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Fractures EQ > 3-Pathofysiology fx > Flashcards

3-Pathofysiology fx Flashcards

1
Q

Organic, inorganic and water components of the bone in %

A

35% organic
45% inorganic
25% water

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2
Q

What is the major inorganix component?

A

crystalline hydroxapatite

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3
Q

Organic matrix is compromised of collagen type (mention)

A

Type I (>90% or organic component)

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4
Q

Type I collagen is responsible for which proprietires of the bone?

A

viscoelastic properties

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5
Q

Mineralization confers 2 proprieties

A

strength and stiffness

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6
Q

The collagen phase contributes to

A

ductility and overall toughness

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7
Q

Harvesian systems are present in compact bone to provide what?

A

Vascularization to osteocytes embeddedin bone matrix

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8
Q

Concentric lamellae that surround a central blood vessel in Haversian canals makeup the osteons of the Haversian system in which type of bone?

A

compact bone

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9
Q

During bone formation and growth the first cells to be laid down are

A

Primary osteons

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10
Q

During postnatal growth the long bone diameter is achieved through ______ formation

A

periosteal formation of woven bone that provides the structure for the formation of primary osteons or circumferential lamellae

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11
Q

Cement lines are formed by (type of cell)

A

osteoblasts at the time of transition from bone resorption to formation

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12
Q

Biomechanical response of bone to loading is dependent on its geometry and

A

material composition

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13
Q

Define the loading characteristics

A

Direction, rate, magnitude, frequency, duration

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14
Q

Transverse cracking, where the crack must course
through longitudinally oriented osteons is thougher or lighter than longitudinal cracking?

A

tougher than longitudinal cracking, where the crack splits osteons along the longitudinal axis of the bone

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15
Q

What does it mean that bone is an anisotropic material?

A

Meaning its mechanical properties depend on the direction of the applied forces

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16
Q

because of the structure and orientation of osteons,
compact bone is strongest in _____ (axial or abaxial)

A

Axial compression weaker in tension and weakest in shear

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17
Q

fractures usually propagate along tension and shear planes. Shear planes run at approximately _____º

A

45º from compressive and tensile stresses

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18
Q

Tensile loading occurs when equal and opposite loads are
applied to distract the_________ (ends or midlle) of a bone

A

ends

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19
Q

mention the type of loading

A

tension

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20
Q

mention the type of loading

A

compression

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21
Q

mention the type of loading

A

bending

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22
Q

mention the type of loading

A

bending/compression

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23
Q

mention the type of loading

A

torsion

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24
Q

mention the type of loading

A

shear

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25
Q

Maximum tensile stress occurs on a plane _______________________(perpendicular/parallel) to the direction of applied load

A

perpendicular

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26
Q

Long bones are not well adapted to resist _____________ (uniaxial/biaxial) tensile loads which are not common during normal physiological activities

A

uniaxial

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27
Q

Define compression load

A

Compressive loading occurs when equal and opposite
loads are applied to push the ends of the bone closer
together.

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28
Q

Axial compression causes the bone to

A

shorten and widen

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29
Q

Define torsion load

A

Torsional loading occurs when opposite moments (rotational
forces) are applied to the ends of a bone, such that
the bone twists around the longitudinal axis

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30
Q

Torsional loading induces shear stresses in planes:
a) parallel
b) perpendicular
c) parallel and perpendicular

A

c) parallel and perpendicular

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31
Q

fracture becomes complete when a longitudinal
fissure occurs, connecting the

A

proximal and distal ends of the spiral crack.

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32
Q
A

The fracture originates where
shear stress is greatest on the periphery of the bone and
then propagates due to tensile stresses distracting bone
fragments along a spiral configuration until the fracture
ends are approximately parallel or above one another

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33
Q
A

Tensile loads cause the bone to elongate and narrow. Failure occurs due to tensile forces perpendicular to a transverse
plane. Tension from the suspensory ligament and distal sesamoidean ligaments influenced the transverse configuration of the
mid-body
proximal sesamoid bone fracture shown.

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34
Q
A

Compressive loads cause the bone to shorten and widen. Failure occurs along the plane of maximum shear stress,
oriented approximately 45° from the axis of compressive loading. An incomplete dorsal cortical stress fracture of the third metacarpal
bone illustrates a fracture due predominantly to compressive loading and shear failure. Source (inset): Based on O’Brien et al. [

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35
Q

Define bending load

A

When a bending load is applied, compressive stress is
induced on the concave side and tensile stress is induced
on the convex side of the deforming bone.

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36
Q

Bending creates a longitudinally oriented plane, called

A

the neutral axis, where neither compressive nor tensile stresses are
present

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37
Q

The greater the distance from the neutral axis, the ____________ the tensile or compressive stress

A

larger

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38
Q
A

Bending creates tensile and compressive loads on different sides of the bone. Failure occurs first on the side under tension resulting in a transverse distraction fracture. The fracture then propagates on the side under compression in an oblique configuration, with or without a butterfly fragment, illustrated by a Salter–Harris type II fracture of the proximal tibial physis in a 10-day-old foal and a mid-diaphyseal butterfly fracture of the third metatarsal bone in a foal.

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39
Q

Implants (such as intramedullary nails) that are positioned at the
neutral axis are exposed to lower or higher levels of bending?

A

lower

40
Q

Failure is initiated on the tensile side which is convex or concave

A

convex side of the bone because bone material is weaker in tension

41
Q

Tensile failure causes ______________ crack propagation
until compressive stresses on the concave side of the
bone induce failure in shear at 45° to the longitudinal axis
of the bone.

A

transverse

42
Q

Failure along the plane of highest shear stress
drives the fracture line in oblique directions, producing an _________ fracture face or ________________ fragment

A

oblique or butterfly

43
Q

Define shear force

A

A shear force is one that is applied parallel to a surface or
section through a bone, causing a tendency for surfaces or
sections to slide past one another

44
Q

Shear forces predispose to which type of fractures?

A

A shear force is an external force acting on an object or surface parallel to the slope or plane in which the surface lies.
Cyclic shear loading of an interface between regions of different subchondral bone densities in the distal condyles of the third
metacarpal bone predisposes to condylar fracture in Thoroughbred racehorse

45
Q
A
46
Q

Mid-body fractures of the proximal sesamoid bones provide a good example of which type of fractures

A

complete, mid-body fracture of the proximal sesamoid bone that typically has transverse orientation attributed to longitudinally directed tensile forces

47
Q

Short oblique and butterfly fractures generaly result from _______ forces

A

bending forces which cause tensile loading on the convex side and compressive loading on the concave side of the bone

48
Q

The radius is particularly susceptible to side impact loads like kick injuries typically resulting in _____________ fractures in adult horses

A

comminuted fractures

49
Q

Simple fractures are less common and when they occur the configuration is usually either ______________ or ____________

A

short oblique or butterfly

50
Q

In simple fractures when they occur in butterfly the fragment is on the same side or opposite side of the impact?

A

same side

51
Q

Long oblique and spiral fracture configurations occur in the diaphyses of 3 bones, mae them

A

femur, tibia, humerus

52
Q

Traumatic diaphyseal fractures of the proximal long bones in adult horses are often _______________ fractures

A

comminuted fractures due to substantial energy release at the time of the fracture

53
Q

In FOALS the diaphyseal fractures of the femur, tibia and humerus occur in

A

spiral or long oblique configurations due to combination of compressive and torsional forces placed on the limb during axial loading

54
Q

Which type of loading is responsible for the formatioon of third MC and MT condylar fractures?

A

Cyclic shear loading

55
Q

During high-speed locomotion the load is concentrated on the dorsal or palmar aspect of the distal condyles of MCIII?

A

Palmar and adaptive modelling leads to increased
density of the subchondral bone

56
Q

Fractures that involve significant compressive
forces can occur rarely in horses. Where is common?

A

in the cervical vertebrae as a result of
trauma, such as falls or impact into a fixed object

57
Q

Other type in the limb can result from compression, which one?

A

Dorsal cortical stress fractures of the third metacarpal bone
can also be related to compression

58
Q

The dorsal cortex MCIII have short oblique configuration typically propagating in which direction?

A

Palmaroproximal to dorsodistal direction

59
Q

Define stress

A

Forces expressed relative to the areas of application are
termed stresses

60
Q

Define deformations

A

deformations caused by these stresses and expressed as a proportion of the original dimensions are called strains.

61
Q

Monotonic fracture occur as result as single extreme load deforms the bone or smaller repeated loads?

A

Monotonic is a result of single extreme load deforms the bone beyond its ultimate limit resulting i sudden complete failure

62
Q

Adaptive modelling refers to changes in bone shape and internal structure in response to mechanical forces placed on the bone according to _______ law

A

Wolff’s

63
Q

Give an example of adpatation to load in Thoroughbred racehorses

A

The new bone formation in response to repeated loading where there is the increase in cortical thickness and bone volume fraction

64
Q

What does consiste the bone remodelling observed in replace damaged or fatigued bone

A

Remodelling involves resorption of bone by osteoclasts and replacement by osteoblasts in highly orchestrated and controlled series of events

65
Q

define modelling

A

Living bone not only has the ability to change
its shape and volume to reflect the mechanical loads it
must support (modelling)

66
Q

What is the role of microcrack

A

iniatinting the remodelling process

67
Q

Fractures distal to the carpus and tarsus have beeter or worse prognosis?

A

better prognosis but there are challanges in poor soft tissue coverage

68
Q

What are the predictable sites of stress fracture in humerus

A

Caudoproximal
Crainodistal
Medial diaphyseal
Caudodistal

69
Q

What are the predictable sites of stress fracture in scapula?

A

Distal aspect of the spine

70
Q

What are the predictable sites of stress fracture in carpus

A

dorsomedial third carpal bone
radial carpal bone
intermediate carpal bone

71
Q

What are the predictable sites of stress fracture in Third metacarpal

A

Mid-diaphyseal and supracondylar
Parasagittal groove
Proximal palmar
Dorsal cortex
Distal condyle

72
Q

What are the predictable sites of stress fracture in Proximal sesamoid

A

Palmar flexor region
Medial sesamoid abaxial
mid-body subchondral

73
Q

What are the predictable sites of stress fracture in proximal phalanx

A

sagittal groove

74
Q

What are the predictable sites of stress fracture in pelvis

A

ilial wing
pubis

75
Q

What are the predictable sites of stress fracture in tibia

A

Distomedial
Caudoproximal
Caudal diaphyseal
Proximolateral under the head of the fibula

76
Q

What are the predictable sites of stress fracture in tarsus

A

Dorsolateral third tarsal bone

77
Q

What are the predictable sites of stress fracture in lumbar spine

A

L5-L6 vertebral junction

78
Q

What is the most common physeal fracture in horses?

A

Salter Harris type II

79
Q

Where is the typical sites of Salter Harris type II?

A

Third MC and MT distal physes
Distal femoral physis
Proximal tibial physis

80
Q

Mention the different Location

A

Epiphysis
Physis
Metaphysis

81
Q

Mention the different Direction

A

Diaphysis
Proximodorsal to distopalmar

82
Q

Mention the different Plane for example transverse, oblique, longitudinal, sagittal and dorsal

A

Orientation of the predominant fracture line

83
Q

Mention the different Extent

A

Complete
Incomplete

84
Q

Mention the different Configuration

A

Transverse
Longitudinal
Oblique
Spiral
Butterfly

85
Q

Mention the different displacement

A

Nonsdisplaced
Displaced

86
Q

Mention the different complexity

A

Simple
Intermediate
Complex

86
Q

Mention the different joint involvement

A

Non-articular
Articular

87
Q

Mention the different contamination

A

closed
open

88
Q

Mention the different other

A

avulsion
slab
condylar

89
Q

Salter Harris type IV tend to be unstable and many require….

A

internal fixation

90
Q

Should you perform bridging of the physis during internal fixation of physeal fractures?

A

NO, you should avoid if possible as they may result in premature closure and development of angular limb deformity

91
Q

Type V injuries are rare are they detected radiographically?

A

No they are not radiographically detectable in the begining as they manifest as a progressive angular limb deformity

92
Q

an axial proximal sesamoid fracture occurring concurrently with a displaced lateral condylar fracture is associated with a _________ prognosis

A

poor

93
Q

Can rupture of a vessel such as popliteal artery in femoral fracture
or thrombosis of palmar/plantar digital arteries in acute fetlock breakdown injuries can be the cause of euthanasia?

A

yes

94
Q

What are the most common reasons for complete fracture?

A

Neoplasia and osteomyelitis, pituitary pars intermedia dysfunction (PPID)

Fractures EQ (2 decks)

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