The evaluation of mechanical behavior of plastic Ankle-Foot Orthosis (AFO) is important since AFO can provide an efficient support to patients with disabilities in locomotion. This paper reports on a novel testing apparatus that allows: (a) the evaluation of AFO stiffness in sagittal and frontal planes; (b) the conduction of semi-automatic trials; and, finally, (c) a global accuracy associated to the AFO stiffness values always less than 4%. The stiffness values are determined by the measurements of the imposed relative displacements between the foot and the shank of the orthosis and the induced reaction forces. The data collected together in an exact 2-D approach, together with those provided by gait analysis systems, allows to better understand gait alteration induced by ankle orthosis, and to improve clinical management of patients.

Issue Section:
Technical Briefs
Keywords:
orthotics, elasticity, biomedical measurement, biomedical equipment, gait analysis
Topics:
Orthotics, Stiffness, Testing, Gait analysis, Design, Mechanical behavior
1.
Mollan
,
R. B.
, and
James
,
W. V. A.
,
1977
, “
New flexible design of drop-foot orthosis
,”
Injury
,
8
(
4
), pp.
310
–
314
.
2.
Lehmann
,
J. F.
,
Condon
,
S. M.
,
Price
,
R.
, and
de Lateur
,
B. J.
,
1987
, “
Gait abnormalities in hemiplegia: their correction by ankle-foot orthosis
,”
Arch. Phys. Med. Rehabil.
,
68
, pp.
763
–
771
.
3.
Romkes
,
J.
, and
Brunner
,
R.
,
2002
, “
Comparison of a dynamic and a hinged ankle-foot orthosis by gait analysis in patients with hemiplegic cerebral palsy
,”
Gait & Posture
,
15
, pp.
18
–
24
.
4.
Nahorniak
,
M. T.
,
Gorton
, III,
G. E.
,
Gannotti
,
M. E.
, and
Masso
,
P. D.
,
1999
, “
Kinematic compensations as children reciprocally ascend and descend stairs with unilateral and bilateral solid AFOs
,”
Gait & Posture
,
9
, pp.
199
–
206
.
5.
Thomas
,
S. S.
,
Buckon
,
C. E.
,
Jakobson-Huston
,
S.
,
Sussman
,
M. D.
, and
Aiona
,
M. D.
,
2002
, “
Stair locomotion in children with spastic hemiplegia: the impact of three different ankle foot orthosis (AFOs) configurations
,”
Gait & Posture
,
16
, pp.
180
–
187
.
6.
Duan
,
X. H.
,
Allen
,
R. H.
, and
Sun
,
J. Q.
,
1997
, “
A stiffness-varying model of the human gait
,”
Med. Eng. Phys.
,
19
, pp.
518
–
524
.
7.
Davis
,
R. B.
, and
De Luca
,
P. A.
,
1996
, “
Gait characterization via dynamic joint stiffness
,”
Gait & Posture
,
4
, pp.
224
–
231
.
8.
Winter
,
D. A.
,
Patla
,
A. E.
,
Prince
,
F.
,
Ishac
,
M.
, and
Gielo-Perczak
,
K.
,
1998
, “
Stiffness control of balance in quiet standing
,”
J. Neurophysiol.
,
80
(
3
), pp.
1211
–
1221
.
9.
Morasso
,
P. G.
, and
Schieppati
,
M.
,
1999
, “
Can muscle stiffness alone stabilize upright standing?
,”
J. Neurophysiol.
,
82
(
3
), pp.
1622
–
1626
.
10.
Winter
,
D. A.
,
Patla
,
A. E.
,
Rietdyk
,
S.
, and
Ishac
,
M. G.
,
2001
, “
Ankle muscle stiffness in the control of balance during quiet standing
,”
J. Neurophysiol.
,
85
(
6
), pp.
2630
–
2633
.
11.
Leone, D., Diemente, S., Gustave, S., Lopez, I., 1998, “Structural analysis of solid ankle-foot orthosis,” Bioengineering Conference Proceedings of the 1988 Fourteenth Annual Northeast, pp. 26–28.
12.
Leone
,
D.
,
1987
, “
A structural model for molded thermoplastic ankle-foot Orthosis analysis
,”
J. Biomech. Eng.
,
109
, pp.
305
–
310
.
13.
Leone D., Diemente, S., Lopez-Isa, M., 1991, “Structural stability prediction for thermoplastic ankle-foot orthosis,” Bioengineering Conference, Proceedings of the 1991 IEEE Seventeenth Annual Northeast, pp. 231–232.
14.
Chu, T., 1995, “Experimental validation on finite element stress analysis of a polymeric orthotic device.” IEEE-EMBC and CMBEC, 2, pp. 1259–1260.
15.
Deitz
,
D.
,
1997
, “
Optimizing orthotic designs with FEA
,”
Mechanical Engineering Magazine July issue
,
119
(
7
), pp.
70
–
71
.
16.
Chu
,
T. M.
,
Reddy
,
N. P.
, and
Padovan
,
J.
,
1995
, “
Three dimensional finite element stress analysis of the polypropylene, ankle foot orthosis static analysis
,”
Med. Eng. Phys.
,
17
, pp.
372
–
9
.
17.
Reddy, N. P., Pohit, G., Lam, P. C., Grotz, R. C., 1985, “Finite element modelling of ankle-foot orthoses,” Proc Inter Conf Biomechanics and Clinical Kinesiology of Hand and Foot, Indian Institute of Technology, pp. 97–99
18.
Syngellakis
,
S.
,
Arnold
,
M. A.
, and
Rassoulian
,
H.
,
2000
, “
Assessment of the nonlinear behaviour of plastic ankle foot orthoses by the finite element method
,”
Proc. Inst. Mech. Eng.
,
214
(
5
), pp.
527
–
539
.
19.
Chu
,
T.
,
Reddy
,
N. P.
, and
Padovan
,
J.
,
1995
, “
Stress Distribution in the Ankle-Foot Orthosis Used to Correct Pathological Gait
,”
J. Rehabil. Res. Dev.
,
32
(
4
), pp.
349
–
360
.
20.
Chu
,
T.
, and
Chu
,
T.
,
1996
, “
A Bonding Methods of Strain Gages to the Polypropylene Ankle-Foot Orthosis
,”
Exp. Tech.
,
20
(
5
), pp.
29
–
31
.
21.
Chu
,
T.
,
2000
, “
Determination of peak stress on polypropylene ankle-foot orthoses due to weight change using strain gage technology
,”
Exp. Tech.
,
24
(
2
), pp.
28
–
30
.
22.
Yamamoto
,
S.
,
Ebina
,
M.
,
Iwasaki
,
M.
,
Kubo
,
S.
,
Kawai
,
H.
, and
Kawai
,
H.
,
1993
, “
Comparative Study of Mechanical Characteristics of Plastic AFOs
,”
J of Prosthetics and Orthotics
,
5
, pp.
259
–
264
.
23.
Lunsford
,
T. R.
,
Ramm
,
T.
, and
Miller
,
J.
,
1994
, “
Viscoelastic Properties of Plastic Paediatric AFOs
,”
J of Prosthetics and Orthotics
,
6
, pp.
3
–
9
.
24.
Singerman
,
R.
,
Hoy
,
D. J.
,
Mansour
,
J.
,
1999
, “
Design Changes in Ankle-Foot Orthosis Intended to Alter Stiffness Also Alter Orthosis Kinematics
,”
J of Prosthetics and Orthotics
,
11
, pp.
48
–
56
.
25.
Lai, J. Y., Kitaoka, H., Kaufman, K., 2001, “Orthosis Stiffness Characteristics,” 6th annual GCMAS meeting Sacramento CA USA April 25–28.
26.
Klasson
,
B.
,
Convery
,
P.
, and
Raschke
,
S.
,
1998
, “
Test apparatus for the measurement of the flexibility of ankle-foot orthoses in planes other than the loaded plane
,”
Prosthet. Orthot Int.
,
22
(
1
), pp.
45
–
53
.
27.
Katdare, K., Schwartz, M., Wervey, R., 2000, “The Non-Linear Stiffness of Ankle Foot Orthoses Measurement and Prediction,” 5th GCMAS meeting Rochester MN USA April 12–15.
28.
Grood
,
E. S.
, and
Suntay
,
W. J.
,
1983
, “
A joint coordinate system for the clinical description of three-dimensional motions: application to the knee
,”
J. Biomech. Eng.
,
105
, pp.
136
–
144
.
29.
Cole
,
G. K.
,
Nigg
,
B. M.
,
Ronsky
,
J. L.
, and
Yeadon
,
M. R.
,
1993
, “
Application of the joint coordinate system to three-dimensional joint attitude and movement representation: a standard proposal
,”
J. Biomech. Eng.
,
115
, pp.
344
–
349
.
30.
Tupling
,
S. J.
, and
Pierrynowski
,
M. R.
,
1987
, “
Use of Cardan angles to locate rigid bodies in three-dimensional space
,”
Med. Biol. Eng. Comput.
,
25
, pp.
527
–
532
.
Copyright © 2003
 by ASME
You do not currently have access to this content.