Simulating Quadriceps Muscle Atrophy and Activation Deficits during Gait

Julie ThompsonStanford University

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Simulating Quadriceps Muscle Atrophy and Activation Deficits during Gait

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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

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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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• Weakened the quadriceps of one stance leg in three ways:

Simulated Weakness

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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 Atrophy

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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):

Simulating Activation Deficit

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Simulating Activation Deficit

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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

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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: julie14@stanford.edu

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