Abstract

Natural ankle quasi-stiffness (NAS) is a mechanical property of the ankle joint during dynamic motion. NAS has been historically calculated as the average slope (linear regression) of the net ankle moment versus ankle angle during discrete phases of stance. However, recent work has shown that NAS is nonlinear during the stance phase. Specifically, during the loading phase of stance (∼10 to 60% of total stance), plantarflexion moment increases at an accelerating rate compared to dorsiflexion angle. Updated models have been developed to better capture this inherent nonlinearity. One type of model called bi-linear NAS (BL-NAS) divides the loading phase of stance into two subphases, called early loading (EL) and late loading (LL) NAS. Two papers, written by Crenna and Frigo (2011, “Dynamics of the Ankle Joint Analyzed Through Moment-Angle Loops During Human Walking: Gender and Age Effects,” Hum. Mov. Sci., 30(6), pp. 1185–1198) and Shamaei et al. (2013, “Estimation of Quasi-Stiffness and Propulsive Work of the Human Ankle in the Stance Phase of Walking,” PLoS One, 8(3), p. e59935), outline different BL-NAS models. Both models fit measured data better (lower root-mean-squared error (RMSE)) than standard single linear NAS (SL-NAS) models but have not been widely adopted, possibly because of methodological discrepancies and lack of applicability to physical devices at the time. This paper compares and contrasts these existing BL-NAS models and translates those findings to possible orthotic device designs. Results showed that both BL-NAS models had lower RMSE than SL-NAS, EL-NAS was not significantly different across walking speeds, and LL-NAS increased significantly at faster walking speeds. These improved models of NAS much better approximate natural human movement than commonly used SL-NAS models, and thus provide a basis to design ankle-foot devices with multiple stiffness properties to emulate and facilitate natural human motion.

References

1.
Davis
,
R. B.
, and
Deluca
,
P. A.
,
1996
, “
Gait Characterization Via Dynamic Joint Stiffness
,”
Gait Posture
,
4
(
3
), pp.
224
231
.10.1016/0966-6362(95)01045-9
2.
Kuitunen
,
S.
,
Komi
,
P. V.
, and
Kyröläinen
,
H.
,
2002
, “
Knee and Ankle Joint Stiffness in Sprint Running
,”
Med. Sci. Sports Exerc.
, 34(1), pp.
166
173
.10.1097/00005768-200201000-00025
3.
Powell
,
D. W.
,
Williams
,
D. S. B.
,
Windsor
,
B.
,
Butler
,
R. J.
, and
Zhang
,
S.
,
2014
, “
Ankle Work and Dynamic Joint Stiffness in High- Compared to Low-Arched Athletes During a Barefoot Running Task
,”
Hum. Mov. Sci.
, 34, pp.
147
156
.10.1016/j.humov.2014.01.007
4.
Gabriel
,
R. C.
,
Abrantes
,
J.
,
Granata
,
K.
,
Bulas-Cruz
,
J.
,
Melo-Pinto
,
P.
, and
Filipe
,
V.
,
2008
, “
Dynamic Joint Stiffness of the Ankle During Walking: Gender-Related Differences
,”
Phys. Ther. Sport
,
9
(
1
), pp.
16
24
.10.1016/j.ptsp.2007.08.002
5.
Collins
,
J. D.
,
Arch
,
E. S.
,
Crenshaw
,
J. R.
,
Bernhardt
,
K. A.
,
Khosla
,
S.
,
Amin
,
S.
, and
Kaufman
,
K. R.
,
2018
, “
Net Ankle Quasi-Stiffness is Influenced by Walking Speed but Not Age for Older Adult Women
,”
Gait Posture
,
62
, pp.
311
316
.10.1016/j.gaitpost.2018.03.031
6.
Safaeepour
,
Z.
,
Esteki
,
A.
,
Ghomshe
,
F. T.
,
Azuan
,
N.
, and
Osman
,
A.
,
2014
, “
Quantitative Analysis of Human Ankle Characteristics at Different Gait Phases and Speeds for Utilizing in Ankle-Foot Prosthetic Design
,”
Biomed. Eng. Online
,
13
(
1
), pp.
1
8
.10.1186/1475-925X-13-19
7.
Koller
,
C.
, and
Arch
,
E. S.
,
2018
, “
State of the Prescription Process for Dynamic Ankle-Foot Orthoses
,”
Curr. Phys. Med. Rehabil. Rep.
,
6
, pp.
55
61
.10.1007/s40141-018-0177-x
8.
Arch
,
E. S.
, and
Reisman
,
D. S.
,
2016
, “
Passive-Dynamic Ankle-Foot Orthoses With Personalized Bending Stiffness Can Enhance Net Plantarflexor Function for Individuals Poststroke
,”
J. Prosthetics Orthot
,
28
(
2
), pp.
60
67
.10.1097/JPO.0000000000000089
9.
Arch
,
E. S.
, and
Stanhope
,
S. J.
,
2015
, “
Passive-Dynamic Ankle-Foot Orthoses Substitute for Ankle Strength While Causing Adaptive Gait Strategies: A Feasibility Study
,”
Ann. Biomed. Eng
,
43
(
2
), pp.
442
450
.10.1007/s10439-014-1067-8
10.
Nigro
,
L. R.
,
Koller
,
C.
,
Glutting
,
J.
,
Higginson
,
J. S.
, and
Arch
,
E. S.
,
2021
, “
Nonlinear Net Ankle Quasi-Stiffness Reduces Error and Changes With Speed but Not Load Carried
,”
Gait Posture
, 84, pp.
58
65
.10.1016/j.gaitpost.2020.11.023
11.
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
12.
Crenna
,
P.
, and
Frigo
,
C.
,
2011
, “
Dynamics of the Ankle Joint Analyzed Through Moment-Angle Loops During Human Walking: Gender and Age Effects
,”
Hum. Mov. Sci.
, 30(6), pp.
1185
1198
.10.1016/j.humov.2011.02.009
13.
Holden
,
J. P.
, and
Stanhope
,
S. J.
,
1998
, “
The Effect of Variation in Knee Center Location Estimates on Net Knee Joint Moments
,”
Gait Posture
,
7
(
1
), pp.
1
6
.10.1016/S0966-6362(97)00026-X
14.
Bohannon
,
R. W.
,
1997
, “
Comfortable and Maximum Walking Speed of Adults Aged 20-79 Years: Reference Values and Determinants
,”
Age Ageing
,
26
(
1
), pp.
15
19
.10.1093/ageing/26.1.15
15.
Sinclair
,
J.
,
Atkins
,
S.
, and
Taylor
,
P. J.
,
2016
, “
The Effects of Barefoot and Shod Running on Limb and Joint Stiffness Characteristics in Recreational Runners
,”
J. Mot. Behav.
, 48(1), pp.
79
85
.10.1080/00222895.2015.1044493
16.
Derrick
,
T. R.
,
van den Bogert
,
A. J.
,
Cereatti
,
A.
,
Dumas
,
R.
,
Fantozzi
,
S.
, and
Leardini
,
A.
,
2020
, “
ISB Recommendations on the Reporting of Intersegmental Forces and Moments During Human Motion Analysis
,”
J. Biomech.
,
99
, p.
109533
.10.1016/j.jbiomech.2019.109533
17.
Patzkowski
,
J. C.
,
Blanck
,
R. V.
,
Owens
,
J. G.
,
Wilken
,
J. M.
,
Blair
,
J. A.
, and
Hsu
,
J. R.
,
2010
, “
Can an Ankle-Foot Orthosis Change Hearts and Minds?
,”
J. Surg. Orthop. Adv.
,
20
(
1
), pp.
8
18
.https://pubmed.ncbi.nlm.nih.gov/21477527/
18.
De Wit
,
D. C. M.
,
Buurke
,
J. H.
,
Nijlant
,
J. M. M.
,
Ijzerman
,
M. J.
, and
Hermens
,
H. J.
,
2004
, “
The Effect of an Ankle-Foot Orthosis on Walking Ability in Chronic Stroke Patients: A Randomized Controlled Trial
,”
Clin. Rehabil.
,
18
(
5
), pp.
550
557
.10.1191/0269215504cr770oa
19.
Nolan
,
K. J.
, and
Yarossi
,
M.
,
2011
, “
Clinical Biomechanics Preservation of the First Rocker is Related to Increases in Gait Speed in Individuals With Hemiplegia and AFO
,”
JCLB
,
26
(
6
), pp.
655
660
.10.1016/j.clinbiomech.2011.03.011
20.
Collins
,
S. H.
,
Wiggin
,
M. B.
, and
Sawicki
,
G. S.
,
2015
, “
Reducing the Energy Cost of Human Walking Using an Unpowered Exoskeleton
,”
Nature
,
522
(
7555
), pp.
212
215
.10.1038/nature14288
21.
Glanzer
,
E. M.
, and
Adamczyk
,
P. G.
,
2018
, “
Design and Validation of a Semi-Active Variable Stiffness Foot Prosthesis
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
,
26
(
12
), pp.
2351
2359
.10.1109/TNSRE.2018.2877962
22.
Jafari
,
A.
,
Tsagarakis
,
N. G.
,
Sardellitti
,
I.
, and
Caldwell
,
D. G.
,
2014
, “
A New Actuator With Adjustable Stiffness Based on a Variable Ratio Lever Mechanism
,”
IEEE/ASME Trans. Mechatronics
,
19
(
1
), pp.
55
63
.10.1109/TMECH.2012.2218615
23.
Shepherd
,
M. K.
, and
Rouse
,
E. J.
,
2017
, “
The VSPA Foot: A Quasi-Passive Ankle-Foot Variable Stiffness
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
,
25
(
12
), pp.
2375
2386
.10.1109/TNSRE.2017.2750113
24.
Patzkowski
,
J. C.
,
Blanck
,
R. V.
,
Owens
,
J. G.
,
Wilken
,
J. M.
,
Kirk
,
K. L.
,
Wenke
,
J. C.
, and
Hsu
,
J. R.
,
2012
, “
Comparative Effect of Orthosis Design on Functional Performance
,”
J. Bone Jt. Surg
,
94
(
6
), pp.
507
515
.10.2106/JBJS.K.00254
You do not currently have access to this content.