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Recon > Nonunion > Flashcards

Nonunion Flashcards

1
Q

What is nonunion

A

Absence of healing across two opposing bony surfaces
- may be the result of fracture, osteotomy, arthrodesis

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2
Q

Is nonunion chronic or acute condition

A

Chronic

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3
Q

What are some symptoms of non-union

A

Pain
Deformity
Instability

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4
Q

What is Campbell’s Operative Orthopedics Timeframe for nonunion

A

6 month timetable to differentiate delayed versus non-union

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5
Q

What is the FDA timeframe for a non-union

A

Established when a minimum of 9 months has elapsed since the injury, and the fracture site shows no visibly progressive signs of healing for a minimum of 3 months

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6
Q

What is the rate of non-union in young triple arthrodesis patients

A

2-3%

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7
Q

What is the rate of nonunion in adult triple arthrodesis patients

A

17-30%

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8
Q

What is the rate of nonunion in calcaneocuboid joint fusions

A

~30%

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9
Q

What is the rate of nonunion in Talonavicular fusions

A

~20%

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10
Q

What is the rate of nonunion in ankle fusions

A

~40%

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11
Q

What is the rate of nonunion in 1st MTPJ and 1st TMTJ

A

<10%

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12
Q

What is the Weber & Cech Classficaiton

A

considers osteogenic potential in non unions

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13
Q

What are the 2 categories of Weber & Cech Classification?

A
  • Hypervascular/Hypertrophic
  • Avascular/Atrophic
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14
Q

What are the 3 types of hypervascular/hypertrophic weber & Cech classification

A
  • Elephant’s foot
  • Horse’s hoof
  • Oligotrophic
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15
Q

What are the 4 types of avascular/atrophic nonunions

A
  • torsion wedge
  • comminuted
  • defect
  • atrophic
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16
Q

What is the treatment guidelines for hypervascular/hypertrophic Weber & Cech

A

There is the potential to heal conservatively

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17
Q

What is the treatment guidelines for avascular/atrophic Weber & Cech?

A

Usually requires surgical intervention

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18
Q

Describe the hypervascular/hypertrophic Weber and Cech

A

Continuing proliferation of blood vessels at the fracture ends - enough biological activity to promote callus formation/healing

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19
Q

Describe the Elephant’s foot vascular supply

A
  • rich in vascular supply, viable bone with an abundance of callus formation
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20
Q

What does elephant’s foot results from

A

Results from premature weight bearing or insufficient fixation

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21
Q

What does the elephant’s foo require to facilitate union

A

Requires improved stability

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22
Q

Describe the bone ends of Horse’s hoof

A
  • vocable bone ends but marked decrease in callus formation
  • may appear sclerotic at the ends of the bony surfaces
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23
Q

What dies horse’s hoof results from

A

Fatigue of internal fixation

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24
Q

Describe the bone ends in Oligotrophic hypervascular/hypertrophic Weber & Cech

A

Viable bone ends, but callus is minimal or absent

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25
Q

Which type of the hypervascular/hypertrophic nonunion has the least biological activity

A

Oligotrophic

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26
Q

What does a Oligotrophic hypervascular nonunion results from

A

Poor initial apposition of osseous surfaces or distraction of the bony fragments

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27
Q

Describe the biologics of avascular/atrophic nonunion

A

Little or no vascular supply, exhibit poor osteogenic potential and are considered non viable

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28
Q

Describe the torsion wedge avascular nonunion

A

Butterfly fragment with diminished blood supply at the fracture site
- typically only unites with one side of the fracture

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29
Q

Describe the comminuted avascular nonunion

A

Multiple fragments that may exhibit necrosis and persistent gapping at the fracture site

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30
Q

Describe the Defect Avascular nonunion

A
  • complete loss of bone substance within the fracture site, significant gapping at fracture site
  • due to distance, it is hard to for bone to heal, therefore, union is only possible with replace of bone
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31
Q

What dies Defect nonunion results from

A

Excessive bone resection ie infection, open fracture

32
Q

What is an example of a surgery that can result in Defect nonunion

A

Brachymet

33
Q

Describe atrophic avascular nonunion and what it results from

A

Results from necrosis of a fragment with fibrous tissue filling the void
- partial absorption of osseous surfaces (rounded of ends), osteoporosis, atrophy

34
Q

Which type of non-union is also known as pseudoarthrosis

A

Atrophic

35
Q

What is pseudoarthrosis

A

False fluid and tissue filled space between two fracture fragments

36
Q

What is primary bone healing

A
  • direct, surgical intervention/ apposition of bone or joint
37
Q

Does primary bone healing have a callus formation stage

A

No

38
Q

What is secondary bone healing

A
  • indirect, conservative management
  • initial connective/fibrous tissue bridge, replaced by bone
39
Q

Is there callus formation in secondary bone healing

A

Yes

40
Q

Is there motion present in secondary bone healing

A

Yes

41
Q

What are the steps in primary bone healing

A
  • anatomic reduction
  • stable fixation
  • cutting cones
42
Q

What is anatomic reduction

A

Osseous surfaces need to be in direct contact

43
Q

Why is stable fixation required

A

To resist deforming forces, facilitate adequate compression across the surgical site

44
Q

What is cutting cones

A

New lamellar bone laid down along the path of osteoclasts, facilitates the ingrowth of new vasculature and the delivery of bone forming cells

45
Q

During primary bone healing, how much new bone is seen after 2-3 days

A

One millimeter

46
Q

At what rate do cutting cones advance

A

50-80 micro meters per day

47
Q

After the union, what does the newly formed bone do

A

Begins the remodeling process

48
Q

What are the different phases in secondary bone healing

A
  • impaction phase
  • induction phase
  • inflammatory phase
  • soft callus
  • hard callus
  • remodeling phase
49
Q

How long is the inflammatory phase in secondary bone healing

A

Usually lasts 3-5 days from the inciting event

50
Q

When does the soft callus develop

A

Up to 16 weeks to develop

51
Q

When does the hard callus develop and how long can it last

A

Begin 7-10 days
Lasts up to 1-4 years

52
Q

What is the remodeling phase

A

Immature woven bone resorted by the osteoclasts and replaced with lamellar bone by osteoblasts

53
Q

What is the relationship between diabetes and bone healing

A

Studies show that HbA1c >7 is a risk factor for the development of complications, inducing nonunion

54
Q

Relationship between smoking and bone healing

A

Smoking affects tissue oxygenation and impedes wound healing

55
Q

What are some operative factors we have to consider in a nonunion

A
  • inadequate joint prep - must resect all cartilage, subchondral drilling
  • inadequate fixation - must be stable to avoid micro motion, chosen based on anatomic location/procedure/patient characteristics
  • mal position - must have good apposition, compression helpful but not necessary
56
Q

What is the clinical hallmark of nonunion

A

Pain, Edema, erythema

57
Q

What is the standard imaging for evaluation of bony healing process

A

X-ray

58
Q

What type of imaging is best to visualize trabeculation, and when nonunion is questionable on X-ray

A

CT

59
Q

What type of imaging is used when vascular it’s is questioned regarding a non-union

A

MRI

60
Q

What type of imaging is 100% sensitive for AVN

A

MRI

61
Q

What represents hypertrophic nonunion on bone scan

A

Hot spot - dark colored, increased uptake

62
Q

What resents atrophic non-union n a bone scan

A

Cold spot, lighter colored

63
Q

What type of treatment do you recommend if you suspect delayed union and why

A

Conservative NWB, immobilization treatment, to avoid progression to nonunion

64
Q

What is the piezoelectric property of bone stimulation

A

Electrical potentials that occur within a bone with an external force is applied

65
Q

What are the two types of bone stimulation

A

Internal
External

66
Q

What type of current is used with internal bone stimulation

A

Direct current

67
Q

What type of surgery is internal bone stimulation used for

A

Revisional surgery

68
Q

Where is the cathode and anode placed in internal bone stimulation

A

Cathode - at nonunion site
Anode - in nearby subcutaneous

69
Q

What are the 3 types of external bone stimulation

A
  • capacitive coupling (CC)
  • pulsed electromagnetic fields (PEMF)
  • low-intensity pulsed ultrasound (LIPUS)
70
Q

Describe capacitive coupling bone stimulation

A

Low voltage
Alternating/oscillating current
Electrode pads applied on either side of nonunion
24 hours a day

71
Q

What are some disadvantages of capacitive coupling

A

Compliance
Skin irritation

72
Q

Describe PEMF bone stimulation

A

Broad field
Low level current
Wire coil transducer
3-10 hours a day

73
Q

What is one benefit of PEMF bone stimulation

A

Can be used over cast/splint

74
Q

Describe LIPUS bone stimulation

A
  • mechanical signal creates micro motion at nonunion site
  • 20 minutes a say
  • must be in contact with the skin
  • depends on stable fixation, minimal gapping
  • most commonly used one nowadays
75
Q

What is the paprika sign?

A

Bleeding through medullary bone after joint prep

76
Q

What type of bone graft do you need for nonunion

A

Autogenous bone graft

Recon (10 decks)

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