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MSK Exam 1 > MSK Pathophysiology > Flashcards

MSK Pathophysiology Flashcards

1
Q

What are some of the functions of bones?

A
  • Stability
  • Mobility
  • Hematopoiesis
  • Buffer calcium
    concentrations
  • Protection to vital organs
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2
Q

Layers of the Bone

A
  • Periosteum: Outer layer, contains vessels,
    nerves, cells for repair
  • Cortex: Hard outer (Compact) bone
    layer
  • Cancellous bone: Soft (Spongy or trabecular) inner bone
  • Endosteum: Inner layer
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3
Q

Salt deposits are primarily ____ and ____ (Hydroxyapatite)

A

Caᐩ; PO4

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4
Q

What makes up the Tough organic matrix (30%) of bone ?

A

– (30%) Organic matrix is made up of collagen fibers (90-95%) and
ground substance
* Collagen fibers extend along lines of tensional force
– This gives the bones their tensile strength
* Ground substance- proteoglycans (connective tissue) and cells

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5
Q

Osteoblasts function

A
  • Secrete collagen and ground substance
  • Leads to formation of osteoids
  • Collagen fibers (Osteoids) then bind to calcium salts→ mineralization
  • Secrete tissue-nonspecific alkaline phosphatase (TNAP) which inhibits
    pyrophosphate
  • Pyrophosphate inhibits hydroxyapatite crystallization→ ie. inhibits
    bone mineralization
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6
Q

Osteoclasts tunnel through
bone for several weeks, than
are replaced by osteoblasts
which fill in the tunnel, until
just a blood vessel is left. This
remnant is called a ______

A

haversian canal

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6
Q

Osteocytes function

A

Osteoblasts become entrapped in osteoid, and they become osteocytes

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6
Q

Osteoclasts function

A
  • Large phagocytic, multinucleated cells
  • Stimulated by parathyroid hormone (PTH) indirectly
  • PTH binds to osteoblasts
  • Osteoblasts signal osteoclast precursors→ become mature osteoclasts
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6
Q

Recall what happens to bone in hyperparathyroidism?

A

PTH stimulates osteoclast activity and formation of osteoclasts, recruiting CA and phosphate from the bone

Calcitonin is the opposite of PTH and decreases osteoclast activity and inhibits the formation of osteoclasts

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7
Q

The mechanism of bone resorption

A
  • Osteoclasts work by tunneling through bone
  • Osteoclasts secrete proteolytic enzymes and acids
  • Enzymes digest or dissolve the organic matrix
  • Acids dissolve the bone salts
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8
Q

End of the bone

A

Epiphysis

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9
Q

Bone growth, highly vascular

A

Physis

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10
Q

Narrowed section before
growth plate

A

Metaphysis

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11
Q

Central shaft, cortical bone

A

Diaphysis

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12
Q

Fibrous band of connective tissue, holding bone to bone, or bone to cartilage

A

Ligament

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13
Q

Long bundles of collagen holding muscle to bone. Surrounded by a synovial membrane (Tendon sheath)

A

Tendon

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14
Q

Cartilage function

A
  • Ends of the bones
  • Covers the area of the epiphysis
  • Provides smooth gliding surface
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15
Q

Fibrous joints

A

have minimal movement

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16
Q

Cartilaginous joints

A

have Fibrocartilaginous
segments, minimal movement

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17
Q

Synovial joints

A

– Most common, allows free movement
– Joint cavity, synovial membrane (lining)

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18
Q

Myofibrils contain _____

A

myosin and actin

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19
Q

I bands contain

A

actin

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20
Q

A bands contain

A

myosin and the tips of the actin

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21
Q

Z disk contains

A

ends of the actin filaments

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22
Q

sarcomere

A

the area of a Myofibril between Z disks

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23
Q

Cross Bridge

A

myosin filament protrusions that
interact with actin filament

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24
Q

Go over the process of muscle contraction

A
  1. Action potential moves along muscle motor neuron.
  2. Acetylcholine (ACh) is released and causes opening of ACh gated channels.
  3. Naᐩ is allowed to flow into muscle membrane causing depolarization. Kᐩ flows out
  4. Action potential travels along muscle fiber causing sarcoplasmic reticulum to release Caᐩ.
  5. Caᐩ ions initiate cross-bridge action between the myosin and actin filaments. Requires ATP to slide.
  6. Contraction ceases when Caᐩ are pumped back into the sarcoplasmic reticulum.
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25
Q

Characteristics of slow muscle fibers?

A

(Red Muscle)
1. Prolonged muscle activity
2. Smaller
3. Greater blood supply → more
oxygen
4. More mitochondria→ more
metabolism
5. Contains more myoglobin which
allows for increased oxygen
transport to mitochondria. Also
contains more Fe giving a red color

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25
Q

Isometric vs. isotonic

A
  • Isometric: the muscle does not shorten
  • Isotonic: the muscle shortens
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26
Q

Characteristics of fast muscle fibers

A
  1. Powerful muscle contractions
  2. Extensive sarcoplasmic reticulum for
    rapid release of Caᐩ
  3. Large amount of glycolytic enzymes
    for fast release of energy
  4. Less extensive blood supply as less
    oxidative metabolism is needed
  5. Fewer mitochondria
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27
Q

Muscle action is balanced by these four factors

A
  • Agonist- movement occurs
  • Antagonist- opposes movement
  • Synergist- aide movement
  • Stabilizer- restrict unnecessary
    movement
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28
Q

Hypertrophy

A

– Increased muscle mass
– Increased number actin and myosin filaments, not increase in
muscle fibers

29
Q

Atrophy

A

– Decrease in muscle mass
– Degradation of actin & myosin is greater than replacement

30
Q

Denervation Atrophy

A
  • Loss of nerve supply to a muscle
  • Rapid atrophy occurs
  • Degenerative changes occur in the muscle fiber within months
  • Without return of innervation, chances of functional recovery become less and less, with no return possible in 1-2 years.
  • Muscle fibers are replaced by fibrous fatty tissue
  • Can lead to muscle contractures- important for PT
31
Q

Forces Applied to cause a
fracture

A
  • Compression
  • Tension
  • Shearing
  • Torque
32
Q

When the stress applied overcomes
the elastic region, then the tissues will
_____

A

begin to fail

33
Q

3 Phases of healing an orthopedic injury

A
  • Hematoma and inflammation
  • Repair and proliferation
  • Maturation and remodeling
34
Q

Hematoma and inflammation phase of healing

A
  • Bleeding to the area causes a hematoma formation
  • Migration of bioactive cells. Phagocytosis of necrotic debri
35
Q

Repair and proliferation phase of healing

A
  • New blood vessels form
  • Soft cartilaginous bridging callus forms and is then mineralized
    by osteoblasts and is converted to immature bone
36
Q

Maturation and remodeling phase of healing

A
  • Can continue for months
  • Immature (woven) bone is replaced by cancellous bone
37
Q

Callus Formation

A

Periosteal and intraosseous reactions recruit osteoblasts formed from
osteoprogenitor cells to the area followed by deposition of calcium salts
→ The hematoma forms into a callus

38
Q

What is Nonunion?

A

Fractures that do not unite
– Poor stability or reduction, atrophic, consider indolent infection, smoking, NSAID
– May require revision surgery and bone graft

39
Q

What is Malunion?

A

Fractures that heal with unacceptable alignment and/or poor reduction
– May require revision, based on progress of healing, becomes a more
challenging surgery

40
Q

Avascular necrosis of bone

A

delayed complication of interrupted blood
supply. eg. scaphoid, femoral head

41
Q

Previously referred to as a
“compound” fracture

A

open fracture

42
Q

Bowing Fracture

A
  • Occurs in long bones
  • Often in children
  • Bent bone without
    cortical disruption
  • May require completion
    of the fracture
43
Q

Torus/ Buckle Fracture

A
  • Typically forearm
  • Occurs in children
  • Younger elastic
    bones
  • Likely simple cast
    and protection
44
Q

Greenstick fracture

A
  • An incomplete fracture
    with an angular deformity
  • Fracture to one cortex
  • Occurs in children as the
    bones are more elastic
  • Possible need for reduction
45
Q

Transverse Fracture

A
  • Fracture perpendicular to bone shaft
  • Typically long bones
  • Fracture extends through the bone
  • Be alert to displacement, rotation,
    and shortening
46
Q

Oblique Fracture

A
  • Typically long bones
  • Angulated fracture line
  • Be alert to displacement,
    rotation, and shortening
47
Q

Spiral Fracture

A
  • Long bones
  • Multiplanar long bone fracture
  • Occurs from a rotational force
  • High risk of displacement
48
Q

Longitudinal Fracture

A
  • Fracture along axis of the bone
  • Be alert for extension towards
    the articular surface
49
Q

Comminuted Fracture

A
  • A multi-part fracture with
    multiple fragments
  • The bone has been crushed
  • Likely will require ORIF
50
Q

Avulsion Fracture

A
  • Occurs in numerous
    locations
  • Fragment of bone breaks
    away, often at attachment
    point of tendon or ligament
  • Essentially the bone breaks
    instead of the tendon or
    ligament
51
Q

Segmental Fracture

A
  • Long bones
  • Fracture with an
    isolated free segment
  • Usually unstable
  • May need surgery
52
Q

Intra Articular Fracture

A
  • Fracture that extends into a joint
  • Higher chance of disruption of
    the joint
  • Can lead to chronic pain and
    degenerative changes, may f/u
    with CT or MRI
53
Q

Pathologic Fracture

A

Fracture occurring at a weak point in
the bone
- Eg. Malignant or benign tumor,
osteoporosis, poor bone health and
quality, advanced age, etc.

54
Q

Diagnosis and treatment of a pathologic fracture

A
  • X-ray and/or f/u with MRI or CT
  • Biopsy (eg. Bone lesion)
  • DEXA scan (eg. Osteoporosis)
  • Tx based on underlying etiology
55
Q

Are fractures more common in adults or children?

A

Children

56
Q

Growth plate fractures are more
worrisome for ______

A

growth disturbance. (eg. growth arrest)

57
Q

Think surgery consult for these types of fractures:

A
  • Open, displaced, angulated, or unstable fractures that cannot be reduced or don’t stay reduced with splinting and/or casting.
  • Compartment Syndrome
  • Remember your IV Antibiotics for open
    fractures
58
Q

What is a Strain?

A

● Injury to a muscle or
musculotendinous junction
● Muscle undergoes a forced
eccentric load (eg.forced
lengthening)
● eg. gastrocnemius,
hamstring
● With age brings decreased
elasticity

59
Q

What is a Sprain?

A

● An injury to a ligament
● Failure occurs when they
are stretched beyond
capacity
● eg. Ankle is a common
example
● Uncommon in kids because
the physis is weaker than
the ligament

60
Q

Vascular or neurologic compromise can
occur for several reasons:

A
  • Neurovascular bundle gets “kinked”
    around a dislocation
  • Blood supply is interrupted by vascular
    injury (eg. compression or disrupted)
61
Q

What should you assess every time if you are concerned about Compromised Neurovascular injuries?

A

peripheral nerve function

62
Q

Examples of injuries highly associated with
vascular compromise

A
  • Dislocation of the knee→(Routine arteriography)
  • Fracture-dislocation of the ankle
  • Displaced supracondylar fracture of the
    elbow in children
63
Q

Compartment Syndrome

A
  • Intracompartmental pressure exceeds vascular perfusion pressure
  • Leads to ischemia of muscles, nerves, vessels
  • Compartment Syndrome defined
64
Q

Possible causes of compartment syndrome

A
  • Anything that has caused bleeding or edema in closed nonelastic muscle
    compartment surrounded by fascia & bone
  • High energy injuries (fractures and/or severe soft tissue injuries)
  • Crush injuries- most common
  • Burns, coagulopathy, gunshot wounds
  • Snake Bite
  • Prolonged limb compression (“Tight cast”- A commonly feared complication)
  • Spontaneous- Rare
  • Chronic Exertional Compartment Syndrome- Sudden ↑ in activity or workout
65
Q

6 Ps of compartment syndrome presentation

A
  • Pain (esp. with stretch)- Most specific. “Pain out of proportion”
  • Pink skin or pallor
  • Paresthesias
  • Poikilothermia- Cold skin distally
    (misnomer in this case)
  • Pulselessness- Very Late
  • Paralysis or paresis- Very Late
66
Q

Diagnosis of Compartment Syndrome

A

– “6 Ps”
– Measured intracompartmental pressure

67
Q

Normal tissue pressure vs. compartment syndrome

A

Normal tissue < 10 mmHg
* Consultation with Orthopedist at > 30 mmHg or simply suspect clinically

Diagnostic
1. Mean pressure of > 30 mmHg
2. ΔP < 30 mm Hg
a. (Diastolic - Compartment
pressure = ΔP )

68
Q

Compartment Syndrome management

A
  • Position affected limb at heart level
  • Maintain ankle in neutral position if leg is affected
  • Immediate fasciotomy recommended for
    – Clinical or suspected diagnosis or elevated intracompartmental
    pressure
    – Absolute compartment pressure >30 mm Hg
    – Perfusion pressure (diastolic blood pressure - compartment pressure)
    < 30 mm Hg (Some references say 20 mmHg eg. AAOS 5th ed.)
69
Q

How long does it take for muscle necrosis to begin?

A

Interrupted arterial circulation to an
extremity > 4-6 hours

70
Q

Rheumatism is derived from a greek word implying ____

A

an influx of fluid to the joints
Rheum- meaning body fluid

71
Q

Rheumatologic Pathophysiology

A
  • Localized and systemic musculoskeletal inflammation and
    damage to internal organs, loss of immune homeostasis
  • Dysregulated immunity rather then Immunodeficiency
72
Q

Stages of Rheumatologic Pathophysiology

A
  1. Initiation
  2. Propagation
  3. Flare
    * Acute vs Chronic
    * Symptoms vary between
    diseases based mechanism,
    and target tissues affected
73
Q

Chronic rheumatologic Disease

A

– Propagation when the body creates an autoimmune response →
self-amplifying cycle of damage
* Also described as an auto-amplifying loop
* Loss of T cell and B cell immune response checkpoints

74
Q

Antibodies against self antigens

A
  • Inflammatory response normally balanced
  • Apoptosis and cell damage liberates secretory granules and mediators from inflammatory cells
  • Normally these are cleared
  • With autoimmune diseases these released products in
    large amounts can become “self antigens”
75
Q

Rheumatoid Arthritis

A
  • Autoimmune- chronic inflammation of
    synovial joints, genetic w/ environmental
    trigger
  • Attacks the synovial lining of joints
    – Can affect other tissues eg. lung, skin, vessels
  • Synovial thickening, cartilage damage, bone
    erosions
    – Typically symmetrical joints

MSK Exam 1 (5 decks)

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