bone structure and development readings: –frankel and nordin, chapter 2 –bailey, d.a. (1996)...
TRANSCRIPT
![Page 1: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/1.jpg)
Bone Structure and Development• Readings:
– Frankel and Nordin, Chapter 2– Bailey, D.A. (1996) Growth, Physical Activity, and Bone
Mineral Acquisition. Ex & Sp Sci Rev, 24: 233-266.– Turner, Charles H. and Robling, A.G. (2003) Designing
exercise regimens to increase bone strength. Ex & Sp Sci Rev, 31:1 pp 45-50.
• Structure and architecture • Development and growth
– Process – continuous remodeling– Factors affecting bone density and strength
• Mechanical properties • Osteoporosis
![Page 2: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/2.jpg)
Bone Gross Structure, Architecture and Development
![Page 3: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/3.jpg)
Long Bone Structure
![Page 4: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/4.jpg)
Bone Micro-Structure, cont’dProjections of osteocytes are
thought to be cite of strain
sensing, which
stimulates bone to form
![Page 5: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/5.jpg)
![Page 6: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/6.jpg)
Bone Composition & Structure• Material Constituents:
– Calcium carbonate and Calcium phosphate• 60-70% bone weight• Adds stiffness• Primary determinant for compressive strength.
– Collagen• Adds flexibility• Contributes to tensile strength
– Material Constituents– Water
• 25-30% bone weight• Contributes to bone strength• Provides transportation for nutrients and wastes.
![Page 7: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/7.jpg)
Bone Composition & Structure• Structural Organization
– Bone mineralization ratio specific to bone
– Two categories of porous bone:
• Cortical bone(70-95% mineral content)
• Trabecular bone (10-70% mineral content)
– More porous bones have:
• Less calcium phosphate
• More calcium carbonate
• Greater proportion of non-mineralized tissue
![Page 8: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/8.jpg)
Bone Composition & Structure
• Cortical Bone– Low porosity– 5-30% bone volume is non-
mineralized tissue– Withstand greater stress but less
strain before fracturing
![Page 9: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/9.jpg)
Bone Composition & Structure
• Trabecular Bone– High porosity– 30 - >90% bone volume is non-mineralized
tissue– Trabeculae filled with marrow and fat– Withstand more strain (but less stress) before
fracturing
![Page 10: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/10.jpg)
Bone Composition & Structure
• Both cortical and trabecular bone are anisotropic – stress/strain response is directional
• Bone function determines structure
• Strongest at resisting compressive stress
• Weakest at resisting shear stress
![Page 11: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/11.jpg)
Bone Growth & Development
• Longitudinal Growth– at epiphyses or epiphyseal plates– Stops at 18 yrs of age (approx.)
• can be seen up to 25 yrs of age
• Circumferential Growth– Diameter increases throughout lifespan– Most rapid growth before adulthood
• Periosteum build-up in concentric layers• Endosteal growth• Internal remodeling
![Page 12: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/12.jpg)
Bone Growth & Development
• Osteoblasts
• Osteoclasts
• Adult Bone Development– Balance between oseoblast and osetoclast
activity– Increase in age yields progressive decrease in
collagen and increase in bone brittleness.• Greater in women
![Page 13: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/13.jpg)
lamella
![Page 14: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/14.jpg)
![Page 15: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/15.jpg)
Bone Growth & Development
• Women– Peak bone mineral content: 25-28 yrs.
– 0.5%-1.0% loss per year following age 50 or menopause
– 6.5% loss per year post-menopause for first 5-8 years.
• Youth – bones are vulnerabe during peak growing years– Bone mineral density (BMD) is least during peak growing
years
– Growth plates are thickest during peak growing years
![Page 16: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/16.jpg)
Bone Growth & Development
• Aging– Bone density loss as soon as early 20’s– Decrease in mechanical properties and general
toughness of bone– Increasing loss of bone substance– Increasing porosity– Disconnection and disintegration of trabeculae
leads to weakness
![Page 17: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/17.jpg)
Bone loading modes: Compression – pushing together Tension – pulling apart Torsion – twisting Shear – cutting across
![Page 18: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/18.jpg)
Cutting across
![Page 19: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/19.jpg)
Load-deformation relationship:
Stress-strain curve:
![Page 20: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/20.jpg)
Repetitive vs. Acute Loads
• Repetitive loading
• Acute loading
• Macrotrauma
• Microtrauma
![Page 21: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/21.jpg)
I: bone vs glass and metal
II: Anisotropic behavior of bone
![Page 22: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/22.jpg)
Comparison of tendon andligament
![Page 23: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/23.jpg)
![Page 24: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/24.jpg)
![Page 25: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/25.jpg)
Bone Response to Stress
• Wolf’s Law– Indicates that bone strength increases and decreases as the
functional forces on the bone increase and decrease.
• Bone Modeling and Remodeling– Mechanical loading causes strain– Bone Modeling
• If Strain > modeling threshold, then bone modeling occurs.
– “conservation mode”: no change in bone mass– “disuse mode”: net loss of bone mass
• Osteocytes – projections sense strain, begins remodeling process
![Page 26: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/26.jpg)
Bone Response to Stress
• Bone mineral density generally parallels body weight– Body weight provides most constant
mechanical stress– Determined by stresses that produce strain on
skeleton– Think: weight gain or loss and its effect on
bone density
![Page 27: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/27.jpg)
Bone Hypertrophy
• An increase in bone mass due to predominance of osteoblast activity.
• Seen in response to regular physical activity– Ex: tennis players have muscular and bone hypertrophy
in playing arm.
• The greater the habitual load, the more mineralization of the bone.– Also relates to amount of impact of activity/sport
![Page 28: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/28.jpg)
Bone Atrophy
• A decrease in bone mass resulting form a predominance of osteoclast activity– Accomplished via remodeling– Decreases in:
• Bone calcium
• Bone weight and strength
• Seen in bed-ridden patients, sedentary elderly, and astronauts
![Page 29: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/29.jpg)
Osteoporosis
• Website on osteporosis: http://www.nof.org National Osteoporosis Foundation• A disorder involving decreased bone mass and
strength with one or more resulting fractures.• Found in elderly
– Mostly in postmenopausal and elderly women– Causes more than 1/2 of fractures in women, and 1/3 in
men.
• Begins as osteopenia
![Page 30: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/30.jpg)
Osteoporosis
• Type I Osteoporosis = Post-menopausal Osteoporosis– Affects about 40% of women over 50– Gender differences
• Men reach higher peak bone mass and strength in young adulthood
• Type II Osteoporosis = Age-Associated Osteoporosis– Affects most women and men over 70
![Page 31: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/31.jpg)
Osteoporosis
• Symptoms:– Painful, deforming and debilitating crush
fractures of vertebrae• Usually of lumbar vertebrae from weight bearing
activity, which leads to height loss– Estimated 26% of women over 50 suffer from these
fractures
![Page 32: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/32.jpg)
Osteoporosis
• Men have an increase in vertebral diameter with aging– Reduces compressive stress during weight
bearing activities– Structural strength not reduced– Not known why same compensatory changes
do not occur in women
![Page 33: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/33.jpg)
Female Athlete Triad
• 1) Eating Disorders affect 1-10% of all adolescent and college-age women.– Displayed in 62% female athletes
• Mostly in endurance or appearance-related sports
• 2) Amenorrhea is the cessation of the menses.
• 3) Osteoporosis is the decrease in bone mass and strength.
![Page 34: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/34.jpg)
Position Statement of ACSM on Osteoporosis
• Weightbearing physical activity is essential for developing and maintaining a healthy skeleton
• Strength exercises may also be beneficial, particularly for non-weightbearing bones
• An increase in physical activity for sedentary women can prevent further inactivity-related bone loss and can even improve bone mass
• Exercise is not an adequate substitute for postmenopausal hormone replacement
• Ex programs for older women should include activities for improving strength, flexibility, and coordination, to lessen the likelihood of falls
![Page 35: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/35.jpg)
Osteoporosis Treatment
• Hormone replacement therapy• Estrogen deficiency damages bone• Increased dietary calcium• Lifestyle factors affect bone mineralization• Risk factors for osteoporosis:
– Smoking, alcohol– Inactivity– Low body fat– White, female, postmenopausal
![Page 36: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/36.jpg)
Osteoporosis Treatment
• Future use of pharmacologic agents– May stimulate bone formation– Low doses of growth factors to stimulate
osteoblast recruitment and promote bone formation.
• Best Bet:– Engaging in regular physical activity– Avoiding the lifestyle (risk) factors that
negatively affect bone mass.
![Page 37: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/37.jpg)
Common Bone Injuries
• Bone stronger in resisting compression than tension, so the side loaded with tension will fracture first.– Acute compression fractures (in absence of
osteoporosis) is rare
• Stress Fractures occur when there is no time for repair process (osteoblast activity)– Begin as small disruption in continuity of outer
layers of cortical bone.
![Page 38: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/38.jpg)
Epiphyseal Injuries
• Include injuries to:• Cartilaginous epiphyseal plate
• Articular cartilage
• Apophysis
• Acute and repetitive loading can injure growth plate– Leads to premature closing of epiphyseal
junction and termination of bone growth.
![Page 39: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/39.jpg)
Epiphyseal Injuries
• Osteochondrosis– Disruption of blood supply to epiphyses– Associated with tissue necrosis and potential
deformation of the epiphyses.
• Apophysitis– Osteochondrosis of the apophysis– Associated with traumatic avulsions.
![Page 40: Bone Structure and Development Readings: –Frankel and Nordin, Chapter 2 –Bailey, D.A. (1996) Growth, Physical Activity, and Bone Mineral Acquisition. Ex](https://reader030.vdocuments.site/reader030/viewer/2022032722/56649f435503460f94c63573/html5/thumbnails/40.jpg)
Summary
• Bone is an important living tissue that is continuously being remodeled.
• Bone Strength and Resistance to fracture depend on its material composition and organizational structure.
• Bones continue to change in density.• Osteoporosis is extremely prevalent among
the elderly.