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Changes in Internal Prosthetic Changes in Internal Prosthetic Moment with Walking Speed: Moment with Walking Speed:

A Case Study.A Case Study.

Jason Wening MS, CPO

Mark Kaiser, CO, prosthetic resident

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As speed increases…As speed increases…

Gait asymmetry increases. (Isakov et al., 1996)

Peak GRF increases. (Nolan et al.,2003)

Ankle work in both limbs increases. (Silverman et al., 2008)

Muscle EMG increases, especially at initial contact. (Fey et al., 2010)

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Quantifying Dynamic AlignmentQuantifying Dynamic AlignmentDifficult to do with a gait lab. (Van Velzen et al.,

2006)

• Good walkers manage moments well?• Resolution may not be sufficient?

Roll over shape may be useful. (Hansen )

Alignment is a

6 DoF problem.

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A new clinical tool: A new clinical tool: Compass and Smart Compass and Smart

PyramidPyramid

Pyramid with integrated strain gauges.

Software computes moments in the sagittal and coronal planes.

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Would a moment by any other Would a moment by any other name torque the same? name torque the same?

+-

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Purpose of this studyPurpose of this study

Determine how the moment profile from the Compass System changes with walking speed for a single subject.

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SubjectSubject

36 y.o. M, R Trans-tibial amputeeK4 level ambulatorSuction TSB socket with gel liner,

dynamic response foot

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MethodologyMethodology

Nine walks were collected at a range of walking speeds in a 20 meter hallway.

Data collected in middle 10 meters.Velocity computed from 10m walk time. Moment collected using OI Compass

and Smart Pyramid at 100 Hz.

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A Matter of Semantics? A Matter of Semantics?

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GRF Posterior to Smart Pyramid:Recorded as a negative moment about the smart pyramidin the sagittal Plane

-30

-20

-10

0

10

20

30

40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Posterior Moment

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A Matter of Semantics? A Matter of Semantics?

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GRF through Smart Pyramid:Recorded as zero moment about the smart pyramidin the sagittal Plane

-30

-20

-10

0

10

20

30

40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

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A Matter of Semantics? A Matter of Semantics?

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GRF Anterior to Smart Pyramid:Recorded as a positive moment about the smart pyramidin the sagittal Plane

-30

-20

-10

0

10

20

30

40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Anterior Moment

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Sagittal Moment vs. Time for Stance Phase

-60

-40

-20

0

20

40

60

0 0.2 0.4 0.6 0.8 1

Time (s)

Mom

ent (

Nm

)

0.87 1.04* 1.3* 1.47* 1.6 1.7 1.73 1.86 1.94

Posterior

Anterior

Velocity (m/s)* = compass approved

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Coronal Moment vs. Time for Stance Phase

-15

-10

-5

0

5

10

15

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Time (s)

Mo

men

t (N

m)

0.87 1.04 1.3 1.47 1.6 1.7 1.73 1.86 1.94

Medial

Lateral

Velocity (m/s)

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ConclusionsConclusionsWalking speed changes the moment

profile as recorded by the Compass System.

With increased speed peak heel and keel moments increase.

With increased speed, relative timing of transition across 0 axis did not change.• Aprox. 33% of stance phase.

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DiscussionDiscussion

What is the true quantitative definition of optimal alignment?• Is it speed dependent?….. • Is it device dependent?…..• Is it patient dependent?…..

An effort needs to be made to characterize the Compass system and make that data available to users.

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Calling all Prosthetic Calling all Prosthetic ResidentsResidents

What is the relationship between:• Foot type,• Socket design,• Socket fit,• Limb length,• Age, gender, 2nd condition, time since amputation,• Cause of amputation,• Use of assistive device…

and internal moment.

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AcknowledgementsAcknowledgements

Orthocare Innovations

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Peak Toe Moment vs. Speed

0

10

20

30

40

50

60

0 0.5 1 1.5 2 2.5

Walking Speed (m/s)

Pea

k T

oe

Mo

men

t (N

m)

Peak Heel Moment Vs. Speed

-40

-35

-30

-25

-20

-15

-10

-5

00 0.5 1 1.5 2 2.5

Walking Speed (m/s)

Zero transition occurred at: 32.89% +/- 1% of stance phase