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Sagittal Plane Trunk Posture Influences Patellofemoral Joint Stress during Running
Journal of Orthopaedic & Sports Physical Therapy® Downloaded from www.jospt.org at University of Hong Kong Libraries on September 2, 2014. For personal use only. No other uses without permission. Copyright © ${year} Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.
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Hsiang-Ling Teng, PT, PhD1,2
4
Christopher M. Powers, PT, PhD1
5 6
1
7
Angeles, CA.
8
2
9
San Francisco, CA.
Division of Biokinesiology and Physical Therapy, University of Southern California, Los
Department of Radiology and Biomedical Imaging, University of California, San Francisco,
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This study was approved by the Health Science Institutional Reviewed Board of the University
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of Southern California.
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This study was partially funded by the International Society of Biomechanics Dissertation Grant.
14 15
Correspondence Information:
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University of California, San Francisco
17
Department of Radiology and Biomedical Imaging
18
185 Berry St., Suite 350, San Francisco, CA 94107
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Email: [email protected]
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Journal of Orthopaedic & Sports Physical Therapy® Downloaded from www.jospt.org at University of Hong Kong Libraries on September 2, 2014. For personal use only. No other uses without permission. Copyright © ${year} Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.
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ABSTRACT
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STUDY DESIGN: Cross-sectional, repeated-measures. OBJECTIVES: To examine the
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association between sagittal plane trunk posture and patellofemoral joint (PFJ) stress and
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determine whether modifying sagittal plane trunk posture influences PFJ stress during running.
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BACKGROUND: Patellofemoral pain is the most common injury among runners and is thought
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to be the result of elevated PFJ stress. While sagittal plane trunk posture has been shown to
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influence tibiofemoral joint mechanics, no study has examined the influence of trunk posture on
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PFJ kinetics. METHODS: Twenty-four asymptomatic recreational runners (12 female, 12 male)
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ran overground at a speed of 3.4 m/s under 3 trunk posture conditions: self-selected (SELF),
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flexed (FLEX), and extended (EXT). Trunk and knee kinematics, ground reaction forces, and
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electromyographic signals from selected lower extremity muscles were obtained. A previously
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described PFJ biomechanical model was used to quantify PFJ stress. RESULTS: The mean ± SD
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trunk flexion angles under the SELF, FLEX, and EXT running conditions were 7.3o ± 3.6o, 14.1o
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± 4.8o, and 4.0o ± 3.9o, respectively. A significant inverse relationship was observed between
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mean trunk flexion angle and peak PFJ stress during the SELF condition (r=-0.60, p=0.002).
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Peak PFJ stress was significantly lower in the FLEX condition (mean ± SD, 20.2 ± 3.4 MPa,
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p
Sagittal Plane Trunk Posture Influences Patellofemoral Joint Stress during Running
Journal of Orthopaedic & Sports Physical Therapy® Downloaded from www.jospt.org at University of Hong Kong Libraries on September 2, 2014. For personal use only. No other uses without permission. Copyright © ${year} Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.
2 3
Hsiang-Ling Teng, PT, PhD1,2
4
Christopher M. Powers, PT, PhD1
5 6
1
7
Angeles, CA.
8
2
9
San Francisco, CA.
Division of Biokinesiology and Physical Therapy, University of Southern California, Los
Department of Radiology and Biomedical Imaging, University of California, San Francisco,
10 11
This study was approved by the Health Science Institutional Reviewed Board of the University
12
of Southern California.
13
This study was partially funded by the International Society of Biomechanics Dissertation Grant.
14 15
Correspondence Information:
16
University of California, San Francisco
17
Department of Radiology and Biomedical Imaging
18
185 Berry St., Suite 350, San Francisco, CA 94107
19
Email: [email protected]
1
Journal of Orthopaedic & Sports Physical Therapy® Downloaded from www.jospt.org at University of Hong Kong Libraries on September 2, 2014. For personal use only. No other uses without permission. Copyright © ${year} Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.
1
ABSTRACT
2
STUDY DESIGN: Cross-sectional, repeated-measures. OBJECTIVES: To examine the
3
association between sagittal plane trunk posture and patellofemoral joint (PFJ) stress and
4
determine whether modifying sagittal plane trunk posture influences PFJ stress during running.
5
BACKGROUND: Patellofemoral pain is the most common injury among runners and is thought
6
to be the result of elevated PFJ stress. While sagittal plane trunk posture has been shown to
7
influence tibiofemoral joint mechanics, no study has examined the influence of trunk posture on
8
PFJ kinetics. METHODS: Twenty-four asymptomatic recreational runners (12 female, 12 male)
9
ran overground at a speed of 3.4 m/s under 3 trunk posture conditions: self-selected (SELF),
10
flexed (FLEX), and extended (EXT). Trunk and knee kinematics, ground reaction forces, and
11
electromyographic signals from selected lower extremity muscles were obtained. A previously
12
described PFJ biomechanical model was used to quantify PFJ stress. RESULTS: The mean ± SD
13
trunk flexion angles under the SELF, FLEX, and EXT running conditions were 7.3o ± 3.6o, 14.1o
14
± 4.8o, and 4.0o ± 3.9o, respectively. A significant inverse relationship was observed between
15
mean trunk flexion angle and peak PFJ stress during the SELF condition (r=-0.60, p=0.002).
16
Peak PFJ stress was significantly lower in the FLEX condition (mean ± SD, 20.2 ± 3.4 MPa,
17
p
