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TABLE OF CONTENTS
ABSTRACT……………………………………………………………………………………….4
CHAPTER 1: INTRODUCTION…………………………….…………………………………...6
Introduction…………………….………………………………………………………….6
Purpose…………………………………………………………………………………….8
Research Questions………………………………………………………………………..8
Hypotheses………………………………………………………………………………...8
Study Limitations……………………………………………………………………….....9
Study Delimitations…………………………………………………………………….....9
Variables………………………………………………………….……………………...10
Operational Definitions…………………………………………....……………………..11
CHAPTER 2: REVIEW OF LITERATURE…………………………………………………….13
Physical Activity and Lifetime Health Promotion……………………………………….13
Articular Cartilage of the Knee…………………………………………………………..13
Impact of Movement Profile on Joint………………….………………………………...15
Lean Body Mass and the Knee Joint………………………………………...…………...17
Knee Joint Health………………………………………………………………………...18
The Interactive Influence of Lower Extremity Mass Composition and Movement Profile
on Cartilage Thickness………………………………………………………………..19
CHAPTER 3: METHODOLOGY……………………………………………………………….21
Subjects………………………………………………………………………..................21
Movement Profile Screening…………………………………………………………….22
Study Protocol……………………………………………………………………….......23
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Informed Consent & Ethical Considerations…………………………………….23
Protocol…………………………………………………………………………..23
Data Reduction…………………………………………………………………………...24
Statistical Analysis………………………………………………………..……………...25
CHAPTER 4: RESULTS………………………………………………………………………...26
Demographics………………………………………………………………………........26
Lean Body Mass…...…………………………………………………………………….26
Cartilage……………………………………………………………………….................27
Lean Body Mass and Cartilage……………………………...…………………………...27
Table 1……………………………………………………………………….......29
Table 2……………………………………………………………………….......30
Table 3……………………………………………………………………….......31
CHAPTER 5: DISCUSSION……………..……………………………………………………...32
APPENDIX A………………………………….………………………………………………...37
REFERENCES…………………………………………...……………………………………...38
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ABSTRACT
Emily Dean: The Influence of Movement Profile on Measures of Knee Cartilage Health and
Body Mass Composition
(Under the direction of Dr. Prentice)
Purpose: The primary purpose of this study was to evaluate the effects of an individual’s
movement profile on body mass composition and knee cartilage health; knee cartilage thickness
and quality. The secondary purpose of this study was to determine if there is an association
between lean body mass and measures of knee cartilage health. Design: Cross-sectional.
Methods: Movement profile was determined using the Landing Error Scoring System (LESS).
Upon completion of the screening, trained LESS raters scored each jump-landing trial to assign
the potential study participant into one of two categories: excellent or poor linked to high and
low lower extremity injury risk movement profiles. The participant’s height and weight are
measured and recorded to later be used in DXA scan for lean body mass analyses. Knee cartilage
thickness was determined prior to exercise using an ultrasound of the knee on the subject’s
dominant leg completed during knee flexion centered on the intercondylar notch at 145º.
Independent samples t-Tests were used to evaluate the effects of movement profile on between
movement profile and knee cartilage thickness, and movement profile, total body, and lower
extremity lean mass. Pearson-product moment correlations were calculated between lean body
mass and knee cartilage health measures.
Results: Movement profile significantly effected lean body mass between movement profile
groups. There also seemed to be an inverse relationship between lean muscle mass and cartilage
thickness, as well as a positive relationship between movement profile and cartilage water
content at rest as measured by musculoskeletal ultrasound. However, there was no significant
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association between movement profile and knee cartilage thickness. Conclusion: Movement
profile influences lean body mass, but alone does not influence cartilage thickness and health
measures. There is also a moderate association between lean body mass and measures of
cartilage health, including thickness and fluid content levels. Lean mass composition and
movement profile have the ability to be altered with training, suggesting that if a person’s
biomechanics are improved, their injury risk could be decreased. This could assist in the
preservation of cartilage, thus knee joint, health as seen in association between lean body mass
and cartilage health measures.
Key Words: knee cartilage thickness, lower extremity movement profile, excellent movers, poor
movers, lean body mass
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CHAPTER ONE: INTRODUCTION
Physical activity, as understood to mean the movement of the body utilizing energy as
provided by the body, has shown to have numerous positive impacts on health, such as a
decreased disease risk and improved mental health.27 It is clear that engaging in these activities
as recommended by experts has a multitude of beneficial health impacts on one’s lifestyle.
Though physical activity is beneficial to health, it is important that the potential for harm be
considered in making recommendations for activity in athletes.28, 31
Because of the substantial influence of physical activity on health, it is critical to study
and implement methods of decreasing injury risk potential. In particular, decreased injury risk in
the knee joint is important so that safe and stable movements are able to be maintained in both
daily life as well as physical activity. By comprising the major weight-bearing and functional
joint in the lower extremity, the knee is vital in how it absorbs and manages stresses placed on
the lower extremity during the completion of day-to-day tasks, as well as success in exercise and
sports.32
Movement at this joint is possible because of the structural make-up of the knee and the
forces that these structures create to maintain the joint in proper position.33 These include the
bones of the lower extremity, the femur, the tibia, and the fibula, and various tendons and
ligaments, such as the ACL and MCL.33 Because of the anatomical set-up of these structures,
there is an increased risk when connective tissue is strained or ruptured, as this creates instability
in the joint.8, 33 Instability in a joint of this size and significance in daily function can be
dangerous to joint health. The knee and lower extremity face this risk in activities where there is
the potential for abnormal strain to be placed on the joint during activity. In theory, these risks
will decrease through altering of biomechanical factors to ensure joint stability during
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movement, as well as by altering lean body mass so that fat mass is decreased and fat free mass
is increased. These adjustments are ideal for improvements in health and ease of activity.17, 18, 23,
25
In this study, biomechanical factors will be discussed as movement profile. Movement
profile impacts the manner in which stress and pressure is placed on and ultimately absorbed by
the knee joint. In activities of daily living, or ADLs, having altered gait mechanics can lead to
chronic knee pain and the eventual development of osteoarthritis, a degenerative disease
impacting joints.5, 25 In sufferers of this disease, daily life functions are compromised as a result
of the pain and difficulty of moving around to complete even menial tasks. If movement profile
is shown to be a contributor to the rate of disease progression, but also has the potential to be
altered, recommendations may be made to slow the progression of this disease as well as manage
its side effects for sufferers.
Lean body mass is an additional factor that influences joint stability and health, that can
be altered with physical activity, exercise, and diet changes. Lean mass may have the potential to
decrease injury risk in athletes during physical activity as a result of the muscle’s ability to
absorb energy created during movement.17, 18 Specifically, fat-free mass has shown to have a
protective effect on the joints that it surrounds, contrast to the effects of fat mass.14, 16, 17 Also
included in the category of lean mass, cartilage provides stability at the knee joint, while other
forms of fat-free mass protect and aid in the maintenance of this tissue.17 Fortunately, lean body
mass can be altered through training mechanisms. This will prove to be beneficial if there is an
association between lower extremity lean mass and knee cartilage health.
This study will examine the relationships between movement profile, lean body mass and
knee cartilage thickness to determine if an association between the variables can be made. These
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associations will be explored and identified utilizing the DEXA machine to analyze lean body
mass, the LESS scoring system to evaluate movement profile, as well as ultrasound technology
to analyze knee cartilage area and thickness. If associations exist, guidelines and
recommendations may be formed regarding the alteration of lean body mass and movement
profile in relation to knee injury risk.
PURPOSE
This study will examine the knee joint and the ways in which daily tasks and physical
activity influence the health and functionality of the joint. More specifically, of primary interest
is the cartilage of this joint and the ways in which anatomical factors and biomechanics of the
lower extremity influence its function.
RESEARCH QUESTIONS
1. Is there an effect of movement profile on knee cartilage thickness?
2. Is there an effect of movement profile on lower extremity lean mass?
3. Is there an association between lower extremity lean mass and knee cartilage thickness?
HYPOTHESES
1. Excellent movers will have thicker knee cartilage compared to poor movers.
2. There will be greater lower extremity lean mass (kg) in subjects classified as excellent movers
versus poor movers.
3. Individuals with greater lower extremity lean mass (kg) will have greater knee cartilage
thickness (cm).
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STUDY LIMITATIONS
For the purpose of this study, subjects consisted solely of active females selected based
on convenience. Because of this, data may face population restrictions and may not be
conclusively applied to a larger population consisting also of females or the population in
general.
It is unclear if altering existing lower body exercise routines may also alter these stresses.
The methodology in studying this population is relatively novel in the exercise and sport science
field, providing follow-up studies that may be completed to verify and expand the data and
conclusions found here. Further studies may be beneficial in examining populations such as
sedentary women, recreationally active women, women of different age groups, and even men to
these varying degrees as well.
STUDY DELIMITATIONS
Injury rehabilitation is common practice in active populations in the United States. This
study will only examine the physiological changes to knee cartilage without concern to other
biomarkers that are expressed during high intensity exercise. For the sake of time and efficacy of
data collection and analysis, the most appropriate focus of analysis included pre-exercise knee
cartilage thickness.
This study focused specifically on women aged 18-24 at the University of North Carolina
at Chapel Hill. Subjects were also questioned regarding a series of standards relative to knee
joint health and other general health factors in order to be considered for this study. Further, the
subjects had to qualify as one of the two movement quality groups under examination. These
controls allowed researchers to define and maintain certain boundaries on this study.
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Because of the nature of the subjects—recreationally active women of college age in the
United States—the data and conclusions gathered could be applicable to recreationally active
women of other universities as well. If it can be determined that altering lower extremity muscle
mass has the potential to influence stresses placed on knee cartilage as a result of movement
profile, the ability of therapists and coaches to prescribe individualized exercise routines to aid in
this prevention of disease is possible.
VARIABLES
Dependent
1.
Knee cartilage thickness
2.
Movement profile
1.
Excellent movers
2.
Poor movers
Independent:
1.
2.
Movement quality
1.
Excellent movers
2.
Poor movers
Lean body mass (lower extremity lean mass (kg))
Examining subject biomechanics and classifying them into one of two groups, excellent
mover or poor mover, will determine movement quality. Trained assistants complete this
classification using a standardized form.
Lean body mass measures, as collected from a DEXA machine, will be examined on
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three levels: fat mass, fat free mass, and bone mineral density. For this study, the compositions of
interest are the fat mass and fat free mass, with the area of focus being the lower extremity.
Cartilage thickness will be assessed using ultrasound technology and Image J, a computer
software system that allows for quantitative values to be derived from these images. These
images will be evaluated from pre-testing TRV images at varying knee angles.
A correlation between these variables may help the clinician correct movement and thus
reverse progression towards degenerative osteoarthritis. All variables above, though being
examined in different spheres, are of upmost importance when discussing this disease and further
injury risk prevention in regards to the knee joint.
OPERATIONAL DEFINITIONS
Knee cartilage thickness
1.
Ultrasound imaging
1.
2.
Lines for thickness measurements are drawn downwards at 5 locations
1.
“Outer” medial femoral condyle (OMFC)
2.
Medial femoral condyle (MFC)
3.
Intercondylar notch (ICN)
4.
Lateral femoral condyle (LFC)
5.
“Outer” lateral femoral condyle (OLFC)
Assessed by mean area (cm2)
1.
Total cartilage area assessed based on the measurement obtained using polygon
tool to outline cartilage in the image.
DEXA
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Used for total body as well as compartmental analyses of lean body mass (kg)
1.
Ability to distinguish between fat mass, lean mass, and bone mineral density42
Movement Profile
2.
Excellent movers
1.
Score as “soft” or “average” for total sagittal plane joint displacement and lack
medial knee displacement.
2.
3.
4.
Receive a score of 0 or 1 using the LESS screening system.
Poor movers
1.
Have stiff landings with medial knee displacement.
2.
Receive a score of 1 or 2 using the LESS screening system.
Excluded from participation
1.
Those who have medial knee displacement and score as “soft” for total sagittal
plane joint displacement.
2.
Those who lack medial knee displacement or score as “poor” for total sagittal
plane joint displacement.
Lower extremity lean mass, total body mass, total lean body mass
1.
Measured in kilograms
2.
Lean body mass specifically refers to body mass that is fat-free
1.
Includes muscle, connective tissue, fluid, and bone
12
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CHAPTER TWO: REVIEW OF LITERATURE
Physical Activity and Lifetime Health Promotion
It is widely known and accepted that physical activity is crucial in overall health and
quality of life. Physical activity has shown to have a positive impact on mental health in addition
to overall health benefits. These benefits include decreased risk of potentially fatal disease,
specifically metabolic diseases, cardiovascular disease, protection against non-communicable
diseases, and more. 9, 10
While physical activity provides immeasurable benefits, it is important to remain aware
of the potential injury risk to musculoskeletal health. Of the injuries inflicted on the body during
activity, more than 80% of injuries occur in sport situations, with a large number of occurring at
the knee.27, 30 The knee and lower extremity face this risk in activities involving running,
jumping, and changing direction, as an additional, and sometimes abnormal, strain is placed on
the joint during these activities. Engaging in exercise can put an individual at risk for soft tissue
damage, muscle sprains, strains, or tears, extremity dislocations or fractures, and more.29 For this
reason, maintaining the health of the entire knee joint in sport and daily life is crucial to general
health and well being of the human body.
Articular Cartilage of the Knee
Cartilage has many roles throughout the body. Specifically, articular cartilage is
responsible for covering the articular surfaces of bones, preventing friction between bones,
absorbing loads placed on a joint, and providing a weight-bearing surface to bones it covers. 11
Cartilage acts in a protective manner by dissipating loads placed on the joint and
distributing contact forces over a wider surface area, decreasing overall contact force and
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damage.20 Literature has shown that at times, joints in the knee and hip in particular are
responding to loads many times an individual’s body weight.20 In general, this chronic loading of
the cartilage of the knee joint causes gradual wear and tear, leading to diseases such as
osteoarthritis. While loading the joint can increase cartilage thickness, at a certain point a
threshold is met and cartilage thickness may begin to decrease.21 Once cartilage loss begins, it is
difficult to stop or reverse as physiological processes in the body continue the process.21
Diseases such as osteoarthritis result as the ability of cartilage to handle stresses
decreases. Osteoarthritis has many contributing factors, such as cell death, inflammation, cell
matrix degradation, and incorrect cell activation and differentiation in terms of the remaining
cartilage cells.13 Articular cartilage of the knee has the highest risk of damage, though it is not
the sole reason for the occurrence of osteoarthritis.13 The effects of this tissue go beyond the
covering of bones; as cartilage degrades, it causes a cascade of issues that contribute to the
development of osteoarthritis.13 Because articular cartilage is ‘post mitotic tissue’, the cell
turnover rate is low, and new cartilage cells are not constantly reproduced to replace dead or
non-functioning cells.13 When the health of this cartilage at the knee joint is at risk, the risk of
osteoarthritis is increased.12
In practice, imaging tools can be effective and useful in examining and measuring the
thickness and area of cartilage in this space.1 Utilizing these imaging techniques in studies of the
knee joint can show quantitative differences in cartilage thickness over time, or simply in preand post-study data collection.2 Ultrasound specifically is a reliable, valid, accurate, and effective
imaging technique that is sensitive to changes and abnormalities of tissues, in this case in the
knee joint.22, 40, 41 Ultrasound technology can detect cartilaginous lesions, monitor progression of
damage, and detect inflammation in the joint.22 The advantages of ultrasound technology are
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numerous as it is minimally invasive, reliable, and cost-effective; the disadvantages are limited
and mostly based on technician skill.22 It is for these reasons that ultrasound technology is a
viable and efficient method to analyze knee cartilage thickness.
Impact of Movement Profile on Joint
To prevent injury and eventual degenerative joint disease, it is crucial to understand the
influence of a person’s movement profile on the health of their joint.25 Much of injury prevention
can be centralized around biomechanical factors, or movement profile, and the means of
improving these so that stabilization and health of the joint is of priority.32 Of particular
importance in the means of lower extremity musculature activation and its influence on
movement profile is how forces placed on the knee joint are absorbed and dispersed in ways that
protect it from injury. Injury occurs when these forces overcome the ability of the joint’s
capacity to absorb them efficiently.
Studies have investigated various alterations in landing mechanics and the influence they
have on joints. This is important when considering that in exercise, the knee joint can be subject
to absorb forces up to ten times ones’ body weight.20 This is supported in the work of Blackburn
et al.: in those who landed with a flexed trunk, bringing it closer to the body’s center of mass,
there was a reduction in quadriceps force requirement, which has been shown to cause ACL
stress, strain, and rupture.37 This is indicative of the importance of an excellent movement profile
in that poor movers who have stiff landing mechanics and thus greater force requirements are at
increased risk of injury in comparison to excellent movers. Alentorn-Geli et al. echo this in their
findings regarding varying anatomical influences on the biomechanics of the lower extremity,
suggesting that ACL injuries are more likely to happen when there is minimal to no trunk
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flexion.38 The significance in this data is this: subjects with ACL injuries were more likely to be
classified as pre-osteoarthritic, meaning that injury to the knee joint has a large role in causing
degenerative disease.39 Knowing that injury to structures within the knee joint can lead to
osteoarthritis highlights the necessity of minimizing these injury risks which appear to have
biomechanical causes.
With the indication that poor movement and biomechanics, which are influenced by lean
body mass and fat free mass, lead to an increased risk of injury and ultimately degenerative
disease, the importance of physical activity as a part of ones’ lifestyle becomes very clear.
Sedentary populations, specifically populations of heavier weight and higher body mass indices
(BMI), have less of the muscular control needed to maintain healthy movement profiles across
the knee joint. Aside from the lack of fat free mass to aid in load absorption at the knee joint,
these populations are also placing additional stress on their joints because of their increased size
and weight.24 Again, this contributes to the onset of degenerative disease24, 25
Active populations, alternatively, benefit from exercise-induced muscular strength and
stability. In terms of movement profile as discussed above, this study distinguishes between two
types of movers: excellent movers and poor movers. Excellent movers have high sagittal plane
knee flexion angles with no presence of medial knee collapse. These subjects have soft landings
with no excessive frontal plane knee motion. Poor movers have low sagittal plane knee angles
and the presence of medial knee displacement or dynamic valgus during landing mechanics.
These movers also have a “stiff landing” with medial knee collapse. Maintaining the qualities of
excellent movers is important, however the focus is on qualitative improvements to movement
profiles of poor movers.
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Lean Body Mass and the Knee Joint
Lean body mass generally refers to fat mass and fat free mass in the body. Lean body
mass is a good indicator of overall health and disease risk. In particular, increased volumes of fat
free mass (FFM) are an indicator of better overall health.
Body composition, though having many influences, can be altered by increased physical
activity and dietary changes towards a healthier lifestyle. Specifically, by prescribing physical
activity, the amount of fat free mass and fat mass can be increased and decreased, respectively.
Classified as fat free mass, lean muscle mass is crucial for neuromuscular and skeletal function,
as well as energy absorption during landing mechanics.17, 18,19 Studies have suggested that fat
free mass acts in a protective manner surrounding the joint, while fat mass does not; in fact,
evidence provided by Montgomery et al., suggests fat free mass in the lower extremity
significantly predicts the ability of the knee to absorb energy.17 If indeed there is an association
between knee cartilage thickness and lower extremity musculature, plans of action can be created
to ensure total body health as well as that of the knee joint.
Exercises to increase fat free mass, specifically muscle mass, must be specific to the
needs of the person and maintained over time. In terms of the knee joint, it is necessary that
specific training to alter lean body mass of the lower extremity is prescribed to and carried out by
a person if overall knee joint health is a priority for that person. For example, in studies
examining performance benefits of specific training for jumping exercises, movement specific
training such as plyometric training led to specific adaptations to the musculature and
functionality of the muscle groups that were targeted.19 As also shown by Sato et al., in
examining the influence of core strength training on ground reaction forces and lower leg
stability, exercise that is not specific to one’s goals has no significant influence.36 This highlights
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the importance of specificity in training. By altering the composition of the lower extremity with
specific increases of fat free mass to the musculature surrounding the knee joint, greater health of
the knee can be established and maintained.
Models for body composition that allow for fat mass and fat free mass of a subject to be
measured would be beneficial to this study to evaluate the relationship between fat mass, fat free
mass, and knee cartilage thickness. In this study, the method of measuring each subject was the
Dual-energy X-ray Absorptiometry (DXA) machine. DXA machines provide an analysis of bone
mineral density, fat mass, and fat-free mass. This is helpful in drawing conclusions regarding
lean body mass and knee cartilage thickness. The DXA has the ability to measure total body as
well as compartmental and regional lean body mass, such as the head, thorax, pelvis, and
different extremities.15 In this study, we will take advantage of the DXA capacity to analyze
lower extremity lean body mass, as lower extremity musculature is being studied in relation to
knee cartilage. Collecting data for lean mass in the area of interest allows for the determination
of whether or not associations exist between lower extremity muscle mass and knee cartilage
thickness.
Knee Joint Health
Injuries to the musculoskeletal system are a risk when participating in exercise, with
increasing prevalence occurring to the knee joint. For this reason, it is crucial to not only
understand what maintains the health of this joint, but it’s significance as well.
Much of the forces which are absorbed by the knee occur in daily activities such as
walking, running, jumping, turning, or taking stairs.4, 7, 32, 34 More severe injuries may occur in
sport with altered biomechanics, such as knee valgus or varus resulting from blows to the knee
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from the lateral or medial aspects of the lower extremity, and more.32 The potential for overuse
injuries is also prevalent in those who have chronic biomechanical issues with no physical
therapy or training to alter these movements.32
The knee joint consists of the meeting of the bones of the lower and upper legs, cartilage,
ligaments, and tendons. All aspects of this joint contribute to the carriage of body weight by the
lower body. The stability and health of this joint has an influence on how and the ease with
which these actions are completed. A torn muscle, ligament or tendon prevents movement based
on where these structures insert or originate. For example, damaging the quadriceps muscle may
cause difficulty in leg extension, which is an aspect of many daily tasks. If a ligament or tendon
is damaged, the joint is no longer structurally sound, as the stabilizing anatomy is unable to
function correctly, putting a person at risk of further injury with any movement. If cartilage is
degenerated or thin, the bones of the lower extremity are less protected and at risk of rubbing
together and not adequately absorbing loads, causing tremendous pain to the person.3 In the case
of improper movements, cases of tendonitis or bursitis in addition to the injury risks discussed
previously may appear.6 Cartilage breakdown also occurs as a response to protective factors of
the knee to micro- or macro-trauma, such as inflammation, mechanical stress, inadequate
homeostatic responses and control of apoptosis and cellular stress.6 When this joint is healthy,
movement can be completed at a wide range with relative ease. When any structure of this joint
experiences trauma, the entire body is susceptible to damage.
The Interactive Influence of Lower Extremity Mass Composition and Movement Profile on
Cartilage Thickness
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In examining the knee joint specifically, body composition that is not fat (muscle,
tendons, and ligaments) is what provides this stabilization as discussed above. When these
structures are stronger, it is logical that the joint that is stabilized is also stronger. On the other
hand, fat mass has shown to have a degenerative effect on joints, specifically cartilage tissue.17
Fat mass is unable to connect to anatomical landmarks to provide sound structures in the way
that fat-free mass such as muscle, ligaments, and tendons are.
If there is a link between cartilage thickness, movement profile, and lower extremity
mass composition, an individual’s movement profile and lower extremity mass composition offer
intervention routes to potentially reduce knee joint cartilage stress and benefit long-term knee
health in the physically active population. Correlation does not equal causation, however it is
possible that preventative measures can be implemented to decrease risk of degenerative disease
to this joint. Factors that influence knee cartilage thickness have the ability to be altered without
surgical or extreme intervention. Exercises can easily be prescribed to at risk, as well as healthy,
populations that alter the muscular composition of the lower extremity to assist in this reversal.
Perhaps more easily than altering lean body mass, movement profiles can be altered to
increase exercise safety. With respect to movement profiles, studies have shown that altered
biomechanics also influences knee joint mechanics and the cartilage thickness within this joint.
Movement profiles are a factor that can be altered with specific training. Lean body mass also
has the potential to be altered with continued exercise. With the improvement of movement
profile and lean body mass, there may be greater ease in avoiding potential injury in physical
activity as the stresses placed on the knee joint are altered.
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CHAPTER THREE: METHODOLOGY
Subjects
Forty physically active females aged 18-25 from The University of North Carolina at
Chapel Hill (UNC-CH) were recruited for this study. All participants participate or have
previously participated in a field or court sport, such as soccer, basketball, softball, or lacrosse.
Eligible participants must perform moderate to high intensity exercise for at least thirty minutes
at a minimum of three times per week; must not be pregnant, and; must meet movement profile
inclusion criteria (Figure 1.). Participants who have undergone lower extremity surgery in the
past year, have lower extremity joint surgery, have prior ACL or meniscal injury, have a lower
extremity injury that restricted sport participation for more than three consecutive days, history
of neuroendocrine, neurological, or metabolic disease or conditions, history of dysmenorrhea or
amenorrhea within the past six months, or conditions that would prevent high-intensity exercise
were excluded from this study.
Figure 1. – Movement Screening Inclusion Criteria
21
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Movement Profile Screening
Prior to enrollment, demographically eligible participants reported to The Sports
Medicine Research Laboratory to determine if they met movement profile inclusion criteria
using the Landing Error Scoring System (LESS). 2-dimensinoal video was recorded of the
subjects completing five trials of a jump-landing task (Figure 2.). The subject completed the
jump-landing from a 30 cm box set at a distance 50% of the subject’s height from a landing
target line.
½ Participant
Height
1.5 m
8m
30 cm
Jump Box
Front
GoPro
Target Line
1.5 m
Side
GoPro
8m
Figure 2. – Jump-Landing Assessment
These recordings were captured using two GoPro cameras on respective iPads. Upon completion
of the screening, trained LESS raters scored each jump-landing trial to assign the potential study
participant into one of three categories: excellent, or poor, or excluded. This classification was
crucial to hypothesis testing, as subjects classified as excellent movers may have greater lower
extremity musculature than poor movers. After determining that the participant met the
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movement profile inclusion criteria, the participant was scheduled to report to the Sports
Medicine Research Laboratory for a testing session within two weeks of their LESS screening
(Appendix A).
Study Protocol
Informed Consent & Ethical Considerations
Enrolled participants read and signed an Informed Consent Form approved by the
Institutional Review Board of the University of North Carolina at Chapel Hill to confirm that
they meet the selection criteria and were cognizant of the requirements and potential risks of
participating in this research study.
Protocol
Following informed consent procedures, the participant’s height and weight were
measured using a stadiometer and digital scale. After height and weight were recorded the
participant provided a mid-stream 40 mL urine sample for determination of urine specific gravity
to assess hydration and a dipstick urine test to rule out pregnancy.
To assess knee cartilage thickness prior to exercise, an ultrasound of the knee on the
subject’s dominant leg was completed. This was done using a GE 12L 4 cm linear transducer. It
was B-mode with a transducer frequency of 8.0 MHz. The gain was 70 and the depth of field is
4.0 cm. The subject laid supine on table and the researcher manipulated the knee joint for various
measurements. These included three images of knee flexion centered on the intercondylar notch
at 120* and 145*.
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The subject was then placed in the DXA machine to evaluate bone mineral density, fat
mass, and fat free mass. For this, the subject removed jewelry prior to laying supine and centered
on the table for further manipulation for the scan. The hip was then internally rotated so that the
femoral head and neck were exposed. It has shown that binding the feet helps maintain this
position. The subject remained motionless on the table in the anatomical position they were
placed in for the duration of the DXA scan.
Data Reduction
ImageJ software was used to analyze knee cartilage (Images 1-2). The image was opened
in this program and cartilage was then traced and measured to assess area, followed by the
addition of lines to assess thickness at 5 locations (OMFC, MFC, ICN, LFC, and OLFC). The
measured values were then added to a spreadsheet for analysis.
Using DXA Hologic Analysis Software, total lean mass with the exclusion of bone
mineral content, and total fat mass of the lower extremity was examined.
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Images 1-2. The process of analyzing knee cartilage area and thickness using Image J software.
Statistical Analysis
Data from this study was analyzed utilizing a test of correlation as well as an independent
samples t-test. These tests considered correlation using the lower extremity mass as a predicting
variable for the criterion variable of femoral articular cartilage thickness to determine if the two
were related.35 These tests also compared cartilage thickness between excellent and poor movers.
To reject the null and accept the alternative hypothesis in question, an alpha level of less than
0.05 was needed.
The use of technology and software that analyzes knee cartilage thickness and lean body
mass specifically of the lower extremity, which are two variables of interest in this study, aided
in the analysis of the relationship between movement profile and knee cartilage thickness, as
well as determining if there was in fact an association between lower extremity musculature and
knee cartilage thickness. Categorization based on the LESS also allowed for the association of
movement profile and knee cartilage thickness to be established. These variables may have
impacts on the ease of daily and physical activities in terms of the health and functionality of the
knee joint, the relationship of which is the purpose of this study.
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CHAPTER FOUR: RESULTS
DEMOGRAPHICS
The average age of all subjects was 20.53 years old with a standard deviation of 1.57 years. The
average age of excellent movers was 20.75 years old with a standard deviation of 1.83 years. The
average age of poor movers was 20.30 years old with a standard deviation of 1.26 years. The
average height of all subjects was 168.17 cm with a standard deviation of 6.96 cm. The average
height of excellent movers was 167.32 cm with a standard deviation of 6.77 cm. The average
height of poor movers was 169.02 cm with a standard deviation of 7.21 cm. The average mass of
all subjects was 63.17 kg with a standard deviation of 7.32 kg. The average mass of excellent
movers was 65.21 kg with a standard deviation of 7.83 kg. The average mass of poor movers was
61.13 kg with a standard deviation of 6.33 kg. There were no significant differences in terms of
age, height, and mass between groups (P>.05).
LEAN BODY MASS
t-tests were run for measures of lean body mass for each group of interest. There was a
significant difference between trunk and lower extremity musculature normalized to body mass
(kg), subtotal lean mass normalized to body mass (kg), and subtotal lean mass normalized to
body mass and BMC (kg). Excellent movers had greater trunk and lower extremity lean mass
normalized to total body lean mass (kg) relative to poor movers (T=2.215, P=0.033, Cohen’s
d=0.69). Excellent movers had greater subtotal lean mass normalized to body mass (kg) and bone
mineral content relative to poor movers (T=2.238 P=0.031, Cohen’s d=0.70). Excellent movers
had greater subtotal lean mass normalized to body mass (kg) relative to poor movers ((T=2.428,
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P=0.020, Cohen’s d=0.76). The descriptive statistics of non-significant variables can be found in
Table 1.
CARTILAGE
There were no significant differences in terms of cartilage thickness, area, and perimeter between
groups. These descriptive statistics can be found in Table 2.
LEAN BODY MASS AND CARTILAGE
Echogenicity was shown to have a significant negative correlation between subtotal lean mass
(r=-0.319, p<0.05) and subtotal lean mass + bone mineral content (r=-0.325, p<0.05).
There was a significant negative correlation between the outside medial femoral condyle
cartilage height and subtotal lean mass (r=-0.391 p<0.05) and subtotal lean mass + bone mineral
content (r=-0.393, p<0.05). There was a significant negative correlation between the medial
femoral condyle cartilage height and subtotal lean mass (r=-0.410 p<0.01) and subtotal lean mass
+ bone mineral content (r=-0.407, p<0.009). Greater lean mass values were associated with
lower cartilage height. There was a significant negative correlation between the intercondylar
notch height and subtotal lean mass (r=-0.440 p<0.01) and subtotal lean mass + bone mineral
content (r=-0.439, p<0.01). There was a significant negative correlation between the lateral
femoral condyle cartilage height and subtotal lean mass (r=-0.552 p<0.01) and subtotal lean mass
+ bone mineral content (r=-0.550, p<0.01). There was a significant negative correlation between
the outside lateral femoral condyle cartilage height and subtotal lean mass (r=-0.497 p<0.01) and
subtotal lean mass + bone mineral content (r=-0.500, p<0.01). Greater lean mass values were
associated with lower cartilage height. There was no significant correlation found between area
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and subtotal lean mass and subtotal lean mass + bone mineral content. There was no significant
correlation found between area perimeter and subtotal lean mass and subtotal lean mass + bone
mineral content. These descriptive statistics can be found in Table 3.
28
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Table 1. - Descriptive statistics for DXA scans of body composition.
Excellent
Poor
n
Mean
95% CI
n
Mean
95% CI
(SD)
(SD)
Total % fat
21
26.45
[25.0, 27.9]
20
28.46
[27.20,
(3.47)
(2.91)
29.70]
Subtotal lean mass
21
641.41
[628.30,654.50]
20
619.25
[607.20,
normalized to
(30.71)
(27.54)
631.30]
body mass (kg)*
Subtotal lean mass
21
668.23
[654.50, 682.0]
20
646.90
[634.40,
normalized to
(32.20)
(28.63)
659.40]
body mass +
BMC (kg)*
Trunk lean mass
21
342.19
[334.60, 349.80]
20
331.87
[323.90,
normalized to
(17.83)
(18.30)
339.90]
body mass
Trunk lean mass
21
0.75
[0.70, 0.80]
20
0.72
[0.70, 0.70]
normalized to
(0.04)
(0.04)
trunk total mass
Lower extremity
21
235.55
[228.50, 242.60]
20
228.27
[222.40,
lean mass
(16.53)
(13.50)
234.20]
normalized to
body mass (kg)
Lower extremity
21
1.31
[1.30, 1.30]
20
1.27
[1.30, 1.30]
lean mass
(0.07)
(0.06)
normalized to
lower extremity
total mass
Lower extremity
21
0.37
[0.40, 0.40]
20
0.37
[0.40, 0.40]
lean mass
(0.02)
(0.02)
normalized to
total body lean
mass
Trunk & lower
21
577.74
[566.70, 588.80]
20
560.15
[549.20,
extremity lean
(25.76)
(25.07)
571.10]
mass normalized
to body mass
(kg)*
Trunk & lower
21
0.90
[0.90, 0.90]
20
0.90
[0.90, 0.90]
extremity lean
(0.008)
(0.005)
mass normalized
to total body lean
mass
*Significant difference (P< 0.05) between Excellent and Poor movement profile groups.
29
P
Cohen's d
0.052
0.63
0.020
0.76
0.031
0.70
0.075
0.57
0.071
0.75
0.132
0.48
0.146
0.61
0.777
0.00
0.033
0.69
0.099
<0.01
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30
Table 2. - Descriptive statistics for knee cartilage composition (cm2) between excellent and poor
movers.
Excellent
Poor
P
Cohen's
d
n
Mean (SD)
95% CI
n
Mean (SD)
95% CI
Total Area (cm2)
20
0.775 (0.101)
[0.6, 1.0]
20
0.763 (0.115)
[0.5, 1.0]
>0.05
0.11
Total Area Mean
(cm2)
Total Area
Perimeter
OMFC Thickness
(cm)
MFC Thickness
(cm)
ICN Thickness (cm)
20
41.774 (8.301) [26.0, 57.5]
20
44.942 (6.675) [31.9, 58.0] >0.06
0.09
20
8.588 (0.153)
[8.3, 8.9]
20
8.635 (0.163)
[8.3, 9.0]
>0.07
0.07
20
0.167 (0.035)
[0.1, 0.2]
20
0.16 (0.062)
[0.0, 0.3]
>0.08
0.04
20
0.215 (0.041)
[0.1, 0.3]
20
0.209 (0.045)
[0.1, 0.3]
>0.09
0.03
20
0.201 (0.036)
[0.1, 0.3]
20
0.205 (0.057)
[0.1, 0.3]
>0.10
0.02
LFC Thickness
20
0.173 (0.027) [0.1, 0.2]
20 0.181 (0.036) [0.1, 0.3]
(cm)
OLFC Thickness
20
0.172 (0.033) [0.1, 0.2]
20
0.16 ( 0.029) [0.1, 0.2]
(cm)
*Significant difference (P< 0.05) between Excellent and Poor movement profile groups.
>0.11
0.07
>0.12
0.08
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Table 3. Pearson Product-Moment Correlation Coefficients Between Absolute Lean Mass
Variables and Cartilage Measures
Cartilage Measure
Area
Area Perimeter
Area Echogenicity*
Outside Medial Femoral Condyle*
Medial Femoral Condyle**
Intercondylar Notch**
Lateral Femoral Condyle**
Outside Lateral Femoral Condyle**
*Correlation is significant at the p <
0.05 level, **Correlation is
significant at the p < 0.01 level.
Subtotal Lean
Mass
r
0.065
-0.163
-0.319
-0.391
-0.410
-0.440
-0.552
-0.497
p
0.690
0.316
0.045
0.013
0.009
0.004
0.000
0.001
Subtotal Lean
Mass + Bone
Mineral
Content
r
0.067
-0.168
-0.325
-0.393
-0.407
-0.439
-0.550
-0.500
p
0.680
0.300
0.041
0.012
0.009
0.005
0.000
0.001
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CHAPTER FIVE: DISCUSSION
In physically active females, there is a link between movement profile and lean mass.
Specifically, individuals who possess excellent movement profiles have a greater amount of lean
mass per unit of body weight as compared to those with poor movement profiles, thus decreasing
their injury risk. However, movement profile does not appear to have an influence on cartilage
thickness or quality and water content. Further, there seems to be an inverse relationship between
lean muscle mass and cartilage thickness, as well as a positive relationship between movement
profile and cartilage water content at rest as measured by musculoskeletal ultrasound.
Magnetic Resonance Imaging (MRI) allows for accurate and reproducible image analyses
regarding all tissues of a joint, a quality that is extremely helpful when trying to determine if
osteoarthritis is present in a joint. Of interest in this study, knee cartilage distribution is a tissue
type readily observed from MRI imaging of the knee, accessible across gender and lean body
mass make-ups.1, 2 While the use of MRI would be great for use in this study, it was not
practical. The most clinically accepted and feasible imaging tool for this study was ultrasound.
Ultrasound as an imaging tool has been determined to be reliable, valid, accurate, and
effective to measure knee cartilage distribution and abnormalities.22, 40, 41 Data obtained from
ultrasound is both reproducible and has shown to have interobserver validity.40, 41 While this
imaging analysis cannot directly detect osteoarthritis as MRI can, this type of imaging can detect
cartilage thickness, as well as cartilage damage and inflammation that may be linked to
osteoarthritis symptom flares.22
In this study, ultrasound imaging did not show any knee cartilage thickness differences
between movement profile groups. However, ultrasound is still a sound method for measurement
of knee cartilage as it has the potential to detect changes in cartilage diurnally and over time.22
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Dual-energy x-ray absorptiometry (DXA) imaging proved to be a precise and accurate tool to
analyze lean body mass and bone mineral content, which coincides with previous literature
associated with the clinical implications of DXA scans.19 Using this imaging tool allows for
compartmentalized analyses of lean body mass, including lean mass, fat mass, and bone mineral
density.19 Because this study examined the lower extremity specifically, while also comparing
lean mass in the trunk, DXA provided the exact lean body mass data that was needed to
distinguish lean body mass between two groups: excellent movers and poor movers. The ability
to distinguish between different risk groups using DXA, where general lean body mass analyses
have only used this before, indicates that injury risk can potentially be observed by examining
anatomical factors in the body without having to conduct movement analyses.
Differences were not found between groups, but in considering the physiological components
of cartilage, this finding is not unexpected. Cartilage has protective properties that requires
chronic wear and tear to dissolve. This tissue is made up of a solid matrix and interstitial fluid
which is responsible for the initial load absorption.45 This fluid shifts as the load increases,
allowing for the solid matrix to absorb the load.45 This protective factor combined with the
understanding that there was no difference in cartilage thickness between movement profile
groups allows for the assumption to be made that cartilage is equally protective regardless of
injury risk.
Because there were not differences in cartilage between groups, these results suggest that
movement alone does not explain knee cartilage thickness. In general, greater lean mass may
lead to more dynamic loading of the muscle, rather than cartilage loading. When group was
controlled for, a relationship between cartilage echo intensity and poor movers was observed,
suggesting that the SAID (specific adaptation to imposed demands) principle, which explains
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how tissue adapts to stresses placed upon it may contribute to knee cartilage and joint health.44
Work by Koo, Andriacchi, and Scanlan support that, in addition to the SAID principle, Wolff’s
Law suggests that tissue changes as a result of the forces placed on it.46 Studies examining the
influence of stress placement in the knee joint has shown that in healthy subjects, knee cartilage
adapts based on the loading that it undergoes in order to maintain homeostasis.47 These studies
have also shown that cartilage is thickest where this loading is most substantial.48 Further, these
variations are individualized.49, 50 Both of these factors have the ability to be altered with
training, suggesting that if a person’s biomechanics are improved, their injury risk could be
decreased. This can be seen in the between-group difference as excellent movers with lower
injury risk had greater muscle mass quantities.
Current injury prevention practices for women include plyometric and proprioceptive
training which have “promising results” in altering neuromuscular control.43 Specifically, these
studies examine how to prevent knee ligament tears. Knee joint health, which can be affected by
neuromuscular control, ligamentous tears and cartilage degradation, is crucial in the reducing the
risk of developing osteoarthritis.40, 43, 51 In terms of osteoarthritis progression and knee joint
health, these practices do contribute to overall health. However, an approach to protect knee
cartilage is also necessary. Cartilage’s contribution to osteoarthritis symptom progression and
flare-ups prompts this need.22
This study showed that movement profile influences muscle mass and that a correlation
exists between lean mass and cartilage thickness and quality. In fact, higher quantities of lean
mass are correlated negatively with cartilage thickness and quality. There were no differences
between groups in regards to knee thickness. However, the quality of cartilage between groups
may be difference as a result of their biomechanics. Changes could potentially be made in the
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knee joint by altering biomechanics and muscle mass to decrease injury risk and joint health
degradation. Observations have shown that lean mass has the potential to reduce injury risk as
seen in works by Singh and Singh, and promote healthy cartilage status per correlation
analysis.19
These results have limitations. The sample size is an example of this, as data from only 40
subjects was measured. These results were also found based on physically active women preexercise, introducing an additional limit to it’s universality and ability to assume generalizations.
Regarding the measures used to collect data, ultrasound and DXA each have respective
limitations. Ultrasound images and validity may be affected by the technician and potential
technician error. Images obtained from ultrasound technology are also of poor resolution, making
them difficult to analyze at times. DXA results are determined using the scan as well information
on the subject’s demographics. Based on the technician, this information could be incorrect
either by it’s input or when it was gathered.
Based on the significant values obtained from t-tests, a cause and effect may be
investigated between knee cartilage and lower extremity lean mass. From this, future studies
involving movement profile and knee cartilage thickness should manipulate both muscle mass
and movement profile to determine each variable’s specific influence on knee cartilage
thickness. These could be looked at individually as well as together, but a joint examination of
both variables at once may prove to be more significant if their individual manipulation
influences are summed. There may be trouble in manipulating only the movement profile, as this
can be altered in training which in itself can alter muscle mass.
Though the data analyzed based on ultrasound imaging did not prove to be significant,
the methods of cartilage thickness analysis, as well and lean body mass analysis, all proved to be
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beneficial to this study. Because of the relationship between movement profile and lower
extremity lean mass, implications regarding movement profile and its influence on lower
extremity lean mass can be created and further interventions put into place regarding injury
prevention, an important factor in preventing osteoarthritis.40, 51
36
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APPENDIX A
SESSION I
Jump-Landing Assessment (LESS
Movement Screening)
Classified as excellent, poor, or
excluded
Ultraasound
- 120* and 145*
Poor (n=25)
Sample (N=40)
Low sagittal plane knee angles,
presence of medial knee
displacement or dynamic valgus
during landing mechanics.
- 3 images recorded at each
angle, Pre- and Post-testing
sessions
DXA
Analysis of body composition of
the lower extremity
SESSION II
Ultrasound
- 120* and 145*
Excellent (n=25)
- 3 images recorded at each
angle, Pre- and Post-testing
sessions
High sagittal plane knee flexion
angles with no presence of medial
knee collapse.
DXA
Analysis of body composition of
the lower extremity
37
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38
References
1. Faber, S. C., Eckstein, F., Lukasz, S., Mühlbauer, R., Hohe, J., Englmeier, K.-H., & Reiser, M.
(2001). Gender differences in knee joint cartilage thickness, volume and articular surface
areas: assessment with quantitative three-dimensional MR imaging. Skeletal
Radiology, 30(3), 144–150. doi:10.1007/s002560000320
2. Eckstein, F., & Wirth, W. (2011). Quantitative Cartilage Imaging in Knee
Osteoarthritis. Arthritis, 2011, 1–19. doi:10.1155/2011/475684
3. Hall, F. M., & Wyshak, G. (1980). Thickness of articular cartilage in the normal knee. The
Journal of Bone and Joint Surgery, Inc., 62(3), 408–413. doi:1535-1386
4. Kuroki, H., Nakagawa, Y., Mori, K., Kobayashi, M., Yasura, K., Okamoto, Y... Nakamura, T.
(2008). Ultrasound properties of articular cartilage in the tibio-femoral joint in knee
osteoarthritis: Relation to clinical assessment (international cartilage repair society
grade). Arthritis Research and Therapy, 10(4), R78-R78. doi:10.1186/ar2452
5. Goldring, M. B. (2007). Osteoarthritis. Journal of cellular physiology, 213(3), 626–634.
doi:10.1002/jcp.21258
6. Sherwood, J., Bertrand, J., Eldridge, S., & Dell’Accio, F. (2014). Cellular and molecular
mechanisms of cartilage damage and repair. Drug Discovery Today, 19(8), 1172–1177.
doi:10.1016/j.drudis.2014.05.014
7. NIAMSD: National Institute of Arthritis and Musculoskeletal and Skin Diseases. (2014). Knee
Problems. Retrieved from http://www.niams.nih.gov/Health_Info/Knee_Problems/default.asp
8. Goldring, M. B., & Goldring, S. R. (2007). Osteoarthritis. Journal of Cellular
Physiology, 213(3), 626–634. doi:10.1002/jcp.21258
Dean
39
9. Ekblom-Bak, E., Ekblom, B., Vikström, M., de Faire, U., & Hellénius, M.-L. (2014). The
importance of non-exercise physical activity for cardiovascular health and longevity. British
Journal of Sports Medicine, 48(3), 233–238. doi:10.1136/bjsports-2012-092038
10. Deslandes, A., Moraes, H., Ferreira, C., Veiga, H., Silveira, H., Mouta, R., . . . Laks, J.
(2009). Exercise and mental health: Many reasons to move. Neuropsychobiology, 59(4), 1918. Retrieved from http://search.proquest.com/docview/233443086?accountid=14244
11. Ogden, J.A., Neame, P. J. (1992). Articular cartilage and osteoarthritis. Journal of
orthopaedic trauma, 6(3), 398–399. ISSN:0890-5339
12. Carter, D. R., Beaupré, G. S., Wong, M., Smith, R. L., Andriacchi, T. P., & Schurman, D. J.
(2004). The Mechanobiology of Articular Cartilage Development and Degeneration. Clinical
Orthopaedics and Related Research, 427S, S69–S77. ISSN:0890-5339
13. Lotz, M., & Carames, B. (2011). Autophagy and cartilage homeostasis mechanisms in joint
health, aging and OA. Nature Reviews Rheumatology,7(10), 579–587.
doi:10.1038/nrrheum.2011.109
14. Ding, C., Stannus, O., Cicuttini, F., Antony, B., & Jones, G. (2013). Body fat is associated
with increased and lean mass with decreased knee cartilage loss in older adults: A prospective
cohort study. International Journal of Obesity, 37(6), 822-7.
doi:http://dx.doi.org/10.1038/ijo.2012.136
15. Wagner, D. R., & Heyward, V. H. (1999). Techniques of body composition assessment: A
review of laboratory and field methods. Research Quarterly for Exercise and Sport, 70(2),
135-49. Retrieved from http://search.proquest.com/docview/218501343?accountid=14244
Dean
40
16. Mezhov, V., Ciccutini, F. M., Hanna, F. S., Brennan, S. L., Wang, Y. Y., Urquhart, D. M.
and Wluka, A. E. (2014), Does obesity affect knee cartilage? A systematic review of
magnetic resonance imaging data. Obesity Reviews, 15: 143–157. doi: 10.1111/obr.12110
17. Montgomery, M. M., Shultz, S. J., Schmitz, R. J., Wideman, L., & Henson, R. A. (2012).
Influence of Lean Body Mass and Strength on Landing Energetics. Official Journal of the
American College of Sports Medicine, 2376–2383.
18. Bell, D. R., Sanfilippo, J., Binkley, N., & Heiderscheit, B. C. (2014). Lean Mass Asymmetry
Influences Force and Power Asymmetry During Jumping in Collegiate Athletes. Journal of
Strength and Conditioning Research, 28(4), 1. doi:10.1519/JSC.0000000000000367
19. Singh, D., & Singh, S. (2012). Influence of Exercise Specificity on Depth Jump
Performance. Brazilian journal of biomotricity, 6(4), 261–268. ISSN:1981-6324
20. Desmarais, M., Aissaoui, R. (2008). Modeling of Knee Articular Cartilage Dissipation
During Gait Analysis. Journal Of Mechanics In Medicine & Biology, 8(3), 377-394.
21. Mithoefer, K., Hambly, K., Logerstedt, D., Ricci, M., Silvers, H., & Della Villa, S. (2012).
Current concepts for rehabilitation and return to sport after knee articular cartilage repair in
the athlete. The journal of orthopaedic and sports physical therapy, 42(3), 254–273.
doi:10.2519/jospt.2012.3665
22. Pineda, C., Hernández-Díaz, C., Pena, A., & Villaseñor-Ovies, P. (2011). The place of
ultrasonography in knee joint osteoarthritis: An update. International Journal of Clinical
Rheumatology, 6(6), 635-642. doi:http://dx.doi.org/10.2217/ijr.11.59
23. Butler, R. J., Queen, R. M., Wilson, B., Stephenson, J., & Barnes, C. L. (2014). The Effect of
Extension Constraint Knee Bracing on Dynamic Balance, Gait Mechanics, and Joint
Alignment. PM&R, 6(4), 309–315. doi:10.1016/j.pmrj.2013.09.011
Dean
41
24. Harding, G. T., Hubley-Kozey, C. L., Dunbar, M. J., Stanish, W. D., & Astephen Wilson, J.
L. (2012). Body mass index affects knee joint mechanics during gait differently with and
without moderate knee osteoarthritis. Osteoarthritis and Cartilage, 20(11), 1234–1242.
doi:10.1016/j.joca.2012.08.004
25. Stief, F., Böhm, H., Dussa, C. U., Multerer, C., Schwirtz, A., Imhoff, A. B., & Döderlein, L.
(2014). Effect of lower limb malalignment in the frontal plane on transverse plane mechanics
during gait in young individuals with varus knee alignment. The Knee, 21(3), 688-93.
doi:http://dx.doi.org/10.1016/j.knee.2014.03.004
26. Kumar, D., Souza, R. B., Subburaj, K., MacLeod, T. D., Singh, J., Calixto, N. E., Nardo, L.,
et al. (2015). Are There Sex Differences in Knee Cartilage Composition and Walking
Mechanics in Healthy and Osteoarthritis Populations? Clinical Orthopaedics and Related
Research, 473(8), 2548–2558. doi:10.1007/s11999-015-4212-2
27. Cordero, A., Masiá, M. D., & Galve, E. (2014). Physical Exercise and Health.Revista
Española de Cardiología (English Edition), 67(9), 748–753. doi:10.1016/j.rec.2014.04.005
28. Campbell, K., Foster-Schubert, K., Alfano, C., Duggan, C., Irwin, M., & McTiernan, A.
(2012). Injuries in Sedentary Individuals Enrolled in a 12-Month, Randomized, Controlled,
Exercise Trial. Journal Of Physical Activity & Health,9(2), 198-207.
29. Jones, C. S., Christensen, C., & Young, M. (2000). Weight training injury trends: a 20-year
survey. The Physician and Sportsmedicine, 28(7), 748–753. doi:10.3810/psm.2000.07.1086
30. Nicolini, Alexandre Pedro, Carvalho, Rogério Teixeira de, Matsuda, Marcelo Mitsuro,
Sayum Filho, Jorge, & Cohen, Moisés. (2014). Common injuries in athletes' knee: experience
of a specialized center. Acta Ortopédica Brasileira, 22(3), 127131.https://dx.doi.org/10.1590/1413-78522014220300475
Dean
31. Pescatello, L. S., Arena, R., Riebe, D., & Thompson, P. D. (Eds.). (2013). Chapter 1:
Benefits and Risks Associated with Physical Activity. ACSM’s Guidelines for Exercise
Testing and Prescription (pp. 1–11). Baltimore, MD: Lippincott Williams & Wilkins.
32. Patricia, D. A. (2001). Common knee injuries in primary care. Nurse Practitioner, 26(10),
26-45; quiz 46-7. Retrieved from
http://search.proquest.com/docview/222349393?accountid=14244
33. Madeti, B. K., Chalamalasetti, S. R., & Sundara siva rao Bolla Pragada, S. K. (2015).
Biomechanics of knee joint — A review. Frontiers of Mechanical Engineering, 10(2), 176–
186.
34. Fukaya, T., Mutsuzaki, H., Ito, H., & Wadano, Y. (2014). Relationships Between Kinetic
Variables and Smoothness Of Knee Joint Movement in the Stance Phase. Journal Of
Mechanics In Medicine & Biology,14(5), -1. doi:10.1142/S0219519414500791
35. Stone, E. R. (2010). t Test, Independent Samples. In N. J. Salkind (Ed.),Encyclopedia of
research design. Sage Publications.
doi:http://dx.doi.org.libproxy.lib.unc.edu/10.4135/9781412961288.n475
36. Sato, K., & Mokha, M. (2009). Does Core Strength Training Influence Running Kinetics,
Lower-Extremity Stability, and 5000-m Performance in Runners? Journal of Strength and
Conditioning Research, 23(1), 133-40. Retrieved from
http://search.proquest.com/docview/213041059?accountid=14244
37. Blackburn, J. T., & Padua, D. A. (2009). Sagittal-Plane Trunk Position, Landing Forces, and
Quadriceps Electromyographic Activity. Journal of Athletic Training, 44(2), 174–179.
38. Alentorn-Geli, E., Mendiguchía, J., Samuelsson, K., Musahl, V., Karlsson, J., Cugat, R., &
Myer, G. D. (2013). Prevention of anterior cruciate ligament injuries in sports—Part I:
42
Dean
43
Systematic review of risk factors in male athletes. Knee Surgery, Sports Traumatology,
Arthroscopy, 22(1), 3–15.
39. Wu, H., Webber, C., Fuentes, C., Bensen, R., Beattie, K., Adachi, J., & ... Levy, D. (2007).
Prevalence of knee abnormalities in patients with osteoarthritis and anterior cruciate ligament
injury identified with peripheral magnetic resonance imaging: a pilot study. Canadian
Association Of Radiologists Journal, 58(3), 132-175
40. Naredo, E., Acebes, C., Garrido, J., Delgado-Baeza, E., áenz-Navarro, I., de Miguel, E.,
Filippucci, E., et al. (2009). Ultrasound validity in the measurement of knee cartilage
thickness. Annals of the Rheumatic Diseases, 68, 1322–1327. doi:10.1136/ard.2008.090738
41. Iagnocco, A., Perricone, C., Scirocco, C., Ceccarelli, F., Modesti, M., Gattamelata, A.,
Vavala, C., et al. (2012). The interobserver reliability of ultrasound in knee
osteoarthritis. Rheumatology, 51(11), 2013–2019. doi:10.1093/rheumatology/kes161
42. van der Ploeg, G. E., Withers, R. T., & Laforgia, J. (2003). Percent body fat via DEXA:
comparison with a four-compartment model. Journal of Applied Physiology, 94(2), 499–506.
43. Ajuied, A., Wong, F., Smith, C., Norris, M., Earnshaw, P., Back, D., & Davies, A. (2014).
Anterior Cruciate Ligament Injury and Radiologic Progression of Knee Osteoarthritis A
Systematic Review and Meta-analysis. The American Journal of Sports Medicine, 42(9),
2242–2252.
44. Accardi, M. A., Dini, D., & Cann, P. M. (2011). Experimental and numerical investigation of
the behaviour of articular cartilage under shear loading—Interstitial fluid pressurisation and
lubrication mechanisms. Tribology International, 44(5), 565–578.
doi:10.1016/j.triboint.2010.09.009
Dean
44
45. Kent, M. (2007). SAID Principle. The Oxford Dictionary of Sports Science & Medicine (3
ed.). Oxford University Press. eISBN:9780191727788
46. Kent, M. (2007). Wolff’s law. The Oxford Dictionary of Sports Science & Medicine (3 ed.).
Oxford University Press. eISBN:9780191727788
47. Koo, S., Rylander, J. H., & Andriacchi, T. P. (2011). Knee Joint Kinematics during Walking
Influences the Spatial Cartilage Thickness Distribution in the Knee. Journal of Biomechanics,
1405–1409. doi:10.1016/j.jbiomech.2010.11.020
48. Koo, S., & Andriacchi, T. P. (2007). A comparison of the influence of global functional loads
vs. local contact anatomy on articular cartilage thickness at the knee. Journal of
Biomechanics, 40(13), 2961–2966.
49. Andriacchi, T. P., Koo, S., & Scanlan, S. F. (2009). Gait Mechanics Influence Healthy
Cartilage Morphology and Osteoarthritis of the Knee. The Journal of Bone and Joint Surgery,
Incorporated, 91-A, 95–101.
50. Andriacchi, T. P., & Dyrby, C. O. (2005). Interactions between kinematics and loading
during walking for the normal and ACL deficient knee. Journal of Biomechanics, 38, 93–298.
51. Roos, E. M. (2005). Joint injury causes knee osteoarthritis in young adults. Current Opinion
in Rheumatology, 17(2), 195–200. ISSN:1040-8711