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Simulating Quadriceps Muscle Atrophy and Activation Deficits during Gait
Julie ThompsonStanford University
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Webinar Objectives
• Background on prevalence of quadriceps muscle weakness• 2 types of weakness: atrophy and activation deficit
• Motivating questions• How we addressed questions using OpenSim• Methodological details of simulating weakness• Major findings and take-away
• Thompson et al., Journal of Biomechanics; 46(13): 2165-72, 2013.
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Background
• Osteoarthritis (OA): • musculoskeletal disease • progressive deterioration of the
articular cartilage of the joint
• Very Common• 49.9 million in U.S. (22.2% of
the population) between 2007 and 20091
• 67 million (25%) by 20302
• 37% over age 60 have radiographic evidence of OA3
7
http://health.yahoo.com
www.centracare.com1. MMWR, 59: 1261-65, 2010.2. Hootman et al., Arthr Rheum 54: 226-29, 2006.3. Dillon et al., J Rheumatol 33: 2271-79, 2006.
Background
• Approximately 21.1 million adults in the U.S. report activity limitations due to symptoms of arthritis1
• Increased dependence and difficulty during activities2:• Climbing stairs, Walking
84. Moxley Scarborough et al., Gait Posture 10: 10-20, 1999.3. Lord et al., J Am Geriatr Soc 47: 1077-81, 1999.
5. Walsh et al., Phys Ther 78: 248-58, 1998.
unitednationsroadrunners.orgHealthsharenews.blogspot.com
www.besthealthtips4you.com
2. Fisher et al., SJRM 29: 213-21, 1997.1. MMWR, 59: 1261-65, 2010.
http://daiseypt.com/Articles/anatomyart/quads.htm
Background
• Approximately 21.1 million adults in the U.S. report activity limitations due to symptoms of arthritis1
• Increased dependence and difficulty during activities2:• Climbing stairs, Walking
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• Quadriceps weakness, in particular, has been linked to functional impairment3-5
• Increased fall risk• slower walking speed
4. Moxley Scarborough et al., Gait Posture 10: 10-20, 1999.3. Lord et al., J Am Geriatr Soc 47: 1077-81, 1999.
5. Walsh et al., Phys Ther 78: 248-58, 1998.
unitednationsroadrunners.orgHealthsharenews.blogspot.com
www.besthealthtips4you.com
2. Fisher et al., SJRM 29: 213-21, 1997.1. MMWR, 59: 1261-65, 2010.
http://daiseypt.com/Articles/anatomyart/quads.htm
pelvis
knee
Quadriceps Weakness
• Quadriceps weakness is one of the earliest and most common symptoms of OA1
• Two sources of muscle weakness:• Atrophy
• Decrease in number or size of muscle fibers
• Reduced voluntary activation• Inability to recruit (activate) all of the muscle’s motor units2
(groupings of muscle fibers)
92. Kent-Braun and Le Blanc, Muscle Nerve 19: 861-69, 1996.1. Fisher et al., Disab Rehab 19: 47-55, 1997.
Quadriceps Weakness
• Strength deficits• As high as 38% in late stage OA1
• As high as 64% after total knee replacement for treatment of knee OA2
• Activation deficits• As high as 34% in OA3
• Underlying mechanism relating quadriceps function to gait impairments is unknown
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1. Petterson et al., JBJS Am-89: 2327-33, 2007.
3. Hassan et al., Ann Rheum Dis 60: 612-18, 2001.
2. Mizner et al., Phys Ther 83: 359-65, 2003.
Dynamic Computer Simulations
• Powerful tool for investigating cause-effect relationships1
• Allow us to determine individual roles of muscles in coordinated movement
• Predictive studies: how muscle function changes in response to rehab, surgery, or gait re-training
111. Delp et al., IEEE Trans Biomed Eng 54: 1940-50, 2007.
Muscle Contributions during Gait
• Two major motor functions used to transport the body in human gait are1:• Forward progression (forward acceleration of the body)• Vertical support (vertical accel. of body against gravity)
121. Winter, University of Waterloo Press, 1991.
Previous Research
• Previous research has investigated muscle function in healthy and some pathological populations1-6
• Main contributors to progression and support during gait are the quadriceps, gluteus maximus, and plantarflexors
• Muscle force generally increases with gait speed
131. Higginson et al., J Biomech 39: 1769-77, 2006.2. Liu et al., J Biomech 39: 2623-30, 2006. 5. Steele et al., J Biomech 43: 2099-105, 2010.
6. Van der Krogt et al., Gait Posture 36: 113-9, 2012.
4. Neptune et al., Gait Posture 19: 194-205, 2004.
3. Liu et al., J Biomech 41: 3243-52, 2008.
Motivating Questions
• Muscle compensations in populations with weak quadriceps
• Do other muscles compensate for weakness in the quadriceps? How?
• Do compensations differ between the two types of weakness (atrophy and activation failure)?
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Motivation
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Estimate
Maintain normal gait
Muscle compensations in response to weak
quadriceps
Improve patient outcomes
Inform and Guide Rehabilitation
Apply similar method
Muscle compensations in pathological gait (OA, ACL)
Purpose
• To estimate changes in muscle forces and contributions to support and progression to maintain normal gait in response to two sources of quadriceps muscle weakness: atrophy and activation failure
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Methods
• Motion capture data collected in the OSU Movement Analysis and Performance Lab
• 7 healthy subjects (4M/3F, 21.9 ± 2.3 years)• IRB-approved written consent
• Bilateral gait data collected from each subject• Walking on level ground at a self-
selected speed (1.32 ± 0.13 m/s)• Full-body Point-Cluster Technique1
• Surface EMG from bilateral lower extremity muscles
171. Andriacchi, T.P., et al., J Biomech Eng, 1998. 120(6): p. 743-9.
Computer Models and Simulations
• Generated walking simulations of one gait cycle using the open-source software package OpenSim1 and gait2392 model
181. Delp et al., IEEE Trans Biomed Eng 54: 1940-50, 2007.
Experimental Marker Trajectories
Muscle ActivationsMuscle Forces
Generic Model
Computed Muscle Control (CMC)
• Produces a muscle-driven simulation of subject’s movement1
191. Thelen and Anderson, J Biomech 39: 1107-15, 2006.
Dark Red = fully activated (“on”)Dark Blue = de-activated (“off”)
Induced Acceleration Analysis (IAA)
• Computes the contributions of individual muscles to forward progression and vertical support
• Foot-contact constraints combined with equations of motion are used to solve for accelerations caused by each muscle force from CMC
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Simulated Weakness
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1. “Atrophy Only” - Decreased quadriceps’ peak isometric force to 40% of normal
• Weakened the quadriceps of one stance leg in three ways:1. “Atrophy Only” - Decreased quadriceps’
peak isometric force to 40% of normal
Simulated Weakness
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Simulated Weakness
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2. “Activation Failure Only” - Decreased quadriceps’ peak activations by 35% compared to full-strength simulation
• Weakened the quadriceps of one stance leg in three ways:1. “Atrophy Only” - Decreased quadriceps’
peak isometric force to 40% of normal2. “Activation Failure Only” - Decreased
quadriceps’ peak activations by 35% compared to full-strength simulation
Simulated Weakness
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• Weakened the quadriceps of one stance leg in three ways:1. “Atrophy Only” - Decreased quadriceps’
peak isometric force to 40% of normal2. “Activation Failure Only” - Decreased
quadriceps’ peak activations by 35% compared to full-strength simulation
3. “Atrophy + Activation Failure” -Combination of simulated atrophy and activation failure
• Re-ran CMC and IAA for each weakened case• While tracking normal gait
Simulated Weakness
26• Re-calculated muscle forces and contributions
Simulating Atrophy
• Decreasing peak isometric force to 40% of normal:• Vastus lateralis in generic model = 1871 N• Weakened model = 1871 * 0.4 = 748.4 N
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Simulating Activation Deficit
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0.399
0.175 1st peak: 0.399 * 0.65 = 0.259 t=0.57-0.923 s2nd peak: 0.175 * 0.65 = 0.114 t=1.54-1.709 s
Muscle “off”: t = 0.923-1.54 s
Constraining peaks to 65% of their full-strength value (ie, 35% deficit):
Evaluating Results
• Compare CMC with experimental EMG
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• Check coordinate errors• <2 degrees (or 2 cm for translations)
• Check residual forces and moments• <20N or 50 Nm
Results: Gluteus maximus and soleus compensate for quadriceps
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Muscle
Force Forward Progression Vertical Support
Change from Normal (N)
% change
Change from Normal (m/s²)
% change
Change from Normal (m/s²)
% change
RF -152.4 -37.7 0.20 -31.2 0.03 5.7
Vasti -73.8 -9.0 0.16 -10.3 -0.26 -7.9
Glute Max 95.9 26.0 -0.06 27.2 0.30 19.7
Soleus 166.6 9.8 0.06 3.5 0.63 8.8
MG -58.1 -5.1 -0.07 -5.2 -0.15 -3.3
BFlh -18.2 -4.4 -0.01 -4.6 -0.03 -5.6
Glute Med -19.7 -2.1 0 0 -0.02 -0.7
TA 4.5 4.2 0.03 -1.7 -0.10 -2.1
• = greatest compensation: gluteus maximus and soleus muscles
Gluteus maximus compensates in early stance
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• Gluteus Maximus generates more force in early stance• Average peak increase of 162.9 N (42.4% change from
normal) for weakest case (p=0.0003)
162.9 N *
% Gait Cycle
Soleus compensates in late stance
• Soleus generates more force in late stance• Greater compensation needed to overcome activation deficit• Average peak increase of 217.2 N (13.1% increase over
normal) in response to “Activation Failure Only” (p=0.0016)35
217.2 N *
% Gait Cycle
Gluteus maximus contributes more to braking and support
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• To compensate for weak quads:• Glute Max contributes more
to slow forward progression (45.8% increase over normal) (p=0.0003)
• Contributes more to maintain vertical support (32.2% increase over normal) (p=0.0001)
Soleus contributes more to propulsion and support
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• To compensate for weak quads:• Soleus contributes slightly
more to maintain forward progression (7.0% increase over normal) (p=0.0039)
• Contributes more to maintain vertical support (12.1% increase over normal) (p=0.0418)
Discussion
• First study to develop muscle-driven simulations investigating the two sources of quadriceps weakness:• Atrophy • Activation failure
• To maintain normal gait pattern, gluteus maximusand soleus show greatest potential to compensate for weak quadriceps• Different responses to atrophy and activation failure
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Discussion
• Limitations• Forced simulations to track healthy
gait• Activation deficit assumptions• Generic musculoskeletal model
• Future work in impaired populations (OA)• Patient-specific muscle properties• Evaluation of compensation
strategies through clinical interventions 39
Take-Home Message
• Gluteus maximus and soleus muscles may be potential targets for strength training during rehabilitation
• Understanding compensation strategies that are necessary to maintain normal gait provides a foundation to investigate role of muscle weakness in pathological gait
40
Paper reference
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Thompson et al., Gluteus maximus and soleus compensate for simulated quadriceps atrophy and activation failure during walking, Journal of Biomechanics Sept; 46(13): 2165-72, 2013.
• Contact info: [email protected]
Acknowledgments
• Co-authors:• Robert Siston, PhD• Ajit Chaudhari, PhD• Laura Schmitt, PT, PhD• Thomas Best, MD, PhD
• OSU staff and students:• Mike McNally• Becky Lathrop• Jay Young• Molly Mollica• Michelle Cullen• Laura Henkel
• Funding sources: • NSF Graduate Research Fellowship • The Ohio State University Graduate
Fellowship program
• OpenSim team:• Scott Delp• Jen Hicks• Jeff Reinbolt• Kat Steele• Ajay Seth• Sam Hamner• Ayman Habib• Tim Dorn