Abstract

Prosthetic foot selection for individuals with lower limb amputation relies primarily on clinician judgment. The prosthesis user rarely has an opportunity to provide experiential input into the decision by trying different feet. A prosthetic foot emulator (PFE) is a robotic prosthetic foot that could facilitate prosthesis users' ability to trial feet with different mechanical characteristics. Here, we introduce a procedure by which a robotic PFE is configured to emulate the sagittal plane effective ankle stiffness of a range of commercial prosthetic forefeet. Mechanical testing was used to collect data on five types of commercial prosthetic feet across a range of foot sizes and intended user body weights. Emulated forefoot profiles were parameterized using Bezier curve fitting on ankle torque-angle data. Mechanical testing was repeated with the PFE, across a subset of emulated foot conditions, to assess the accuracy of the emulation. Linear mixed-effects regression and Bland–Altman Limits of Agreement analyses were used to compare emulated and commercial ankle torque-angle data. Effective ankle stiffness of the emulated feet was significantly associated with the corresponding commercial prosthetic feet (p <0.001). On average, the emulated forefeet reproduced the effective ankle stiffness of corresponding commercial feet within 1%. Furthermore, differences were independent of prosthetic foot type, foot size, or user body weight. These findings suggest that commercial prosthetic foot properties can be effectively mimicked by a PFE, which is the important first step toward enabling prosthesis users to quickly trial different feet using a PFE as part of prosthetic foot prescription.

References

1.
Stevens
,
P. M.
,
Rheinstein
,
J.
, and
Wurdeman
,
S. R.
,
2018
, “
Prosthetic Foot Selection for Individuals With Lower-Limb Amputation: A Clinical Practice Guideline
,”
JPO
,
30
(
4
), pp.
175
180
.10.1097/JPO.0000000000000181
3.
Raschke
,
S. U.
,
Orendurff
,
M. S.
,
Mattie
,
J. L.
,
Kenyon
,
D. E.
,
Jones
,
O. Y.
,
Moe
,
D.
,
Winder
,
L.
,
Wong
,
A. S.
,
Moreno-Hernandez
,
A.
,
Highsmith
,
M. J.
,
D
,
J. S.
, and
Kobayashi
,
T.
,
2015
, “
Biomechanical Characteristics, Patient Preference and Activity Level With Different Prosthetic Feet: A Randomized Double Blind Trial With Laboratory and Community Testing
,”
J. Biomech.
,
48
(
1
), pp.
146
152
.10.1016/j.jbiomech.2014.10.002
5.
Hofstad
,
C.
,
Linde
,
H.
,
Limbeek
,
J.
, and
Postema
,
K.
,
2004
, “
Prescription of Prosthetic Ankle-Foot Mechanisms After Lower Limb Amputation
,”
Cochrane Database Syst. Rev.
, (
1
), p.
Cd003978
.10.1002/14651858.CD003978.pub2
6.
Van Der Linde
,
H.
,
Geertzen
,
J. H.
,
Hofstad
,
C. J.
,
Van Limbeek
,
J.
, and
Postema
,
K.
,
2003
, “
Prosthetic Prescription in The Netherlands: An Observational Study
,”
Prosthet. Orthotics Int.
,
27
(
3
), pp.
170
178
.10.1080/03093640308726679
7.
Van Der Linde
,
H.
,
Geertzen
,
J. H.
,
Hofstad
,
C. J.
,
Van Limbeek
,
J.
, and
Postema
,
K.
,
2004
, “
Prosthetic Prescription in The Netherlands: An Interview With Clinical Experts
,”
Prosthet. Orthotics Int.
,
28
(
2
), pp.
98
104
.10.1080/03093640408726694
8.
van der Linde
,
H.
,
Hofstad
,
C. J.
,
Geurts
,
A. C.
,
Postema
,
K.
,
Geertzen
,
J. H.
, and
van Limbeek
,
J.
,
2004
, “
A Systematic Literature Review of the Effect of Different Prosthetic Components on Human Functioning With a Lower-Limb Prosthesis
,”
J. Rehabil. Res. Dev.
,
41
(
4
), pp.
555
570
.10.1682/JRRD.2003.06.0102
9.
Hafner
,
B. J.
,
2005
, “
Clinical Prescription and Use of Prosthetic Foot and Ankle Mechanisms: A Review of the Literature
,”
JPO
,
17
(
4
), pp.
S5
S11
.https://journals.lww.com/jpojournal/Fulltext/2005/10001/Clinical_Prescription_and_Use_of_Prosthetic_Foot.4.aspx?casa_token=RDiSsRj4uEkAAAAA:-62-CHGbgBgHMs0kTBrHM7dFizd4pr2ocvnl3ocoONGSQ25HDjxYWCb2MovVyWidBwrlHUCtzuHTTa2mjUysIWQ
10.
Hafner
,
B. J.
,
Halsne
,
E. G.
,
Morgan
,
S. J.
,
Morgenroth
,
D. C.
, and
Humbert
,
A. T.
,
2021
, “
Effects of Prosthetic Feet on Metabolic Energy Expenditure in People With Transtibial Amputation: A Systematic Review and Meta-Analysis
,”
PMR.
, pp.
1
17
.10.1002/pmrj.12693
11.
Fogelberg
,
D. J.
,
Allyn
,
K. J.
,
Smersh
,
M.
, and
Maitland
,
M. E.
,
2016
, “
What People Want in a Prosthetic Foot: A Focus Group Study
,”
JPO
,
28
(
4
), pp.
145
151
.10.1097/JPO.0000000000000102
12.
Murray
,
C. D.
, and
Forshaw
,
M. J.
,
2013
, “
The Experience of Amputation and Prosthesis Use for Adults: A Metasynthesis
,”
Disabil. Rehabil.
,
35
(
14
), pp.
1133
1142
.10.3109/09638288.2012.723790
13.
Van der Linde
,
H.
,
Hofstad
,
C. J.
,
Geertzen
,
J. H.
,
Postema
,
K.
, and
Van Limbeek
,
J.
,
2007
, “
From Satisfaction to Expectation: The Patient's Perspective in Lower Limb Prosthetic Care
,”
Disabil. Rehabil.
,
29
(
13
), pp.
1049
1055
.10.1080/09638280600948375
14.
McDonald
,
C. L.
,
Cheever
,
S. M.
,
Morgan
,
S. J.
, and
Hafner
,
B. J.
,
2019
, “
Prosthetic Limb User Experiences With Crossover Feet: A Pilot Focus Group Study to Explore Outcomes That Matter
,”
JPO
,
31
(
2
), pp.
121
132
.10.1097/JPO.0000000000000240
15.
Caputo
,
J. M.
,
Adamczyk
,
P. G.
, and
Collins
,
S. H.
,
2015
, “
Informing Ankle-Foot Prosthesis Prescription Through Haptic Emulation of Candidate Devices
,”
IEEE International Conference on Robotics and Automation: ICRA: International Conference on Robotics and Automation
, Seattle, WA, May 26–30, pp.
6445
6450
.10.1109/ICRA.2015.7140104
16.
Caputo
,
J. M.
, and
Collins
,
S. H.
,
2014
, “
A Universal Ankle-Foot Prosthesis Emulator for Human Locomotion Experiments
,”
ASME J. Biomech. Eng.
,
136
(
3
), p.
035002
.10.1115/1.4026225
17.
Quesada
,
R. E.
,
Caputo
,
J. M.
, and
Collins
,
S. H.
,
2016
, “
Increasing Ankle Push-Off Work With a Powered Prosthesis Does Not Necessarily Reduce Metabolic Rate for Transtibial Amputees
,”
J. Biomech.
,
49
(
14
), pp.
3452
3459
.10.1016/j.jbiomech.2016.09.015
18.
Caputo
,
J. M.
, and
Collins
,
S. H.
,
2015
, “
Prosthetic Ankle Push-Off Work Reduces Metabolic Rate but Not Collision Work in Non-Amputee Walking
,”
Sci. Rep.
,
4
(
1
), p.
7213
.10.1038/srep07213
19.
Tafti
,
N.
,
Hemmati
,
F.
,
Safari
,
R.
,
Karimi
,
M. T.
,
Farmani
,
F.
,
Khalaf
,
A.
, and
Mardani
,
M. A.
,
2018
, “
A Systematic Review of Variables Used to Assess Clinically Acceptable Alignment of Unilateral Transtibial Amputees in the Literature
,”
Proc. Inst. Mech. Eng. Part H J. Eng. Med.
,
232
(
8
), pp.
826
840
.10.1177/0954411918789450
20.
Beck
,
O. N.
,
Taboga
,
P.
, and
Grabowski
,
A. M.
,
2016
, “
Characterizing the Mechanical Properties of Running-Specific Prostheses
,”
PloS One
,
11
(
12
), p.
e0168298
.10.1371/journal.pone.0168298
21.
Jonkergouw
,
N.
,
Prins
,
M. R.
,
Buis
,
A. W.
, and
van der Wurff
,
P.
,
2016
, “
The Effect of Alignment Changes on Unilateral Transtibial Amputee's Gait: A Systematic Review
,”
PLoS One
,
11
(
12
), p.
e0167466
.10.1371/journal.pone.0167466
22.
Malcolm
,
P.
,
Quesada
,
R. E.
,
Caputo
,
J. M.
, and
Collins
,
S. H.
,
2015
, “
The Influence of Push-Off Timing in a Robotic Ankle-Foot Prosthesis on the Energetics and Mechanics of Walking
,”
J. Neuroeng. Rehabil.
,
12
, p.
21
.10.1186/s12984-015-0014-8
23.
Kim
,
M.
,
Chen
,
T.
,
Chen
,
T.
, and
Collins
,
S. H.
,
2018
, “
An Ankle‐Foot Prosthesis Emulator With Control of Plantarflexion and Inversion‐Eversion Torque
,”
IEEE Trans. Rob.
,
99
, pp.
1
12
.10.1109/TRO.2018.2830372
24.
Major
,
M. J.
,
Twiste
,
M.
,
Kenney
,
L. P.
, and
Howard
,
D.
,
2016
, “
The Effects of Prosthetic Ankle Stiffness on Stability of Gait in People With Transtibial Amputation
,”
J. Rehabil. Res. Dev.
,
53
(
6
), pp.
839
852
.10.1682/JRRD.2015.08.0148
25.
Major
,
M. J.
,
Twiste
,
M.
,
Kenney
,
L. P.
, and
Howard
,
D.
,
2014
, “
The Effects of Prosthetic Ankle Stiffness on Ankle and Knee Kinematics, Prosthetic Limb Loading, and Net Metabolic Cost of Trans-Tibial Amputee Gait
,”
Clin. Biomech.
,
29
(
1
), pp.
98
104
.10.1016/j.clinbiomech.2013.10.012
26.
Fey
,
N. P.
,
Klute
,
G. K.
, and
Neptune
,
R. R.
,
2013
, “
Altering Prosthetic Foot Stiffness Influences Foot and Muscle Function During Below-Knee Amputee Walking: A Modeling and Simulation Analysis
,”
J. Biomech.
,
46
(
4
), pp.
637
644
.10.1016/j.jbiomech.2012.11.051
27.
Fey
,
N. P.
,
Klute
,
G. K.
, and
Neptune
,
R. R.
,
2011
, “
The Influence of Energy Storage and Return Foot Stiffness on Walking Mechanics and Muscle Activity in Below-Knee Amputees
,”
Clin. Biomech.
,
26
(
10
), pp.
1025
1032
.10.1016/j.clinbiomech.2011.06.007
28.
Fey
,
N. P.
,
Klute
,
G. K.
, and
Neptune
,
R. R.
,
2012
, “
Optimization of Prosthetic Foot Stiffness to Reduce Metabolic Cost and Intact Knee Loading During Below-Knee Amputee Walking: A Theoretical Study
,”
ASME J. Biomech. Eng.
,
134
(
11
), p.
111005
.10.1115/1.4007824
29.
Adamczyk
,
P. G.
,
Roland
,
M.
, and
Hahn
,
M. E.
,
2017
, “
Sensitivity of Biomechanical Outcomes to Independent Variations of Hindfoot and Forefoot Stiffness in Foot Prostheses
,”
Human Mov. Sci.
,
54
, pp.
154
171
.10.1016/j.humov.2017.04.005
30.
Klodd
,
E.
,
Hansen
,
A.
,
Fatone
,
S.
, and
Edwards
,
M.
,
2010
, “
Effects of Prosthetic Foot Forefoot Flexibility on Oxygen Cost and Subjective Preference Rankings of Unilateral Transtibial Prosthesis Users
,”
J. Rehabil. Res. Dev.
,
47
(
6
), pp.
543
552
.10.1682/JRRD.2010.01.0003
31.
Klodd
,
E.
,
Hansen
,
A.
,
Fatone
,
S.
, and
Edwards
,
M.
,
2010
, “
Effects of Prosthetic Foot Forefoot Flexibility on Gait of Unilateral Transtibial Prosthesis Users
,”
J. Rehabil. Res. Dev.
,
47
(
9
), pp.
899
910
.10.1682/JRRD.2009.10.0166
32.
Klute
,
G. K.
, and
Berge
,
J. S.
,
2004
, “
Modelling the Effect of Prosthetic Feet and Shoes on the Heel-Ground Contact Force in Amputee Gait
,”
Proc. Inst. Mech. Eng. H
,
218
(
3
), pp.
173
182
.10.1243/095441104323118897
33.
Hansen
,
A. H.
,
Childress
,
D. S.
, and
Knox
,
E. H.
,
2004
, “
Roll-Over Shapes of Human Locomotor Systems: Effects of Walking Speed
,”
Clin. Biomech.
,
19
(
4
), pp.
407
414
.10.1016/j.clinbiomech.2003.12.001
34.
Gard
,
S. A.
,
Su
,
P. F.
,
Lipschutz
,
R. D.
, and
Hansen
,
A. H.
,
2011
, “
Effect of Prosthetic Ankle Units on Roll-Over Shape Characteristics During Walking in Persons With Bilateral Transtibial Amputations
,”
J. Rehabil. Res. Dev.
,
48
(
9
), pp.
1037
1048
.10.1682/JRRD.2010.07.0136
35.
Versluys
,
R.
,
Beyl
,
P.
,
van Damme
,
M.
,
Desomer
,
A.
,
van Ham
,
R.
, and
Lefeber
,
D.
,
2009
, “
Prosthetic Feet: State-of-the-Art Review and the Importance of Mimicking Human Ankle-Foot Biomechanics
,”
Disabil. Rehabil. Assist. Technol.
,
4
(
2
), pp.
65
75
.10.1080/17483100802715092
36.
Womac
,
N. D.
,
Neptune
,
R. R.
, and
Klute
,
G. K.
,
2019
, “
Stiffness and Energy Storage Characteristics of Energy Storage and Return Prosthetic Feet
,”
Prosthet. Orthotics Int.
,
43
(
3
), pp.
266
275
.10.1177/0309364618823127
37.
Beck
,
O. N.
,
Taboga
,
P.
, and
Grabowski
,
A. M.
,
2017
, “
Reduced Prosthetic Stiffness Lowers the Metabolic Cost of Running for Athletes With Bilateral Transtibial Amputations
,”
J. Appl. Physiol.
,
122
(
4
), pp.
976
984
.10.1152/japplphysiol.00587.2016
38.
Koehler-McNicholas
,
S. R.
,
Nickel
,
E. A.
,
Barrons
,
K.
,
Blaharski
,
K. E.
,
Dellamano
,
C. A.
,
Ray
,
S. F.
,
Schnall
,
B. L.
,
Hendershot
,
B. D.
, and
Hansen
,
A. H.
,
2018
, “
Mechanical and Dynamic Characterization of Prosthetic Feet for High Activity Users During Weighted and Unweighted Walking
,”
PLoS One
,
13
(
9
), p.
e0202884
.10.1371/journal.pone.0202884
40.
Halsne
,
E. G.
,
Czerniecki
,
J. M.
,
Shofer
,
J. B.
, and
Morgenroth
,
D. C.
,
2020
, “
The Effect of Prosthetic Foot Stiffness on Foot Ankle Biomechanics and Relative Foot Stiffness Perception in People With Transtibial Amputation
,”
Clin. Biomech.
,
80
, p.
105141
.10.1016/j.clinbiomech.2020.105141
41.
Zelik
,
K. E.
,
Collins
,
S. H.
,
Adamczyk
,
P. G.
,
Segal
,
A. D.
,
Klute
,
G. K.
,
Morgenroth
,
D. C.
,
Hahn
,
M. E.
,
Orendurff
,
M. S.
,
Czerniecki
,
J. M.
, and
Kuo
,
A. D.
,
2011
, “
Systematic Variation of Prosthetic Foot Spring Affects Center-of-Mass Mechanics and Metabolic Cost During Walking
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
,
19
(
4
), pp.
411
419
.10.1109/TNSRE.2011.2159018
42.
Shamaei
,
K.
,
Sawicki
,
G. S.
, and
Dollar
,
A. M.
,
2013
, “
Estimation of Quasi-Stiffness and Propulsive Work of the Human Ankle in the Stance Phase of Walking
,”
PLoS One
,
8
(
3
), p.
e59935
.10.1371/journal.pone.0059935
43.
Singer
,
E.
,
Ishai
,
G.
, and
Kimmel
,
E.
,
1995
, “
Parameter Estimation for a Prosthetic Ankle
,”
Ann. Biomed. Eng.
,
23
(
5
), pp.
691
696
.10.1007/BF02584466
44.
Major
,
M. J.
,
Scham
,
J.
, and
Orendurff
,
M.
,
2018
, “
The Effects of Common Footwear on Stance-Phase Mechanical Properties of the Prosthetic Foot-Shoe System
,”
Prosthet. Orthotics Int.
,
42
(
2
), pp.
198
207
.10.1177/0309364617706749
45.
Major
,
M. J.
,
Twiste
,
M.
,
Kenney
,
L. P.
, and
Howard
,
D.
,
2011
, “
Amputee Independent Prosthesis Properties–a New Model for Description and Measurement
,”
J. Biomech.
,
44
(
14
), pp.
2572
2575
.10.1016/j.jbiomech.2011.07.016
46.
Hansen
,
A. H.
, and
Childress
,
D. S.
,
2010
, “
Investigations of Roll-Over Shape: Implications for Design, Alignment, and Evaluation of Ankle-Foot Prostheses and Orthoses
,”
Disabil. Rehabil.
,
32
(
26
), pp.
2201
2209
.10.3109/09638288.2010.502586
47.
Hansen
,
A. H.
,
Sam
,
M.
, and
Childress
,
D. S.
,
2004
, “
The Effective Foot Length Ratio: A Potential Tool for Characterization and Evaluation of Prosthetic Feet
,”
JPO
,
16
(
2
), pp.
41
45
.https://journals.lww.com/jpojournal/Fulltext/2004/04000/The_Effective_Foot_Length_Ratio__A_Potential_Tool.2.aspx?casa_token=VEWSQHvPiFwAAAAA:AtLgi_NFlkKbmBYw6SqqQkTb4OnvZDxckGZQFrE27pJrK5FRUkO5JAB8WpCUuOIslKtqaidnQj0mDTd7HhVHigo
48.
Hansen
,
A. H.
,
Childress
,
D. S.
,
Miff
,
S. C.
,
Gard
,
S. A.
, and
Mesplay
,
K. P.
,
2004
, “
The Human Ankle During Walking: Implications for Design of Biomimetic Ankle Prostheses
,”
J. Biomech.
,
37
(
10
), pp.
1467
1474
.10.1016/j.jbiomech.2004.01.017
49.
Adamczyk
,
P. G.
,
Roland
,
M.
, and
Hahn
,
M. E.
,
2013
, “
Novel Method to Evaluate Angular Stiffness of Prosthetic Feet From Linear Compression Tests
,”
ASME J. Biomech. Eng.
,
135
(
10
), pp.
104502
104505
.10.1115/1.4025104
50.
Halsne
,
E. G.
,
Turner
,
A. T.
,
Curran
,
C. S.
,
Hansen
,
A. H.
,
Hafner
,
B. J.
,
Caputo
,
J. M.
, and
Morgenroth
,
D. C.
,
2022
, “
Effects of Shear Force Reduction During Mechanical Testing and Day-to-Day Variation on Stiffness of Commercial Prosthetic Feet: A Technical Note
,”
Prosthet. Orthotics Int.
, 46(2), pp.
206
211
.10.1097/PXR.0000000000000088
51.
Webber
,
C. M.
, and
Kaufman
,
K.
,
2017
, “
Instantaneous Stiffness and Hysteresis of Dynamic Elastic Response Prosthetic Feet
,”
Prosthet. Orthotics Int.
,
41
(
5
), pp.
463
468
.10.1177/0309364616683980
52.
Simba
,
K. R.
,
Uchiyama
,
N.
, and
Sano
,
S.
,
2016
, “
Real-Time Smooth Trajectory Generation for Nonholonomic Mobile Robots Using Bézier Curves
,”
Rob. Comput. Integr. Manuf.
,
41
, pp.
31
42
.10.1016/j.rcim.2016.02.002
53.
Yang
,
G. J.
, and
Choi
,
B. W.
,
2013
, “
Smooth Trajectory Planning Along Bezier Curve for Mobile Robots With Velocity Constraints
,”
Int. J. Control Autom.
,
6
(
2
), pp.
225
234
.10.1007/978-3-642-35485-4_18
54.
Elhoseny
,
M.
,
Tharwat
,
A.
, and
Hassanien
,
A. E.
,
2018
, “
Bezier Curve Based Path Planning in a Dynamic Field Using Modified Genetic Algorithm
,”
J. Comput. Sci.
,
25
, pp.
339
350
.10.1016/j.jocs.2017.08.004
55.
Choi
,
J.
,
Curry
,
R.
, and
Elkaim
,
G.
,
2008
, “
Path Planning Based on Bézier Curve for Autonomous Ground Vehicles
,”
Proceedings of Advances in Electrical and Electronics Engineering-IAENG Special Edition of the World Congress on Engineering and Computer Science
,
IEEE
, San Francisco, CA, Oct. 22–24, pp.
158
166
.10.1109/WCECS.2008.27
56.
Tharwat
,
A.
,
Elhoseny
,
M.
,
Hassanien
,
A. E.
,
Gabel
,
T.
, and
Kumar
,
A.
,
2019
, “
Intelligent Bézier Curve-Based Path Planning Model Using Chaotic Particle Swarm Optimization Algorithm
,”
Cluster Comput.
,
22
(
S2
), pp.
4745
4766
.10.1007/s10586-018-2360-3
57.
R. C. Team
,
2018
,
R: A Language and Environment for Statistical Computing
,
R Foundation for Statistical Computing
,
Vienna, Austria
.
58.
Parker
,
R. A.
,
Scott
,
C.
,
Inácio
,
V.
, and
Stevens
,
N. T.
,
2020
, “
Using Multiple Agreement Methods for Continuous Repeated Measures Data: A Tutorial for Practitioners
,”
BMC Med. Res. Methodol.
,
20
(
1
), p.
154
.10.1186/s12874-020-01022-x
59.
Bland
,
J. M.
, and
Altman
,
D. G.
,
1986
, “
Statistical Methods for Assessing Agreement Between Two Methods of Clinical Measurement
,”
Lancet
,
1
(
8476
), pp.
307
310
.https://pubmed.ncbi.nlm.nih.gov/2868172/
60.
Rouse
,
E. J.
,
Hargrove
,
L. J.
,
Perreault
,
E. J.
,
Peshkin
,
M. A.
, and
Kuiken
,
T. A.
,
2013
, “
Development of a Mechatronic Platform and Validation of Methods for Estimating Ankle Stiffness During the Stance Phase of Walking
,”
ASME J. Biomech. Eng.
,
135
(
8
), p.
81009
.10.1115/1.4024286
61.
South
,
B. J.
,
Fey
,
N. P.
,
Bosker
,
G.
, and
Neptune
,
R. R.
,
2010
, “
Manufacture of Energy Storage and Return Prosthetic Feet Using Selective Laser Sintering
,”
ASME J. Biomech. Eng.
,
132
(
1
), p.
6
.10.1115/1.4000166
62.
Hamilton
,
C.
, and
Stamey
,
J.
,
2007
, “
Using Bland−Altman to Assess Agreement Between Two Medical Devices–Don't Forget the Confidence Intervals!
,”
J. Clin. Monit. Comput.
,
21
(
6
), pp.
331
333
.10.1007/s10877-007-9092-x
63.
Shepherd
,
M. K.
,
Azocar
,
A. F.
,
Major
,
M. J.
, and
Rouse
,
E. J.
,
2018
, “
Amputee Perception of Prosthetic Ankle Stiffness During Locomotion
,”
J. Neuroeng. Rehabil.
,
15
(
1
), p.
99
.10.1186/s12984-018-0432-5
You do not currently have access to this content.