Fracture Complications

Question 1

Fracture complications

Answer 1

Non-healing
Implant failure
Infection
OA

Question 2

Delayed union

Answer 2

Fracture that has not healed when adequate period of time has elapsed for that particular fracture to achieve union

Question 3

Non-union

Answer 3

Cessation of all reparative processes of bone healing

Union not possible without intervention

*Failure of progressive change in radiographs for at least 3 mo

Question 4

Causes of delayed/non-union

Answer 4

Inadequate reduction
Inadequate stabilization
Loss of blood supply
Infection
Systemic factors

Question 5

Blood supply in bones

Answer 5

Separation blood supply for epiphysis and metaphysis
Periosteum highly vascular

Main blood supply: nutrient artery
Metaphysis anastomose with diaphysis
Periosteal supply outer 1/3 of cortex

Question 6

Post-fracture blood supply

Answer 6

Primary: extra osseous - surrounding soft tissue to early callus

Secondary: medullary takes over after some healing

Question 7

Weber-Cech Classification of Non-Union Fractures

Answer 7

Viable (biologically active, variable proliferative reaction)

Non-viable (avascular, non-reactive) - less common

Question 8

Viable Non-unions

Answer 8

Hypertrophic
Moderately Hypertrophic
Oligotrophic

Question 9

Non-viable non-unions

Answer 9

Dystrophic
Necrotic
Defect
Atrophic

Question 10

Viable hypertrophic non-union

Answer 10

“Elephant foot”
Abundant callus unable to bridge gap

Cause: inadequate stabilization/excessive motion

Question 11

Viable moderately hypertrophic non-union

Answer 11

“Horse foot”
Moderate callus that doesn’t bridge fracture site
Somewhat subjective (relative to hypertrophic classification)

Usually due to inadequate stabilization/excessive motion

Question 12

Viable oligotrophic non-union

Answer 12

Viable without radiographic evidence of biological activity (hard to distinguish from non-viable)

Callus absent/minimal
Fuzzy/hazy appearance of bone ends

Cause: excessive motion + lack of cellular activity; loose implants in area of fracture healing

Question 13

Non-viable dystrophic non-union

Answer 13

One or both sides of fracture ends are non-viable

Fracture fragment that has healed to one main fragment but not the other

Most often distal radius/ulna of toy/mini breeds

Question 14

Non-viable necrotic non-union

Answer 14

Fracture fragment with no blood supply (sequestrum)

Sharp edges - become more sclerotic with time

Question 15

Non-viable defect non-union

Answer 15

Fracture gap too large for normal biological activity

> 1.5 x bone diameter
Open fractures, high velocity gun shot fracture

Question 16

Non-viable Atrophic non-union

Answer 16

End result of other non-viable non-unions

Resorption/rounding of edges, complete cessation of osteogenic activity

Most difficult to resolve

Question 17

Clinical signs of delayed/non-union

Answer 17

Persistence of:
Pain at fracture site
Lameness
Disuse atrophy of limb
Movement at fracture site

Question 18

Radiographic signs of non-union

Answer 18

Fracture gap
No activity at fracture ends
Obliteration of marrow cavity
Osteopenia of surrounding bond
Non-bridging callus

Question 19

Treatment of delayed/non-unions

Answer 19

Allow more time
Increase rigidity of stabilization
Enhance blood supply
Bone graft
Treat underlying condition (infection, gap, metabolic health of animal)

Question 20

Surgery on a delayed/non-union

Answer 20

Apply rigid fixation

Culture + sensitivity testing —> antibiotics

Cancellous bone graft (blood supply)

Question 21

Malunion

Answer 21

Fracture that heals in a non-anatomic position

Question 22

Results of malunion/non-union

Answer 22

Angular limb deformities
Limb shortening
Degenerative joint disease
Disuse muscle atrophy
Gait abnormalities
Never weight bears/uses limb —> amputation

Question 23

Goals of post-op fracture assessment

Answer 23

Determine if adequate repair method chosen applied
Confirm progression of healing
Guide for clinical recommendations
Detect complications ASAP
Surgeon growth

Question 24

Radiographs of fracture sites

Answer 24

Joints above + below
Two orthogonal views

Assess quality/technique, soft tissue, fracture repair/healing/implant integrity

Question 25

4 A’s

Answer 25

Alignment
Apposition
Apparatus
Activity

Question 26

Alignment

Answer 26

Orientation of bone with respect to normal anatomic axis

Look at position of joints above and below fracture

Look in all planes

Question 27

Apposition

Answer 27

How well the fracture fragments relate to one another

Significance will depend on goal of healing (i.e., biologic vs anatomic reconstruction)

Question 28

Apparatus

Answer 28

Implant assessment:
type
relationship to bone
principles of application
Function as intended
Address forces
Integirty

Question 29

Activity

Answer 29

Biological response
Asssessed weeks to months post-op
Will differ for direct vs indirect healing

Question 30

Direct / primary bone healing

Answer 30

Bone healing without callus formation in stable fracture conditions

Contact healing or gap healing (<1 mm)

Question 31

Indirect / secondary bone healing

Answer 31

Bone healing with callus formation

(Hematoma —> granulation tissue —> connective tissue —> cartilage —> cartilage mineralization —> woven bone)

Question 32

Radiographs of direct fracture healing

Answer 32

Decreased opacity of fracture margins
Progressive disappearance of fracture line

Question 33

Radiographs of indirect fracture healing

Answer 33

Initial resorption of fracture ends —> radiolucency/widening of fracture gap; decreased definition of fracture ends

10-14d —> periosteal/endosteal calcified callus

3-6 w —> callus more prominent, may bridge
12 w —> bridging bony callus
>12 w —> remodeling