Malunion, delayed union, nonunion

Question 1

What are major causes of delayed, absent bone healing?

Answer 1

poor blood supply

inadequate stabilization

Question 2

What is “fracture disease”?

Answer 2

a general term for poor use of a limb after a fracture

1. muscle atrophy
2. joint stiffness
3. tissue fibrosis
4. pain on palpation of the fracture site
5. poor limb function

Question 3

What can predispose to fracture disease?

Answer 3

methods that immobilize the joints but don’t adequately immobilize the fracture fragments

Question 4

What is quadraceps contracture?

Answer 4

The quadraceps musculature becomes incorporated into the fibrous tissue involving the callus–stifle fixed in extensino

Question 5

What can cause quadraceps contracture?

Answer 5

1. complicated or delayed healing of midshaft to distal femoral fractures
2. young dogs with seemingly normal healing
3. schroederthomas splint

Question 6

What are the treatments for quadraceps contracture?

Answer 6

1. avoidance–stabilize the fracture NOT splint, rehab
2. quadraceps release–physical rehap, surgery to free quadraceps
3. quadraceps release and elastic band placement w/ transfixation pins–flexion of stifle
4. stifle arthrodesis–fusing stifle joint in a more useful position–ok for cats, smaller dogs
5. amputation-if chronic severe

Question 7

What is malunion?

Answer 7

1. healing of fracture in abnormal alignment (angular, rotational, axial)

Question 8

Why can femur fracture cause hip luxation?

Answer 8

because when breaks, external rotation occurs because external rotators are stronger–can be easy to repair femur while inadvertently allowing hip to stay externally rotated

Question 9

Why can femur fracture cause hip luxation?mies?

Answer 9

because when breaks, external rotation occurs because external rotators are stronger–can be easy to repair femur while inadvertently allowing hip to stay externally rotated

Question 10

Why can bent bones slowly become straighter?

Answer 10

Because can remodel–Wolff;s law

Question 11

What malunions can never remodel to a more normal form?

Answer 11

rotational

Question 12

What are 7 types of osteotomies?

Answer 12

1. closing wedge osteotomy
2. opening wedge osteotommy
3. combination wedge osteotomy
4. oblique osteotomy
5. dome osteotomy
6. step osteotomy or step-wedge osteotomy
7. distraction osteogenesis

Question 13

What is closing wedge osteotomy?

Answer 13

1. wedge removed from side with greater curvature–good boney contact, rapid healing, some bone length loss

Question 14

What is opening wedge osteotomy?

Answer 14

transverse cut, open the cut to a wedge until bone realigned–no bone shortening but healings more slowly due to gap

Question 15

What is combination wedge osteotomy?

Answer 15

cut wedge out of one side, reverse it and put in other side. not common

Question 16

What is oblique osteotomy?

Answer 16

cut oblique, then spear point of oblique end into medullary canal of distal end–use bone plate, similar to opening wedge

Question 17

What is dome osteotomy?

Answer 17

cut a dome then rotate one piece relative to the other–good bone contact but can only rotate the fragments in one plane. used in TPLO

Question 18

what is step osteotomy/step-wedge osteotomy?

Answer 18

almost exclusively in young large animals–due to cuts required. good bone to bone contact, relative movement of boney fragments in two planes

Question 19

What is distraction osteogenesis?

Answer 19

bone is cut and pieces are gradually aligned (and may be lengthened) by gradually moving them apart and into place–most commonly with circular external fixator

Question 20

What is the qualification for a delayed union?

Answer 20

if does not heal as expect (not on way to keeling in 6-10 wees or 2-6 weeks if young)

Question 21

What is the qualification for a nonunion

Answer 21

6-8 months

Question 22

what are causes of nonunions?

Answer 22

1. inadequate blood supply
2. instability of fracture fragments
3. excessive distance between fracture fragments–critical gap in adults –usually twice diameter of bone at site
4. infeciton

Question 23

What types of nonunion are there?

Answer 23

1. vascular nonunion

2. avascular nonunion

Question 24

What occurs in vascular (trophic/hypertrophic) nonunion?

Answer 24

instability–bone cannot heal because ther eis two much motion
“elephant foot appearance”

Question 25

What is the treatment for a vascular nonunion?

Answer 25

rigid stabilization