1
Q
what % of trabecular bone is calcified
A
15-25%
(rest is red bone marrow, blood vessels, connective tissue)
2
Q
trabecular bone is found most where
A
- short
- flat
- irregular bones
3
Q
this definition explains what type of bone
- spongy
- no osteons
- lamelle = irregular, thin lattice columns
A
Trabecular Bone
4
Q
describe Intramembranous ossification
A
- formation of flat bones (cranial bones, ribs, clavicle)
steps:
1. Mesenchymal cells cluster then cells differentiate into osteoblasts
- osteoblasts secrete osteoid
- osteoid allows for the influx of collagen, calcium, phosphorus which traps osteoblast cluster (ossification centre)
WHERE OSTEOID IS SECRETED IT BECOMES TRABECULAR BONE
Process continues and the outside is periosteum: compact bone and inner portion which is largely surrounded by capillaries is considered Trabecular bone
5
Q
describe Endochondral ossification
A
- development of long bones (Tibia, Femur, Humerus)
steps
1. Mesenchymal cells differentiate into chondrocytes
- development of membrane; perichondrium (surrounds and protects cartilage model)
- chondrocytes grow in size and capillaries penetrate this area
- bone collar forms: perichondrium –> periosteum
- primary ossification centre formed in middle (first step of bone growth)
- secondary ossification centres (growth plates) develop at ends of the bone at/after birth
- cartilage remains at end of bone (growth plate) & at joint surface –> called articular cartilage
6
Q
for bone tissue formation you need what to happen?
A
osteogenesis or ossification
7
Q
where bone growth in length occurs
A
growth plate
8
Q
explain growth plate process
A
- mitosis produces chondrocytes
- chondrocytes mature, hypertrophy, calcify
- calcified cartilage is reabsorbed, new bone formed in its place
9
Q
what regulates growth plate activity
A
IGF-1: chondrocyte proliferation
thyroid hormone: chondrocyte regulation (growth, maturation, matrix)
estrogen:
- stim growth spurt
- stim epiphyseal fusion
10
Q
how can someone with hyper or hypothyroidism have decreased bone health?
A
thyroid hormones helps to regulate chondrocyte growth, maturation, matrix synthesis
if someone has too much, hyper or too little, hypo thyroid hormone there growth is affected
how…
hyper:
- bone loss
- osteoclastic bone resorption
hypo:
- slows bone/ tissue growth
- stunt height
11
Q
how does GH help bones develop
A
- Ant pit secretes GH
- stims IGF-1
- increase osteoblast function
- increase protein synthesis
- stim chondrocyte differentiation, proliferation –> longitudinal growth and bone formation
12
Q
can bone strength be altered
A
true
13
Q
how can bone strength be altered
A
- changing MATERIAL PROPERTIES of bone
- changing bone MASS
- changing bone SHAPE, SIZE, MICROARCHITECTURE
14
Q
What specific material properties change bone strength
A
increase mineralization
decrease collagen
= brittle and decreased bone strength
15
Q
what genetic conditions affect bone material
A
- osteomalacia
> soft bones
> bone pain, fracture, vit D, low phosphate - osteoporosis
> congenital disorder
> osteoclast cant resorb bone
> easy fracture, brittle - osteogenesis imperfecta:
> gene mut
> defective collagen
> brittle fracture easy, short, spinal curvature
16
Q
changes in trabecular structure with aging
A
- decreased
- volume
- trabecular thickness
- trabecular number
- connectivity
17
Q
changes in cortical bone with age
A
increased:
- cortical porosity
- bone size
decreased:
- cortical thickness
18
Q
how do you measure bone mass?
A
DXA
19
Q
what does DXA do?
A
- measures amount of energy of x-rays attenuated
- attenuation profile is used to divide into bone and soft tissue
- soft tissue pixels compares to calibration material to determine fat free and fat masses
20
Q
how do you measure bone mass
A
- determine mass of mineral bone (attenuation) (g)
- determine area (cm2)
- BMD g/cm2
- translate BMD to T or Z score
21
Q
what are the examples of structural components of bone
A
- size, shape, and mass
- cortical thickness
- porosity
- trabecular thickness
22
Q
how does changing the bone size and shape effect bone strength
A
more material in cross section –> the better it is ti resist applied loads
+
increases strength from distributing material farther from
- axis of bending
(resists bending)
- central axis (resits
shear/ torsion)
23
Q
strength of a vertical trabeculae is inversely proportional to _____
A
length
(shorter=stronger)
24
Q
1 single cross-tie affects _____ vertical trabeculae
A
2
25
what trabecular is lost first with aging?
horizontal
26
explain how resorption pits or thinner trabecular can create points of weakness
vertical trabeculae Bow slightly when loaded
27
what factors influence bone strength and fracture risk
- genetics
- medications
- alcohol, smoking
- hormones
- nutrition
- PA
28
what are the estrogen effects on bone remodelling
decrease in:
- osteoclasts
- RANKL
- Cytokines
increase in:
- Apoptosis
29
consequences + risk of RED-S from low energy
low energy effects:
- Gonadal Steroid Production
low energy --> estrogen deficiency and decrease IGF-1 and decrease in bone formation --> increase in bone resorption = bone loss
30
what does RED-S stand for
relative
energy
deficiency
in sport
31
bone stress s/s
- pain with activity (progresses to night)
- hop test/ squeeze test
- visible on X-RAY
32
*where do bone stress injuries occur
location depends on how the skeleton is loaded
x-country: knee
basketball: ankle
rowers: ribs
gymnastics: spine
33
*what causes bone stress injuries
- repeated loads applied to bone create micro damage at a rate that exceeds the rate of normal bone remodelling
+
when load applied is greater than bone strength
34
*how to prevent bone stress injuries
- gradually increase speed, volume
- address risk factors for reduced bone strength
- Low Vit D
- Low Calcium
- Low Energy
- Early exposure to high Impact
35
*bone stress injury treatment
medical: surgery, non-operative, hormone, medications
activity modification
progressive loading program
address risk factors (sleep, diet, biomechanics)
36
factors associated with bone stress injuries
- sex; females
- low energy
- sleep disorders
- medications (corticosteroids, NSAID)
- impact surface
- high loading reps, rapid change in load
ex (preseason--> reg season)
37
what type of activities cause bone stress injuries
- cross country
- gymnastics
- basketball
- track
38
*timeline for fracture healing
DAYS 1-5
DAYS 5-11
DAYS 11-28
MONTHS-YRS
DAYS 1-5
inflammatory response
- hematoma
- immune cells influx
- necrotic tissue removal
- angiogenesis
- repair
cytokines > recruitment of cells > tissue regeneration
DAYS 5-11:
soft callus formation
- VEGF > Angiogenesis, mesenchymal stem cells . fibroblasts, chondroblasts
- cartilaginous callus formed
- some bone formed
DAYS 11-28
Hard Callus Formation
- cartilaginous callus > RANKL > cartilage resorption > hard callus
MONTHS-YRS
secondary bone formation
- woven bone into cortical/lamellar bone
39
how are serum calcium levels maintained
40
what hormones are involved
1. Calcitonin
- hormone produced by thyroid gland
- secreted via EC ca2+
DECREASES
- blood ca+
-bone resorption
-Renal resorption of ca2+
2.PTH
- Produced by parathyroid glands
- secreted via EC ca2+
INCREASES:
- blood ca2+
- bone resorption
- 1,25(OH)2D3 production
- Ca2+ reuptake in kidneys
3. VIT D
- produced in kidney
increases
- Blood ca2+
- absorbs ca2+ in Small Intestine
-
41
your uncle has kidney disease and is on dialysis. he recently fractured his humerus after a fall. why is he at increased risk of fractures? what is happening to put him at risk?
His kidneys can’t properly regulate:
Calcium
Phosphate
Vitamin D
Parathyroid hormone
This causes calcium to be pulled from his bones over time, making them weaker and more brittle. When he fell, his humerus fractured more easily than it would in someone with normal kidney function.
42
what decreases phosphate reabsorption
PTH
FGF23 (protein)
in kidney
43
what increases phosphate reabsorption
1,25(OH)2D3
in intestine
44
FGF23 (protein) _____ down regulates
1,25(OH)2D3 production
45
what is Cholecalciferol
- Naturally occurring VIT D
-Called vit D3
made: in skin post UVB exposure
46
what is Ergocalciferol
- VIT D2
47
what is calcidiol 25(OH2)D3
- Pre-hormone in blood made in liver
48
What is Calcitriol 1,25-(OH)2 D3
- ACTIVE form of VIT D
- most potent
- made in b/l kidneys
49
what are some natural sources of vit D
name 3
- egg yolks
- fatty fish
- fish liver oils
- milk
- margarine
- cereals
50
how can someone with a fat malabsorption issue have complications with vit D
Vitamin D is a fat-soluble vitamin. That means it needs:
Fat
Bile
Pancreatic enzymes
An intact small intestine
51
how does someone with a pancreatic enzyme deficiency have affected vit D
low lipase
=
Fat isn’t digested/absorbed properly
52
how does someone with Chrons disease have affected vit D
IBD affects SI and causes diarrhea and fat malabsorption
53
how does someone with cystic fibrosis have affected vit D
hereditary, thick sticky mucus secreted clogs the pancreas + lungs
54
how does someone with celiac disease have affected vit D
damages SI
55
how does someone with Liver disease have affected vit D
impaired liver function
=
Less bile → poor fat absorption
Impaired vitamin D activation
56
What is the level of Vit D deficiency
serum 25 (OH)D
=
< 25 nmol/L
57
What is the level of Vit D Insufficiency
between
25-74 nmol/L
58
What is the normal level of Vit D Insufficiency
abnormal
toxic
between
75-250 nmol/L
250.1 nmol/L
>357 nmol/L
59
what is osteomalacia
Newly formed bone does not mineralize (soft bones)
60
osteomalacia risk factors
VIT D causes
1. deficiency/ impaired
2. impaired calcidiol production
3. impaired calcitriol production
4. impaired Vit D
- Hypophosphatemia: genetic disorder, elevated FGF23, Low phosphate
- kidney disease
- tumor-induced osteomalacia
61
osteomalacia prevention + treatment
- adress Vit D deficiency, hypocalcemia, hypophosphatemia
62
what is Rickets
newly formed bone at growth plate or other sites do not mineralize
63
Rickets risk factors
- hypocalcemia
- Elevated PTH
- Elevated Alkaline phosphotase
- low serum 25 (OH) D
64
Rickets prevention
Routine vitamin D supplementation in infants and adequate intake in children.
65
Rickets treatment
- VIT D replacement
- calcium supplementation
-
66
rickets clinical presentation
- muscle weakness
- bowing
- waddle gait
- indentation of lower ribs
- diffuse bone pain
67
RDA's for calcium
m: 1000mg
f: 1200mg
68
RDA's for Vit D
800 IU
69
explain how bone cells sense and respond to mechanical loading
1. muscles pull on bone = tension
2. muscles contract across joints = compression
3. in response long bones bend
4. ground reaction forces
70
RDA's for protein
0.8 g of protein per Kg
71
how does a mechanical signal get converted to a cellular signal?
Mechanical force → deformation of cytoskeleton → activation of signalling proteins → gene transcription changes.
But the core idea is:
Force changes cell shape → shape change triggers chemistry → chemistry changes behavior.
72
what types of loads are osteogenic
- higher mag
- high load freq
- high strain rate
- dynamic loading
- multiple bouts
73
why is peak strain increased in trochanteric region compared to the femoral neck
1. farther from the central axis= more bending force experienced
2. farther from neutral axis = higher tensile/ compressive forces
3. The femoral neck: dense cortical bone
The trochanteric: more trabecular bone
74
why might strains be higher during stair ascent and descent than jumping
compare jumping and stair ascent/descent
1. joint position:
S: hip flexed @peak
J: hip extended @peak
2. time under load
S: Longer
J: shorter
3. Bending Moment (S) vs Pure Compression (J)
4. Muscle Forces
S: larger muscles forces
J: more ground rx forces than muscle
75
why might strains be higher during stair ascent and descent than jumping
*strain increases w/ more bending*
Strains may be higher during stair ascent/descent because:
The hip is flexed
Loading is off-axis
Bending moments are larger
Muscle forces add significant stress
Bone experiences more tensile strain
76
true or false BMD among athletes are different depending on their sports
TRUE
higher:
- basketball
- soccer
- football
- hockey
not higher:
- swimming
- cycling
77
You work for the school board. they want you to pick two exercises to add to gym class to help kids develop healthy bones
1. what exercises would you prioritize? 2. what characteristics of the exercises make them osteogenic?
3. how often should they do it and why? 4. if you were designing a study ti see if it worked, how long should it be and why?
1.
- jumping
- short bursts
2. osteogenic because
Bone responds best to:
Dynamic
High-impact
Variable loading
3. 👉 3–4 times per week
👉 10–15 minutes per session
👉 ~50–100 high-impact contacts
why? desensitization
4. Ideal: 9–12 months
Why?
Bone remodelling cycle:
Resorption phase: ~2–3 weeks
formation phase: ~3–4 months
78
___. --> ____ = critical period for bone mineral accumulation (accrual)
childhood to adolescents
79
children who exercised had a _____ % greater annual increase in bone accrual
0.6%-1.7%
80
what do we know about exercise and aBMD in adult premenopausal women?
1. progressive resistive training increases LS aBMD (areal BMD)
2. high impact or jumping training results in increase in FN aBMD
81
if you were designing an exercise program to be osteogenic, what types of exercises would you include and why?
1. Jump / Plyometric Training
- high strain rate
- high ground rx force
- strong muscle contraction
2. resistance training
- Large muscle forces pull on bone
- Increases bending and compressive strain
3. Multidirectional Agility
- Loads bone in different directions
- Enhances structural adaptation
82
what exercises prevent fractures
Gait, balance, co-ordination, functional task training
83
slips and trips out doors is the highest reason for fractures t/f?
true
84
what is osteoporosis
- low bone density
- micro-architectural deterioration
- increase bone fragility/ fracture
85
1/3 ____ will have an osteoporotic fracture
women
86
what are examples of primary osteoporosis?
1. postmenopausal
2. age related
3. idiopathic
87
secondary causes of osteoporosis
1. medications
2. hereditary
3. endocrine/ metabolic
4. immobilization
5. other diseases (cancer, CKD)
88
what is the definition of Osteoporosis from DXA
89
what is the definition of Osteopenia from DXA
between:
-1.0 and -2.5
90
what is the FRAX tool
used for assessing 10yr prob of hip/ major osteoporotic fracture
91
what are screen signs of possible spine fracture?
1. occiput to wall distance > 5 cm
2. prospective height loss >2cm or >6cm
3. rib to pelvis distance
92
t/f?
avoid assesments of spinal ROM in people w/acute vertebral fracture or multiple fractures?
true
93
what to do when ur patient presents with
- sudden onset of back/ radicular pain
- decreased mobility due to pain
- increase/ worsen of thoracic kyphosis, lost height, shortness of breath
cease exercise/ therapy and refer to physician
94
what are some strategies used to prevent fracture?
Nutrition: Meet RDA for vit D, calcium, protein
Physical Activity: exercise
Pharmacologic therapy:
- Biophosphonates
- Denosumab
- romosozumab
95
what is the medication mechanism of
DENOSUMAB
RANK ligand inhibitor
96
what is the medication mechanism of
BIOPHOSPHONATES
bind to bone and inhibits osteoclasts
97
what is the medication mechanism of
ROMOSOZUMAB
Anti-sclerostin antibody
98
what is the ratio to avoiding fracture: serious side effects of biophosphonates?
2500:25
99
should you discontinue DENOSUMAB slowly or quickly and why?
slowly
sudden discontinuation can cause rapid bone loss
100
when setting goals or prescribing exercise, what key things should and exercise professional ask, observe, screen for, or assess?
name 3
1. Medical history
2. Fracture risk
3. Fall risk
4. Physical performance
5. standing posture
6. barriers and facilitators to PA (time, access, pain, preference)
101
true or false
DENOSUMAB
BIPHOSPHONATES
ROMOSOZUMAB
All reduce bone resorption and increase bone formation
false
DENOSUMAB
BIPHOSPHONATES
- reduce bone formation and resorption
ROMOSOZUMAB
- reduce bone resorption
- increase bone formation
102
if someone asks because of my osteoporosis medication will i be able to still exercise and recieve the same benefits you say
- they dont completely stop it from happening its just reduced
- strength and balance should be trained on medications or not
- no one knows for sure if doing exercise while on osteoporosis medications can increase
- medications will reduce risk of fracture and are beneficial if you have osteoporosis or are at risk and that you shouldn't not take it cause resistance training wont yield the same results as if you were off of the meds
103
when choosing assessment tools what should you consider?
- patient characteristics (impairments, cognitive status)
104
what are some tool to assess balance and mobility?
Clinical:
-Berg
-TUG
-SPPB
Sensors:
-iTUG
force plate Ax
-> com
-> Sway
perturbation:
-> reactive balance response
105
what type of exercises prevent falls in older adults?
- multicomponent (balance, functional, RT) (34% dec)
- Gait, balance, and functional training (24% dec)
- Tai Chi
(19% dec)
106
exercise for fall and fracture prevention guidelines?
2 times a week at least =
- balance
- functional
- RT
107
should rapid, repetitive twisting or flexion of spine be avoided?
no just modified
108
what types of balance training are most effective
- anticipatory control
- dynamic control
- reactive balance control
- functional stability limits
109
- anticipatory control
- dynamic control
type of exercises
heel/toe raises
sit to stand
tandem walking
on leg heel raise
split squat
clock exercise
110
- reactive balance control
type of exercises
weight shifting
catching and throwing ball
hitting/catching ball while moving
111
functional stability limits
type of exercises
weight shifting
weight shifting + reaching
hip airplanes
112
Strength training should involve what movements
- push
- pull
- squat
- hinge
- carry
- reach/press
113
strength training should include exercises targeting
abdominals
back extensors
scapular stabilizers
114
when training back muscles (lats, SA, rhomboid, trap) focus on what exercises?
strength/ power training
those are strength/power type fibres
115
when training back muscles (erector spinae) focus on what exercises?
- endurance type fibres
rep range: 12-15 RM
holds/ isometrics
116
if someone has
- scapular protraction
- medial rotation of arm
whats the recommended exercises
ROM: pec's
strengthen: scapular area
ex examples:
- SA slides
- push ups
- w's
- T row
117
if someone has forward head posture what exercises are recommended
- isometric holds/ endurance ex targetting erector spinae
- chin tucks (cervical retraction)
ROM: traps, SCM, pecs, scalene
118
in people with hyperkyphosis
they have very low:
- back extensor strength + endurance
- sit to stand
what exercises should you focus on
- avoid too much weight infront of body
- strengthen hip extensors, address mobility of hip flexors
- target back extensor muscles and shoulder stabilizers
119
what are the pros and cons of AMRAP
As Many Reps As Possible
pros:
- time efficient
- less likely to underestimate ability
- progress w/ rep
cons:
- good technique needed
- over training
- high reps = less ideal for strength
120
your patient has tennis elbow feeling a little better and asks to go back into to tennis casually playing this summer what do you do?
- understand fall/ fracture risk
- can the game be modified
- discuss risk and harms
121
what are 3 goals for someone who has a spine fracture?
1. pain management
- assess
- medication
- procedures if needed
2. improve physical functioning
- promote movement
- strength/ functional exercise
3. falls and fracture prevention
- assess fall and fracture risk
- discuss: medications, exercises, prevention, nutrition
122
how might cancer and cancer treatments affect bone?
- chemo: toxic effect on osteoblasts
- Aromatase inhibitors: bone loss
- tumors: hypercalcemia (increased bone resorption and renal tubular reabsorption
123
what are the types of bone metastases
1. osteolytic
2. osteoblastic
124
whats the difference between osteolytic bone metastases and osteoblastic bone metastases
Osteolytic metastases increase osteoclast activity and cause bone resorption, leading to radiolucent lesions and hypercalcemia. most common in lung, renal, breast cancer patrients. Osteoblastic metastases increase osteoblast activity, causing sclerotic lesions that appear dense on imaging but are structurally weak.
125
what are some concequences of bone metastases
- pain
- cancer not curable
- fractures
- anemia
- sc/ nerve root compression
- hypercalcemia
KIN429
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