healthy shoe design - how shoes affect joints
TRANSCRIPT
D. Casey Kerrigan, M.D., M.S.Chairman, OESH Shoes and JKM Technologies, LLCFormer Professor and Chair, University of Virginia
Department of Physical Medicine and RehabilitationAdjunct Professor, University of Virginia Department
of Mechanical and Aerospace EngineeringFaculty, University of Virginia School of Architecture
Healthy Shoe Design: How Shoes Affect Joints
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Studies of the effects of shoes on forces and loads in the body done at Harvard Medical School and the University of Virginia
10 Camera Vicon Motion Analysis System
Marker Placement
Force Plate
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Force Plate Measurements
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Force Plates in a Treadmill
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Walking, Running, Standing
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Studied Subjects of All Ages
(This one’s now at Oxford!)
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0 10 20 30 40 50 60 70 80 90 100 -0.1
0.0
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High Heels Barefoot
% Gait Cycle
Coronal Knee Torque
Val
gus
V
arus
N-m
/kg
-m
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Lancet 2001;357:1097-1098
…more studies on all different types of shoes
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ABC 20/20 Feature Presentation
Women's shoes and knee osteoarthritis.Kerrigan DC, Lelas JL, Karvosky ME.Lancet. 2001 Apr 7;357(9262):1097-8.
Wide heeled shoes also increase torques
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Effect of Running Shoes on Knee Varus Torque
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And shoe components – orthotics and off the shelf arch supports
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Knee joint torques during runningArrows point to the moment of peak “impact”
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Peak torques relate to:
Illiotibial Band SyndromeGluteus Medius TendonopathyTrochanteric BursitisHip osteoarthritisPatellofemoral Knee PainMedial Knee OsteoarthritisShin SplintsTibial Stress FracturePlantar FasciitisMetatarsal Stress Fracture
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And here’s what all these injuries have in common:
The torques, forces, pressures stresses and strains that cause ALL of them occur at the same moment in the gait cycle – when the foot is firmly planted on the ground – NOT AT IMPACT
Plantar Fasciits
TibialStress Fracture
Medial Knee Osteoarthritis
MetatarsalStress Fracture
Illiotibial BandSyndrome
Shin Splints
Gluteus Medius Tendinopathy
TrochantericBursitis
PatellofemoralKnee Pain
HERE….
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N=74
Natural Springiness of the Foot During Gait
Walking
Running
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This is the moment of Impact
Note the tiny ground reaction force
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Note the large ground reactionforce
This is when the foot is firmly planted
Peak stresses occur at time of peak GRFtwice during walking
Sagittal plane walking
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Peak stresses occur at peak GRF once during running
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Sagittal plane running
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Impact
Planted
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Planted
Impact
(This one’s going to Yale next year!)
Ground Reaction Force Curve in Running
First peak The impact peakHas nothing to do
with injurySecond peak
The so called “active” peak
Has everything to do with injury
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Force(body weight)
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Absorption Acceleration
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The research papers that define OESH Shoe Construction
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Shoe attributes that abnormally increase loads on jointsHeel height differential Arch supportSide to side contouring (the typical
shoe has a cradle running side to side
Cushioning which effectively produces unwanted contours during weight support -- a heel differential, arch support, side to side contouring
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What then comprises a good shoe?
Flat in the heel to toe directionFlat in the side to side directionNo arch supportNo cushioning or dampening which
causes unwanted contouringTrue responsiveness or springiness
in a perfectly flat sole that works in unison with foot compliance
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