Overview of Fractures

Question 1

What are transverse, short oblique, and long oblique fractures like?

Answer 1

TRANSVERSE = fracture line is perpendicular to the long axis of the bone

SHORT OBLIQUE = fracture like is diagonal and less than twice the diameter of the diaphysis

LONG OBLIQUE = fracture line is diagonal and more than twice the diameter of the diaphysis

Question 2

What are segmental and comminuted fractures like?

Answer 2

SEGMENTAL = multiple fracture lines are present and do not converge or communicate

COMMINUTED = multiple fracture lines are present and converge or communicate

Question 3

What is the difference between complete and incomplete fractures?

Answer 3

COMPLETE = both cortices are affected

INCOMPLETE = one cortex affected

Question 4

What are the 5 types of Salter-Harris physeal fractures?

Answer 4

1. physis only
2. physis and metaphysis
3. physis and epiphysis (articular fracture)
4. metaphysis, physis, and epiphysis
5. physeal compression results in partial or complete physeal closure

Question 5

What does proper fracture healing require?

Answer 5

blood supply, lack of infection, and stability

(no matter the age of the patient)

Question 6

What is the fracture timeline like?

Answer 6

• initial fracture (day 0) = acute trauma where fracture lines are sharply marginated, lacking periosteal reaction
• day 7-10 = initial radiographic changes where there is fibroblastic invasion (hemorrhage, fibrous layers) into fracture site with replacement of the initial blood clot/hemorrhage
• day 14 = cambium layer prolliferation where osteoclasts and osteoblasts act on the fracture lining, making it more ill-defined and irregular and osteoprogenitor cells differentiation into healing osseous callus
• day 21-28 = osseous callus formation where osteoblasts lay down organic matrix with subsequent mineralization with hydroxyapatite crystals (secondary intention)
• day 28-30 = healing by primary intention, where cutting cones cross the fracture line with a closing cone resulting in normal ossification and fracture healing (decreases the appearance of the fracture line)
• day 60 = complete healing where the fracture line is no longer visualized, orthopedic deviced are stable without lucencies, and no bridging callus (primary) or there is a circumferential bridging callus present with no fracture line (secondary)
• day 180 = remodeling of second intention callus back to original cortical thickness according to Wolff’s law

Question 7

What are 9 fracture complications?

Answer 7

1. atrophic non-union - osseous tapering of the ends of fracture fragments
2. hypertrophic non-union - abundant callus formation with no bridging bone
3. avascular fragment - piece of bone lost its blood supply and looks like the original fracture fragment without reaction
4. sequestrum - infected avascular fragment causes the formation of an involucrum and a draining tract to the outside (cloaca)
5. malunion - healed fracture segments are no longer in correct anatomical alignment
6. plate protection - surgical plate takes on the burden of weight bearing, which causes the bone underneath it to atrophy and possibly non-union
7. pathological fracture - abnormal bone (neoplasia, hyperparathyroidism, skeletal developmental abnormalities, infection) fractures without necessary trauma
8. sarcoma induction - internal fixation or chronic infection causes the bone to undergo neoplastic transformation (primary sarcoma)
9. delayed union - delay in normal fracture healing associated with infection, comminuted, or motion of the fracture site

Question 8

What are the 4 A’s of fracture healing?

Answer 8

1. ALIGNMENT = fracture fragments are properly aligned to their normal anatomical position (especially in Type III and IV Salter-Harris fractures)
2. APPOSITION = fracture fragments are in complete contact
3. ACTIVITY = callus formation should be occuring at the fracture site (reactions away from the fracture site may indicate infection)
4. APPARATUS = external or internal fixation should be reviewed for evidence of motion or loosening (may require oblique projections)

Question 9

How should the fracture in this radiograph be described? How are the bones displaced? Is there soft tissue reactions?

Answer 9

• sharply marginated, simple, short oblique closed fracture within the mid-diaphysis of the fibula with lateral, cranial, and proximal displacement of the distal fracture fragment
• sharply marginated, simple, long oblique, closed fracture within the mid-diaphysis of the tibia with lateral, caudal, and proximal displacement of th distal fracture fragment
• there is thichening of the surrounding soft tissue

Question 10

How should the fracture in this radiograph be described? How is the bone displaced? Are there soft tissue reactions?

Answer 10

• sharply marginated, complete, comminuted, closed fracture within the mid-diaphysis of the femur with multiple large fracture fragments
• cranial and proximal displacement of the distal fracture fragment
• moderate stifle joint effusion and surrounding soft tissue thickening

Question 11

What type of Salter-Harris physeal fracture is present in this radiograph? How is the bone displaced?

Answer 11

Type I (physis only)

• epiphysis = cranial and lateral
• diaphysis = caudal, proximal, and medial

Question 12

How has the fractured bone been displaced in this radiograph?

Answer 12

• femoral head still in acetabulum
• femur displaced cranially and laterally

Question 13

What are the 4 major steps to fracture healing?

Answer 13

1. fracture and hemorrhage
2. inflammatory response and mobilization of fibroblasts from inner cambium layer of endosteum and periosteum
3. callus formation —> fibrous, cartilage, osseous with complete bridging
4. remodeling

Question 14

What are some factors that impact fracture healing?

Answer 14

• age (young > old)
• species (cats, cows > dogs, horses)
• open vs closed fracture (infection)
• simple vs comminuted
• pathologic fracture
• blood supply
• local environment
• rigidity of fixation

Question 15

What are the 4 radiographic stages of fracture repair? What is primary intention healing?

Answer 15

1. acute phase = sharp fracture margins
2. fracture margin resorption
3. osseous callus formation
4. complete loss of fracture lines

rigid and stable fixation

Question 16

What is indicated in this radiograph of a healing fracture?

Answer 16

callus formation with faint fracture lines —> indicates proper healing

Question 17

Osteosarcoma:

Answer 17

Question 18

Non-union healing:

Answer 18

Question 19

Mal-union healing:

Answer 19

Question 20

Neoplasia:

Answer 20

osteolysis and irregular cortical margination with periosteal reactions and present fracture line

Question 21

What 6 attributes are present in the fracture seen below the orthogonal radiographic study from a 2 year old mixed breed dog after being hit by a car?

a. closed fracture
b. open fracture
c. segmental radial fracture
d. transverse radial fracture
e. segmental ulnar fracture
f. spiral ulnar fracture
g. lateral displacement of distal fragments
h. medial displacement of distal fragments
i. cranial displacement of distal fragments
j. caudal displacement of distal fragments
k. proximal displacement of distal fragments
l. distal displacement of distal fragments

Answer 21

A, D, E, G, I, K

Question 22

What are 6 attributes of the fracture seen on the orthogonal radiographic study from a 1 year old mixed breed dog after being hit by a car?

a. closed fracture
b. open fracture
c. Salter-Harris type I of tibial apophysis
d. diaphyseal fracture of the femur
e. comminuted fracture
f. simple fracture
g. lateral displacement of the distal fragment
h. medial displacement of the distal fragment
i. cranial displacement of the distal fragment
j. caudal displacement of the distal fragment
k. proximal displacement of the distal fragment
l. distal displacement of the distal fragment

Answer 22

B, E, F, H, I, K