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MSK2 > Fracture management > Flashcards

Fracture management Flashcards

1
Q

What are the main goals of fracture fixation?

A
  • Early return to function

- Achieve stability

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2
Q

How are fractures classified?

A
  • Bone affected
  • Position within bone affected
  • Fracture pattern
  • Open or closed
  • Additional features e.g. articular
  • Over-riding
  • Displacement of segments
  • Degree of malalignment
  • Soft tissue swelling
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3
Q

What is a simple fracture described as?

A

One with only 1 fracture line i.e. bone split into 2 pieces

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4
Q

What is required in order to classify a fracture?

A

Good radiographs, 2 orthogonal views minimum - need to be able to clearly see the bone and make a detailed examination

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5
Q

What is the classification for a fracture where the fracture line is less than 30˚ to the long axis of the bone?

A

Oblique fracture

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6
Q

What is meant by an interdigitating fracture?

A

One where the fracture surface is irregular with spikes and depressions on both ends of fractured bone that interlock/interdigitate with each other

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7
Q

What forces are transverse fractures stable and unstable to?

A

Stable to compression, unstable to rotation

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8
Q

What forces are interdigitating fractures stable to?

A

Compression and rotation

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9
Q

What classification is given to a fracture where the fracture line is >30˚ to the perpendicular to the long axis of the bone?

A

Oblique fracture

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10
Q

What is meant by a spiral fracture?

A

An oblique fracture that curves/spirals around the bone

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11
Q

When do spiral fractures most commonly occur and what is the importance of this?

A
  • Usually low energy fractures i.e. little/no trauma
  • Osteons debond
  • Often pathologic fractures so need to look for underlying cause
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12
Q

What are comminuted fractures?

A
  • More than one fracture line that connects
  • May me multiple joining fractures
  • Produce 3 or more pieces of bone
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13
Q

What are segmental fractures?

A
  • Rare, specific types of comminuted
  • 2 or more fracture lines that do not connect
  • Each bone has a complete piece of cortex
  • Produces 3 or more pieces of intact bone
  • Wedge/butterfly
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14
Q

How do forces at a fracture site occur?

A
  • Fragments form lever arms

- Coupled with normal loading generate shear, compression/tension and rotation at the fracure site

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15
Q

Explain how avulsion fractures occur

A
  • Apophyseal bone avulses at pointof tendon or ligament insertion
  • Usually puppies/kittens due to open growth plates being weaker than bone
  • Often landing injury from jumping
  • Tendon pulls apophysis away from bone when lands
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16
Q

When do physeal fractures occur?

A

In skeletally immature animals

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17
Q

What are the classifications for physeal fractures?

A
  • Salter Harris classification type 1 to 5
  • TI: complete across the physis
  • TII: spur through metaphysis
  • TIII: articularte fracture
  • TIV: articular and chip in metaphysis
  • TV: compression/crush injury of the growth plate
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18
Q

What are the 5 primary forces acting on normal bone?

A
  • Axial compression
  • bending
  • Shear
  • Torsion
  • Tension (avulsion, only at insertion points of ligaments)
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19
Q

How do avulsive/tension forces occur on bones?

A

Tendons or ligaments apply a distractive force e.g. patellar tendon on tibial tuberosity

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20
Q

Give examples of common sites of avulsive fractures

A
  • Patellar tendon on tibial tuberosity
  • Gluteal insertion on geater trochanter of femur
  • Triceps on olecranon
  • Common calcaneal tendon on the calcaneus of the foot
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21
Q

Compare the effect of axial compression on transverse and oblique fractures

A
  • Transverse: compression is stable,

- Oblique: produces shear force leading to over-riding and collapse of fracture

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22
Q

How do bending forces on bones occur?

A
  • Caused by compression
  • Bones not straight and not loaded centrally so compressive forces become bending
  • Leads to bending on one side and tension on another
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23
Q

Where should plates be placed on a transverse fracture and why?

A

Should be placed on the tension side to minimise the bending of the bone due to compression

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24
Q

Which aspects of the following bones are the tension surfaces?

a: humerus
b: radius
c: femur
d: tibia

A

Humerus: lateral and cranial
Radius: cranial and medial
Femur: lateral
Tibia: medial and cranial

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25
Q

What is meant by shearing forces?

A

Forces that displace the bone perpendicularly

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26
Q

What are the fracture fixation options dependent on?

A
  • Fracture type
  • Patient factors
  • equipment available
  • Surgeon experience/confidence with fixation method
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27
Q

Against which forces are fracture plates stable?

A
  • Compression
  • Torsion
  • Shear
  • Tension
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28
Q

Against which forces are External Skeletal Fixators stable?

A

All forces

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29
Q

Against which forces are IM pins stable?

A

Bending and shear

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30
Q

Against which forces are interlocking nails stable?

A

Best against bending, moderate for compression and ok for torsion and shear forces

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31
Q

Against which forces are pins + tension band stable?

A

Only tension (moderate stability)

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32
Q

What is strain theory?

A

Measurement of the strain (% movement) at a fracture site

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33
Q

How is strain applied to a fracture calculated?

A
  • % movement of a fracture

- Amount of movement divided by the original fracture length i.e. fracture 10mm that moves mm = 10% strain

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34
Q

Explain the application of strain theory to fracture repair

A
  • Different healing tissue types can cope with different degrees of deformation
  • Can reduce strain to increase chance of healing
  • Increase distance between fracture ends and/or reduce fracture movement
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35
Q

List the tissues in bone healing from first to last

A
  • Fracture haematoma
  • Granulation tissue
  • Fibrous tissue
  • Cartilage
  • Bone
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36
Q

Compare the strain limits of the healing tissue of bone

A
  • Haematoma and granulation tolerate 100% strain
  • Fibrous: 20% strain
  • Fibrocartilage: 10% strain
  • Woven/lamellar bone: 2% strain
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37
Q

Explain why having a large fracture gap minimises strain and when this method of reducing strain is used

A
  • For comminuted fractures
  • Large gap means movement creates low strain e.g. 50mm gap, 5mm movement is only 10% strain - tolerated all bone healing tissues
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38
Q

What are the most common causes of high strain on a fracture repair?

A
  • Movement
  • Small fracture gap
  • Incomplete reduction leaving small gap (healing tissue ruptures)
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39
Q

What is meant by primary healing of bone?

A

Bone apposition and reduction used to create stability, ideally compression (contact or gap healing)

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40
Q

What is meant by secondary healing of bone?

A

Bone not apposed or reconstructed, relative movement instability, bone heals by callus formation

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41
Q

What is required in order for a fracture to be describe as reconstructable?

A
  • Must be able to have a perfect reconstruction - all pieces must be able to be put back together
  • Need orthogonal radiographic views
42
Q

Which types of fractures are good candidates for fracture reconstruction?

A

Simple fractures: transverse, oblique and spiral

43
Q

What factors would contraindicate attempts at fracture reconstruction?

A
  • If procedure will be time consuming
  • Large amounts of implants required
  • Risks for further bone fracture
  • Complex (segmental/comminuted) fracture
44
Q

What methods are commonly used for primary bone healing?

A
  • Open Reduction internal Fixation approach (ORIF)
  • Compression plate
  • Lag screw
  • Positional screw
  • K-wires (for physeal fracture)
45
Q

What methods are commonly used for secondary bone healing?

A
  • ESF

- Bridging plate

46
Q

What are tje advantages of an ORIF approach to fracture fixation?

A
  • Precise anatomical reduction of bone fragments
  • Rigid fixation creating stability at the fracture site
  • Bone takes load reducing stress on implants
  • More likely to achieve primary bone healing
47
Q

What are the disadvantages of an ORIF approach to fracture fixation?

A
  • Extensive surgical approach

- Greater soft tissue disruption and compromises bone blood supply

48
Q

Why is a larger fracture gap with small fragments of bone preferable in fracture repair?

A

Provides blood supply which contributes to the healing of a callus

49
Q

What are the risks associated with fracture implants that are too stiff?

A
  • Implants take too much load and reduce load to bone
  • Leads to disuse and slow/inadeqaute healing (Wolff’s law) with delayed union, risk of refracture (esp. if plate requires removal)
50
Q

What are the risks associated with no reconstruction approach to a fracture?

A
  • Less/no loading shared between bone and implants leading to increased stress on fixation, increased risk of failure
  • May require more frequent checks and second operation to remove implants for ESF
  • Rigid stability leads to decreased callus formation
51
Q

What are the 4 surgical approaches for fracture fixation?

A
  • Open
  • Open “look-but-do-not-touch” approach
  • Minimally invasive (MIPO)
  • Closed approach
52
Q

Described advantages the closed approach to fracture reduction

A
  • Most biological
  • No surgical incision
  • No surgical dissection
  • No bone devascularisation
  • Fracture haematoma and growth fractures undisturbed
53
Q

Outline the MIPO approach to fracture reduction

A
  • Limited surgical incisions for implant placement only
  • Prevents massive dissection and preserves biology better
  • More dissection than closed but not much more
  • Fluoroscopy/intraoperative x-ray guidance common
54
Q

Outline the “look-but-do-not-touch” approach to fracture reduction

A
  • Big incisions
  • More dissection and trauma but minimise dissection to that required to place implants
  • Leave fracture haematoma alone
  • Allows for lag screws/compression palte
  • Prevents devascularisation
55
Q

Outline the reconstruction (open) approach to fracture reduction

A
  • Big incisions, more dissection and trauma (but aim for minimal)
  • If possible leave haematoma alone
  • Allows for lag screws/compression paltes
  • Massive trauma, often remove haematoma
56
Q

Why should removal of the fracture haematoma during fracture repair be avoided?

A

Contains a lot of growth factors beneficial to new bone growth

57
Q

What is the fracture healing score?

A
  • How likely/unlikely a fracture is to heal based on fracture features, patient factors, owner factors, surgeon factors
  • 10 = high chance of healing with low risk of complication
  • 1 = high risk of complication and unlikely to heal without a problem
58
Q

Compare the healing in cancellous and cortical bone

A

Cancellous heals better and faster than cortical

59
Q

What are the indications for use of intramedullary pins in fracture repair?

A
  • Non-reconstructable comminuted fractures (main indication)
  • Intraoperative fracture alignment
  • Long oblique fractures e.g. cat femur
60
Q

Describe the use of intramedullary pins for intraoperative fracture alignment

A
  • Restores fracture length and stabilises bone

- Combine with ESF or plate application

61
Q

Describe the use of intramedullar pins for long oblique fractures

A
  • Usually combine wide IM pin with multiple cerclage wires

- Rarely the best option as more stable methods are available

62
Q

What are the methods for the insertion of IM pins? Briefly describe these

A
  • Normograde: from end of bone towards fracture

- Retrograde: from fracture towards bone ends

63
Q

Compare the advantages and disadvantages of the methods for the insertion of IM pins

A
  • Normo: generally best method, but more difficult to achieve
  • Retro: easier but can enter joints or cause nerve damage
64
Q

What bones can IM pins be inserted into?

A
  • Only femur, tibia, humerus and ulna

- Never the radius as will inevitably encroach on joints

65
Q

Discuss the use of IM pins in the repair of oblique or comminuted fractures

A
  • IM pins cannot resist compression
  • Oblique or comminuted have no inherent stability to compression
  • IM pin must be combined with pate or ESF in these types of fractures
66
Q

Name the different ways in which orthopaedic wire can be used

A
  • Cerclage wire
  • Tension band
  • Hemicerclage wire
  • K-wire figure of 8
67
Q

Discuss the use of cerclage wires in fracture fixation

A
  • Loop around bone
  • Usually placed inappropriately
  • Require more dissection to place
  • Loosen quickly and easily
  • Cause injury to bone and vessels when loosen
  • Usually better options available (unavoidable in hip replacement)
68
Q

What are the indications for the use of cerclage wire?

A
  • Hip replacement
  • Only in reconstructable fractures, oblique/spiral fractures
  • Only bones with even shape
69
Q

Outline the principles for cerclage wire use

A
  • Encircle bone and twist ends around each other evenly
  • Length of fracture minimum 2x bone diameter
  • Minimum for 2 wires
  • Place 1cm apart, at least 5mm from fracture end
  • Must be tight
  • Cut ends short (1.5 twists) or leave longer (3-4 twists) and bend ends over
  • Check tension after bending
  • Remove even if slightly loose
70
Q

Compare single loop cerclage wire and double loop cerclage wire (advantages, dequipment required)

A
  • Single: more robust, easier to place well, need single eyed cerclage wire and single wire tightener
  • Double: more robust, more difficult to place, need normal oerthopaedic wire and double wire tightener
71
Q

Explain the theory underlying use of pin and tension band for avulsion fractures

A
  • Converts avulsion into compression forces
  • Based on Newton’s 2nd law
  • 2 opposing forces = resultant vector force that compresses the fracture
  • Summation of forces in x axis compressing the fragment against the bone
72
Q

Outline the principles of tension band wires in fracture repair

A
  • Wire resists major forces so must be thick
  • Pins maintain alignment and prevent shear forces
  • Cortex that forms the bending point must be intact
  • Most effective when animal is weight bearing (dynamic)
73
Q

What are the main considerations when treating physeal fractures?

A
  • Cartilage weaker than bone
  • Physis usually interdigitating so stable following reduction
  • TI and II have good contact and ability to load share when fracture reduced
  • Less bending forces as are at ends of bone
  • Use smaller less rigid implants in most cases
  • Most growth stops due to original injury
  • Avoid implants that will cause compression across physis during other repairs
  • Limbs may be shorter if 4-5mo old
  • Limbs may deviate during growth
74
Q

In physeal fractures, what would lead to limbs deviating during growth?

A
  • If damage to growth plate is asymmetrical

- If one of a “paired” bone set is damaged

75
Q

What are the specific considerations regarding articular fracture repair?

A
  • Will develop traumatic/secondary OA
  • Any incongruency in articular surface will make OA worse
  • Articular surfaces are subject to compressive loads
  • Require perfect reduction
  • Must have primary bone healing, no callus
  • Repair must facilitate early limb use
76
Q

Why is it important that repair of articular fractures facilitates early limb use?

A

If cannot use limb will develop joint stiffness and eventual fibrosis with poor range of motion

77
Q

What are the most important factors in articular fracture repair?

A
  • Accurate (perfect) anatomic alignment
  • Rigid internal fixation (compression to give primary bone union and no callus)
  • As rapidly as possible, max 1-5 days
78
Q

Outline the use of arthrotomy in articular fracture repair

A
  • Usually required
  • Need good surgical approach to ensure adequate visualisation, perfect reduction, optimal implant placement
  • Protect cartilage using dab or lavage
  • Flush joint thoroughly before closure
79
Q

Explain the methods are required in articular fracture repair

A
  • Rigid stabilisation e.g. use of positional screw (alone not good, no compression, relatively unstable)
  • Compression with lag screw or dynamic compression plate (possible, but usually not possible in joint) required
80
Q

Explain how compression of an articular fracture can be achieved using a lag screw

A
  • Gap closed using reduction forceps then place lag screw

- Then place anti-rotational K-wire or screw

81
Q

What methods can be used for articular fracture repair where perfect reconstruction/compression is not possible?

A
  • Arthroplasty (e.g. hip replacement)
  • Arthrodesis (e.g. pancarpal arthrodesis)
  • Amputation as a final resort
82
Q

What repair methods are typically used for Type I or II physeal fractures? What forces are these types of fractures stable to?

A

Cross K wires or parallel K wires, are relatively stable when reduced, resistant to compression, moderately resistant to bending and rotation

83
Q

What repair methods are typically used for Type III and IV physeal fractures?

A

Need to compress so use lag screws, must have anatomic reduction and alignment, and rigid stabilisation

84
Q

What is a possible consequences of a Type V physeal fracture?

A

Premature closure of the growth plate and angular limb deformities, can prevent progression of deformity but not stop it happening

85
Q

Which site is prone to type V physeal fracture?

A

Distal ulnar growth plate (conical shape)

86
Q

Compare self-tapping and non-self tapping screws

A
  • Self tapping have thread on screw and cutting flutes at end, cut own thread so are faster to place, risk of bone fracture with placement
  • Non-self tapping have no cutting flutes so must use tap
  • No difference in effictiveness
87
Q

What does screw size relate to?

A

Diameter of the thread

88
Q

Name the different types of bone screw

A
  • Lag

- Positional

89
Q

Name the different types of plate screw

A
  • Non-locking: axial compression or neutral

- Locking (neutral screw)

90
Q

Describe the function of positional bone screws

A
  • Hold 2 pieces of bone in position

- Not to be used where there is a gap

91
Q

Describe the function of lag screws in bone

A
  • Compresses/squeezes 2 pieces of bone together as far (trans) cortex is pulled towards near (cis) cortex
  • Not to be used where there is a gap
92
Q

Describe the placement of a positional bone screw

A
  • Drill both cortices
  • Measure depth of hole, add 2mm
  • Use appropriate tap for screw in guide and tap both cortices
  • Place screw of appropriate length
  • Tighten but not overtightened
93
Q

Describe the placement of a lag screw

A
  • Drill glide hole in near cortex (same diameter as screw)
  • Insert sleeve into glide hole
  • Drill far cortex as for normal preparation
  • Countersink hole
  • Measure depth of hole, add 2mm
  • Use tap to tap trans cortex
  • Choose and place screw of appropriate length until tight
94
Q

When should lag screws be used?

A
  • For oblique fractures only
  • Fracture held reduced with bone holding forceps
  • Lag screw placed 90˚ to fracture line
95
Q

Compare the use of fully threaded or partially threaded screws

A
  • Fully threaded can be used as lag or positional screws

- Partially threaded can only be used as lag screws

96
Q

Explain the use of non-locking plate screws

A
  • Screwplaced inbone through plate, head of screw engages plate
  • Tighten screw, pulls bone up towards plate and squeezes plate onto bone
  • leads to high friction at interface between bone and plate
  • Screws placed as for positional
97
Q

Describe the use of plate screws as lag screws

A
  • Fracture reduced
  • Plate applied,
  • Lag screw applied at 90˚ to fracture line
  • Place lag screw first to compress fracture, then place others
  • Becomes neutralisation plate
98
Q

Name the different types of fracture repair plate based on function

A
  • Compression
  • neutralisation
  • Bridging
  • Locking (can neutralisation or bridging)
99
Q

What is the size of plate determined by?

A

The size of screws the place works with i.e. 3.5mm plate is for use with 3.5mm screws

100
Q

How can plates be named other than based on mechanical function?

A

Size, manufacturer and features e.g. dynamic compression plate, 3.5mm Synthes locking TPLO plate

MSK2 (29 decks)

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