results. The Flex-Foot was found to be superior in late stance dorsiflexion.

Hsu, M. J., Nielsen, D. H., Yack, H. J. and Shurr, D. G. Physiological measurements of walking and running in people with transtibial amputations with 3 different prostheses. J Orthop Sports Phys Ther, 29, 526-33, 1999.

Synopsis: The study compared three different feet (SACH,Modular III and Re-Flex) in walking at different speeds and running. Five young and active subjects were included in this test. The session were performed on a treadmill measuring energy cost per meter traveled(mL O2/kg/m)
The Re-Flex VSP appears to have a positive effect on energy cost, gait efficiency, and relative exercise intensity compared with other prosthetic foot types during walking and running

Macfarlane, P., Nielson, D., Shurr, D., Meier, K., Clark, R., Kerns, J., Moreno, M. and Ryan, B. Transfemoral Amputee Physiological Requirements: Comparisons Between SACH Foot Walking and Flex-Foot Walking. Journal of Prosthetics and Orthotics, 9, 138-143, 1997.

Synopsis: This study compared exercise intensity, oxygen uptake and gait efficiency of five male subjects in two test sessions. Active traumatic transfemoral amputees used a SACH foot or a Flex-Foot" attached below a hydraulic knee joint. Walking on level surface at three different speeds was performed. Heart rate was recorded by telemetry, and expired gas was collected. The analysis indicate that the Flex-Foot was associated with significantly lower exercise intensity, less energy expenditure and improved gait efficiency compared to the SACH foot.

Snyder, R. D., Powers, C. M., Fontaine, C. and Perry, J. The effect of five prosthetic feet on the gait and loading of the sound limb in dysvascular below-knee amputees. J Rehabil Res Dev, 32, 309-15, 1995.

Synopsis: The study investigated the effects of prosthetic foot design on the vertical ground reaction forces experienced by the sound limb of seven dysvascular below-knee male amputees. 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). The 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. This indicates the Flex-Foot protects the sound limb against excessive vertical forces by virtue of its flexible long keel and large arc of dorsiflexion motion.

Barth, D., Schumacher, L. and Sienko Thomas, S. Gait Analysis and Energy Cost of Below- Knee Amputees Wearing Six Different Prosthetic Feet. Journal of Prosthetics and Orthotics, 4, 63-75, 1992.

Synopsis: Comparison of sound-limb to prosthetic-limb symmetry is the used method to analyze and evaluate different prosthetic feet in this study. Six male vascular amputee showed they benefit from the high range of ankle motion of the Flex-Walk especially when walking inclines

Engsberg. JR, Macintosh. BR and JA, H. Comparison of Effort Between Below-Knee Amputee and Normal Children. Journal of the Association of Children's Prosthetic-Orthotic Clinics, 26, 46, 1991.

Synopsis: This is a preliminary investigation on a comparison of physiological and biomechanical measurements of three below-knee-amputee and two normal children. Oxygen uptake, heart rate and vertical displacement of a marker approximating the whole body center of mass were measured. One was fitted to a Flex foot and two wore a SACH foot. Measurements were taken on a treadmill in four different speeds. Results indicated the children with the SACH generally displayed greater effort for all walking speeds when compared to respective values of the normal children and the one fitted with the Flex-Foot.

Macfarlane, P., Nielsen, L. P. T., Ph.D. , Shurr, L. P. T., CO. and Meier, C. P. Perception of Walking Difficulty by Below-Knee Amputees Using a Conventional Foot Versus the Flex-Foot. Journal of Prosthetics and Orthotics, 3, 114-119, 1991.

Synopsis: The study on seven male unilateral BK amputees showed significantly differences on the subjects using an FF compared to a CF. It appears the increased length of time the subjects were willing to spend in single support on the FF as compared to the CF allows them to take larger, more normal steps with their uninvolved leg and, hence, they needed fewer steps per minute to match CF walking speeds. Walking with the Flex Foot was associated with a smoother, more uniform vertical trunk motion, suggesting an increase in biomechanical efficiency.