Energy Storage and Return Prostheses: Developing a Biomechanical Model of Amputee Sprinting
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Transcript of Energy Storage and Return Prostheses: Developing a Biomechanical Model of Amputee Sprinting
NeverStandS+ll FacultyofEngineering GraduateSchoolofBiomedicalEngineering
Energy Storage and Return Prostheses: Developing a Biomechanical Model of Amputee Sprinting
Presenter: StaceyRigneySupervisors: Prof.AnneSimmons,Dr.LaurenKark
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Background
Photo: Courtesy of WBGH ‘Medal Quest’ <http://www.pbs.org/newshour/multimedia/paralympics/5.html>
• Human gait cycle
• Anatomical vs prosthetic lower-limbs
2
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Background
Photo: Courtesy of WBGH ‘Medal Quest’ <http://www.pbs.org/newshour/multimedia/paralympics/5.html>
• Human gait cycle
• Anatomical vs prosthetic lower-limbs
2
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Human Gait Cycle
IC# LR# MS# TS# PS# IS# MS# TS#
St+A##
St+G##
Sw+G##
Sw+R##
Sw+A##
IC# LR# MS# TS# PS# IS# MS# TS#
St+A##
St+G##
Sw+G##
Sw+R##
Sw+A##
Walking
Running
Figures:S.M.Rigney,A.SimmonsandL.Kark,“AmputeeGait:AReviewofBiomechanicalModels,”IEEEReviewsinBiomedicalEngineering,underreview.3
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Human Gait Cycle Walking
Running
Images:hMp://www.dingosbreakfastclub.net/DingosBreakfastClub/BioMech/BioMechLightness.html
InvertedPendulum
Spring-loadedmass
4
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Background
Photo: Courtesy of WBGH ‘Medal Quest’ <http://www.pbs.org/newshour/multimedia/paralympics/5.html>
• Human gait cycle
• Anatomical vs prosthetic lower-limbs
5
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Anatomical Lower-limb
• Ankle joint + calf muscles and tendons =
‘bouncy ball’
• Muscles act as struts maintaining tension
– active element
• Tendons act as elastic springs
– passive element
• Anatomical limb is 241% efficient
6
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Prosthetic Lower-limb
• No ankle joint or muscles
• ‘Springiness’ achieved via compression
• Passive element only
• Maximum 100% efficiency
7
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Running-Specific Prostheses (RSP)
Flex-Run Flex-Sprint Cheetah Xtend
Cheetah Xtreme Sprinter 1E90 C-Sprint 1C2
Össur Ottobock
8
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Disabled or Super-abled?
Video: https://www.youtube.com/watch?v=HNtZ_lbhafE 9
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
– Mechanical testing
10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
– Mechanical testing
• Assess prosthesis during gait: in vivo
Photo: http://www.ibtimes.co.uk/otto-bock-sports-prosthesis-amateur-everyday-athletes-377186 10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
– Mechanical testing
• Assess prosthesis during gait: in vivo
– Indirectly: measure speed, VO2, personal preference
– Directly: gait analysis
Photo: http://www.ibtimes.co.uk/otto-bock-sports-prosthesis-amateur-everyday-athletes-377186 10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
– Mechanical testing
• Assess prosthesis during gait: in vivo
– Indirectly: measure speed, VO2, personal preference
– Directly: gait analysis
Photo: http://www.ibtimes.co.uk/otto-bock-sports-prosthesis-amateur-everyday-athletes-377186 10
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mechanical Testing
Support block (‘socket’) Fixed base
Prosthesis
y
x • Compress prosthesis in a Material
Testing System (INSTRON)
• Measure Force-Displacement
• Compare results for different
prostheses under same load
Load cell
Figure: S. M. Rigney, A. Simmons and L. Kark, “Stance phase mechanical characterisation of a running-specific lower-limb prosthesis,” in Proc. 2014 Aus. Biomed. Eng. Conf., Canberra, A.C.T., Australia, 2014. 11
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mechanical Testing
Support block (‘socket’) Fixed base
Prosthesis
y
x • Compress prosthesis in a Material
Testing System (INSTRON)
• Measure Force-Displacement
• Compare results for different
prostheses under same load
Figure: S. M. Rigney, A. Simmons and L. Kark, “Stance phase mechanical characterisation of a running-specific lower-limb prosthesis,” in Proc. 2014 Aus. Biomed. Eng. Conf., Canberra, A.C.T., Australia, 2014. 11
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
How Do We Decide?
• Assess prosthesis alone: in vitro
– Mechanical testing
• Assess prosthesis during gait: in vivo
– Indirectly: measure speed, VO2, personal preference
– Directly: gait analysis
Photo: http://www.ibtimes.co.uk/otto-bock-sports-prosthesis-amateur-everyday-athletes-377186 12
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Infrared motion-capture cameras
• Passive-reflective markers
• Displacement of markers tracked
over time
• Force plates embedded in
ground
Photo: http://mocap.cs.cmu.edu/info.php 13
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
Raw data
14
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
15
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
• Label markers using VICON Nexus software
15
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
• Label markers using VICON Nexus software
• Construct link-segment model of skeleton and prosthesis
15
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
• Label markers using VICON Nexus software
• Construct link-segment model of skeleton and prosthesis
15
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lower-limb Models
Anatomical lower-limb
• Rigid shank and foot • Articulating ankle joint
Prosthetic lower-limb
• Continuous and elastic • ‘Springiness’ achieved by
compression
16
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Continuum Mechanics
• Change shape under load
• Undergo displacement
• Undergo deformation
M$
M$
N$
R$
R$
M$
DISPLACE&
DEFORM$
O$
M$N$
O’’$
M$
N$
R$
O’$
DEFORM$
R$
N$ M$
O’’’$
DISPLACE&
Figures:S.M.Rigney,A.SimmonsandL.Kark,“AmputeeGait:AReviewofBiomechanicalModels,”IEEEReviewsinBiomedicalEngineering,underreview.17
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics
• Maintain shape under load
• Undergo displacement
• Undergo deformation
M$
M$
N$
R$
R$
M$
DISPLACE&
DEFORM$
O$
M$N$
O’’$
M$
N$
R$
O’$
DEFORM$
R$
N$ M$
O’’’$
DISPLACE&
Figures:S.M.Rigney,A.SimmonsandL.Kark,“AmputeeGait:AReviewofBiomechanicalModels,”IEEEReviewsinBiomedicalEngineering,underreview.18
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lower-limb Models
Two-linksegment
Exis+ng
19
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lower-limb Models
Two-linksegment
Exis+ng
Mul+ple-linksegment
New
20
FiniteElementAnalysis
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mul+ple-linksegment
Lower-limb Models
21
FiniteElementAnalysisTwo-linksegment
Exis+ng New
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mul,ple-linksegment
Lower-limb Models
21
FiniteElementAnalysisTwo-linksegment
Exis+ng New
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Two-link Segment Model
• Shank and foot connected via an
articulating ‘ankle’ joint
22
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Two-link Segment Model
• Shank and foot connected via an
articulating ‘ankle’ joint
22
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Multiple-link Segment Model
• No distinct shank and foot segments
• Entire prosthesis modeled as
multiple segments connected via
articulating joints
• 1DoF sagittal plane joints
23
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Multiple-link Segment Model
• No distinct shank and foot segments
• Entire prosthesis modeled as
multiple segments connected via
articulating joints
• 1DoF sagittal plane joints
23
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Multiple-link Segment Model: Inverse Dynamics
• Similar process to two-link
segment model
• Calculate joint reaction forces
and moments for additional
segments
24Figure:Rigney,S.M.,A.Simmons,andL.Kark,“Lower-limbkinema+csandkine+csduringamputeerunning:anewapproach”,
25thCongressoftheInterna+onalSocietyofBiomechanics,Glasgow,UK,2015.
RPL1
RPL2
RPL3
RTIB
RPL4 RPL5
RPL6 RPL7
RANK
RTOE RHEE
RPB1 RPB2
RPB3
k3, b3
Fx
M
m6, I6
GRFy
GRFx
GRFM
Fy
m5, I5
m4, I4
m3, I3
m2, I2
m1, I1
k5, b5 k4, b4
k2, b2
k1, b1
y
x
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
OpenSim Inverse Kinematics and Dynamics
24
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Design of Experiments for MLS model
• Half factorial DoE, 95% CI
• Factors/variables tested:
– Joints 1-5, fixed or free
– 2nd degree interactions
– 16 configurations in total
• Results of interest:
– Hip flexion and moment
– Knee flexion and moment
J5J4
J3
J2J1
25Figure:Rigney,S.M.,A.Simmons,andL.Kark,“Lower-limbkinema+csandkine+csduringamputeerunning:anewapproach”,
25thCongressoftheInterna:onalSocietyofBiomechanics,Glasgow,UK,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Results - Moments
26
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-300
-200
-100
0
100
200
300Affected
Hip
Mom
ent (
Nm
)
0 20 40 60 80 100-300
-200
-100
0
100
200
300Unaffected
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
Kne
e M
omen
t (N
m)
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-300
-200
-100
0
100
200
300Affected
Hip
Mom
ent (
Nm
)
0 20 40 60 80 100-300
-200
-100
0
100
200
300Unaffected
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
Kne
e M
omen
t (N
m)
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Results - Angles
26
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-300
-200
-100
0
100
200
300Affected
Hip
Mom
ent (
Nm
)
0 20 40 60 80 100-300
-200
-100
0
100
200
300Unaffected
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
Kne
e M
omen
t (N
m)
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-300
-200
-100
0
100
200
300Affected
Hip
Mom
ent (
Nm
)
0 20 40 60 80 100-300
-200
-100
0
100
200
300Unaffected
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
0 20 40 60 80 100% Stance Phase
-200
-100
0
100
200
300
Kne
e M
omen
t (N
m)
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
0 20 40 60 80 100-60
-40
-20
0
20
40
Hip
Fle
xion
(deg
)
0 20 40 60 80 100-60
-40
-20
0
20
40
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Kne
e Fl
exio
n (d
eg)
PiG Hybrid MLS
0 20 40 60 80 100% Stance Phase
-60
-40
-20
0
20
40
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mul+ple-linksegment
Lower-limb Models
27
FiniteElementAnalysisTwo-linksegment
Exis+ng New
✓ ✓
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mul+ple-linksegment
Lower-limb Models
27
FiniteElementAnalysisTwo-linksegment
Exis+ng New
✓ ✓
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
• Label markers using VICON Nexus software
• Construct link-segment model of skeleton and prosthesis
28
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Gait Analysis
• Passive-reflective markers
• Label markers using VICON Nexus software
• Construct link-segment model of skeleton and prosthesis
Finite Element
28
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Overview of Methodology
1. Experimental gait analysis
= spatial boundary conditions
2. Inverse FEA
= material properties
3. Dynamic FEA
= elastic strain energy
29Figure:Rigney,S.M.,A.Simmons,andL.Kark,”Finiteelementanalysisofalower-limbrunning-specificprosthesis”inThe8thAustralasian
CongressonAppliedMechanics2014.Barton,A.C.T,Australia:EngineersAustralia.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Passive-reflective Markers
• Custom marker set
• Coordinates recorded at 250Hz
• Allows fully prescribed movement of the femur, tibia, socket and prosthesis
30
RTHI
RKNE
RSOT
RSOB
RPL1-3RPB1RPB2RPB3
RTIBRPL4RPL5
RPL6 RPL7 RANK
RHEE RTOE
Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputeeRunning”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Finite Element Analysis (FEA)
• Quasi-static parametric solver
• Prescribed displacement
– 1DOF rotation of femur @ RTHI
– 3DOF translation of socket + prosthesis @ RPL1
– 3DOF translation of shoe @ RTOE
• 1DOF hinge knee joint
MPa MPa
RTHI (θx)
RPL1 (x,y,z)
RTOE (x,y,z)
31Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputee
Running”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Finite Element Analysis (FEA)
MPa
31
• Quasi-static parametric solver
• Prescribed displacement
– 1DOF rotation of femur @ RTHI
– 3DOF translation of socket + prosthesis @ RPL1
– 3DOF translation of shoe @ RTOE
• 1DOF hinge knee joint
Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputeeRunning”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Simulated vs Actual Marker Displacement
preliminary quasi-static study demonstrates the potential of subject-specific multibody models for amputee gait analysis.
A number of areas have been identified where the model could be further refined. The simulated reaction force did not exhibit the oscillations of the experiments due to the quasi-static nature of the simulation. The use of a time-dependent solver that includes inertial effects may improve the accuracy of the oscillatory phenomena at initial contact. The model utilized a 1DOF prescribed displacement of the femur and 1DOF hinge joint at the knee; this simplification considerably reduced computational effort, however this affected the accuracy of the simulated prosthesis motion in the lateral direction (x-axis). The reaction force and moment in this plane of movement is very low, therefore it is unlikely to be of great consequence when calculating joint torque and power in future time-dependent studies. The shape of the longitudinal (y-axis) reaction force was offset from the experimental results in the time domain, which is likely to be improved by refining the shoe geometry. Finally, improved accuracy could be obtained by modeling the carbon fiber as a heterogeneous orthotropic material, as its very nature as a composite is to have varying stiffness depending on thickness, composition and layering.
Extension of this project will include the addition of viscoelastic damping parameters to enable a time-dependent simulation, which will result in the ability to calculate: joint torque and power; energy absorbed, dissipated and returned by the prosthesis; prosthesis work and efficiency; and the comparison of these values with results obtained through conventional link-segment rigid-body mechanics models. Seamless integration with motion capture software, such as Vicon Nexus, will facilitate the integration of FE analysis with existing clinical practices. Additionally, the presented skeletal and prosthesis model can be combined with other clinical measures, such as MRI, to enable patient-specific hard and soft tissue modeling, such as the menisci of the knee and/or residual limb tissue mechanics. Concurrent multibody and FE models present an exciting new avenue for patient-specific modeling.
REFERENCES [1] L. G. Stansbury, S. J. Lalliess, J. G. Branstetter, M. R. Bagg and J. B.
Holcomb, “Amputations in US military personnel in the current conflicts in Afghanistan and Iraq,” J. Orthop. Trauma, vol. 22, no. 1, pp. 43-46, 2008.
[2] G. P. Bruggeman, A. Arampatzis, F. Emrich and W. Potthast, “Biomechanics of double transtibial amputee sprinting using dedicated sprint prostheses,” Sports Technol., vol. 4-5, no. 1, pp. 220-227, 2008.
[3] A.B. Sawers and M.E. Hahn, “The potential for error with use of inverse dynamic calculations in gait analysis of individuals with lower limb loss: A review of model selection and assumptions,” J. Prosthet. Orthot., vol. 22, no. 1, pp. 56-61, 2010.
[4] D.A. Winter, Biomechanics and motor control of human movement. Hoboken, New Jersey: John Wiley & Sons, Inc., 2009.
[5] M. D. Geil, M. Parnianpour, P. Quesada, N. Berme and S. Simon, “Comparison of methods for the calculation of energy storage and return in a dynamic elastic response prosthesis,” J. Biomech., vol. 33, no. 12, pp. 1745-1750, 2000.
[6] C. A. Truesdell, Essays in the history of mechanics. New York: Springer, 1968.
[7] S. M. Rigney, A. Simmons and L. Kark, “Finite element analysis of a lower-limb running-specific prosthesis,” in 8th Aust. Cong. App. Mech., Barton, A.C.T, Australia, 2014, pp. 297-305.
[8] M.P. Kadaba, H. Ramakrishnan and M. Wootten, “Measurement of lower extremity kinematics during level walking,” J. Orthop. Res., vol. 8, no. 3, pp. 383-392, 1990.
[9] S. M. Rigney, A. Simmons and L. Kark, “Stance phase mechanical characterisation of a running-specific lower-limb prosthesis,” in Proc. 2014 Aust. Biomed. Eng. Conf., Canberra, A.C.T., Australia, 2014, to be published.
[10] S. M. Rigney, A. Simmons and L. Kark, “Mechanical Efficiency of a Running-Specific Energy Storage and Return Prosthesis,” in Bk Abstracts 9th Aust. Biomech. Conf., Wollongong, NSW, Australia, 2014, pp. 43.
[11] S. L. Delp, F. C. Anderson, A. S. Arnold, J. P. Loan, A. Habib, C. T. John, E. Guendelman and D. G. Thelen, “OpenSim: open-source software to create and analyze dynamic simulations of movement,” IEEE Trans. Biomed. Eng., vol. 54. No. 11, pp. 1940-1950, 2007.
[12] S. L. Delp, J. P. Loan, M. G. Hoy, F. E. Zajac, E. L. Topp and J. M. Rosen, “An interactive graphics-based model of the lower extremity to study orthopaedic surgical procedures,” IEEE Trans. Biomed. Eng., vol. 37, no. 8, pp. 757-767, 1990.
[13] F. C. Anderson and M.G. Pandy, “A dynamic optimization solution for vertical jumping in three dimensions,” Comput. Meth. Biomech. Biomed. Eng., vol. 2, no. 3, pp. 201-231, 1999.
[14] F. C. Anderson and M.G. Pandy, “Dynamic optimization of human walking,” J. Biomech. Eng., vol. 123, no. 5, pp. 381-390, 2001.
[15] G.T. Yamaguchi and F.E. Zajac, “A planar model of the knee joint to characterize the knee extensor mechanism,” J. Biomech., vol. 22, no. 1, pp. 1-10, 1989.
[16] X. Bonnet, H. Pillet, P. Fodé, F. Lavaste and W. Skalli, “Finite element modelling of an energy-storing prosthetic foot during the stance phase of transtibial amputee gait,” Proc. Inst. Mech. Eng. Part H: J. Eng. Med., vol. 226, no. 1, pp. 70-75, 2012.
[17] M. Omasta, D. Paloušek, T. Návrat and J. Rosický, “Finite element analysis for the evaluation of the structural behaviour of a prosthesis for trans-tibial amputees,” Med. Eng. Phys., vol. 34, no. 1, pp. 38-45, 2012.
(a) (b) (c)
Figure 5. Experimental and simulated marker displacement in the laboratory (a) lateral or x-axis, (b) longitudinal or y-axis, and (c) vertical or z-axis.
32
-100
0
100
200
300
400
500
0 20 40 60 80 100
MarkerD
isplacem
ent(mm)
StancePhase(%)
0 20 40 60 80 100
StancePhase(%)0 20 40 60 80 100
StancePhase(%)
Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputeeRunning”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Results
33
-30
0
30
60
90
-600 -300
0 300 600 900
1200 1500 1800
0 20 40 60 80 100
Ela
stic
Str
ain
Ene
rgy
(J)
Gro
und
Rea
ctio
n Fo
rce
(N)
Stance Phase (%) Exp RFx Exp RFy Exp RFz FEA RFx FEA RFy FEA RFz FEA Energy
Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputeeRunning”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Benefits of FEA
34
• Replicates prosthesis
compression
• Elastic strain energy cannot be
calculated via other methods
• Seamlessly integrates prosthesis
and skeletal models
• Viable alternative to the existing
2-link segment model
Figure:Rigney,S.M.,A.Simmons,andL.Kark,“ConcurrentMul+bodyandFiniteElementAnalysisoftheLower-limbDuringAmputeeRunning”,in37thAnnualInterna:onalConferenceoftheIEEEEngineeringinMedicineandBiologySociety,Milano,Italy,2015.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Mul+ple-linksegment
Lower-limb Models
35
FiniteElementAnalysisTwo-linksegment
Exis+ng New
✓ ✓ ✓
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Cost-benefit analysis
• High-accuracy models require
additional:
– computer power
– solution time
– operator expertise
• Clinical effect of new models
currently unknown Accuracy
Compu
ta+o
nalCost
Two-linksegment
Mul+ple-linksegment
FEA
36
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Conclusions
• Able-bodied gait analysis techniques usually directly applied to
amputee gait
37
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Conclusions
• Able-bodied gait analysis techniques usually directly applied to
amputee gait
• Prosthetic lower-limb ≠ anatomical lower-limb
37
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Conclusions
• Able-bodied gait analysis techniques usually directly applied to
amputee gait
• Prosthetic lower-limb ≠ anatomical lower-limb
• Two new in vivo gait analysis models
37
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Conclusions
• Able-bodied gait analysis techniques usually directly applied to
amputee gait
• Prosthetic lower-limb ≠ anatomical lower-limb
• Two new in vivo gait analysis models
• Multiple-link segment model produces significantly different results
compared to conventional methods
37
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Conclusions
• Able-bodied gait analysis techniques usually directly applied to
amputee gait
• Prosthetic lower-limb ≠ anatomical lower-limb
• Two new in vivo gait analysis models
• Multiple-link segment model produces significantly different results
compared to conventional methods
• FEA model gives results not available through conventional methods
37
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Questions?
Contact: [email protected]
38
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics: Assumptions
1. Point mass m
m
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics: Assumptions
1. Point mass m
2. Location of m is constant
m
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics: Assumptions
1. Point mass m
2. Location of m is constant
3. Mass moment of inertia I remains constant
m, I
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics: Assumptions
1. Point mass m
2. Location of m is constant
3. Mass moment of inertia I remains constant
4. Segment lengths remain constant
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Rigid Body Mechanics: Assumptions
1. Point mass m
2. Location of m is constant
3. Mass moment of inertia I remains constant
4. Segment lengths remain constant
5. Segments connected by frictionless joints
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Two-link Segment Model: Inverse Dynamics
• Find m and I
– Measure subject
– Calculate using anthropometry data
• Measure GRFx, GRFy and GRFM
using force plates
• Calculate Fx, Fy, and M
Figure:Rigney,S.M.,A.Simmons,andL.Kark,Lower-limbkinema:csandkine:csduringamputeerunning:anewapproach.2015,tobepublished.
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
(Klute and Berge 2004)
Springelement
Damperelement
Viscoelas+cmechanicalsystem
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Springelement
Damperelement
Viscoleas+cmechanicalsystem
Lumped-parameter Model
(Klute and Berge 2004)
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Non-linear spring and damper
– modified Voigt model
• Models overall behaviour
• Also known as ‘phenomenological model’
– describes observed phenomena
– not developed from theoretical principles
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Non-linear spring and damper
– modified Voigt model
• Models overall behaviour
• Also known as ‘phenomenological model’
– describes observed phenomena
– not developed from theoretical principles
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
F F F F
F
F
F
F
F FG
• Strain-hardening spring
– Proportionality constant a
– Position exponential constant b
• Position-dependent damper
– Proportionality constant c
– Position exponential constant d
– Velocity exponential constant e
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
– Allows for viscoelastic behaviour of the prosthesis
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
– Allows for viscoelastic behaviour of the prosthesis
– Computationally efficient
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
– Allows for viscoelastic behaviour of the prosthesis
– Computationally efficient
• Disadvantages
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
– Allows for viscoelastic behaviour of the prosthesis
– Computationally efficient
• Disadvantages
– Requires mechanical testing to determine parameters
Graduate School of Biomedical Engineering Graduate School of Biomedical Engineering
Lumped-parameter Model
• Advantages
– Allows for viscoelastic behaviour of the prosthesis
– Computationally efficient
• Disadvantages
– Requires mechanical testing to determine parameters
– Currently not integrated with motion-capture software