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Musculoskeletal > SA Bone Healing and Complications > Flashcards

SA Bone Healing and Complications Flashcards

1
Q

In normal bone, blood flows from ___ the bone to ___ the bone

A

Inside

Outside

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2
Q

What are the arteries that supply a normal bone with blood?

A 
Principal nutrient a
Metaphyseal a
Periosteal a
Epiphyseal a
- Immature bone
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3
Q

What are the arteries that supply fractured bones with blood?

A

Extraosseous

- Abundant around flat bones

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4
Q

T/F: Scapula fractures are not often surgical

A

True; dt surrounding musculature, they are well stabilized and vascularized

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5
Q

How is blood supply affected by fractures and how is this compensated?

A

Medullary supply is disrupted
Medullary supply is enhanced and restored once bone is healed
Extraosseous vascular supply supplies bone while healing

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6
Q

How do casts affect blood supply?

A

They should not in a closed reduction

There is also minimal soft tissue disruption

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7
Q

How do external skeletal fixators affect blood supply?

A 
There is minimal soft tissue disruption in closed reduction
Open reduction (avoid) disturbs the extraosseous supply and delays re-establishment of medullary blood supply
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8
Q

How do IM pins affect blood supply?

A

Disrupts medullary supply

Closed placement - minimal soft tissue disruption

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9
Q

How do cerclage wires affect blood supply?

A

Minimal disruption to periosteal supply if tight, can shear if loose
Approach to place wire may necessitate disruption of extraosseous supply

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10
Q

How do bone plates affect blood supply?

A

Open reduction - disruption of extraosseous supply

Affects periosteal supply

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11
Q

What are the four As that need to be assessed on your two orthogonal views?

A

Alignment
Apparatus - placement
Apposition
Activity - healing in follow ups

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12
Q

T/F: rads of healing fractures should be taken every 3 weeks

A

False; rads should be taken every 6 weeks

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13
Q

What are the three types of bone healing?

A

Indirect
Direct
Intramembranous

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14
Q

Describe the inflammatory phase of bone healing

A 
Similar to any tissue wound
- Hematoma
- Influx of mediators
 . IL-1, IL-6, platelet derived growth factor, TGFB1, PGE1 and PGE2
- Little rad evidence of bone healing
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15
Q

Describe the process of indirect bone healing

A

Endochondrial bone formation (bone formed on cartilage precursor)

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16
Q

What is strain?

A

The change in gap width over the original width between fragments

A measure of instability and motion

17
Q

What is the progression of bone healing and how does it affect strain? (10)

A
  • Hematoma
  • Granulation tissue
  • Widening of fracture gap dt resorption
  • Fibrous CT
  • Fibrocartilage
  • Mineralization of cartilage
  • Resorption of mineralized tissue
    . Gap fills with new blood supply
  • Woven bone
  • Lamellar bone
  • Cortical bone

As healing progresses, strain is lessened dt stability of material and environment becomes more conducive to bone formation

18
Q

T/F: With indirect bone healing, healing goes from external to internal

A

False; healing is from internal to external

19
Q

How does indirect bone healing appear radiographically?

A
  • Sclerotic areas at fracture surface (endosteal and periosteal new bone formation)
  • Initial increase in width of fracture gap (bone resorption)
  • Arch of callus spanning fracture (periosteal proliferation)
  • Fracture gap becomes less distinct (callus overlays fracture, mineralization of fibrocartilage)
  • Bone remodeling (decrease in callus bone density, cortical bone at fracture site)
20
Q

Describe direct bone healing

A
  • Bone formation without a cartilage precursor
  • Occurs where there is rigid fragment stability
    . Fracture gap <150-300um
    . <2% strain
  • Contact healing: simultaneous union and remodeling
  • Gap healing: small gaps fill with fibrous bone; Haversian remodeling
    . Osteoclastic resorption of bone
    . Resorption cavities fill with vascular loops, mesenchymal cells, osteoblast precursors
    . Lamellar bone formation: osteoblasts secrete osteoid
21
Q

How does direct bone healing appear radiographically?

A

Fracture line slowly increases in density

No bridging periosteal or endosteal callus

22
Q

Describe Intramembranous bone healing

A
  • Form of direct bone healing
  • Strain <5%
  • Combination of direct and indirect healing
  • Bridging of comminuted bone fragments occurs
  • Smaller callus than indirect bone healing
  • Resorption of woven bone
  • Formation of lamellar bone
  • Cortical bone formation
23
Q

Describe metaphyseal bone healing

A

Since trabecular bone of the metaphysis has a rich vascular bed, osteoblasts fill in the fracture and healing occurs from the inside out

24
Q

Describe physeal bone healing

A
  • If the fracture occurs at the junction of the hypertrophic and provisional calcification zones, the fracture heals by continued formation of cartilage
  • If the fracture occurs at the reserve zone, healing occurs by endochondrial ossification
25
Q

Describe the four complications in fracture healing

A

Delayed Union- Healing is slower than anticipated
Non-Union- Bone healing has ceased and will not continue without surgical intervention
Malunion- Poor anatomic alignment while healing can lead to angular limb deformities
Osteomyelitis- Inflammatory condition of bone and medullary canal often associated with bacteria

26
Q

Where do delayed unions often happen?

A 
Long bones (evidence of healing by 12wk)
If implants are stable and intact, it should continue to heal (physical therapy is important)
May add cancellous bone autograft
Unstable implants should be removed/replaced
27
Q

What are factors that may lead to a delayed union?

A
  • Systemic illness: malnutrition, anemia
  • High energy fracture: significant soft tissue trauma, open fracture
  • Poor surgical decision making
  • Pharmacologic factors: steroids, NSAIDs (not supported yet)
28
Q

What factors can lead to non-union?

A
  • Poor decision making
  • Technical failure
  • Instability at fracture site: most common cause
  • Poor biological environment: extensive soft tissue disruption
29
Q

How does a non-union appear radiographically?

A

Lack of activity on sequential rads
Hypertrophic: large amount of non-bridging callus
Atrophic: biologically inactive, no evidence of bone activity at fracture site

Musculoskeletal (7 decks)

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