Shoe-Turf Interaction, Injury Risk, and Performance of Elite ... - STMA

1/10/2013
Shoe-Turf Interaction, Injury Risk, and
Performance of Elite Athletes
Richard Kent, PhD
University of Virginia
Center for Applied Biomechanics
Foot-and-Ankle Subcommittee, NFL
UVA Center for Applied Biomechanics
• Mechanical and Aerospace Engineering
• Founded 1989 with support from U.S. D.O.T.
• Engineers, Epidemiologists, and M.D.’s
• Staff of ~60
– Faculty from Schools of Medicine, Engineering
– 15 Research staff
– 40 Support staff and students
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1/10/2013
UVA Center for Applied Biomechanics
• Mechanical and Aerospace Engineering
• Founded 1989 with support from U.S. D.O.T.
• Engineers, Epidemiologists, and M.D.’s
• Staff of ~60
– Faculty from Schools of Medicine, Engineering
– 15 Research staff
– 40 Support staff and students
CENTER for APPLIED BIOMECHANICS
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1/10/2013
CENTER for APPLIED BIOMECHANICS
Applied
Research
Characterize
Shoe-Turf
Interaction
Mechanics
(BEAST)
Literature
Existing practices
New research
Develop
Recommended
Practices (RPs)
for NFL
Surfaces
Measure mechanics
of NFL players
during performance
Determine loads
and toe angle that
cause turf toe
Determine loads
and foot
deformations that
cause Lisfranc
injuries
Determine
mechanisms of
syndesmotic ankle
sprains
Fundamental Research
•Gait laboratory study
•Literature review
•Video analysis
•Cadaver experiments
•Relate to NFL players
•Literature review
•Determine next steps
CENTER for APPLIED BIOMECHANICS
Fundamental Research – How do injuries happen?
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Applied Research and Testing
CENTER for APPLIED BIOMECHANICS
Implementation – Equipment Recommendations, Practices
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CENTER for APPLIED BIOMECHANICS
Turf toe (Sprain of 1 st metatarsophalangeal joint)
Cadaver tests
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Probability of Injury
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
θ skin
“weakest”
injured
at 101 deg.
50% risk at 108 deg.
Survival analysis (Weibull distribution)
(n=15 cadaver tests)
“strongest”
uninjured
at 132 deg.
0 20 40 60 80 100 120 140 160
Peak Angle (deg)
9 Players
Run, cut (outside
foot), cut (inside
foot), jump, land,
start, walk
Maximum big toe
joint angle measured
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Probability
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Probability of not
attaining that angle
while running
θ skin
Cumulative normal distribution
(n=8 players)
0 20 40 60 80 100 120 140 160
Peak Angle (deg)
Probability
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Probability of not
attaining that angle
while running
θ skin
Cumulative normal distribution
(n=9 players)
Probability of injury
in a cadaver
Survival analysis (Weibull distribution)
(n=15 cadaver tests)
0 20 40 60 80 100 120 140 160
Peak Angle (deg)
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Probability
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Probability of not
attaining that angle
while running
θ skin
Cumulative normal distribution
(n=9 players)
Design
Space
Probability of injury
in a cadaver
Survival analysis (Weibull distribution)
(n=15 cadaver tests)
0 20 40 60 80 100 120 140 160
Peak Angle (deg)
Lisfranc (First tarsometatarsal joint)
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Lisfranc (First tarsometatarsal joint)
Film Analysis Summary
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
At Initiation During General
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Probability of Lisfranc Injury
P(I)
1
0.8
0.6
0.4
0.2
0
60
0
40
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
1
Axial force
0
20
Twist Angle
Cuneiform Coordinates
Cuneiform
Cuneiform
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Second Metatarsal Coordinates
\
Medial Cuneiform
2 nd Metatarsal
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Motion of 1 st and 2 nd Metatarsals
0.03
Distance (m)
0.02
0.01
0
-0.01
-0.02
0⁰ 0⁰
40⁰
0 1 2 3
M1_C1_X_load&rot
M1_C1_Y_load&rot
M1_C1_Z_load&rot
M2_C1_X_load&rot
M2_C1_Y_load&rot
M2_C1_Z_load&rot
-0.03
CENTER for APPLIED BIOMECHANICS
Syndesmotic (“High”) Ankle Sprains
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CENTER for APPLIED BIOMECHANICS
Syndesmotic (“High”) Ankle Sprains
CENTER for APPLIED BIOMECHANICS
Applied Research – Shoe-Turf Interaction
Torg et al., 1974 Heidt et al., 1996
Livesay et al., 2006 Shorten and Himmelsbach---Biomechanica 2002
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CENTER for APPLIED BIOMECHANICS
• Test Type 1 – Start from Stop (Translation)
Inputs: Vertical force and pressure in actuator
Outputs: Does shoe break free? If so, how far and fast does it move?
2.8-kN (630 lb)
static preload applied to
bearing track
Imposed F(t)
170 psi cylinder pressure
• Test 2 – Stop/Cut (Drop)
CENTER for APPLIED BIOMECHANICS
Inputs: Mass, drop height, speed over ground
Outputs: Does shoe snag? Vertical force, lateral force, and
inversion bending moment.
(37.5 kg, 82.5 lb.)
1.5 m/s
then release and drop
(2 5/8”, 6.7 cm)
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• Test 3 – Twist (Rotation)
Inputs: Vertical force and pressure in actuator
Outputs: Does shoe break free? If so, how far and
fast does it rotate?
2.8-kN (630 lb) static
preload applied to bearing track
CENTER for APPLIED BIOMECHANICS
95 psi cylinder pressure
CENTER for APPLIED BIOMECHANICS
BioCore Elite Athlete Shoe-turf Tester (B.E.A.S.T.)
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Detachable cleat
CENTER for APPLIED BIOMECHANICS
Nike Air Zoom Vapor Jet
Molded cleat
Nike Air Zoom Merciless Destroyer
Turf shoe
CENTER for APPLIED BIOMECHANICS
BioCore Elite Athlete Shoe-turf Tester (B.E.A.S.T.)
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CENTER for APPLIED BIOMECHANICS
• SELECTED RESULTS: Start from Stop Test
Comparison Across 5 Turfs
Horizontal Displacement (mm)
250
200
150
100
50
Cleat moves
Cleat catches,
then releases
BEAST33: Baltimore Ravens, Shoe VJTD2
BEAST45: NY Giants Grass, Shoe VJTD3
0
BEAST62: NY Giants Turf, Shoe VJTD3
BEAST74: Atlanta Falcons, Shoe VJTD3
BEAST90: Carolina Panthers, Shoe VJTD3
-50
0.0 0.2 0.4 0.6 0.8 1.0
Time (s)
Displacement
Cleat
“snags”
CENTER for APPLIED BIOMECHANICS
• SELECTED RESULTS : Start from Stop
Comparison Across 5 Turfs
Horizontal Displacement (mm)
250
200
150
100
50
Old Bermuda Grass
New Bluegrass
Infill manuf 1
BEAST33: Baltimore Ravens, Shoe VJTD2
BEAST45: NY Giants Grass, Shoe VJTD3
0
BEAST62: NY Giants Turf, Shoe VJTD3
BEAST74: Atlanta Falcons, Shoe VJTD3
BEAST90: Carolina Panthers, Shoe VJTD3
-50
0.0 0.2 0.4 0.6 0.8 1.0
Time (s)
Displacement
Infill manuf 2
Infill manuf 2
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CENTER for APPLIED BIOMECHANICS
Interaction Between Shoe and Turf
Nike Air Zoom Merciless Destroyer
Nike Air Zoom Vapor Jet
CENTER for APPLIED BIOMECHANICS
• RESULTS: Start from Stop (Translation)
250
Displacement
Horizontal Displacement (mm)
200
150
100
50
0
-50
Molded on Grass
Molded on Fieldturf Artificial Turf
Turf shoe on Fieldturf Artificial Turf
Turf shoe on Momentum Artificial Turf turf
0.0 0.1 0.2 0.3 0.4 0.5 0.6
Time (s)
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Recommendations for
Field Performance
Evaluation Rubric for
Cleats and Shoes
Based on Research
NFL “university”
10+ Scientific Papers on
Foot-Ankle in 5 Years
Regular Dissemination
to Equipment and Field
Managers
•Goal: Policies and procedures based on technically
rigorous research (i.e., knowledge) rather than
marketing, historical precedent, or rules of thumb
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