PHTH 511 - Pathophyisology I > Bone > Flashcards

Bone Flashcards

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1
Q

What are 2 developmental origins of bones?

A

1) Endochondral ossification - replacement of cartilage with bone
2) Intramembranous ossification - bones form between 2 sheets of periosteum

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2
Q

What are the classifications of bone based on shaped?

A

1) Long bone
2) Flat bone
3) Irregular bone
4) Sesamoid bone
5) Accessory bone or supernumerary bone

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3
Q

Give an example of supernumerary bone and how it develops?

A

During the ossifiction phase, the secondary ossification centre does not fuse with the rest of the bone, leading to a supernumerary bone

e.g. Os Trigonum

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4
Q

At birth, all bone marrow in children is ____________.

A

red

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5
Q

In adults, red marrow is found mainly in ______ bones and at proximal ends of __________ and ____________.

A

Flat, Femur, Humerus

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6
Q

Where is yellow marrow found?

A

Yellow marrow is found in the HOLLOW interior of the middle portion of LONG bones.

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7
Q

What is the clinical significance of adipose tissue in the bone?

A

In case of fracture, fat can get into bloodstream and form blood clots.

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8
Q

How much of the cardiac output does bone receive?

A

10-20%

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9
Q

Many nerve fibres are contained in the _____________ and _____________ of the bone.

A

endosteum and periosteum

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10
Q

What are the 2 classes of bone based on texture?

A

1) Compact (dense or cortical bone)
2) Spongey (trabecular or cancellous bone)

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11
Q

In which bones can you find Haversian canals?

A

Cortical bones

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12
Q

What are the characteristics of Haversian canals?

A

1) Houses blood/nerve supply
2) Lined by osteoblast and osteoclasts

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13
Q

In cortical bones, osteocytes are embedded in _________ in the bone matrix.

A

Lacunae

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14
Q

In cortical bones, osteocytes communicate via ____________.

A

Canaliculi

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15
Q

Explain the mechanical responsiveness of bones.

A

1) Cannaliculi connects the osteocytes.
2) Osteocytes also communicate with extracellular matrix via tethering filaments.
3) In the case of bones, compression is the signal (squeezes the fluid which will flow in these canal) and act as the mechanical stimulus.
4) Reduces osteoclast (breaking down) and stimulates osteoblast (bone and collagen formation) activity.

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16
Q

What are the effects of mechanical loading (exercise) on bones?

A

1) ↑ osteocyte signalling
2) ↓ osteoclast activity
3) ↑ osteoblast activity

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17
Q

What is the ultimate result of loading the bone?

A

1) Increased cortical cross-sectional area
2) Increased density of trabeculae
3) Alignment of bone along lines of stress

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18
Q

What are the effects of unloading the bone? (e.g. bedrest)

A

1) ↓ osteocyte signalling
2) ↑ osteoclast activity
3) ↓ osteoblast activity

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19
Q

What is the ultimate result of unloading the bone?

A

1) Reduced cortical thickness and trabecular density
2) Loss of connectivity between trabeculae
3) Increased size of medullary cavity

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20
Q

Bone is highly _________.

A

Mechanoresponsive

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21
Q

______________ is key for bone health.

A

Physical activity

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22
Q

What is the normal rate of bone loss in comparison to bone loss with no mechanical load?

A
  • Normal rate of loss - 1% per YEAR
  • No mechanical load - 1% per MONTH
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23
Q

Define “fracture”.

A

A break in the rigid structure and continuity of a bone.

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24
Q

What are the classifications of fractures?

A

1) Traumatic vs pathologic
2) Stable vs unstable
3) Displaced or undisplaced
4) Open vs closed

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25
What are some types of fractures with respect to the nature of fracture line?
1)Transverse 2) Spiral 3) Comminuted 4) Crush 5) Greenstick 6) Avulsion 7) Salter-Harris
26
Explain Salter-Harris fractures.
- Fractures in children at the level of growth plate (Type I to V) - In type III to V, growth plates can growth can be really affected. - Either the entire growth plate stops working or only works in part.
27
Give an example of a "pathologic" fracture.
Metastatic fracture
28
What is a metastatic fracture?
Growth of cancer cells within the bone.
29
What can result in a post-infection fracture?
Localized osteoporosis as a result of chronic inflammation in a joint.
30
Fracture is strongly _____ related.
age
31
A third of the community dwelling people > 65 years will experience a fall and _____ of these will lead to fractures.
10%
32
________ mortality within 30 days of hip fracture.
6%
33
What are some risk factors of fracture?
1) Age 2) Low bone mineral density 3) Underlying bone condition 4) Increased risk of falls
34
What constitutes an increased risk for falling?
1) Dizziness/fainting 2) Poor balance 3) High-risk activity 4) Environmental hazards
35
What is the pathophysiology of fracture?
1) A force exceeds the capacity of the bone, causing it to break. 2) Blood vessels tear and bleed, leading to necrosis of the bone fragments 3) Adjacent soft tissues are usually damaged as well 4) A clot and inflammatory reaction develops in response to the debris
36
What are the possible systemic complications of fractures?
1) Shock (loss of blood) 2) Fat embolism 3) Deep vascular thrombosis 4) Compartment syndrome 5) Avascular necrosis 6) Infection 7) Early OA development
37
** What fractures are associated with high rate of avascular necrosis? **
1) Proximal femur 2) Base of 5th metatarsal 3) Proximal humerus 4) Scaphoid 5) Neck of talus
38
Open fractures have a very high rate of __________.
infections
39
Explain primary healing of fracture.
1) Occurs if bony ends are in exact contact 2) Slower as there is not much inflammation and 3) Minimal callus - occurs during normal physical activity, or following small breaks, or well reduced and fixated breaks
40
Explain secondary bone healing.
1) If there is a GAP between bony ends 2) Fibrocartilage – bony callus – bone remodelling 3) FASTER than primary healing
41
What are the possible local complications of fractures?
1) Joint contracture / adhesions 2) Muscle weakness and stiffness 3) Re-fracture 4) Infection 5) Delayed Union 6) Malunion 7) Cross-union 8) Non-union
42
What are some signs and symptoms of fractures?
1) Abnormal movement in a limb due to movement at the fracture site 2) Crepitus (grating) between bone ends 3) Deformity that can be seen or felt. 4) Bruising or swelling around the fracture 5) Tenderness of the fracture site 6) Pain on stressing the limb by bending or compressing 7) Impaired function
43
What are some diagnostic tests associated with fractures?
1) X-ray 2) CT scan for small or irregularly shaped bones or complex fracture lines 3) Bone scan for stress fractures
44
What is the treatment overview for fractures?
1) Assessment of nature (type and extent) of break 2) Reduction (if displaced) 3) Immobilization 4) Treatment of associated injuries 5) Pain control 6) Protected weight bearing until healed 7) Progressive rehabilitation
45
When are we clear to start rehabilitation for a fracture?
1) Typically once the fracture is healed 2) Absence of pain on weight-bearing, lifting or movement 3) Absence of tenderness on palpation of fracture site 4) Blurring or disappearance of the fracture line on X-ray
46
What is the immediate fracture post-op protocol by PT?
1) Stretching and ROM of uninjured structures 2) Education 3) Training and practice with crutches 4) Discharge planning
47
Define "osteomyelitis".
Inflammation of bone due to invasion by a pathogen (usually a bacteria like Staphylococcus aureus)
48
Osteomyelitis is common after _________ fractures.
Open
49
20% of foot infections in patients with __________ involve bone.
Diabetes
50
What are some risk factors for osteomyelitis?
1) Open trauma (e.g. puncturing wounds), surgery (e.g. joint replacement surgery for arthritis or fracture management) 2) History of immune system compromise / poor healing
51
What is the pathophysiology of osteomyelitis?
1) Local accumulation of pus with local destruction of bone 2) Pressure on periosteum causes severe pain 3) New bone forms in reaction to inflammatory cytokines, walling off the necrotic/infected area 4) There may be a fluid-filled “sinus tract” through the soft tissues 5) Infection may spread through the bone to the joint 6) If growth plate is infected, children’s bone growth may be affected
52
What are some signs and symptoms of osteomyelitis?
1) Cardinal signs of inflammation 2) Systemic signs - Fever, increased WBC count, malaise
53
What are some diagnostic tests associated with osteomyelitis?
1) X-ray, CT 2) Body temperature, hematology profile 3) Bone biopsy and culture – to determine the responsible pathogen and appropriate antibiotic
54
What is the leading cause of osteomyelitis in the U.S.?
MRSA
55
What is the treatment overview for osteomyelitis?
1) Usually intravenous antibiotics, followed by oral antibiotics 2) Once the infection is controlled, PT maybe essential to regain lost strength, ROM and mobility 3) Surgical management may consist of debridement/rest/ reconstruction, or amputation 4) If there has been a surgical intervention, PTs may be heavily involved in rehabilitation – ROM, strength, pain, balance, education
56
Define "Osteoporosis".
- A metabolic bone disorder characterized by a decrease in bone mass and density, combined with a loss of bone matrix and mineralization. – It is defined specifically as a bone mineral density (BMD) of > 2.5 standard deviations (SD) below the young adult reference mean.
57
What is severe osteoporosis?
BMD > 2.5 SD below young adult reference mean, plus 1 or more fragility fractures
58
What is a fragility fracture?
A pathologic fracture resulting from a fall from standing height or less
59
Where is the most common location for fragility fractures?
1) Neck of femur 2) vertebrae 3) Distal radius
60
What are the classifications of osteoporosis?
1) Primary - Includes senile, post-menopausal, and idiopathic forms 2) Secondary - Related to other pathology, e.g. Cushing’s syndrome (chronic corticosteroid use), hyperparathyroidism
61
What are some risk factors of osteoporosis?
1) Age 2) Gender 3) Low lifetime accumulated physical activity 4) Menopause 5) Hereditary factors, body build 6) Nutrition (calcium, Vitamin D, fatty food, caffeine, alcohol)
62
What is the pathophysiology of osteoporosis?
1) Bone resorption (by osteoclasts) exceeds bone formation (by osteoblasts) 2) Bones gradually become thinner (osteopenic) and more fragile, eventually reaching the point where they fracture under normal conditions 3) Bones with a lot of cancellous material (e.g. vertebra, femoral neck) are predisposed, as bone remodelling is faster
63
What are some signs and symptoms of osteoporosis?
1) Initially, it is asymptomatic 2) First symptom may be a fracture --> Fragility fracture 3) Kyphosis --> Results from vertebral compression fractures, associated with pain and observable deformity
64
What are some diagnostic tests associated with osteoporosis?
1) DEXA scan 2) Screening is performed in all people aged 65>, or in younger women who are deemed at greater risk of developing osteoporosis
65
What is the role of PT in care of osteoporosis?
1) Exercise prescription 2) Usually, BMD cannot be restored, but further losses can be slowed down 3) Balance and muscle strength can be improved 4) Posture --> Active exercise, stretching, manual therapy 5) “Osteofit” classes 6) Post-surgical PT --> may include home care PT
66
Define "stress fracture".
A fatigue fracture which develops due to excessive stress/strain in the bones.
67
Who are more at risk of stress fractures?
Runners and ballet dancers
68
What are the 3 most common bones where stress fractures can happen?
1) Tibia 2) Metatarsals 3) Femur
69
What are some intrinsic risk factors for stress fractures?
1) Individual biomechanics (leg lengths, pronation, etc) 2) Excessive weight 3) Caloric intake; Vitamin D, Calcium
70
What are some extrinsic risk factors for stress fractures?
1) Overuse (volume and intensity of loading) 2) Footwear, training surface
71
What is the pathophysiology of stress fractures?
1) Wear and tear in the bones, including micro-cracks, is normal 2) Bone is continually renewed by osteoblast/ osteoclast activity 3) If wear and tear outpaces the remodelling activity, then microcracks can extend into larger cracks 4) Presence of debris (bone, cellular) starts an inflammatory response 5) There may be attempted cycles of primary healing (but no callus unless a large fracture occurs)
72
What are some signs and symptoms of stress fractures?
Usually presents as a gradual onset of bone pain with a history of overloading
73
What are some diagnostic tests associated with stress fractures?
1) MRI - Bone marrow edema 2) Bone scan, CT
74
What is the general treatment overview for stress fractures?
Most stress fractures or stress reactions, usually resolve with: 1) Reduction of activity 2) Biomechanical correction.
75
What stress fractures require more treatment than just rest and biomechanical correction?
1) Navicular 2) Femoral neck 3) Anterior tibial cortex 4) Base of 2nd metatarsal 5) Base of 5th metatarsal
76
What is the treatment of navicular stress fracture?
1) Can be a career-stopping injury 2) 8 weeks NWB cast 3) Very inconvenient treatment 4) Results of weight bearing rest are poor 5) Surgery data are not encouraging
77
What is the treatment of femoral neck stress fracture?
1) Undisplaced --> initial bedrest for 1 week, then gradual WB 2) Displaced --> surgical fixation
78
What is treatment of anterior tibial cortex stress fracture?
1) 6-8 weeks NWB on crutches 2) 6-8 weeks walking in AirCast boot 3) Intra-medullary screw fixation
79
What is treatment of base of 2nd MT stress fracture?
1) NWB for 2 weeks 2) PWB for 2 weeks
80
What is the treatment of base of 5th MT stress fracture?
1) 6 weeks cast immobilization 2) or percutaneous screw fixation
PHTH 511 - Pathophyisology I
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