Chapter 45 Delayed Unions, Nonunions, and Malunions

Question 1

What are the 4 tenets of bone healing and regeneration

Answer 1

Mechanics
Scaffold
Growth factors
Cells

Question 2

What are the three types of viable nonunions

Answer 2

Hypertrophic nonunion
Moderately hypertrophic nonunion
Oligotrophic nonunion

Question 3

Describe hypertrophic nonunion - Characterized by? Cause? Treatment?

Answer 3

Considerable callus “elephants foot”
Commonly due to excessive motion or lack of adequate mechanical environment
Excessive motion results in fibrous tissue
Fibrous tissue is resistant to bony union therefore should be removed during revision

Question 4

Describe moderately hypertrophic nonunion

Answer 4

Less callus than hypertrophic - “horses foot”

Question 5

Describe oligotrophic nonunion

Answer 5

Viable nonunion, without radiographic evidence of biologic activity*
Difficult to differentiate from biologically inactive (nonviable) nonunion

Question 6

Whats the cause of oligotrophic nonunions

Answer 6

Cause: lack of cellular activity
Commonly caused by loose implants (cerclage, screws etc)

Question 7

How to treat oligotrophic nonunion

Answer 7

Remove loose implants
Re-establish biologically active environment
Autogenous bone graft, demineralized bone matrix, bone marrow, and growth factors

Question 8

What are the four types of nonviable nonunion

Answer 8

Dystrophic, necrotic, defect, and atrophic nonunion

Question 9

Describe dystrophic nonunion

Answer 9

Nonviable bone on one or both sides of the fracture

Question 10

Describe necrotic nonunion

Answer 10

Infected section of bone or sequestrum

Question 11

Describe defect nonunion

Answer 11

Gap at the fracture site

Question 12

Describe atrophic nonunion

Answer 12

Can be a result of any type of nonviable nonunion
Dead bone of the fracture area is removed by the host without a healing or restorative process. - resorption