BIOMECHANICAL GAIT ASSESMENT ON A PATIENT WITH
FRAGILE X-ASSOCIATED TREMOR/ATAXIA SYNDROME (FXTAS):
A CASE STUDY
A Thesis
Presented to the faculty of the Department of Kinesiology
California State University, Sacramento
Submitted in partial satisfaction of
the requirements for the degree of
MASTER OF SCIENCE
in
Kinesiology
(Exercise Science)
by
Jonathan Simon Lee
SPRING
2014
© 2014
Jonathan Simon Lee
ALL RIGHTS RESERVED
ii
BIOMECHANICAL GAIT ASSESMENT ON A PATIENT WITH
FRAGILE X-ASSOCIATED TREMOR/ATAXIA SYNDROME (FXTAS):
A CASE STUDY
A Thesis
by
Jonathan Simon Lee
Approved by:
__________________________________, Committee Chair
Rodney Imamura, PhD
__________________________________, Second Reader
Daryl Parker, PhD
____________________________
Date
iii
Student: Jonathan Simon Lee
I certify that this student has met the requirements for format contained in the University
format manual, and that this thesis is suitable for shelving in the Library and credit is to
be awarded for the thesis.
__________________________, Graduate Coordinator
Daryl Parker, PhD
Department of Kinesiology
iv
___________________
Date
Abstract
of
BIOMECHANICAL GAIT ASSESMENT ON A PATIENT WITH
FRAGILE X-ASSOCIATED TREMOR/ATAXIA SYNDROME (FXTAS):
A CASE STUDY
by
Jonathan Simon Lee
Introduction
Biomechanical reference values for healthy gait patterns have been widely reported
in the peer-reviewed literature for various genders and ages. Gait is considered
pathological when observed variables in individuals deviate from healthy reference
points. The process of identifying gait characteristics may reveal distinct neurological
disorders. Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) was first identified
in 2001, and has since been extensively researched in the fields of genetics and
neurobiology. However, to date, no gait studies to our knowledge have been performed
on individuals affected with FXTAS. Therefore, the purpose of this pilot case study was
to initiate a descriptive gait profile on an individual clinically diagnosed with FXTAS.
Purpose
The purpose of this study was to conduct a biomechanical gait analysis on
individuals affected with Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS).
v
Methods
One 68-year old male participant clinically diagnosed with FXTAS participated in a
biomechanical gait analysis. The participant was required to walk at a self-selected pace
across 5 meters in a straight line over a force plate imbedded in the ground. A 34 joint
marker system was placed on the participant to generate a stick figure model that
calculates kinematic variables. An eight infra-red camera motion capture system was
used to recognize the reflective joint markers and a Vicon Nexus software program was
used to synchronize the force plate data with the reflective joint markers. After the
participant completed the self-selected speed walking trials, the participant completed 3
tandem walking trials, 2 30-second standing feet-together balance tasks, and 1 30-second
single-leg balance task. For statistical analyses, each variable was averaged with standard
deviations.
Results
During a basic walking task, our participant had an average velocity of 103.7 cm/s
compared to healthy age-matched referenced males with an average velocity of 133.84
cm/s. The average cadence in our study was 101.7 steps per minute compared to healthy
populations with an average of 114.84 steps per minute. The stance and swing times
between the two populations were the same with approximately 60% of the gait cycle
dedicated to stance and 40% of the gait cycle dedicated to swing time. The average step
length in our FXTAS participant was 56.5 cm compared to average healthy populations
of 66.02 cm. There was a small difference of distance in step width between the FXTAS
vi
and healthy population with the average step width values being 10.7 cm and 11.77 cm,
respectively. The average stride length in the FXTAS population was 118.4 cm compared
to the average of 137.32 cm in age-matched health males. The hip angles between the
two populations were comparable. The average knee angle of the FXTAS was 56.7
degrees compared to healthy populations showing averages of 63.51 degrees. The
average ankle angle of our study was 22.79 degrees compared to the average of 27.23
degrees in healthy populations.
Peak joint moments were reported for a normal walking trial. The average peak hip
extension moment for healthy populations and FXTAS were -0.65 and -0.97 N-m/kg,
respectively. The average peak hip flexion moment for the same populations listed before
were 0.63 and 0.74 N-m/kg, respectively. The average knee extension moment for
healthy and FXTAS populations were 0.40 and 0.31 N-m/kg, respectively. The average
knee flexion moment for the previously mentioned populations were -0.35 and -0.49 Nm/kg. The average ankle dorsiflexion moment for healthy and FXTAS populations were
0.92 and 1.64 N-m/kg, respectively. The average ankle plantarflexion moment for the
previously mentioned populations were -0.08 and -0.077 N-m/kg, respectively.
During the tandem walk, our study showed the FXTAS velocity to be 11.10 cm/s
compared to healthy populations of 27.0 cm/s. The cadence in our study was 25.86 steps
per minute compared to 69.7 steps per minute in healthy populations. The step width was
0.4 cm in healthy populations compared to 2.66 cm in our study. The number of missteps
showed an average of 0.2 missteps/minute in healthy populations and 6.25
missteps/minute in FXTAS.
vii
Conclusion
There is a difference in gait variables in our FXTAS population compared to
healthy and age-matched males. Our FXTAS participant most similarly mimics ataxic
and Parkinson’s Disease populations. For most variables, our participant was in between
values of healthy, age-matched males and Parkinson’s Disease and Ataxic populations.
This could be due to our participant being in the earlier stages of development in the
FXTAS disease.
_______________________, Committee Chair
Rodney Imamura, PhD
_______________________
Date
viii
ACKNOWLEDGEMENTS
My desire to understand biomechanics in the geriatric population is what inspired
me to conduct this study. I have not had the opportunity, prior to this graduate school
experience, to pursue an academic question that remained unknown within the
community of scholars. It is a great pleasure to have provided a contribution towards
science and research in an unexamined area. I would not have been able to conduct this
study without the contribution of important colleagues, family, and friends.
I would first like to thank my advisor, Dr. Rodney Imamura, for providing me
with immeasurable amounts of support, advice, and patience through this entire thesis
process. I have learned so much from Dr. Imamura that I cannot even write enough of an
acknowledgement in here to cover everything he has done for me. I still am unable to
fathom where and how he found the time to assist me with my graduate work, but he
always found and made time for me. Dr. Imamura was one of the original reasons why I
pursued a Master’s degree and from the beginning of the program, he has guided me
through the process of developing an idea and building upon it. More importantly than
learning about the research process, Dr. Imamura has helped me grow into a better person
and has taught me many life lessons. I hope to aspire to be as patient and caring to all
people as he is.
I would also like to thank my second reader, Dr. Daryl Parker, for his
contributions to my academic preparation in this Master’s program during the last two
years. His courses for thesis development assisted me tremendously for embarking upon
the thesis project and guiding me through the process. Dr. Parker supported me during the
ix
proposal process through being a second set of eyes to my paper and proposing fresh
perspectives on how to approach my topic. He was also a massive support in the process
of preparing me for my oral thesis proposal and defense. I appreciate all of the time and
efforts put in by Dr. Parker to help me become a better researcher.
I would like to thank my graduate committee member, Dr. David Mandeville, for
being such an important part of my time here at CSUS. He never showed the slightest
hesitancy to help me troubleshoot problems with the equipment in our laboratory and
always made himself available for any questions that I, or any other student, might have
had.
I would like to thank Dr. Dian Baker who first initiated contact with the
California State University of Sacramento’s Biomechanics Laboratory to get us in touch
with the Medical Investigation of Neurodevelopmental Disorders (MIND) Institute. Dr.
Baker showed great enthusiasm and encouragement for me before and during the process
of writing my thesis and performing my data collections. Dr. Baker has been a
tremendous source of support for this project and I cannot express enough gratitude
towards her. I would also like to thank Dr. Randi Hagerman from the MIND Institute for
dedicating her research career to working with individuals with FXTAS and for referring
patients to our laboratory to conduct gait analyses on her patient.
Finally, I would like to thank my family. My dad (Simon), mom (Elaine), and
sister (Jaclyn) have always believed in me and pushed me to be the best I can be. Since
day one, they have always supported me in any decision that I made or any passion that I
wanted to pursue. During these times of my academic pursuit, my family has always
x
been there to support me emotionally or financially to an extent that I cannot express
enough gratitude. I could not ask for a better family and I thank them infinitely, for none
of this would have been possible without them. I would also like to thank my girlfriend,
Amanda Confer, for also pushing me to pursue my dreams and supporting me in my
academic career as well. She has been a massive source of encouragement and has been
one of my biggest advocates for my pursuit of what I want to do. A lot of my success
would not have happened without her and I thank her immensely.
xi
TABLE OF CONTENTS
Page
Acknowledgements .................................................................................................................. ix
List of Tables ....................................................................................................................... xvii
List of Figures ..................................................................................................................... xviii
Chapter
1. INTRODUCTION ...................... ……………………………………………………….. 1
Statement of Purpose ................................................................................................... 3
Significant of Thesis ................................................................................................... 3
Limitations ................................................................................................................... 4
Delimitations ................................................................................................................ 4
Hypothesis ................................................................................................................... 4
Definition of Terms ..................................................................................................... 4
2. REVIEW OF LITERATURE ............................................................................................. 8
Analysis of Gait ........................................................................................................... 8
Biomechanics of the Lower Extremity in Normal Gait ............................................ 10
Kinematic Variables in Normal Gait ......................................................................... 12
Velocity ......................................................................................................... 12
Cadence ......................................................................................................... 13
Step Length ................................................................................................... 14
Stance Time .................................................................................................. 14
Swing Time ................................................................................................... 15
Stride Length ................................................................................................. 15
Step (stance) Width ....................................................................................... 15
xii
Hip Sagittal Excursion .................................................................................. 16
Knee Sagittal Excursion ................................................................................ 16
Ankle Sagittal Excursion ............................................................................... 17
Kinetic in Normal Gait ............................................................................................... 17
Hip Joint Moments ........................................................................................ 18
Knee Joint Moments ..................................................................................... 18
Ankle Joint Moments .................................................................................... 19
Abnormal Gait ........................................................................................................... 19
Parkinson’s Disease ................................................................................................... 19
Parkinson’s Disease Gait Kinematics ........................................................................ 20
Velocity ......................................................................................................... 20
Cadence ......................................................................................................... 21
Stride Length ................................................................................................. 21
Stance Durations ........................................................................................... 22
Hip Sagittal Excursions ................................................................................ 22
Knee Sagittal Excursions .............................................................................. 23
Ankle Sagittal Excursions ............................................................................. 23
Parkinson’s Disease Gait Kinetics ............................................................................. 23
Hip Joint Moments ........................................................................................ 23
Knee Joint Moments ..................................................................................... 24
Ankle Joint Moments .................................................................................... 24
Parkinson’s Disease Treatments and Interventions ................................................... 24
Cerebellar Ataxia ....................................................................................................... 25
xiii
Cerebellar Ataxia Gait Kinematics ............................................................................ 25
Velocity ......................................................................................................... 26
Cadence ......................................................................................................... 26
Step Length ................................................................................................... 27
Step Width .................................................................................................... 27
Stride Length ................................................................................................. 28
Stance Durations ........................................................................................... 28
Hip Sagittal Excursions ................................................................................ 29
Knee Sagittal Excursions .............................................................................. 30
Ankle Sagittal Excursions ............................................................................. 30
Cerebellar Ataxia Gait Kinetics ................................................................................. 30
Cerebellar Ataxia Treatment and Interventions ......................................................... 31
Fragile-X Syndrome .................................................................................................. 31
Fragile X-Associated Tremor/Ataxia Syndrome ....................................................... 33
FXTAS Treatment and Interventions ......................................................................... 34
Summary .................................................................................................................... 34
3. METHODS ...................................................................................................................... 36
Participant Selection .................................................................................................. 36
Experimental Procedures ........................................................................................... 37
Experimental Tasks ....................................................................................... 37
Instructional Information .............................................................................. 38
Participant Preparation ............................................................................................... 38
Instrumentation .......................................................................................................... 39
Vicon Motion Capture System ..................................................................... 39
xiv
AMTI Force Plate ......................................................................................... 40
Data Analysis ............................................................................................................. 40
Research Design ........................................................................................... 40
Calculation of Variables ............................................................................... 41
Statistical Treatment ..................................................................................... 42
4. RESULTS ........................................................................................................................ 43
Participant Description .............................................................................................. 43
Basic Walking Task ................................................................................................... 44
Velocity .......................................................................................................... 44
Cadence ......................................................................................................... 45
Temporal Components of Gait ....................................................................... 45
Spatial Characteristics .................................................................................... 46
Hip, Knee, and Ankle Sagittal Excursions ..................................................... 47
Kinetics of the Hip, Knee, and Ankle ............................................................ 48
Walking Tandem Task ............................................................................................... 51
Standing Balance Task ............................................................................................... 52
Single Leg Standing Balance Test ............................................................................. 54
5. DISCUSSION …………………………………………………………………………….56
Basic Walking Task ................................................................................................... 56
Velocity and Cadence ....................................................................................... 55
Temporal Characteristics ................................................................................. 57
Spatial Characteristics ...................................................................................... 58
Hip, Knee, and Ankle Sagittal Excursions ...................................................... 59
Hip, Knee, and Ankle Moments ...................................................................... 61
xv
Walking Tandem Task ............................................................................................... 63
Velocity and Cadence ...................................................................................... 63
Step Width ....................................................................................................... 64
Number of Missteps ........................................................................................ 64
Lateral Sway .................................................................................................... 64
Intra-limb coordination or Balance? .......................................................................... 64
Limitations ................................................................................................................ 68
Future Research ......................................................................................................... 69
Appendices............................................................................................................................... 70
References ............................................................................................................................... 73
xvi
LIST OF TABLES
Tables
Page
1.
Velocity and Cadence at a Self-Selected Walking Pace ………..………………..…. 45
2.
Temporal Values of Gait at a Self-Selected Walking Pace ……………………….....46
3.
Spatial Characteristics of Gait at a Self-Selected Walking Pace …………………….47
4.
Joint Sagittal Excursions at a Self-Selected Pace ............. …………………………. 48
5.
Joint Moments at the Hip, Knee, and Ankle at a Self-Selected Pace .......................... 49
6.
Joint force contributions to different phases of gait .................................................... 50
7.
Joint power at the hip, knee, and ankle during different phases of gait ...................... 50
8.
Velocity and Spatial Characteristics of Tandem Gait at a Self-Selected Pace ............ 52
9.
Spatial Characteristics of a Standing Balance Task .................................................... 53
10.
Spatial Characteristics of a Single Leg Balance Task ................................................. 55
xvii
LIST OF FIGURES
Figures
Page
1.
Movement of the Center of Mass during a Standing Balance Task ...................... …. 53
2.
Movement of the Center of Mass during a Single Leg Standing Balance Task ……. 54
3.
Comparison of the Kinematic variables expressed by the four populations ...... ……. 60
4.
Joint moments for healthy populations and our FXTAS participant .......................... 63
xviii
1
CHAPTER 1
Introduction
Secondary to automobile transportation, most humans perform walking as their
predominant means of primary locomotion. Walking is one of the most idiosyncratic
distinctions that are unique to each individual. While gait parameters deviate between
each person, basic gait parameters are expressed for particular age populations and are
established to provide reference data to classify normal gait (Öberg, Karsznia, & Öberg,
1993; Al-Obaidi, Wall, Al-Yaqoub, & Al-Ghanim, 2003). Documentation of healthy gait
parameters serves as a comparison for pathological gait. Therefore, biomechanical
variables are useful information for classifying an individual’s gait as healthy or
pathological.
Gait is considered pathological upon observation when there are musculoskeletal
or neuromuscular etiologies that cause a deviation from referenced healthy gait. Healthy
gait requires an integration of many systems that work in conjunction with one another
such as strength, motor control, proprioception, sensations and nervous
control. Therefore, gait abnormalities are often indicative of nervous system or
neuromuscular disorders. Irregular patterns of gait have been studied in populations
afflicted with autism (Hallet, Lebiedowska, Thomas, Stanhope, Denckla & Rumsey,
1993; Calhoun, Longworth & Chester, 2011), cerebral palsy (Wren, Rethlefsen, & Kay,
2004; Sagawa, Watelain, Coulon, Kaelin, Gorce, & Armand, 2012; Armand, Watelain,
Roux, Mercier, & Lepoutre, 2007), multiple sclerosis (Holden, Gill, Magliozzi, Nathan,
2
& Piehl-Baker, 1984), Parkinson’s disease (Salarian, Russmann, Vingerhoets, Dehollain,
Blanc, Burkhard & Aminian, 2004), and mental retardation (Sparrow, Shinkfield, &
Summers, 1997).
The process of identifying gait abnormalities is important for researchers so they
may develop treatments dedicated to improving the quality of life in clinical populations.
Monitoring abnormal gait also serves as a measurement for the progression in the
rehabilitation process. Many treatment interventions for clinical populations with
abnormal gait have been introduced based on gait measurements (Marin, Phillips,
Kilpatrick, Butzkueven, Tubridy, McDonald & Galea, 2006; Gage, 1992; Gage &
Novacheck, 2001; Nieuwboer, Kwakkel, Rochester, Jones, Wegen, Willems, Chavret,
Hetherington, Baker & Lim, 2007; Wells, Giantinoto, D’Agate, Areman, Fazzini,
Dowling & Bosak, 1999; Baram & Miller, 2005).
There is a population with a neurodevelopmental disorder, Fragile-X Syndrome,
an inherited genetic abnormality, which is known as the most widespread single-gene
cause of autism and the inherited cause of mental retardation in boys. The genetic
disorder results from a full-mutation of the Fragile-X Mental Retardation 1 (FMR1) gene
on the X chromosome. The disorder itself is manifested in 1 of every 3,600 males and 1
of every 4,000-6,000 females. There are three possible categories an individual may be
classified into based on the trinucleotide sequencing (this will be discussed more in-depth
in the following chapters): Normal, Premutation, and Full-mutation.
Individuals with the premutation on the FMR1 gene may be carriers of the
Fragile-X syndrome but may only exhibit symptoms of depression, anxiety, and
3
emotional instability, if any. The premutation is found in 1 per every 150 females and 1
per every 250-800 males. Towards middle age, and later, of individuals with the
premutation, the development of ataxia and tremors in both males and females may
occur, along with premature ovarian failure in solely females. If ataxia, tremors, or
premature ovarian failure occurs, the individual is known to have what is classified as
Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS). Ataxia is a neurological sign,
suggestive of disruption in the cerebellum, where an affected individual loses voluntarily
motor coordination, and demonstrates a significantly impaired gait. The FXTAS disorder
will be discussed in greater details in the following chapter.
There are current gait studies on other populations with
neurodevelopmental disorders such as autism, autism spectrum, down-syndrome and
cerebral palsy, Parkinson’s Disease and Ataxia. There is currently no prior research
studies conducted that analyze gait patterns in populations that have Fragile X-Associated
Tremor/Ataxia Syndrome (FXTAS).
Statement of Purpose
The purpose of the study is to conduct a biomechanical gait assessment on an
individual clinically diagnosed with Fragile X-Associated Tremor/Ataxia Syndrome.
Significance of Thesis
The research that is currently available regarding gait assessments of individuals
with Fragile X-Associated Tremor/Ataxia Syndrome is non-existent. This study is
significant because it is the first study to describe a population with this specific disorder.
The intentions of this study are to establish gait parameters for adults with FXTAS.
4
Another intention of this study is to possibly examine the observations of these
individual’s gait and determine if this gait is unique enough to be clinically specific to
diagnose individuals with Fragile X-Associated Tremor/Ataxia Syndrome in the
Diagnostic and Statistical Manual.
Limitations
1. The amount of walking the individual participated in every day was not regulated.
2. There are no official measurements published to date that classify individuals into
specific stages within the FXTAS, therefore the stage of FXTAS that our
participant is in remains unknown.
Delimitations
1. The participant was screened to make sure that he was able to walk independently
and also did not have a history of falls.
2. The participant was clinically diagnosed, and genetically confirmed, to have
Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS).
3. The participant was strictly accepted as a volunteer.
Hypothesis
There will be differences observed between the gait biomechanics of healthy
individuals and those with Fragile X-Associated Tremor/Ataxia Syndrome.
Definition of Terms
Cadence – The number of steps taken per minute.
Center of Mass – A centralized location on an object where the distribution of
mass is evenly balanced around this point.
5
Contralateral – Occurring on or acting in conjunction with a part on the opposite
side of the body.
Double Support – The period where both lower extremities are in contact with the
group at the same time.
Gait Analysis – A method for diagnosing the way people walk (Perry, 1992).
Ground Reaction Forces – The force exerted by the ground on a body in contact
with it.
Ipsilateral – Located on, or affect, the same side of the body.
Internal Forces (Moments) – The torque production of a muscle creating force
about an axis.
Intra-limb coordination – Bimanual movements that integrate and sequence
actions between limbs.
Kinetics – The study of forces that causes movement, both internal and
external. Internal forces come from muscle activity, ligaments, or from friction in the
muscle or joints. External forces come from the ground or from external loads from
active bodies or passive sources (Kreighbaum & Barthels, 1996).
Kinematics – The study of describing movement independent of forces. Linear
and angular displacements, velocities, accelerations, and joint angles are included
(Kreighbaum & Barthels, 1996).
Lateral Sway – The difference in lateral excursion demonstrated by an
individual’s center of mass.
Power – The product of angular velocity and the joint moment.
6
Preferred Walking Speed – The walking speed that is perceived by the subject as
their normal or comfortable pace.
Sagittal Sway – The different in sagittal excursion demonstrated by an
individual’s center of mass.
Stance Phase – The series of events that occur during gait from the onset of the
heel strike until the time the same limb breaks contact with the floor. The sub-phases of
the stance phase are heel strike (HS), foot flat (FF), mid-stance (MS) and push off, which
has its own two phases, heel off (HO) and toe off (TO).
Step Length – The anteroposterior distance between one heel strike and the other
contralateral heel strike in the double support phase of gait.
Step Width – The mediolateral distance between the contralateral heels in the
double support phase of gait.
Stride Length – The distance between one heel strike and the subsequent
ipsilateral heel strike.
Stride Frequency – The number of strides taken per minute.
Swing Phase – The events that occur during gait from toe off to immediately prior
to the heel strike. During swing phase, there are three sub-phases that describe the lower
extremity, the acceleration, mid-swing and deceleration.
Tandem Walk – Walking with each foot attempted to be placed successfully in
front of the contralateral foot.
7
Velocity – The forward displacement of the subject expressed in centimeters per
second (cm/sec). Angular velocity of the subject is expressed in degrees per second
(˚/sec).
8
CHAPTER 2
Review of Literature
The amount of literature dedicated to the study of gait demonstrates the importance
of a walking task. This chapter will provide a historical overview of gait analysis
followed by an introduction of the biomechanics of normal gait. The established
parameters of temporal, kinematic and kinetic variables will be reviewed here.
Pathological gait, specifically Parkinson’s Disease and Ataxia, will be discussed here,
minimally with the pathology of the disease and more in-depth with the gait parameters
established for those populations for both pre- and post- treatment interventions. The
final section will describe, in brief, the neurobiology and genetics of Fragile-X Syndrome
(FXS) and Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) and the gaps in
literature regarding these population’s gait assessments.
Analysis of Gait
The characteristics of gait can be described in two basic manners through the use
of temporal, kinematic and kinetic variables. The primary means of quantitatively
evaluating clinical gait for normal and pathological populations is through a motioncapture system. Temporal analysis is ascertained through observation in the timing of
certain events, while kinematic analysis describes the movement itself without regards to
forces. Kinetic measurements record forces that exist in the present system during
observation.
9
The need for measurements in analyzing normal gait is highly important in the
clinical rehabilitative setting. Normative values for gait parameters are required as an
established baseline to serve as a comparison to pathological gait. The normative values
in describing gait may assist the clinician by observing changes in gait as a result of
clinical interventions and to assess the end result to the initial state of the patient. Gait
may also be used to assist clinicians by serving as an indication for diagnosing certain
pathological conditions.
The first technological gait analyses were conducted in the 1970’s, when cameras
became readily available, and used simple and inexpensive methods to measure gait
variables. The earliest researchers of gait used fixed distances for people to walk and
used a stop watch to conduct variables like velocity (Jims, 1974; Robinson, 1977;
Robinson & Smidt, 1981). Other techniques involve foot print analyses which determine
step widths and foot angles (Boenig, 1977 & Shores, 1980). Cinematography and
electrogoniometers were also used to calculate temporal and kinematic variables (Stanic,
1977 & Winter, 1979). Peak Motus is a motion capture system and was introduced in
1995 and allowed researchers to use joint markers and high speed cameras to track
movement in 2-dimensions to analyze kinematic variables. The gold standard for
recording human locomotion is through a method known as motion capture. Our study
utilized the Vicon Motus system that incorporates joint markers and multiple infra-red
cameras which are capable of recording human movement in 3 dimensions.
10
Biomechanics of the Lower Extremity in Normal Gait
The review of normal gait in this section will draw from many different sources.
There is a general agreement between sources on this basic information and they are
referenced here for the reader to refer to if necessary. The references are Brunnstrom
(1972), Corcoran and Peszczynski (1978), Daniels and Worthingham (1972), Hoppenfeld
(1976), New York University (1977), Perry (1967) and Rancho Los Amigos (1978).
The gait cycle is comprised of two distinct phases consisting of a stance and
swing phase. In normal gait, stance accounts for approximately 60% of the gait cycle
while swing accounts for the remaining 40%. There is a brief moment of overlapping
between stances on both legs that is known as double support. Double support is
responsible for 22% of the gait cycle.
The stance phase begins at the moment of the heel strike. During heel strike, the
hip is flexed to its maximum amount at 30˚, the knee is fully extended and the ankle is in
neutral position. As the foot progresses to a flat position, the hip moves through slight
extension, the knee flexes roughly 15˚ and the ankle plantar flexes to 15˚ to provide
enough stretch to rest the foot flat on the floor. Mid-stance occurs as the body shifts its
weight to position itself over the stance leg. During mid-stance, the hip extends into
neutral, the knee extends to 0˚, and the ankle moves from a plantar flexed position into
slight dorsiflexion. The final phase of stance is termed “push off” and is then separated
into two phases, heel off and toe off. At heel off, the hip moves into 10-15˚ of extension,
the knee has slight flexion and the ankle dorsiflexes 15˚. When toe off occurs, the hip has
11
obtained its maximum extension of 20˚, the knee flexes to 35˚ and the ankle plantar
flexes to 20˚ to generate push off.
Once toe off is complete, the swing phase begins. The swing phase is critical for
advancing the leg forward to prepare for another stance phase. As the leg begins to
accelerate forward, the hip flexes 20˚, the knee flexes to its maximum of 60˚ and the
ankle dorsiflexes to allow floor clearance of the toes. At mid-swing, the hip continues to
flex while the leg passes directly under the body, the knee begins to move through
extension and the ankle shifts into neutral position. The leg begins to decelerate to
prepare for the heel strike. At this phase, the hip is flexed into its maximum amount of
30˚, the knee shifts into full extension and the ankle remains in neutral position. Once the
heel makes contact with the surface, heel strike begins and the swing phase ends. This is
the beginning of another stance phase and the start of a new gait cycle.
The shifting of the center of gravity within an individual is assessed to determine
the efficiency of walking. The greater the displacement of the center of gravity, the more
is required to walk. Normal center of gravity displacement is approximately two inches
vertically and one and three quarters inches horizontally. The movement of the center of
gravity does not occur in a single plane, but moves in a three-dimensional sinusoidal
curve. The vertical peak of the center of gravity occurs at mid-stance and the lowest peak
occurs at double support. In the horizontal plane, the center of gravity is at its farthest
point laterally during mid-stance over the extremity.
12
Kinematic Variables in Normal Gait
Normal gait is studied for the use of comparison to other populations who have
abnormal gait. It is important to determine the parameters of gait in individuals without
pathological disorders (neurodevelopmental or neurological) so that those values may
yield a standard value to compare with obtained values in those with gait disorders.
This section will review normative data on each of the variables that are to be
described in this study. The variables being reviewed in this study are the following: (a)
velocity, (b) cadence, (c) step length; (d) step width); (e) stand and swing times; (f) stride
length and (g) hip, knee and ankle sagittal excursions. Due to the subject in this study
being between the ages of 60-69, the values obtained for normative to describe normal
gait in this study were from individuals between the ages of 60-69. Stance durations were
excluded from this section because it was mentioned in the previous one. However,
stance durations will be described for each pathological section.
Velocity
There have been several studies conducted looking at average velocities of
healthy subjects and there is a wide range of “normal” values. Öberg, Karsznia, &
Öberg (1993) found the average velocity of 15 men between the ages of 60-69 was 127.7
cm/s. A meta-analysis conducted by Bohannan & Andrews (2011) used 12 articles
combining 941 men in total between the ages of 60-69 and found their gait speed to be
133.9 cm/s with the range from 126.6-141.2cm/s. Bohannan (1997) found that men in
their 60’s walked with a velocity of 135.9cm/s. Öberg et al. (1993) found that 15 women
between the ages of 60-69 had an average velocity of 115.7 cm/s. Ble et al. (2005)
13
analyzed 37 females between the ages of 60-69 and found their average velocity to be
123.9 cm/s. Busse, Wiles, & van Deursen (2006) sampled 11 females between the ages of
60-69 and discovered that their average velocity was 123.2 cm/s, a close comparison to
Ble et al.’s results. Hageman and Blanke (1986) looked at 13 women with a mean age of
66 years old and found their average gait speed to be 131.94 cm/s. The meta-analysis by
Bohannan & Andrews (2011) compiled 17 studies with average velocities of 5,013
women between the ages of 60-69 and found their average gait speed to be 124.1 cm/s
with a range of 118.3 to 130.0 cm/s.
Adjustments in velocity may induce effects on other gait associated variables
(Andriacchi, Ogle & Galante, 1977). Changes in velocity were found to alter
observations in joint motion, and muscle activity (Craik, Cook & D’Orazio, 1980).
Changes in velocity manifest as a result of the alterations in cadence and/or stride length
(Andriacchi, Ogle & Galante, 1977). Smidt (1974) concluded that there was a low
correlation of velocity to cadence, but another study found that there is a linear
relationship between the two variables (Larson, Odenrick, Sandlund, Weitz and Oberg,
1980).
Cadence
Like velocity, there has been a wide range in the values obtained for describing
“normal” cadence. Öberg, Karsznia, & Öberg (1993) found the average cadence for men
between the ages of 60-69 to be 117.0 steps per minute. Parvataneni, Ploeg, Olney &
Brouwer (2009) found the average cadence in the elderly to be 109.0 steps per minute.
Judge, Davis, & Ounpuu (1996) found the average cadence to be 116.0 steps per minute.
14
Kadaba, Ramakrishnan & Wootten (1990) looked at 28 males between the ages of 18-40
and found the average cadence to be 112.0 steps per minute. These values are similar to
the men aged between 60-69. Öberg et al. (1993) also found that the average cadence for
women between the ages of 60-69 is 123.6 steps per minute. Kadaba et al. (1990)
investigated the gait of 12 women between 18-40 and found their average cadence to be
115.0 steps per minute, similar to Öberg et al. It seems that cadence might be similar
between the different ages, respective of gender.
Step Length
The step length between studies did not deviate greatly. Parvataneni et al. (2009)
found that the average step length was 63.0 cm. Judge et al. (1996) and Öberg et al.
(1993) both had similar results, reporting the average step length in the elderly to be 65.0
cm. DeVita & Hortobagyi (2000) found the average step length of their elderly
participants to be 72 cm.
Stance Time
The stance time in healthy populations are relatively similar. As mentioned in the
“Biomechanics of the Lower Extremity in Normal Gait” section above, Kadaba et al.
(1990) found the stance time to be 61.0% of the entire gait cycle. Parvataneni et al.
(2009) and DeVita & Hortobagyi (2000) found that their elderly participants had an
average stance time of 64.1% and 64.8%, respectively. The stance time has been agreed
upon by many studies to be approximately 60.0% of the gait cycle.
15
Swing Time
The swing time in healthy populations has also been well documented as shown
in the “Biomechanics of the Lower Extremity in Normal Gait” section above. Kadaba et
al. (1990) found the average swing time to be 39.0%. Pavataneni et al. (2009) and
DeVita & Hortobagyi (2000) found that their elderly participants had an average swing
time to be 35.0% and 35.8%, respectively. These values closely mimic the swing time
found in the originally referenced articles of 40.0% of the gait cycle.
Stride Length
Linear relationships between stride length and velocity have both been identified
as correlated by Larson and others (1980) and not correlated (Crowinshield and others
(1978). During the subject’s preferred walking pace, the average stride length of men
between the ages of 60-69 was 130.0 cm. Parvataneni, Ploeg, Olney & Brouwer (2008)
found that the average stride length in the elderly were 127.0 cm, a similar result to
Crowinshield’s. Kadaba, Ramakrishnan & Wooten observed the stride length in males
between the ages of 18-40 and found their average to be 141.0 cm, which is a value
longer than the average elderly. The average stride length of women between the ages of
60-69 is 110.6-134.92 cm (Öberg, Karsznia, & Öberg, 1993; Hageman & Blanke, 1986).
Stride length is a variable that is easily altered by limb length, so there are not a lot of
studies analyzing stride length.
Step (stance) Width
There was one study documenting the step width in their participants, and that
was Parvataneni et al. (2009) who found the average step width to be 12.0 cm.
16
Hip Sagittal Excursion
Maximum hip flexion occurs during the late swing phase while maximum hip
extension is obtained during the late stance phase. Andriacchi et al. (1997) found that the
range of hip motion increases with increases in velocities with most of the range of
motion increase occurring in hip flexion. Murray, Drought & Kory (1964) found the hip
range of motion went through 42˚. Johnston and Smidt (1969) observed the hip range of
motion to be 52˚. Winter (1983) and Sutherland & Hagy (1972) both found the hip to go
through 43˚ of range of motion, while Kadaba, Ramakrishnan & Wootten (1990) found
the hip to go through 43.2˚.
Knee Sagittal Excursion
As mentioned earlier, the knee extends at heels strike and then flexes to absorb
the impact and weight of the body. It extends at mid-stance and goes into flexion during
heel off. The changes in knee excursion are primary utilized for assisting in shock
absorption. The knee was shown to go through 56.7˚ and 58˚ by Kadaba et al. (1990) and
Sutherland et al. (1980), respectively. In these findings with 56.7-58˚ knee flexion, the
method used to obtain the data was motion capture. In two other studies that used
goniometer measurements, knee flexion was shown to be 60.6˚ and 68.0˚ by Isacson,
Gransberg & Knutsson (1986) and Chao, Laughman, Schneider & Stauffer (1983),
respectively. Winter (1983) used a Video recording and found knee flexion to be 64˚.
Murray et al. (1964) found that the knee went through 60˚ of range of motion during a
gait cycle. While the knee flexion during walking varies between studies, the values
obtained are rather close to one another and do not show significant differences.
17
Ankle Sagittal Excursion
The range of ankle motion during normal gait has been reported to be roughly 20˚
of ankle plantar flexion and 10˚ of dorsiflexion (Murray, 1967). At heel strike, we see the
ankle move into plantar flexion, and then move into dorsiflexion as the body moves over
the supporting limb. During the heel off and toe off of the push off phase, the ankle
moves into plantar flexion before moving into dorsiflexion to allow clearance of the foot
during the swing phase. Sutherland (1972) and Winter (1983) had a similar conclusion
about ankle excursion and found the range of ankle motion to be 28˚. Kadaba et al.
(1990) observed a 25.5˚ of ankle range of motion. Hageman & Blanke (1986) observed
two groups of women, one group of young women and one group of elderly women. The
young women’s sagittal ankle excursion was 31.31˚ and the elderly women’s sagittal
ankle excursion was 24.62˚. While there was only one study that analyzed the effects of
aging on ankle sagittal excursion, all of the other observed ankle excursions seem to be in
agreement with one another. There is a possible decrease in ankle excursion as
individual’s age.
Kinetics in Normal Gait
This section will review the current normative data regarding kinetics that will be
described in the study. Stoquart, Detrembleur & Lejeune (2007) established kinetic
reference values on individuals using a treadmill. To validate the use of a treadmill,
Parvataneni, Ploeg, Olney & Brouwer (2009) compared kinematic, kinetic and metabolic
parameters using a treadmill versus overground walking in older individuals. The results
from Parvataneni et al. (2009) found that the values for the parameters were strikingly
18
similar between the two surfaces. The following areas of kinetics will be examined: (a)
hip joint moments, (b) knee joint moments, and (c) ankle joint moments.
Hip Joint Moments
Stoquart et al. (2009) assessed individuals kinematic and kinetic variables at
varying speeds of 1km/h, 2 km/h, 3 km/h, 4km/h and 5km/h. The kinetic variables at a
velocity of 5 km/h measurement was used for this thesis because it most closely
represents the average velocity of individuals being examined in our study.
At a velocity of 5 km/h, or 138.8 cm/s, within range of the average male velocity,
Stoquart et al. (2008) found that the peak hip moment extension is 0.68±0.17 Nm/Kg and
the hip moment flexion peak is-0.72±0.10 Nm/kg. Another study by Moisio, Sumner,
Shott, & Hurwitz (2003) had a similar finding to Stoquart et al.’s results and found that
the peak hip extension moment was 0.65±0.21 Nm/Kg. Moisio et al. (2003) reported
values for the peak hip flexion moment to be 0.93±0.26 Nm/Kg which is higher than
Stoquart et al.’s value.
Knee Joint Moments
During a velocity of 5 km/h, or 138.8 cm/s, Stoquart et al. (2008) found that
the peak knee flexion moment was 0.71±0.26 Nm/Kg and the peak knee extension
moment was 0.88±0.09 Nm/Kg. Moisio et al. (2003) found lower results and reported the
peak knee flexion moment to be 0.49±0.24 Nm/Kg and the peak knee extension moment
to be 0.56±0.14 Nm/Kg.
19
Ankle Joint Moments
During a velocity of 5 km/h, or 138.8 cm/s, Stoquart et al. (2008) found the
maximum plantarflexion was 0.68 ± 0.24 Nm/Kg. Moisio et al.( 2003) did not mention
plantarflexion for the ankle in their measurements but reported values for ankle
dorsiflexion, which is what Stoquart et al. (2008) did not report. Moisio et al. (2003)
found the ankle dorsiflexion moment to be 1.64±0.17 Nm/Kg.
Abnormal Gait
Abnormal gait often exposes underlying pathologies, or also be the contributor of
the symptoms itself. The study of pathological gait is important as it allows intervention
strategies to be made. Gait analysis techniques enable the assessments of gait disorders
and to monitor the effects of corrective interventions. This section describes pathological
gaits, specifically Parkinson’s Disease and Ataxia, and their associated treatments to
demonstrate the importance of studying the biomechanics of individuals.
Parkinson’s Disease
One of the trademark characters of Parkinson’s disease is the presence of lesions
in the substantia nigra, or a portion of the midbrain that is responsible for motor planning
and learning. There are lower levels of dopamine being produced when this area results
in death of dopaminergic neurons. Motor function in this population is severely
hampered by this degenerative disease. Tremors and decreased stride lengths during
walking are typical hallmarks of idiopathic Parkinson’s Disease, and these disturbances
tend to progressively worsen as this disease reaches advanced stages.
20
Parkinson’s Disease Gait Kinematics
This section will try to mimic, as best as possible, the kinematic variables
described in the healthy gait section. This will allow for the most accurate comparison of
the current data published. The following kinematic variables will be reviewed in this
section; (a) velocity, (b) cadence, (c) stride length, (d) stance durations, and (e) hip, knee
and ankle sagittal excursions.
Velocity
The velocity of those with later stages of Parkinson’s disease tends to be slower
when compared to healthy individuals. Mitoma, Hayashi, Yanagisawa & Tsukagoshi
(2000) compared control groups to two groups of Parkinson’s Disease groups, one group
being in the stages I-III and the second group being in the late stage IV. Mitoma et al.
found that the velocity for the control group was 63.1 cm/s and the speed for the group
with stages I-III was similar at 66.7 cm/s. The Parkinson’s Disease stage IV had a
significantly slower velocity of 25.5 cm/s.
Sofuwa, Nieuwboer, Desloovere, Willems, Chavret & Jonkers (2005) did not
break down their Parkinson’s group but showed that the walking velocity of 11 males and
4 females with an average age of 63.14 years old with Parkinson’s Disease is 94.0 cm/s.
Morris, Iansek, Matyas & Summers (1996) investigated 8 subjects with Parkinson’s
Disease and found their average velocity to be 82.8cm/s. Ebersbach, Sojer, Valldeoriola,
Wissel, Müller, Tolosa & Poewe (1999) observed 30 participants with Parkinson’s
Disease and found their average velocity to be 82.0 cm/s, similar to Morris et al.’s (1996)
findings.
21
Cadence
Morris et al. (1996) observed cadence in individuals with Parkinson’s Disease and
found their number of steps per minute to be 104.4, a value not too different from healthy
populations. Sofuwa et al. (2005) found a similar result to Morris et al.’s finding and
found the Parkinson’s Disease group’s cadence to be 108.5 steps per minute. Morris,
McGinley, Huxham, Collier & Iansek (1999) used normative data to describe Parkinson’s
Disease patient’s cadence with a value range of 107.8-111.6 steps per minute. In a metaanalysis by Morris, Huxham, McGinley, Dodd & Iansek (2001), they found cadence in
individuals with PD to be 125 steps per minute. When these values are compared to
healthy values, we do not see large discrepancies between cadences. Ebersbach et al.
(1999) found the average cadence to be 94.5 steps per minute in their PD group.
Stride Length
The stride lengths of individuals with Parkinson’s Disease seemed to show similar
observations in stride length. Sullivan, Said, Dillon, Hoffman & Hughes (1998) ran three
trials on individuals with the degenerative disease and found their stride length to be 96.0
cm, 93.0 cm and 94.0 cm, respectively. Sofuwa et al. (2005) found the stride length of
Parkinson’s Disease patients to be 103cm. Morris et al. (1996) observed a very similar
value to the stride length of O’Sullivan et.al’s (1998) with a stride length of 97 cm. A
meta-analysis ran by Morris et al. (2001) found the average stride length to be 106cm.
Most of the data reviewed does not seem to show large ranges in stride length between
studies. It seems that the average stride length of individuals with PD is significantly
different than those individuals considered to be healthy.
22
Stance durations
When the double support period and the single support periods are observed, we
see an increase in the time spent during support phases in individuals affected with
Parkinson’s when compared to healthy individuals. Mitoma, Hayashi, Yamagiasawa &
Tsukagoshi (1999) found that the control group spent 0.19s in the double support phase
and 0.41s in the single support phase. The PD stage I through III spent 0.20s in double
support phase and 0.35s in the single support phase, values similar to the control group.
When the PD stage IV group was observed, there was a difference in the support phases.
The stage IV group had a double support period duration of 0.37s and a single support
period of 0.27s. These values indicate that people with advanced stages of Parkinson’s
Disease require more time to support themselves when compared to healthy and less
advanced groups.
Hip sagittal excursion
Shorter strides and less time being spent in swing phase of a walk can be inferred
from a shorter range in hip excursions. Mitoma et. al (2000) found that the control groups
had 30.6˚ of excursion, while Parkinson’s Disease stage I-III groups showed 24.4˚. The
advanced staged Parkinson’s stage IV group had a smaller amount of excursion, going
through 18.6˚. Sofuwa et al. (2005) found that the control group went through 45.64˚ of
excursion while the Parkinson’s Disease group experienced 39.82˚ in their range of
motion at the hip.
23
Knee Sagittal Excursions
Mitoma et. al (2000) examined the amount of knee excursion in healthy controls,
Parkinson’s stage I-III and Parkinson’s stage IV groups. The control group demonstrated
58.6˚ of knee excursion, while the PD stage I-III group showed 49.6˚. The greatest
reduction in knee excursion was found in the group with advanced Parkinson’s Disease
stage IV. This group had a total knee excusion of 36.8˚. Sofuwa et al. (2005) showed
different results in her comparison of healthy and PD groups in knee excursions. The
maximum excursion performed by the knee (flexion) was 58.09˚ in healthy groups and a
similar value of 54.54˚ was observed in the groups with Parkinson’s Disease.
Ankle Sagittal Excursion
There have not been many articles investigating the sagittal ankle excursion in
populations with Parkinson’s Disease. Sofuwa and others (2005) showed the ankle range
of motion a gait cycle was 21.54˚.
Parkinson’s Disease Gait Kinetics
This section will try to mimic, as best as possible, the kinetic variables described
in the healthy gait section. This will allow for the most accurate comparison of the
current data published. The following kinetic variables will be reviewed in this section;
(a) hip joint moments, (b) knee joint moments, and (c) ankle joint moments.
Hip Joints Moments
Sofuwa, Nieuwboer, Desloovere, Willems, Chavret & Jonkers (2005) assessed a
group of individuals affected with Parkinson’s Disease. Sofuwa et al. (2005) found that
24
the maximum hip extension moment during stance was 0.71±0.12 Nm/Kg and the
maximum hip flexion moment during stance was
-0.70±0.06 Nm/Kg.
Knee Joint Moments
Sofuwa et al. (2005) reported values for maximum knee flexion and extension
moments during the stance phase. For the maximum knee flexion moment, the value
found was -0.32±0.05 Nm/Kg and the knee extension moment was found to be 0.32±0.04
Nm/Kg.
Ankle Joint Moments
Sofuwa et al. (2005) invested the ankle joint during three different phases: the
moment at loading response, the maximum moment in mid and terminal stance, and the
minimum moment in pre-swing. The moment at the loading response was -0.08±0.01
Nm/Kg. The maximum moment during the mid and terminal stance was found to be
1.32±0.05 Nm/Kg and the minimum moment in pre-swing was reported to be 0.05±0.01
Nm/Kg.
Parkinson’s Disease Treatments and Interventions
Studies published before and after gait assessment data on Parkinson’s patients on
medication to analyze the efficacy of the treatments (O’Sullivan, Said, Dillon, Hoffman,
& Hughes, 1998). In O’Sullivan et. al’s study, they found that gait velocity increased by
25.2 cm/s, or 35.4%, after L-dopa was administered. Along with velocity, stride length
increased by 24 cm (+30.0%), and cadence increased by 0.07 steps per second (+4.6%).
25
Therefore, it is important to measure gait parameters to assess the efficacy of the
rehabilitation or intervention process.
Lim, Wegen, Goege, Deutekom, Nieuwboer, Willems, Jones, Rochester &
Kwakkel (2005) performed a meta-analysis of combining 24 studies, or 626 patients,
were examined to determine the effect of auditory cues on improving walking speed in
patients affected with Parkinson’s Disease. There is strong evidence to demonstrate that
auditory cues can increase walking velocity in Parkinson’s Disease patients. Visual and
tactile cues were also administered but were shown to be ineffective.
Cerebellar Ataxia
Cerebellar ataxia is commonly referred to when describing dysfunction to the
cerebellum. The cerebellum is used for the regulation of neural information used to
coordinate movement patterns and to assist in motor planning. When the cerebellum
becomes disrupted, movement patterns may become sporadic and ataxia may develop.
Ataxic gait has been studied and described with clinical observations such as a widened
base stance, unsteadiness and irregularity of step patterns, trunk instability, and lateral
veering. In order to compensate for these pathological observances, the individual with
ataxia may attempt to shorten their step to increase their time spent in the support phases
of gait and shuffle their feet.
Cerebellar Ataxia Gait Kinematics
Similar to the Parkinson’s Gait section, the Cerebellar Ataxia Gait section will
review the same biomechanical gait variables; (a) velocity, (b) cadence, (c) step length;
26
(d) step width; (e) stride length, (f) stance durations and (g) hip, knee and ankle sagittal
excursions.
Velocity
There have been several studies conducted on describing the velocity of gait in
Ataxic patients and the results are varied. Palliyath, Hallett, Thomas & Lebiedowska
(1998) reported values for ataxic gait to be 47.0 cm/s. Stolze, Klebe, Petersen, Raethjen,
Wenzelburg, Witt & Deuschl (2013) found a different value for the velocity compared to
Palliyath et al. and reported a velocity of 96.0 cm/s. Mitoma et al. (2000) looked at
individuals with moderate and severe ataxia and observed their velocity to be 60.5 cm/s
and 27.6 cm/s, respectively. Another study by Ebersbach, Sojer, Valldeoriola, Wissel,
Müller, Tolosa & Poewe (1999) reported a different value as well, finding the velocity of
their ataxia subjects to be 74.6 cm/s. It should be noted that age could possibly have
affected the values obtained by these studies. Palliyath and others (1998) used subjects
between the ages of 43-64, Mitoma and others (2000) used subjects ranging from 60-80
years old, Ebersbach and others (1999) used subjects with an average of 41.4 and Stolze
and others (2013) did not present age of participants. Ilg, Golla, Thier, & Giese (2007)
investigated individuals with a mean average of 50.14 years old and found their gait
velocity to be 83.0 cm/s.
Cadence
The values reported for cadence in individuals with Ataxia varied, but not as
much as velocity. Ebersbach and others (1999) reported the cadence in their ataxic
subjects to be 94.6 steps/min. Stolze and others (2013) and Palliyath and others (1998)
27
showed similar results in their subjects of 106.4 steps/min and 102.2 steps per minute,
respectively. It should be noted that the cadence found in ataxic individuals, Parkinson’s
Disease individuals and healthy subjects do not vary by much. While the cadence do not
vary, the walking discrepancies are made up in other areas such as joint range of motions,
steps lengths and stride frequencies.
Step Length
Stolze et al. (2013) found the average step length of their participants to be
53.7cm. Ilg and others (2007) found a similar result for step length in ataxic populations
and recorded a value of 47.5cm. Mitoma et al. (2000) reported shorter values for their
patients, producing results of 20.3cm for step length.
Step Width
Step width is the known as the distance between the left and right heels. The
outcome measurement for step width is dependent on which task is being performed.
During a normal walking task, there should be some space in between the heels, but not
too much. There is an observed increase in distance between the heels in ataxic
individuals (Stolze, Raethejen, Wenzelburger, Witt & Deuschl, 2013). This typically
manifests itself as a compensatory action to provide a larger base of support. In some
cases, a negative step width may occur, which is indicative of the feet crossing over each
other as a result of a lack of coordination from the cerebellum being damaged.
Stolze and others (2013) found the average step width of ataxic populations
during a basic walking task to be 18.4cm compared to healthy populations of 11.6cm.
Palliyath et al. (1998) found the average step width in ataxic populations to be 24.5cm.
28
Stolze and others (2013) also looked at the step width during tandem walking, or walking
with each foot placed in front of the other, and noted that healthy subjects should be close
to zero while ataxic populations typically demonstrate 5cm or more. As thought, Stolze et
al (2013) found that the step width during tandem walking for ataxic populations was
4.8cm and the step width for healthy controls was 0.4cm.
Stride Length
Stride lengths reported in individuals with ataxia varied. Stolze and others (2013)
found the stride length to be 53.7cm. Mitoma and others (2000) found much shorter
stride lengths and measured moderate and severe ataxic groups. For the moderate group,
they found the stride length to be 37.0cm. The severe ataxic group was found to have a
stride length of 27.6cm. Palliyath and others (1998) did not measure stride length
directly, but reported values for stride length based on percentage of height. Stride length
published by Palliyath et al. (1998) was 59 % of the total height. The average height of
the participants was 175cm, thus producing a stride length of 103cm. The stride length
may be affected by many factors such as different limb lengths, varying force production
in muscle contractions, range of motion of the joints and differences in the duration of
stance times.
Stance Durations
The studies that involve stance durations had different measurements. Stolze et al.
(2013) found that the individuals with ataxia spent 65% of their gait cycle in stance and
35% of their gait cycle in swing. These results are expected as we would anticipate these
individuals needing more time in stability and less time balancing on single support.
29
Mitoma et al. (2000) analyzed individuals with moderate and severe ataxia for how many
seconds they spent in double support period and single support period. In individuals with
moderate ataxia, the researchers found that the subjects spent 0.30 seconds in the double
support period and 0.37 seconds in the single support period. The researchers found that
the individuals with severe ataxia spent 0.52 seconds in the double support period and
0.27 seconds in the single support period. This correlates to later stages of requiring
more time to stabilize themselves in order to compensate for their loss of balance.
Palliyath et al. (1998) measured stance durations in terms of “heel time off” and
“toe off time.” “Heel off time” is defined in the article as the moment in stance when the
heel leaves the floor, measured in percent of gait cycle when the ankle begins to plantar
flex. “Toe off time” is defined as the end of stance phase when the toe leaves the floor,
measured in percent of gait cycle when the ankle angle shows a maximum of plantar
flexion and begins to dorsiflex. In terms of percent of gait cycle, the subjects with ataxia
spent 50% in “heel off time” and 68% in “toe off time.”
Hip sagittal excursions
The hip sagittal excursions demonstrated in the literature showed similar results.
Mitoma et al. (2000), again, looked at individuals with moderate and severe ataxia. They
found that the moderate ataxic group exhibited 26.4 degrees in range of motion and the
severe ataxic group went through 24.2 degrees. Stolze et al. (2013) observed a similar
range of motion in the hip during walking and found it to be 26 degrees. Palliyath et al.
(1998) differed slightly, but still within a close range, and observed the hip range of
motion to be 31.3 degrees.
30
Knee sagittal excursions
Ankle sagittal excursions had two studies that showed similar results and one that
varied. Stolze et al. (2013) measured 50 degrees in the range of motion in the knee with
individuals affected with ataxia. Palliyath et al. (1998) also found a similar result and
observed the subjects going through 53.9 degrees in knee range of motion. Mitoma et al.
(2000) analyzed moderate and severe groups with ataxia and found both groups had
different range of motion in the knees. The researchers observed 41.8 degrees of ROM in
the knee in the moderate ataxic group and 35.8 degrees of ROM in the severe ataxic
group.
Ankle sagittal excursions
The three previous articles mentioned for the hip and knee sagittal excursions
found similar results when measuring the ankle sagittal excursions. Stolze et al. (2013)
found that the ankle went through 25.0 degrees in ROM. Palliyath et al. (1998) observed
a similar result with their subjects going through 23.2 degrees of ROM. Mitoma et al.
(2000) looked at moderate and severe groups of ataxia and found that the moderate group
went through 20.0 degrees of ROM and the severe group went through 19.0 degrees.
Cerebellar Ataxia Gait Kinetics
There are currently no studies demonstrating the kinetics, moments or joint
torques, of populations afflicted with cerebellar ataxia. This study currently involves an
individual with Fragile X-Associated Tremor/Ataxia Syndrome which has some
similarities as ataxia and the results will be placed in chapter 4, along with the discussion
in chapter 5.
31
Ataxia Treatment and Interventions
Currently, there are no known pharmaceutical interventions that are known to
remotely reduce motor disability, let alone reverse, damage caused by cerebellar
degeneration. Due to the nature of the degenerative disease, usually a focal lesion or
tumor, efficacy of rehabilitation interventions in this population remain difficult to
produce. This does not mean, however, that there are no efforts to investigate this
population and help improve their motor functioning. There have a couple of studies that
attempt to find improvements in individuals affected with ataxia, but none have shown
significant improvements (Cernak, Stevens, Price & Shumway-Cook, 2008; Ilg,
Synofzik, Brötz, Burkard, Giese & Schöls, 2009).
Fragile-X Syndrome
Fragile-X Syndrome is a disorder that stems from a genetic abnormality. All
humans have the Fragile-X Mental Retardation 1 (FMR1) gene, also known as gene
xq27.3. The FMR1 gene is located on the X chromosome and within the DNA of the
FMR1 gene, there is a trinucleotide sequence called CGG, with the C representing
Cytosine and the G representing Guanine (Verkerk, Pieretti, Sutcliffe, Fu, Kuhl, Pizzuti,
Reiner, Richards, Victoris, Zhang, Eussen, Ommen, Blonden, Riggins, Chastain, Kunst,
Gaijaard, Caskey, Nelson, Oostra, & Warren, 1991). In healthy individuals this
trinucleotide sequence repeats itself 6-44 times. The FMR1 gene creates a protein known
as Fragile-X Mental Retardation protein (FMRP1) that controls the expression of many
other genes, particularly how the messages of other genes are translated into their
proteins. In the normal range for the CGG sequence, FMRP1 expresses itself normally.
32
The genes that FMRP1 affects other genes that are directly responsible for regulating
development such as brain development, cognitive reasoning, memory, learning, and
even aesthetic facial features.
Individuals with the CGG sequence repeating itself 200 or more times is known to
have the full mutation and are considered to be affected with the Fragile-X Syndrome. In
the full mutation, the FMR1 gene is silenced and the FMRP1 is not expressed. When this
gene is not expressed, the other genes associated with it do not function properly and
proper development does not occur. Fragile-X Syndrome is known to lead to facial
feature distortion and cognitive problems. Fragile-X Syndrome is known to be a leading
cause of genetically inherited mental retardation and is also linked with the diagnosis of
autism.
The population being investigated in this thesis is known to not have the full
mutation, but the premutation. The premutation has the CGG sequence repeat itself
between 45-200 times. This premutation allows the FMR1 to express itself, so many of
the affected people develop normally and show no signs of learning disabilities or facial
distortions. People with the premutation may exhibit symptoms like depression, anxiety
or emotional instability. Having the premutation makes the individual a carrier which
means they may pass it on to their offspring. Individuals with the premutation, roughly 1
out of every 130 females or 1 out of every 250-800 males, produce too much messenger
RNA. The abundance of mRNA causes toxicity. This toxicity may lead to unanticipated
developments such as premature ovarian failure and Fragile X-Associated Tremor/Ataxia
Syndrome.
33
Fragile X-Associated Tremor/Ataxia Syndrome
Fragile X-Associated Tremor/Ataxia Syndrome typically manifests during the
later stages of the individual’s life. It is most commonly diagnosed in middle-aged males,
but it does not completely exclude females or individuals of a younger age. It is important
to note that the full mutation of 200+ CGG sequence repeats silences the gene, resulting
in a deficiency of the FMR1 protein. In the permutation range of 45-200 CGG sequence
repeats, individuals are susceptible to the adverse complications that arise with the
disorder like autoimmune, endocrine, neurological, and psychiatric problems. Individuals
affected with Fragile-X Tremor/Ataxia Syndrome exhibit some symptoms that resemble
Parkinson’s Disease. Bacalman et al. described six progressive stages of physical
disability for FXTAS: 1.) subtle tremor/balance problems; 2.) minor tremor with or
without balance problems, minimal disruption in activities of daily living (ADLs); 3.)
moderate tremor and/or balance problems with significant disruption in ADLs; 4.) severe
tremor and/or balance problems, with dependence on cane or walker; 5.) daily use of a
wheelchair; and 6.) confined to the bed. A group of 23 individuals diagnosed with
FXTAS was compared with 37 controls of relative age, education, and ethnicity. The
amount of postural sway during a 30-second stand with eyes open was calculated and
shown to be 25.41mm2 in FXTAS and 5.17mm2 in the control group (Narcisa, Aguilar,
Nguyen, Campos, Brodovsky, White, Adams, Tassone, Hagerman, & Hagerman, 2010).
This demonstrates that the FXTAS population has a significant difference in abdominal
postural control compared to a control group. It can be inferred that the FXTAS gait will
also show significant abnormalities when compared to a healthy control group.
34
In the later stages of FXTAS, the cerebellum (superior, middle and inferior
peduncles) demonstrates a reduction in the number of descending motor fibers. There is
also a reduction in the volume of the tract fibers in the corpus callosum (Wang, Hessl,
Schneider, Tassone, Hagerman & Rivera, 2013). This gives an explanation for why the
FXTAS population loses their ability to have voluntary motor control and coordination.
In order to counter the loss of motor function in these individuals, many pharmaceutical
companies have attempted to create medications to increase motor function.
FXTAS Treatment and Interventions
There have been studies showing interventions to the FXTAS population in order
to remedy their symptoms. Memantime is currently approved by the Food and Drug
Administration and is used for the treatment of Alzheimer’s disease. Memantime has
been recorded to improve neurological and cognitive function in individuals affected with
Alzheimer’s and was hypothesized to alleviate neurodegenerative diseases such as
FXTAS. This drug was shown to be ineffective in the treatment of the disorder (Seritan,
Nguyen, Mu, Tassone, Bourgeois, Schneider, Cogswell, Cook, Leehey, Grigsby,
Olichney, Adams, Legg, Zhang, Hagerman & Hagerman, 2013).
To date, there are no studies investigating the pathological gait of the FXTAS
population.
Summary
This chapter discusses research on healthy and pathological gait, specifically
Parkinson’s Disease and Cerebellar Ataxia. This review of literature weaves together
different pathological conditions and biomechanical gait variables for comparison to one
35
another. Further, it is important to note that it is critical to study gait of particular
pathological conditions because it can lead to the discovery of rehabilitation treatments or
pharmaceutical interventions, all of which can lead to a reduction in adverse symptoms of
the disease or disorder. In order to begin the process of researching treatment methods for
gait disturbances, describing baseline parameters for a population must first be
conducted. This literature review briefly explains the current treatment interventions for
other populations related to Fragile X-Associated Tremor/Ataxia Syndrome. The purpose
of this literature review is to provide ample background of Fragile X-Associated
Tremor/Ataxia Syndrome and its need for being studied. The other purpose of this review
is to give a comprehensive background of gait, in particular about how it is described and
analyzed.
36
CHAPTER 3
Methods
The purpose of this study was to describe the gait patterns in an individual that
developed Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) through selected
kinematic and kinetic variables using a motion capture system with a force plate. This
method section is outlined and divided into four sections: (a) Participant Selection; (b)
Experimental Procedures; (c) Instrumentation; and (d) Data Analysis.
Participant Selection
The subject recruited for this study was clinically diagnosed by a physician
through genetic testing to have the premutation on the Fragile-X Mental Retardation-1
Gene, and developed Fragile X-Associated Tremor/Ataxia Syndrome. Due to this
syndrome developing later on in life, the subject recruited was 68-years old. Our
participant was 177 cm tall, weighed 110 kg, and had a BMI of 77.2. The participant was
recruited from the Medical Investigation of Neurodevelopmental Disorders (MIND)
Institute under recommendation and reference from medical director of the facility, Dr.
Randi Hagerman. One male participant was directed from the MIND institute to the
California State University, Sacramento Biomechanics Lab. The participant had the
experimental procedures outlined to him twice before he signed the informed consent.
The participant was notified that if he was unable to sign the consent, any other legal
guardian would be able to sign on his behalf. The participant was considered healthy after
his physicians cleared him to be able to walk for participation in our study. It was made
37
clear to the participant that his participation in this study was entirely voluntary and that
he would be able to withdraw from this study at any time during this project for any
reason, without question.
Experimental Procedures
The following experimental procedures were performed as described below. This
specific section is divided into the following subsections: (a) Experimental tasks (b)
Instructional information
Experimental tasks
The participant was required to perform four tasks: one task was performing a
basic walking task at a self-selected pace across a designated walkway of 5 meters in
length; the second task was walking in tandem, with one foot in front of the other and
walking the length of the force plate; the third task was to stand stationary on a force
plate with both feet next to each other for 30 seconds; and the final task was to perform a
balance task by standing on his dominant leg with the other leg off the ground for 30
seconds. Reflective markers were placed on the individual as noted below in the
“Participant Preparation” section. For a trial to be considered successful, the participant
had to walk the entire distance established and also make complete contact of a force
plate with one foot. If the participant was unable to strike the force plate, the trial was
thrown out and another was requested. The participant was not notified that he was
supposed to make contact with the force plate because we do not want him to adjust his
gait in order to meet the criteria. By allowing him to freely walk, the most accurate
representation of his natural gait was acquired. For the entire procedure, 3 trials of
38
walking, 2 trials of tandem walking, 2 trials of standing balance tasks and 1 trial of a
single leg balance task were analyzed.
Instructional information
The participant was instructed to walk on a designated walkway at his preferred
walking speed. This preferred walking speed was described to him as what he found his
typical and comfortable pace to be. The walking pace was not controlled by any external
means and no practice sessions were deemed necessary. For any reason, when trials were
deemed unacceptable and excluded, the participant was informed that his trial was
incomplete and that he needed to perform another.
Participant Preparation
The participant was instructed to wear comfortable clothing that he may walk in
without experiencing any restrictions in his range of motion or walking capabilities. Due
to this study being conducted on hardwood floors in the laboratory, the subject was
instructed to walk barefoot for all of the trials. The subject was also offered the
availability of a one-piece jump suit that would allow for markers to be securely fastened
by Velcro, but he declined. Because the participant opted to wear his own clothing, the
reflective joint markers were reinforced onto his clothing with double sided tape. If any
joint markers were not properly sticking, non-reflective adhesive tape was placed on the
base of the joint marker to fasten it to the participant’s clothing. A standard 37 reflective
joint marker placement was implemented for our subject. These joint marker locations
were placed in these contralateral locations: (a) hallux; (b) 5th metatarsal; (c) ankle; (d)
leg; (e) knee; (f) hip; (g) front waist; (h) back waist (i) shoulder; (j) upper arm; (k) elbow
39
(l) forearm; (m) medial wrist; (n) lateral wrist; (o) finger; (p) lateral forehead; and noncontralateral positions, (q) clavicle; (r) sternum; (s) C7; (t) r10; and (u) T10.
Instrumentation
The instruments that were used in this study are described as follows: (a) Vicon
Motion Capture System (Vicon 612; Vicon Motion Systems, Lake Forest, CA) and (b)
AMTI Force Plate (Model OR6-6-1000 Advanced Mechanical Technology Inc.,
Watertown, MA).
Vicon Motion Capture System
The Vicon Motion Capture System (Vicon 612; Vicon Motion Systems, Lake
Forest, CA) that was used in this study was set up on a truss system in the California
State University, Sacramento Biomechanics Lab. A Motion Capture System, such as
Vicon, is widely regarded as the gold standard for assessing human movement. This
system utilized eight infra-red high speed cameras suspended 10 feet high. The cameras
created a perimeter that formed and covered a rectangular area with the dimensions of 15
by 25 feet. The motion capture system collected kinematic data at a frequency of 100 Hz.
The Vicon Motion Capture System uses infra-red lighting to view reflective joint markers
placed on an individual.
Proprietary software, Nexus (Will add information here on program), was used to
analyze the raw data. The Nexus program translated the raw data collected from the
individuals movements and calculates the kinematic and kinetic variables.
40
AMTI Force Plate
The measurement of kinetic data was conducted with the use of an AMTI force
plate (Model OR6-6-1000 Advanced Mechanical Technology Inc., Watertown, MA). The
AMTI force plate measured ground reaction forces at a frequency of 1000 Hz. The force
plate lied within the rectangular area that was monitored and calibrated by the motion
capture system. The force plate was imbedded into the laboratory floor so it did not
affect the individual’s gait when walking over the plate.
Data Analysis
Thirteen separate components of gait were analyzed from the raw data. These
were the following: (a) velocity; (b) cadence; (c) stride length; (d) stride frequency; (e)
stance time; (f) swing time; (g) double-stance time; (h) hip, knee and ankle sagittal
excursions; (i) hip, knee and ankle angular velocities; (k) ground reaction forces; and (l)
hip, knee and ankle moments. This section will describe how the value of these variables
were used and how some of them were obtained and calculated.
Research Design
A descriptive method of research was conducted for this study. Creswell (1994)
defined the descriptive type of research by stating that the purpose of the descriptive
method of research is to gather information about the present existing condition. The
emphasis is on describing the observations rather than interpreting or making
conclusions. The goal of descriptive research is to verify the hypothesis with respect to
the present situation for the ability of future researchers to elucidate it. Descriptive
41
research is important because it brings new issues and questions to the table as a result
from the study.
This study takes the quantitative approach in nature, as kinetic and kinematic
variables yield numerical data. Quantitative data-gathering methods establish
relationships between measured variables. The Quantitative approach is a useful tool as it
helps the researcher prevent biases in gathering and presenting research data. This study
explicitly looked at quantitative values such as velocities, joint angles, and other
numerical observations as listed above. Kadaba, Ramakrishnan, Wootten, Gainey, Gorton
& Cochran (1989) found that the repeatability of kinematic, kinetic and
electromyography data were very reliable between testing within the same day and within
different days.
Calculation of Variables
There are different approaches to calculating variables like velocity, which can be
measured through distance traveled over time, using stride length and stride frequency, or
monitoring the center of mass. This section seeks to clarify calculations used to assist the
reader in interpreting the values reported in the following chapter.
The center of mass location on the participant was one of the outputs exported
from the Nexus software. The velocity was then calculated by taking the change in ycoordinate of the center of mass divided by the change time for the duration of the
walking trial.
Lateral Sway calculations were also derived from the center of mass outputs.
During the walking trials, the x-coordinate of the center of mass was calculated for its
42
greatest and lowest values. The difference between these two coordinates were used to
describe the total amount of lateral excursion the participant experienced.
The angles represented in this study provide values that describe the entire range
of motion that the joint progressed through. For all three joints, the hip, the knee, and the
ankle, the angles were exported through the Nexus software which provided the angle
during every 1/100th of a second for the walking trial. The maximum and minimum angle
values were calculated and the range of motion was determined.
Statistical Treatment
The purpose of this study was entirely descriptive in nature, therefore means and
standard deviations for each biomechanical variable analyzed at their preferred walking
speed was calculated and presented as the normative data for an individual affected with
Fragile X-Associated Tremor/Ataxia Syndrome. The observed range differences in our
subject were also presented as well to give a better representation of how the participant
varied.
43
CHAPTER 4
Results
The purpose of this study was to describe the gait patterns in a sample of
individuals with a genetic mutation known as Fragile X-Associated Tremor/Ataxia
Syndrome (FXTAS) through selected kinematic and kinetic variables. Infra-red
cinematographic synchronized with force plates were used to obtain the following
information for a basic walking task: (a) velocity; (b) cadence; (c) step length; (d) step
width; (e) stance time; (f) swing time; (g) stride length; (h) hip, knee and ankle sagittal
excursion patterns; and (i) moments at the hip, knee and ankle. The same equipment was
used to obtain the following information for a walking tandem task: (a) foot angle; (b)
step width; and (c) center of mass lateral excursions. The same equipment was used to
ascertain the following information for two different balance tasks, a 30-second feet
together trial and a 30-second single-legged trial: (a) center of mass lateral excursion. The
results these variables from self-selected pace walking trials are presented in this chapter.
Participant Description
One male, diagnosed with FXTAS, with an age of 68 years old participated in this
study. The height of the participant was 175cm. The participant was screened at the
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute and was
clinically confirmed through genetic testing to have FXTAS in 2007. During a phone
interview for screening, the participant reported no significant difficulties in basic
walking tasks, but had difficulty in balance during tandem walks and balance activities.
44
Basic Walking Task
This section will represents the kinematic and kinetic results for the basic walking
task: (a) velocity; (b) cadence; (c) cycle duration; (d) stance time; (e) swing time; (f)
double support time; (g) swing to stance ratio; (h) step length; (i) step width; (j) stride
length; (k) hip, knee and ankle sagittal excursion patterns; and (l) moments at the hip,
knee and ankle.
Velocity
Table 1 shows the velocity for the participant during a self-selected pace walking
trial. Our participant’s velocity is placed in the table along with normative values for
males in the age-matched demographics, ataxic populations, and Parkinson’s Disease
populations. These values are from the studies mentioned in the review of literature and
will be cited here again. Different values were found from different studies for the same
disease, so the range is applied for the results.
45
Table 1
Velocity and Cadence at a Self-Selected Walking Pace
Variable
Healthy
Parkinson’s Disease
Ataxic
FXTAS
Velocity (cm/s)
133.84 ± 0.81
84.36 ± 8.16
67.7 ± 21.31
101.5 ± 3.1
(127.7-135.9)
(66.7-99)
(47.0-96.0)
(99.3-103.7)
Cadence
114.84 ±4.69
95.48 ± 5.48
98.9 ± 5.46
102.89 ± 2.13
(steps/min)
(109.0-124.0)
(94.5-125)
(93.1-106.4)
(100.0-105.26)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
Cadence
The calculated cadence in steps per minute is provided in Table 1 for individuals
walking at a self-selected pace. Similar to velocity, there is a wide range of cadences for
each different population.
Temporal Components of Gait
The temporal components of gait in this sample of men are listed in Table 2. The
values provided are representative of Age-matched healthy individuals, Parkinson’s
Disease populations, ataxic populations, and our FXTAS participant.
46
Table 2
Temporal Values of Gait at a Self-Selected Walking Pace
Healthy
Parkinson’s Disease
Ataxic
FXTAS
0.66 ± 0.29
0.64 ± 0.004
0.66 ± 0.20
0.735 ± 0.03
(0.64-0.72)
(0.64-0.65)
(0.37-0.79)
(0.71-0.76)
0.39 ± 0.028
0.36 ± 0.004
0.407 ± 0.04
0.41 ± 0.004
(0.35-0.42)
(0.35-0.36)
(0.3-0.43)
(0.408-0.416)
Variable
Stance Time (s)
Swing Time (s)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
Spatial Characteristics
The mean values for the spatial variables of step length, step width, and stride
length are presented in Table 3. The values provided are representative of age-matched
healthy individuals, Parkinson’s Disease populations, ataxic populations, and our FXTAS
participant.
47
Table 3
Spatial Characteristics of Gait at a Self-Selected Walking Pace
Variable
Step Length (cm)
Step Width (cm)
Stride Length (cm)
Lateral Sway (cm)
Healthy
Parkinson’s Disease
Ataxic
FXTAS
66.02 ± 3.01
38.2 ± 13.9
46.31 ± 10.9
54.02 ± 3.5
(63.0-72.0)
-
(20.3-53.7)
(51.6-56.5)
11.77 ± 0.202
17.36 ± 0.95
18.79 ± 5.12
12.25 ± 2.19
(11.6-12.0)
(13.7-17.6)
(14.4-24.5)
(10.7-13.8)
137.32 ± 6.24
103.19 ± 0.75
103.43 ± 4.5
113.55 ± 6.8
(127-141)
(103-106)
19.5 ± 1.3
-
52.26 ± 7.4
5.64 ± 0.24
-
-
-
(5.47-5.81)
(93.2-109.2) (108.7-118.4)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
Hip, Knee, and Ankle Sagittal Excursions
The sagittal excursions for the hip, knee, and ankle are represented in Table 5.
The values shown in the table describe the entire range of motion that each joint goes
through from maximum extension to maximum flexion. The values are representative of
age-matched populations of healthy, Parkinson’s Disease, Ataxic, and FXTAS.
48
Table 4
Joint Sagittal Excursions at a Self-Selected Pace
Variable
Hip Angle (˚)
Knee Angle (˚)
Ankle Angle (˚)
Healthy
Parkinson’s Disease
Ataxic
FXTAS
45.43 ± 4.09
33.79 ± 7.58
27.87 ± 2.47
43.97 ± 0.02
(42.0-52.0)
(24.4-39.82)
(26.0-31.3)
(43.96-43.99)
63.51 ± 4.71
42.15 ± 6.38
49.11 ± 4.79
57.23 ± 0.74
(56.7-68.0)
(36.8-49.6)
(41.8-53.9)
(56.7-57.76)
27.23 ± 1.15
27.22 ± 3.22
23.06 ± 2.03
27.03 ± 5.9
(25.5-28)
(17.5-28.2)
(20.0-25.0)
(22.79-31.26)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
Kinetics of the Hip, Knee, and Ankle.
The moments (joint torque) of the hip, knee, and ankle are presented in Table 6
below. The peak moments of muscle actions will be represented in the table. All values
are in Nm/kg.
49
Table 5
Joint Moments at the Hip, Knee, and Ankle at a Self-Selected Pace
Variable
Healthy
Parkinson’s Disease
Ataxic
FXTAS
Hip Extension (N·m/kg)
-0.65 ± 0.009
-0.71 ± 0.12
-
-0.97 ± 0.05
(0.65-0.68)
-
-
(-0.939- -1.01)
0.63 ± 0.30
0.70 ± 0.06
-
0.74 ± 0.04
(0.29-0.93)
-
-
(0.716-0.773)
Knee Extension
0.40 ± 0.16
0.32 ± 0.04
-
0.31 ± 0.05
(N·m/kg)
(0.23-0.56)
-
-
(0.279-0.356)
Knee Flexion (N·m/kg)
-0.35 ± 0.15
-0.32 ± 0.05
-
-0.49 ± 0.11
(0.19-0.59)
-
-
(-0.42- -0.58)
Ankle Dorsiflexion
0.92 ± 0.76
-
-
1.64 ± 0.001
(N·m/kg)
(0.11-1.64)
-
-
(1.631-1.645)
Ankle Plantarflexion
-0.08 ± 0.04
-
-
-0.077 ± 0.02
-
-
-
(-0.06- -0.092)
Hip Flexion (N·m/kg)
(N·m/kg)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
50
Table 6
Joint force contributions to different phases of gait
Hip
Knee
Ankle
Heel Strike
62.9%
34.8%
2.12%
Walk
Mid Stance
26.2%
3.66%
70.1%
Toe Off
54.7%
22.4%
22.8%
Heel Strike
45.8%
21.9%
32.2%
Tandem
Mid Stance
3.31%
11.4%
85.2%
Toe Off
54.1%
31.1%
14.8%
Table 6. The contribution of each joint moment in comparison to the entire summation of
all lower extremity forces during different phases of gait.
During the different phases of gait, specifically the heel strike, mid stance, and toe
off, each phase had the summation of the total forces on the lower extremity added
together. Each joint moment was divided by the total summation of the forces to find the
contribution of force at each joint.
Table 7
Joint power at the hip, knee, and ankle during different phases of gait
Hip
Velocity
Hip
Moment
Hip
Power
Knee
Velocity
Knee
Moment
Knee
Power
Ankle
Velocity
HS -23.42
-0.018 0.428
100.7
-0.096 -9.64 -52.78
MS 196.84 -0.602 118.49 1243.7 -0.084 -104
-84.49
TO -63.15
-0.182 11.49
2726.0 0.101
275.3 43.395
Table 7. HS = Heel strike, MS = Mid stance, and TO = Toe off.
Ankle
Moment
Ankle
Power
0.005
1.610
-0.091
-0.28
-136
-3.94
Joint power was calculated by multiplying the joint velocity by the same joint
moment at the desired phase during gait. A positive power value represents energy
generated through a concentric contraction. A negative power value is indicative of
energy absorbed through an eccentric contraction.
51
Walking Tandem Task
This section represents the kinematic results for the walking tandem task: (a)
velocity; (b) cadence; (c) step width; (d) number of missteps; and (e) lateral sway. For the
walking task to be considered tandem, the participant is required to attempt to place one
foot in front of the ipsilateral foot while moving forward. The walking tandem task
requires a substantially greater amount of balance as the base of support is diminished.
Table 8 will represent the information of healthy populations, ataxic populations
and FXTAS. The values of healthy and ataxic populations come from Stolze and others
(2013) who looked at ataxic populations with matched controls during basic walking and
tandem tasks.
52
Table 8
Velocity and Spatial Characteristics of Tandem Gait at a Self-Selected Pace
Variable
Velocity (cm/s)
Cadence (steps/min)
Healthy
Parkinson’s Disease
Ataxic
FXTAS
27.0 ± 0.05
-
29.0 ± 0.08
11.34 ± 0.35
-
-
-
69.7 ± 15.2
-
67.2 ± 10.8
(11.1-11.59)
32.9 ± 5.83
(25.8-40.0)
Step Width (cm)
0.4 ± 0.13
-
4.8 ± 4.5
5.4 ± 3.32
(2.0-8.8)
Number of Missteps
0.2 ± 0.4
-
8.2 ± 11.5
(missteps/minute)
Lateral Sway (cm)
6.25 ± 1.76
(5.0-7.5)
-
-
-
11.9 ± 6.63
(7.21-16.6)
Note: Numbers after the “±” sign denote the standard deviation. Numbers in parenthesis
are the range.
Standing Balance Task
This section represents the kinematic results for the standing balance tasks: (a)
center of mass excursion; (b) lateral sway; and (c) sagittal sway. Two tests presented in
this section, one being a 30-second standing balance with both feet together, and the
second being a 30-second single-legged balance task.
53
200
195
Y position (mm)
190
185
180
175
170
165
210
215
220
225
230
235
240
245
X position (mm)
Figure 1. Movement of the Center of Mass during a Standing Balance Task.
Table 9
Spatial Characteristics of a Standing Balance Task
Variable
Lateral Sway (cm)
FXTAS
2.63 ± 3.59
(2.04-3.22)
Sagittal Sway (cm)
2.9 ± 1.69
(1.7-4.1)
Note: Numbers after the “±” sign denote the standard deviation.
Numbers in parenthesis are the range.
Single Leg Standing Balance Test
This section represents the kinematic results for the single-legged standing
balance task: (a) lateral sway and (b) sagittal sway. The single-legged balance tasks
54
required our participant to stand on his dominant leg, in this case right, for 30 seconds.
The participant was instructed to maintain balance on one leg for as long as possible and
if balance was lost, the participant was to regain control with both legs and then attempt
to continue balance on the dominant leg.
COM-Y position (mm)
235
215
195
175
155
135
115
95
75
85
135
185
235
285
335
COM-X position (mm)
Figure 2. Movement of the Center of Mass during a Single Leg Standing Balance Task.
55
Table 10
Spatial Characteristics of a Single Leg Balance Task
Variable
FXTAS
Lateral Sway (cm)
22.67
Sagittal Sway (cm)
9.32
Note: Numbers after the “±” sign denote the standard deviation.
Numbers in parenthesis are the range.
56
CHAPTER 5
Discussion
As mentioned earlier in this thesis, there is an absence of literature
describing the biomechanical gait variables, whether kinematic or kinetic, of the walking
patterns in individuals with Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS). In
the previous chapter, kinematic and kinetic characteristics of healthy groups, Parkinson’s
Disease, Ataxic and FXTAS groups were presented. In this chapter, the reported values
are compared and discussed with the implications of changes as a genetic abnormality
progresses. This section is divided into the following discussions for walking at a selfselected pace: (a) Velocity and Cadence; (b) Stance and Swing times; (c) Step Length,
Step Width, Stride Length, and Lateral Sway; (d) Hip, Knee, and Ankle Sagittal
Excursions; and (e) Joint Moments of the Hip, Knee, and Ankle. This section discusses
the following topics regarding a tandem walking task: (f) Velocity and Cadence; (g) Step
Width; (h) Number of Missteps; and (i) Lateral Sway. The discussion of the standing
balance task reviews the following characteristics: (j) Center of Mass Excursion, Lateral
Sway, and Sagittal Sway. The final part of the discussion will review the single-legged
standing balance task and the following characteristics: (k) Lateral Sway, Sagittal Sway;
and Number of Missteps.
Basic Walking Task
Velocity and Cadence
The average velocity at a self-selected pace of our participant was found to be
103.7cm/s compared to healthy age-matched individuals average of 133.84 cm/s at self-
57
selected paces. Our participant’s velocity was found to be in between healthy subjects
and those with pathological gaits averages, Parkinson’s Disease being 84.36cm/s and
Ataxic populations with 67.7cm/s. Our participant was diagnosed with FXTAS in 2007
and is most likely in the earlier stages of the FXTAS disorder, which is why our
participant’s velocity is somewhere in between healthy and pathological.
Similar to velocity, our participant’s cadence fell in between healthy populations
and pathological populations of Parkinson’s and Ataxia. Healthy populations have an
average cadence of 114.84 steps/min compared to PD and Ataxic populations with
averages of 95.48 steps/min and 98.9 steps/min, respectively. Our participant’s cadence
was reported to be 101.7 steps/min.
Temporal Characteristics
The stance and swing times between all four populations previously mentioned
were similar except for the FXTAS value for stance time. Healthy, Parkinson’s Disease,
and Ataxic populations showed average stance times of 0.66, 0.64, and 0.66 seconds,
respectively. Our participant with FXTAS had a reported stance time of 0.735 seconds.
The swing time was similar among the healthy, PD, Ataxic, and FXTAS populations with
average swing times of 0.39, 0.36, 0.407, and 0.41 seconds, respectively. While the
stance time is slightly longer in the FXTAS participant compared to the other groups, the
stance time was still within an approximate 60% of the gait cycle as noted by Brunnstrom
(1972), Corcoran and Peszczynski (1978), Daniels and Worthingham (1972), Hoppenfeld
(1976), New York University (1977), Perry (1967) and Rancho Los Amigos (1978). The
58
stance time could also be longer due to the fact that the gait speeds were not normalized
by any means and all participants were walking at a self-selected pace.
Spatial Characteristics
The step length followed the same trend as the velocity and cadence, having the
FXTAS participant have values in between healthy and pathological populations. The
healthy, PD and ataxic populations had average values of 66.02, 38.3 and 46.31 cm,
respectively, compared to the FXTAS step length of 56.5 cm. Typically, a shorter step
length is indicative of a compensatory mechanism to reduce the amount of time balancing
on one leg while the contralateral leg is in swing phase.
The step width of the FXTAS participant was the lowest of all populations
analyzed with a step width of 10.7 cm. The healthy, PD, and Ataxic population reported
average step widths of 11.77, 17.36, and 18.79 cm, respectively. A wider step width is
usually displayed when there are balance issues as compensatory mechanism to increase
the base of support.
Many authors have concluded that increased walking velocity is a direct result of
increases in stride length or cadence (Andriacchi et al., 1977; Brunnstrom, 1972; Murray
et al., 1966; Smidt, 1971; Smidt, 1974). The stride length values reported followed
similar patterns as the step length, velocity, and cadence as the FXTAS value fell in
between the healthy and pathological populations. The stride length value from our
FXTAS participant was 118.4 cm long, compared to the average values of the healthy,
PD and Ataxic populations with stride lengths of 137.3, 103.19, and 103.43 cm,
respectively. In values of stride length, a longer stride length indicates that an individual
59
spent more time balancing on one leg which is also indicative of a greater ability to
balance.
There were no lateral sway values reported PD populations, but there are values
for healthy and ataxic populations. The ataxic population showed an average lateral sway
of 52.26 cm and the healthy population showed an average of 19.5 cm. Our FXTAS
patient showed an average lateral sway of 5.64 cm. Of all the variables assessed in this
study, this value is the most obscure, as the FXTAS patient demonstrated less lateral
sway than healthy populations during walking. This correlates with the value the other
stability variable, step width, in that our participant demonstrated highly functional gait in
terms of stabilization. These values will be noted again in the tandem walking section.
Hip, Knee, and Ankle Sagittal Excursions
At the hip, the total excursion in our study was found to be 43.96 degrees, a
comparable value to healthy population averages of 45.43 degrees. In pathological
conditions of Parkinson’s Disease and Ataxia, average hip excursions were reduced with
values at 33.79 and 27.87 degrees, respectively. Our participant had a faster speed than
the typical PD and ataxic populations, which could be a reason for a greater hip excursion
(Murray et al., 1964; Murray et al., 1966; Murray et al., 1969).
In this study, the motion occurring at the knee in the sagittal plane during gait was
similar with healthy populations, and further demonstrates our subject’s placement in
earlier stages of FXTAS. The total motion at the knee for our participant was 56.7
degrees compared to the averages of 63.51 degrees in healthy populations, 42.15 degrees
in PD, and 49.11 in ataxic populations.
60
The pattern of motion at the ankle in our study was similar to the healthy and PD
populations. The FXTAS participant had a total ankle excursion of 27.03 degrees
compared to the healthy and PD group with an average value of 27.23 and 27.22 degrees,
respectively. The FXTAS participant demonstrated a greater ankle excursion than the
ataxic population which had a reported value of 23.06 degrees. While ankle excursion is
supposed to decline as individuals age (Murray et al., 1969), it would be expected that
range of motion would decline in individuals with pathological conditions. This will be
Expressed as Percentages of Healthy
Values (%)
further explained in the moments section.
160
140
Healthy
120
PD
100
Ataxic
80
FXTAS
60
40
Vel
Cad
STPL
STPW
STRL
HIPAng KneeAng AnkleAng
Kinematic Variables
Figure 3. Comparison of the Kinematic variables expressed by the four populations. Vel = Velocity; Cad =
Cadence; STPL = Step Length; STPW = Step Width; STRL = Stride Length; HIPAng = Hip Angle;
KneeAng = Knee Angle; and AnkleAng = Ankle Angle.
The kinematic variables analyzed for the four populations of healthy, Parkinson’s
Disease, Ataxia, and Fragile X-Associated Tremor/Ataxia Syndrome were placed into a
graph (see above) and to show the differences in variation. The healthy age-matched
61
population’s values were set to be 100% and the pathological values were taken as a
percentage compared to the healthy reference.
The FXTAS patient observed hovers in between pathological populations and the
healthy reference, most likely due to his earlier stage of progression with FXTAS. In the
following years, if the FXTAS disorder progresses further, we would expect to see the
line for this FXTAS patient incorporate characteristics more similar to Parkinson’s
Disease or Ataxic populations.
It should be noted that the step width in the pathological and FXTAS populations
increased above 100% of the healthy populations. While obtaining 100% of the healthy
reference is ideal for the other kinematic variables, a higher than 100% step width is not
beneficial in this case. A wider step width is usually a compensatory mechanism
designed to create a larger base of support in response to complications with stability.
Hip, Knee, and Ankle Moments
The values in the results section regarding joint moments were reported as
maximum values for the respective joint movement. The peak hip extension joint
moment for our participant was -0.97 Nm/kg compared to the averages of healthy and PD
populations with -0.65 and -0.71 Nm/kg, respectively. The maximum hip flexion joint
moment for our subject was 0.74 Nm/kg compared to the healthy and PD populations
with an average hip flexion moment of 0.63 and 0.70 Nm/kg, respectively.
The maximum knee extension joint moment in our participant was 0.31 Nm/kg
compared to healthy and PD population’s average knee extension moment of 0.40 and
0.32 Nm/kg, respectively. The peak knee flexion joint moment for our participant was
62
reported to be -0.49 Nm/kg compared to the averages of healthy and PD populations with
peak knee flexion at -0.35 and -0.32 Nm/kg.
The maximum ankle plantar flexion joint moment in our participant was -0.077
Nm/kg compared to healthy populations with an average of -0.68 Nm/kg. The maximum
dorsi flexion joint moment for our participant was 1.64 Nm/kg compared to healthy
populations reporting 0.92 Nm/kg.
As the previous section mentioned that the ankle excursions were strikingly
similar to healthy and PD populations, it is observed that our FXTAS participant had a
noticeably lower peak plantar flexion moment at the ankle. Because plantar flexion has
an important role in propulsion and it is abated in our participant, this could be the reason
that we see an increase, exceeding healthy reference values, in peak hip flexion and knee
flexion moments. The larger peak hip flexion may potentially be a compensatory
mechanism to propel the leg forward since it is no longer utilizing plantar flexion. The
increase in the knee flexion moment may also be a compensatory mechanism to assist in
toe clearance during the swing phase. Graph 1. shows a comparison of healthy gender
and age-matched population’s moment to our FXTAS participant’s moments.
As Table 6 demonstrated, the ankle contributed 70.1% of the entire torque
production during the mid stance. This contribution is due to the eccentric contraction of
the dorsiflexors while going through slight plantarflexion. The eccentric contraction of
the dorsiflexors are not typically not seen in the ankle joint during mid stance. The typical
contribution demonstrates eccentric contraction of the soleus and gastrocnemius muscle,
which allow control for the ankle progressing through the sagittal plane while also
63
providing stability. During the tandem walk when further ankle stabilization is required,
the lack of eccentric contraction with the proper muscles may give reason as to why our
patient showed exacerbated signs of instability. The ankle torque in the tandem walk
contribution increased to 85.2% of the overall force production during mid stance. This
may potentially be a compensatory mechanism to stabilize our participant’s body while
balancing on one leg while the contralateral leg is in swing motion.
Moment (N-m/kg)
1.5
1
0.5
Healthy
FXTAS
0
Hip Ext
Hip Flx
Knee Ext
Knee Flx
Ank DF
Ank PF
-0.5
-1
Joint Movement
Figure 4. Joint moments for health populations and our FXTAS participant. Ext = Extension; Flx
= Flexion; DF = Dorsiflexion; and PF = Plantarflexion
Walking Tandem Task
Velocity and Cadence
The velocity found in our study was much lower than reported values for healthy
and ataxic populations. The velocity of the FXTAS participant was 11.10 cm/s, compared
to the healthy and ataxic populations with averages of 27.0 cm/s and 29.0 cm/s,
respectively.
64
The cadence was also much lower in our participant with FXTAS than compared
to other populations. The cadence was reported to be 25.86 steps per minute in our
participant, compared to averages of 69.7 and 67.2 steps per minute in healthy and ataxic
populations, respectively.
Step Width
The step width in our participant with FXTAS was reported to be 2.66 cm,
compared to the averages of 0.4 cm for the healthy populations and 4.8 cm for ataxic
populations. Stolze and others (2013) noted that individuals that have ataxia typically
have 5.0 cm of step width during a tandem walk compared to healthy individuals that
demonstrate close to 0.0 cm in step width.
Number of Missteps
The average number of missteps, reported as number of missteps per minute, was
found to be 6.3 in our study compared to the average of healthy and PD populations of
0.2 and 8.2 missteps per minute, respectively.
Lateral Sway
The lateral sway during a tandem walk was not reported for healthy, PD, or ataxic
populations. The average lateral sway in our FXTAS participant was shown to be 11.91
cm.
Intra-limb coordination or Balance?
A pronounced discrepancy in our participant’s motor function between walking
and tandem walking became clearly evident during the observation of the tandem walk.
During the basic walking task, from an observer’s perspective, there were no
65
observational abnormalities in our participant’s gait. During the tandem gait, our
participant demonstrated signs of struggling to maintain balance which was quantitatively
confirmed by the lower than pathological values of velocity and cadence, while also
having more lateral sway and number of missteps.
Ilg and others (2013) described two potential reasons for gait deviations in
individuals exhibiting ataxic symptoms. The first possible explanation involves an
irregularity in intra-limb coordination and the second explanation is through balance
disorders. In Ilg and others (2013), their findings found that the variables which
contribute to balance, specifically lateral sway and step width, were no different than
healthy controls, but the temporal values had deviated, suggesting that their participants
had intra-limb coordination issues. Our study found very similar findings to Ilg and
others (2013), in that our participant had very healthy values for step width and lateral
sway during a normal walking trial, but demonstrated an extended amount of time spent
in the stance phase when compared to healthy and pathological populations.
As presented in the results section, the time spent in stance (in seconds) for
healthy, PD, and ataxic populations were 0.66, 0.64, and 0.66, respectively. Our FXTAS
participant had a reported time in stance of 0.735 seconds. It should also be noted that all
four population’s swing times were relatively the same, thus the only difference in the
temporal values were the FXTAS participant’s stance time. Upon further investigation of
our participant’s walking trials, a potential reasoning for the addition time spent in stance
was found. The following discussions regarding the proper muscle activations at specific
phases are referenced from Perry and Burnfield (2010). During the mid-stance phase, the
66
primary muscle acting on the ankle should be the soleus and gastrocnemius, with both
eccentrically contracting. This purpose is to allow the body to continue to shift its weight
over the foot while decelerating the speed and providing good stabilization at the ankle
joint. Our patient demonstrated a near peak dorsiflexion moment of 1.61 N-m/kg during
the mid-stance phase, contrasting with the anticipated type of muscle contraction. While
this may not pose a problem during normal walking, if plantarflexion is responsible for
stabilization during the mid-stance, the individual could experience instability during
slower walking or during tasks such as a tandem walk. It should be noted that there are
not any specific gait analyses for tandem walk, but our participant showed an ankle
moment of 1.04 N-m/kg, indicating that our participant’s ankle was overall producing a
dorsiflexion moment during mid-stance which might possibly lead to instability at the
ankle.
During the participant’s toe-off phase during the stance phase of his dominant leg,
the hip is typically progressing through flexion with the rectus femoris and the vastus
muscles being activated. Our overall hip moment of -0.22 N-m/kg was found to be
acting in the extension movement during our participant’s toe off phase, perhaps
indicating that this muscle activity slowed the hip flexion, and prolonged the duration of
the stance phase. This temporal disturbance follows the intra-limb coordination
complication described by Ilg and others (2013). The knee moment of 90.86 N-m/kg was
indicating that our participant’s knee was overall acting in a knee extension movement.
During the toe-off phase, it is important for the knee to start off in passive flexion and
then progress into knee flexion during the initial swing phase in order to generate toe
67
clearance. The knee moment might also be a contributor to the additional stance time
observed in our participant.
As mentioned earlier in this section, our participant’s step width and lateral sway,
the balance variables we examined, were considered to be healthy which should allow us
to conclude that our participant does not have balance problems, but intra-limb
coordination complications. This cannot be entirely true with our participant though.
While our participant’s normal walking trials appear to be healthy, the participant’s
walking tandem trials portray an individual with severe balance disorders. Upon
examination of the variables observed during a tandem walk, we see that our participant’s
velocity and cadence drop below 50% of the healthy and PD population’s reported
values. Stolze and others (2013) suggested that if the step width during a tandem walk
exceeds 5 cm, the individual is displaying clear signs of ataxia. Our participant’s step
width exceeded the 5 cm, leading to the conclusion that there is a potential balance
disturbance. While there were no healthy references or controls to observe the lateral
sway in a tandem walk, our participant demonstrated a lateral sway of over 11 cm.
Aguilar and others (2008) looked at individuals with FXTAS standing on a
CATSYS plate, similar to a force transducer plate, and had their participants standing on
the plate for 30 seconds with their eyes open. The participants were also instructed to do
a single leg balance test on each of their legs. The results for these two exercises were
reported in millimeters squared for the total postural sway area and there were minimal
differences between the two exercises with the standing balance task showing a postural
sway area of 22 mm and the single leg balance task demonstrating a postural sway area of
68
21 mm. Our study measured our participant’s lateral and sagittal sway through the center
of mass. The results of our standing balance task were similar to Aguilar and others
(2008) showing 2.63 cm in the lateral sway and 2.9 cm in the sagittal sway. The lateral
sway and sagittal sway of our participant during the single leg balance did not yield
similar results to our standing balance task as it did in Aguilar and others (2008). Our
lateral sway increased by 10 fold and our sagittal sway increased by over 4 fold with
reported values of 22.67 cm and 9.32 cm, respectively.
It is unknown as to why our participant demonstrates healthy balance coupled
with intra-limb coordination complications during normal walking trials, but then shows
balance disturbances during tandem walking trials. Further investigations of these
dynamics would assist in the understanding of the balance disorders and the disruption of
the intra-limb coordination.
Limitations
As a case study, there were some limitations impacting the results of this study.
One of the main limitations of this study was the number of participants sampled. Due to
the highly specialized population, the ability to recruit additional participants to further
investigate and draw stronger conclusions was limited. Within 100 miles of Sacramento,
there are roughly three known individuals to be clinically diagnosed with FXTAS. The
contributor to this disease not being diagnosed more frequently is a result of two things;
firstly, the cost of diagnosing is expensive as genetic testing is required. The second
obstacle is the physician’s diagnosis of Parkinson’s before concluding FXTAS.
69
Another limitation of this study comes from the lack of literature on the FXTAS
population with regards to a variation of a Global Assessment of Functioning. There is
currently no official measurement in the progression of the disorder so our participant
cannot be classified into earlier or later stages of FXTAS. If the participant pool were to
be increased, there would be a possible increase in the range for our results based on the
different levels of progression with FXTAS patients.
Future Research
While there is currently no measurement for determining the stages of FXTAS, if
this case study were to be continued longitudinally for the subsequent years, a trend
might be observed as the participant’s disease progresses. Future research may help
create the first classification for stages in the FXTAS disease based on biomechanical
functionality.
Past research conducted with FXTAS populations that involved treatment
medication were shown to be ineffective (Seritan, Nguyen, Mu, Tassone, Bourgeois,
Schneider, Cogswell, Cook, Leehey, Grigsby, Olichney, Adams, Legg, Zhang, Hagerman
& Hagerman, 2013). However, for future research, using baseline gait measurements
prior to an intervention may be useful for observing any motor functioning effects on the
FXTAS participants.
The gait of larger populations of FXTAS should be completed in order to attempt
accurate descriptions of gait for this particular clinical population. A larger sample size
would inherently provide a stronger attempt to ascertain a more representative
observation of the FXTAS population.
70
APPENDICIES
71
Consent to Participate as a Research Subject
Institution: California State University, Sacramento
Participant ID:
I hereby agree to participate in research which will be conducted by Jonathan S. Lee
(graduate student) and Dr. Rodney Imamura (Professor), in the Department of
Kinesiology and Health Science at California State University Sacramento, and which
will involve the following preparations and procedures:
Preparations
1. Being fit with adhesive surface electrodes placed on the skin at various muscles
of the lower body.
2. Wearing a one-piece black outfit fitted with approximately 30 reflective
markers placed on various joint centers.
3. Body appendages being measured with a tape measure.
Procedures
1. Walking 5 meters across the floor using my normal gait (walking) pattern.
2. While doing step 1, walking onto a force plate to capture ground forces from
my supporting foot.
3. Attempt steps 1 and 2 until five sufficient trials (foot making full and direct
contact on the force plate) are obtained.
4. Attempt the steps 1 and 2 while being tracked with infra-red video motion
cameras.
5. Walking three trials across the same floor pattern as above, but with a tandem
walking pattern.
6. Standing on the force plate with both feet at shoulder width apart for 30
seconds to measure balance.
The research will take place in the CSUS Biomechanics Laboratory and will require
approximately two hours of my time.
The purpose of this research project is:
To analyze the biomechanical characteristics of gait patterns in individuals with Fragile
X-Associated Tremor/Ataxia Syndrome (FXTAS).
72
I understand that the research procedures may involve a small chance of the following
physical risks and/or discomforts: muscle strain, joint sprain, bruising, or injuries that
may occur under normal walking conditions. All of the equipment being used has been
thoroughly checked and meets accepted standards for safety. If I experience any physical
discomfort or injury, I may stop my participation and seek help from Jonathan Lee or Dr.
Rodney Imamura who will provide assistance in contacting the Campus Health Center if
I am a student at CSUS, my personal physician, or emergency medical services in case of
severe injury. I also understand that I am responsible for any cost incurred from these
medical services and the researchers are not obligated to provide any monetary assistance
for medical treatment.
And I understand that this research may have the following benefits:
1) A contribution to the process of identifying and assessing gait characteristics in an
important population and 2) in the future, possibly understanding how effective treatment
interventions for tremors and ataxia are.
This information was explained to me by Jonathan Lee. I understand that he will answer
any questions I may have now or later about this research.
Phone number: (916) ***-****
E-mail: ********.*****@*****.com
Phone number: (916) ***-****
E-mail: ********@****.edu
I understand that my participation in this research is entirely voluntary. I may decline to
participate now, or I may discontinue my participation at any time in the future without
risk. I understand that the investigator may terminate my participation at any time. I
understand that my privacy will be protected to the extent that only the researchers will
know my identity and have access to my video footage. Furthermore, I understand that
my video footage will be immediately converted to a stick figure model for analysis,
while my original footage will be maintained under strict privacy and used only as a
back-up to re-create stick figure models that have been lost or destroyed.
I understand that I will not receive any compensation for participating in this study.
Signature: ______________________________
Date: _______________________
73
REFERENCES
Aguilar, D., Sigford, K., Soontarapornchai, K., Nguyen, D., Adams, P., Yuhas, J.,
Tassone, F., Hagerman, P., & Hagerman, R. (2008). A Quantitative Assessment
of Tremor and Ataxia in FMR1 Premutation Carriers Using CATSYS. American
Journal of Medical Genetics Part A, 146(5), 629-635.
Al-Obaidi, S., Wall, J. C., Al-Yaqoub, A., & Al-Ghanim, M. (2003). Basic gait
parameters: A comparison of reference data for normal subjects 20 to 29 years of
age from Kuwait and Scandinavia. Journal of rehabilitation research and
development, 40(4), 361-366.
Andriacchi, T.P., Ogle, J.A., & Glante, J.O. (1977). Walking speed as a basis for normal
and abnormal gait measurements. Journal of Biomechanics, 10, 261-268
Armand, S., Watelain, E., Roux, E., Mercier, M., & Lepoutre, F.-X. (2007). Linking
clinical measurements and kinematic gait patterns of toe-walking using fuzzy
decision trees. Gait & posture, 25(3), 475-484.
Bohannon, R. W., & Williams Andrews, A. (2011). Normal walking speed: a descriptive
meta-analysis. Physiotherapy, 97(3), 182-189.
Brunnstrom, S. (1972). Clinical kinesiology (3rd ed.). Philadelphia: F.A.
Burnfield, J. M., Josephson, K. R., Powers, C. M., & Rubenstein, L. Z. (2000). The
influence of lower extremity joint torque on gait characteristics in elderly men.
Archives of physical medicine and rehabilitation, 81(9), 1153-1157.
Calhoun, M., Longworth, M., & Chester, V. (2011) Gait patterns in children with autism.
Journal of Clinical Biomechanics, (26), 200-206.
Cernak, K., Stevens, V., Price, R., & Shumway-Cook, A. (2008). Locomotor training
using body-weight support on a treadmill in conjunction with ongoing physical
therapy in a child with severe cerebellar ataxia. Physical Therapy, 88(1), 88-97.
Corcoran, P. J., & Peszczynski, M. (1978). Gait and gait retraining. Therapeutic exercise
(3rd ed.). Williams & Wilkins.
Crowinshield, R. O., Brand, R.A., & Johnston, R.C. (1978). The effects of walking
velocity and age on hip kinematics and kinetics. Clinical Orthopedics and Related
Research, 132, 140-144.
Daniels, L. & Worthingham, C. (1972). Muscle Testing. Techniques of manual
examination. (3rd ed.). Philadelphia: W.B. Saunders.
74
Desloovere, K., Molenaers, G., Feys, H., Huenaerts, C., Callewaert, B., & Walle, P. V. d.
(2006). Do dynamic and static clinical measurements correlate with gait analysis
parameters in children with cerebral palsy? Gait & posture, 24(3), 302-313.
DeVita, P., & Hortobagyi, T. (2000). Age causes a redistribution of joint torques and
powers during gait. Journal of Applied Physiology, 88(5), 1804-1811.
Ebersbach, G., Sojer, M., Valldeoriola, F., Wissel, J., Müller, J., Tolosa, E. a., & Poewe,
W. (1999). Comparative analysis of gait in Parkinson's disease, cerebellar ataxia
and subcortical arteriosclerotic encephalopathy. Brain, 122(7), 1349-1355.
Frigo, C., Crenna, P., & Jensen, L. (1996). Moment-angle relationship at lower limb
joints during human walking at different velocities. Journal of Electromyography
and Kinesiology, 6(3), 177-190.
Hageman, P. A., & Blanke, D. J. (1986). Comparison of gait of young women and elderly
women. Physical Therapy, 66(9), 1382-1387.
Hagerman, P. (2013). Fragile X-associated tremor/ataxia syndrome (FXTAS): pathology
and mechanisms. Acta neuropathologica, 126(1), 1-19.
Holden, M., Gill, K., Magliozzi, M., Nathan, J., & Piehl-Baker, L. (1984). Clinical Gait
Assessment in the Neurologically Impaired: Reliability and Meaningfulness.
Journal of the American Physical Therapy Association and Physical Therapy,
(64), 35-40.
Hoppenfeld, S. (1976). Physical examination of the spine and extremities. New York:
Appleton-Century-Crofts.
Ienaga, Y., Mitoma, H., Kubota, K., Morita, S., & Mizusawa, H. (2006). Dynamic
imbalance in gait ataxia. Characteristics of plantar pressure measurements.
Journal of the neurological sciences, 246(1), 53-57.
Ilg, W., Golla, H., Their, P., & Giese, M.A. (2007). Specific influences of cerebellar
dysfunctions on gait. Brain, 130(3), 786-798.
Ilg, W., Synofzik, M., Brötz, D., Burkard, S., Giese, M.A., & Schöls, L. (2009) Intensive
coordinative training improves motor performance in degenerative cerebellar
disease. Neurology, 73(22), 1823-1830.
Ilg, W., & Timmann, D. (2013) Gait Ataxia - specific cerebellar influences and their
rehabilitation. Movement Disorders, 28(11), 1566-1575.
75
JudgeRoy, J. O., Davis, B., & Õunpuu, S. (1996). Step length reductions in advanced age:
the role of ankle and hip kinetics. The Journals of Gerontology Series A:
Biological Sciences and Medical Sciences, 51(6), M303-M312.
Kadaba, M., Ramakrishnan, H., Wootten, M., Gainey, J., Gorton, G., & Cochran, G.
(1989). Repeatability of kinematic, kinetic, and electromyographic data in normal
adult gait. Journal of Orthopaedic Research, 7(6), 849-860.
Kadaba, M. P., Ramakrishnan, H. K., & Wootten, M. E. (1990). Measurement of lower
extremity kinematics during level walking. Journal of Orthopaedic Research,
8(3), 383-392. doi: 10.1002/jor.1100080310
Leehey, M. A. (2009). Fragile X-associated Tremor/Ataxia Syndrome (FXTAS): Clinical
Phenotype, Diagnosis and Treatment. Journal of investigative medicine: the
official publication of the American Federation for Clinical Research, 57(8), 830.
Lelas, J. L., Merriman, G. J., Riley, P. O., & Kerrigan, D. C. (2003). Predicting peak
kinematic and kinetic parameters from gait speed. Gait & posture, 17(2), 106112.
Mitoma, H., Hayashi, R., Yanagisawa, N., & Tsukagoshi, H. (2000). Characteristics of
parkinsonian and ataxic gaits: a study using surface electromyograms, angular
displacements and floor reaction forces. Journal of the neurological sciences,
174(1), 22-39.
Moisio, K. C., Sumner, D. R., Shott, S., & Hurwitz, D. E. (2003). Normalization of joint
moments during gait: a comparison of two techniques. Journal of biomechanics,
36(4), 599-603.
Morris, M. E., Huxham, F., McGinley, J., Dodd, K., & Iansek, R. (2001). The
biomechanics and motor control of gait in Parkinson disease. Clinical
biomechanics, 16(6), 459-470.
Morris, M. E., Iansek, R., Matyas, T. A., & Summers, J. J. (1996). Stride length
regulation in Parkinson's disease normalization strategies and underlying
mechanisms. Brain, 119(2), 551-568.
Morris, M. E., McGinley, J., Huxham, F., Collier, J., & Iansek, R. (1999). Constraints on
the kinetic, kinematic and spatiotemporal parameters of gait in Parkinson's
disease. Human Movement Science, 18(2), 461-483.
Murray, M. P., Brought, A. B., & Kory, R. C. (1964). Walking patterns of normal men.
Journal of Bone and Joint Surgery, 46A(2), 335-360.
76
Murray, M. P., Kory, R. C., & Clarkson, B. H. (1969). Walking patterns in healthy old
men. Journal of Gerontology, 24, 169-178.
Murray, M. P., Kory, R. C., Clarkson, B. H., & Sepic, S. B. (1966). Comparison of free
and fast speed walking patterns of normal men. American Journal of Physical
Medicine, 45(1), 8-24.
O'Sullivan, J. D., Said, C. M., Dillon, L. C., Hoffman, M., & Hughes, A. J. (1998). Gait
analysis in patients with Parkinson's disease and motor fluctuations: influence of
levodopa and comparison with other measures of motor function. Movement
disorders, 13(6), 900-906.
Öberg, T., Karsznia, A., & Öberg, K. (1993). Basic gait parameters: reference data for
normal subjects, 10-79 years of age. Journal of rehabilitation research and
development, 30, 210-210.
Palliyath, S., Hallett, M., Thomas, S. L., & Lebiedowska, M. K. (1998). Gait in patients
with cerebellar ataxia. Movement disorders, 13(6), 958-964.
Parvataneni, K., Ploeg, L., Olney, S. J., & Brouwer, B. (2009). Kinematic, kinetic and
metabolic parameters of treadmill versus overground walking in healthy older
adults. Clinical biomechanics, 24(1), 95-100.
Perry, J. (1967) The mechanics of walking. In J. Perry & H. Hislop (Eds.). Principles of
lower extremity bracing. Washington, D. C.: American Physical Therapy
Association.
Perry, J. & Burnfield, J. (2010) Gait Analysis: Normal and Pathological Function. Slack
Incorporated.
Prince, F., Corriveau, H., Hébert, R., & Winter, D. A. (1997). Gait in the elderly. Gait &
posture, 5(2), 128-135.
Rancho Los Amigos. (1978). Normal and pathological gait syllabus. Downey, CA
Rinehart, N., Tonge, B., Bradshaw, J., Iansek, R., Enticott, P., & McGinley, J. (2006)
Gait function in high-functioning autism and Asperger's disorder. Journal of
European Children Adolescence Psychiatry, (15), 256-264.
Rowe, P. J., Myles, C. M., Walker, C., & Nutton, R. (2000). Knee joint kinematics in gait
and other functional activities measured using flexible electrogoniometry: how
much knee motion is sufficient for normal daily life? Gait & posture, 12(2), 143155.
77
Sagawa Jr, Y., Watelain, E., De Coulon, G., Kaelin, A., Gorce, P., & Armand, S. (2013).
Are clinical measurements linked to the Gait Deviation Index in cerebral palsy
patients? Gait & posture, 38(2), 276-280.
Salarian A., Russman, H., Vingerhoets, F., Dehollain, C., Blanc, Y., Burkhard, P., &
Aminian, K. (2004) Gait Assessment in Parkinson's Disease: Toward an
Ambulatory System for Long-Term Monitoring. Transactions on Biomedical
Engineering, 51(8), 1434-1443.
Schaafsma, J. D., Giladi, N., Balash, Y., Bartels, A. L., Gurevich, T., & Hausdorff, J. M.
(2003). Gait dynamics in Parkinson's disease: relationship to Parkinsonian
features, falls and response to levodopa. Journal of the neurological sciences,
212(1), 47-53.
Seritan, A., Nguyen, D., Mu, Y., Tassone, F., Bourgeois, J., Schneider, A., . . . Grigsby, J.
(2013). Memantine for fragile X-associated tremor/ataxia syndrome: a
randomized, double-blind, placebo-controlled trial. The Journal of clinical
psychiatry.
Shamaei, K., & Dollar, A. M. (2011). On the mechanics of the knee during the stance
phase of the gait. Paper presented at the Rehabilitation Robotics (ICORR), 2011
IEEE International Conference on.
Smidt, G. L. (1974) Methods of studying gait. Physical Therapy, 54(1), 13-17.
Sofuwa, O., Nieuwboer, A., Desloovere, K., Willems, A.-M., Chavret, F., & Jonkers, I.
(2005). Quantitative gait analysis in Parkinson’s disease: comparison with a
healthy control group. Archives of physical medicine and rehabilitation, 86(5),
1007-1013.
Sparrow, W., Shinkfield, A., & Summers, J. (1997) Gait characteristics in individuals
with mental retardation: Unobstructed level-walking, negoatiating obstacles, and
stair climbing. Human Movement Science, (17), 167-187.
Stolze, H., Klebe, S., Petersen, G., Raethjen, J., Wenzelburger, R., Witt, K., & Deuschl,
G. (2002). Typical features of cerebellar ataxic gait. Journal of Neurology,
Neurosurgery & Psychiatry, 73(3), 310-312.
Stoquart, G., Detrembleur, C., & Lejeune, T. (2008). Effect of speed on kinematic,
kinetic, electromyographic and energetic reference values during treadmill
walking. Neurophysiologie Clinique/Clinical Neurophysiology, 38(2), 105-116.
78
Verkerk, A. J., Pieretti, M., Sutcliffe, J. S., Fu, Y.-H., Kuhl, D., Pizzuti, A., . . . Zhang, F.
(1991). Identification of a gene (< i> FMR</i>-1) containing a CGG repeat
coincident with a breakpoint cluster region exhibiting length variation in fragile X
syndrome. Cell, 65(5), 905-914.
Wang, J. Y., Hagerman, R. J., & Rivera, S. M. (2013). A multimodal imaging analysis of
subcortical gray matter in fragile X premutation carriers. Movement disorders,
28(9), 1278-1284.
Wang, J. Y., Hessl, D., Schneider, A., Tassone, F., Hagerman, R. J., & Rivera, S. M.
(2013). Fragile X–Associated Tremor/Ataxia Syndrome: Influence of the FMR1
Gene on Motor Fiber Tracts in Males With Normal and Premutation Alleles.
JAMA neurology, 70(8), 1022-1029.
Winter, D. A. (1979) Biomechanics of human movement. New York: John Wiley &
Sons.
Winter, D. A., & Robertson, D. (1978). Joit torque and energy patterns in normal gait.
Biological Cybernetics, 29(3), 137-142.