MSK 1 Flashcards

(53 cards)

1
Q

what is the weakest place in growing bones?

A

the growth plate or physis

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2
Q

what is the one thing that a fracture MUST have in order to heal?

A

adequate blood supply

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3
Q

young animals often get what kind of fractures?

A

along the growth plate (different salter harris classifications)

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4
Q

what is the most common type of salter harris fracture in young animals?

A

type II along physis and into metaphysis

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5
Q

angular limb deformities are common in what kind of animals?

A

fast growing animals like dogs and horses

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6
Q

what are thw two types of angular limb deformities?

A

valgus: lateral deviation or splay legged
varus: medial deviation or bow legged

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7
Q

you are brought a cute rescue pittie mix with bowed legs and the new owner wants to know what it is and what caused it. You tell them…

A

the dog has varus or medial deviation, form of angular limb deformity, and it is caused most commonly by asymmetric damage to the growth plate (one side closes and the other grows), can also be caused by malposition in utero, joint laxity, hypothyroidism, malnutrition, or sometimes we aren’t sure why

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8
Q

name these conditions

A

top is valgus, bottom is varus, both forms of angular limb deformities

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9
Q

this is from a puppy. what is the arrow pointing to and why is it significant?

A

it is pointing to an area where the growth plate of the radius dissapeared, so no further growth can occur at this site. this likely happened because of some trauma to the radial growth plate in that location

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10
Q

fractures occur when the ______ exceeds the _____

A

mechanical force
bone strength

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11
Q

define a fracture

A

a break/rupture resulting in a physical discontinuity in a bone

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12
Q

what are the two ways in which fractures are classified?

A

traumatic (forces break a normal healthy bone) and pathologic (forces break an unhealthy or diseased bone)

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13
Q

list the ways to classify a fracture

A

open/closed
displaced or not
comminuted
transverse/oblique/spiral/linear
location (proximal, distal, midiaphyseal)
name the bone

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14
Q

what is an avulsion fracture

A

when a ligament pulls bone away from a site of insertion

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15
Q

what is a greenstick fracture?

A

where one cortex is broken but the other side is not, happens in young animals (think of a green twig breaking and only one side breaks while the other stays in tact)

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16
Q

what are the 5 steps in fracture healing?

A
  1. hematoma
  2. fibrous tissue
  3. woven bone and cartilage laid down
  4. soft callus or primary callus forms
  5. hard callus or secondary callus forms (woven bone to lamellar bone)
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17
Q

list some reasons for non-union fractures

A

inadequate blood supply, instability/excessive forces or motion, infection, pathologic underlying disease, malnutrition, necrotic tissue like a sequestrum

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18
Q

what does the word osteodystrophy mean? What causes this? What is a common result?

A

abnormal bone growth
caused by nutritional or hormonal imbalances, toxicities, etc
common result is pathologic fractures and pain

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19
Q

osteodystrophy is more commonly seen in what kind of animal?

A

growing animals

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20
Q

the top arrow is pointing to what? What is the cause of this lesions and what is the pathogenesis?

A

it is showing a growth arrest line (just above the growth plate), caused by debilitating disease or malnutrition. the trabeculae in the metaphysis are abnormally algined so that they are parallel to the physis instead of perpendicular

Pathogenesis: inciting cause–>long bone growth stops–>abnormal osteoclast activity–>lines are carried into metaphysis as growth resumes

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21
Q

what is seen here and what does this indicate?

A

serous atrophy of fat, indicating the animal was either anorexic or in starvation, the medullary fat has become gelatinous and see through rather than white and opague. note also the cortex is thinner than normal

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22
Q

what is osteoperosis? How is it different than osteopenia?

A

reduced bone mass and density with associated pathological fractures
osteopenia is reduced bone mass and density WITHOUT pathological fractures
mineralization is normal in both scenarios

23
Q

what causes osteoperosis?

A

calcium deficinecy: low calcium causes an increase in PTH which stimulates osteoclasts to resorb more bone
starvation: low energy/protein/minerals
physical disuse/atrophy: very little stimulation to lay down new bone
basically anything that tips the balance so that more bone is absorbed than replaced

24
Q

what is a common medical treatment that can lead to osteoperosis?

A

a cast or splint!

25
explain how bones can be normally mineralized in osteoperosis if the pathogenesis involves low calcium levels
when the bones were formed, the individual was healthy and had adequate calcium leading to normal mineralization, then comes the actual cause of osteoperosis such as starvation and the levels of calcium decrease which stimulates osteoclasts to resorb more bone, the bone isn't replaced so the bone desnity goes down and makes them weak and brittle
26
what is this showing?
osteoperosis, note the bottom photo the cortex is thinner and there is hardly any trabecular bone filling the medullary cavity, bones are brittle with reduced density
27
what is rickets? What results will you see from this disease? What causes this disease?
failure of bone mineralization in young growing animals leads to thickened growth plates from lack of cartilage mineralization and abnormal endochondral ossification, bones are soft causes: vitamin D and phosphorus deficinecy
28
what disease is this?
rickets, you can see the thickened growth plate and retained cartilage that will not mineralize
29
list gross features of rickets
segmental growth plate thickening multifocal growth plate lesions prominant at sites of rapid growth (adjacent to growth plates) like the metaphysis and epiphysis may also see on bone cross section, tongues of un resorbed cartilage extending into the metaphysis
30
what disease is this?
rickets, this is showing the costochondral junction and the growth plates of ribs are being thickened and cartilaginous, looking like rosary beads
31
what disease is this?
rickets, this is showing the costochondral junction and the growth plates of ribs are being thickened and cartilaginous, looking like rosary beads
32
this is from a tibiotarsus of a chicken. what disease is this?
rickets, you can see the thickened growth plate and an unmodeled metaphysis on the left. the right is normal
33
what is osteomalacia?
soft bones, similar causes and pathogenesis to rickets but it occurs in adults instead of young/growing animals. the growth plate is not involved. involves defective mineralization during bone remodeling. the bones will have reduced resistance to pressure and tension
34
what are some gross lesions of osteomalacia?
expansion of the marrow cavity, thin spongy soft cortex, pathologic fractures, bones overall will be soft
35
what is fibrous osteodystrophy? What is the pathogenesis?
replacement of bone by fibrous connective tissue (instead of replaced by more healthy bone) pathogenesis: hyperparathyroidism-->elevated PTH-->increased osteoclastic activity and replacement by fibrous tissue--> soft malleable bones
36
what are the two causes fibrous osteodystrophy and how do they differ?
primary hyperparathyroidism: excessive PTH secreted by the parathyroid glands, more rare and often seen with parathyroid gland neoplasia secondary hyperparathyroidism: a compensation for low serum calcium which increases amounts of PTH, more common than primary hyperparathyroidism
37
with fibrous osteodystrophy, bones will be ____
soft and often enlarged
38
what are the two kinds of secondary hyperparathyroidism
nutritional and renal
39
what are some causes of nutritional secondary hyperparathyroidism and how does this disease appear grossly?
caused by low calcium high phosphorus diets in young animals, affecting the skull bones can appear as a "big headed" animal, bilateral enlargement of fascial bones and fascial swelling
40
what are some examples of diets low on calcium and high in phosphorus?
horses: cereal hay (oat straw), bran, grain dogs and cats: all meat diets
41
nutritional secondary hyperparathyroidism will cause ______ and it is most common in what animals with what expection?
cause fibrous osteodystrophy in young animals except in horses, can happen in adults, does not happen in cattle and sheep
42
what is this disease and what is a common result?
this is fibrous osteodystrophy caused by nutritional secondary hyperparathyroidism, you can see the maxillary bone replaced with fibrous tissue including around the teeth, and fibrous tissue is compressing the nasal cavity towards the septum. Common result is for teeth to fall out
43
renal secondary hyperparathyroidism is also known as _______ and what are the 3 associated lesions?
renal osteodystrophy 1. soft, malleablebones 2. soft pliable mandible (rubber jaw) 3. deformed mandible/maxilla and tooth loss
44
what disease is this?
renal osteodystrophy/rubber jaw
45
renal osteodystrophy is a combination of what two things? what is it associated with?
fibrous osteodystrophy and osteomalacia associated with severe chronic renal disease, common in older dogs and cats
46
what is the pathogenesis of renal osteodystrophy?
renal disease, kidneys excrete less phosphate, leading to hyperphosphatemia, phosphate reacts with calcium and causes hypocalcemia in the blood, causes PTH to increase, leading to more bone resorption renal disease also causes reduced renal vit D metabolism leading to reduced calcium absorption from the intestines
47
this dog has chronic renal disease. what is happening here?
renal osteodystrophy, the nasal septum and maxillary bones are undulating and soft, and there is loss of alveolar bone leading to floating teeth
48
What bone lesion is associated with starvation in young animalsand how does it occur?
growth arrest lines happen in young growing animals near the metaphysis or epiphysis and they happen because of the "pausing" or "stopping" of long bone growth during the time of starvation
49
define osteoperosis and list 3 potential causes
osteoporosis: reduced bone mass and density with associated pathological fractures causes: calcium deficiency, starvation, physical disuse
50
What metabolic bone disease would develop from a vit D deficiency in a piglet? what about an adult animal?
rickets in piglet/young animal osteomalacia in adults
51
what is the basic pathogenesis of fibrous osteodystrophy?
hyperparathyroidism, increased PTH, increased osteoclastic resorption and replacement of fibrous tissue, soft malleable bones
52
What type of diet is associated with nutritional osteodystrophy?
low calcium high phosphorus diets dogs and cats: all meat diets horses: cereal hay, bran, grain
53
what condition is associated with fibrous osteodystrophy in older dogs and cats
renal osteodystrophy/chronic renal failure