Musculoskeletal Exam 2

Front 1

what is the most common primary bone tumor?

Back 1

osteosarcoma

Front 2

with osteosarcoma, what percentage occur on the axial and appendicular skeleton?

Back 2

- 25% axial
- 75% appendicular

Front 3

osteosarcoma:
- what type of bone do they occur?
- what part of the bone do they occur?
- what proportion are forelimb vs. hindlimb?

Back 3

- long bones
- in the metaphysis
- forelimb 2X hindlimb

Front 4

where do osteosarcomas usually occur in the forelimb?

Back 4

distal radius and proximal humerus

Front 5

where do osteosarcomas usually occur in the hindlimb?

Back 5

tibia and femur (fibula is rare)

Front 6

bone tumors in the diaphysis are usually what?

Back 6

metastatic sarcomas

Front 7

what is the most important thing to do to diagnose a bone tumor?

Back 7

biopsy

Front 8

which type of bone tumor has the worst prognosis?

Back 8

osteosarcoma

Front 9

where is the appropriate site to biopsy a bone tumor?

Back 9

the center of the lesion, based on radiographs (contrary to other biopsies)

Front 10

what is the median survival time for an osteosarcoma after amputation? No amputation?

Back 10

3-4 months for both

Front 11

how long does it take to receive the results of a bone biopsy and why?

Back 11

4-5 days because the bone needs to be decalcified (which takes time) before analysis

Front 12

how does age affect the prognosis of osteosarcomas?

Back 12

dogs < 5 years have a worse prognosis

Front 13

what are two drugs that can be used to prolong the survival time of a dog with an osteosarcoma? What is the median survival time in these cases?

Back 13

cisplatin or carboplatin increases if to 1 year median survival time (with amputation)

Front 14

what are two surgery options for osteosarcoma?

Back 14

1. amputation
2. limb-sparing

Front 15

when is limb-sparing surgery indicated for osteosarcoma?

Back 15

- tumor grossly confined to limb
- < 50% of bone affected by tumor

Front 16

which bones are best and worst for limb-sparing surgery for osteosarcoma?

Back 16

- distal radius and ulna are the best
- dogs don't do well with the hind limb

Front 17

what is the most effective way to administer chemotherapeutics to treat osteosarcoma?

Back 17

OPLA-Pt (open cell polylactic acid sponge); gives 50x higher local concentrations of cisplatin than a single IV dose

Front 18

what is implanted during a limb-sparing surgery for osteosarcoma?

Back 18

allograft

Front 19

what two things are added to an allograft implant for limb-sparing surgery treating osteosarcoma?

Back 19

1. compression plate (stabilize)
2. bone graft (acceletates healing)

Front 20

how is post-op infection correlated with median survival time when treating osteosarcoma with a limb-sparing surgery?

Back 20

it paradoxically increases survival time, so many surgeons purposely inoculate a distant site to induce infection

Front 21

why does osteosarcoma not lead to anklyosis?

Back 21

because the tumor does not cross the joint space

Front 22

which artery perfuses the ulna?

Back 22

interosseus artery

Front 23

explain how a vascular bone graft works

Back 23

- cancellous bone graft is taken before operation on the tumor
- the tumor on the radius is cut out
- healthy ulna is cut out, and the interosseus artery is preserved on this bone
- the cut-out ulna is grafted onto the radius
- the perfused radial artery is anastamosed with the interosseus artery on the ulna
- the cancellous bone graft and compression plate are applied

Front 24

what are four post-operative expectations during the healing process of a vascularized bone graft of the radius?

Back 24

1. periosteal new bone in 2 weeks
2. bridging callus in 4 weeks
3. graft united to proximal radius and radiocarpal bone at 8 weeks
4. graft hypertrophy by 3 months

Front 25

how do cats with osteosarcoma differ than dogs and why?

Back 25

- cats do much better than dogs
- amputation may be "curative" because the tumor is less aggressive and juxtacortical, not medullary bone

Front 26

what are the most common bacteria involved in infectious osteomyelitis?

Back 26

1. S. intermedius
2. S. aureus

Front 27

what are two ways in which a bone can become infected?

Back 27

1. hematogenous (e.g. secondary to metastasis from the lung)
2. posttraumatic

Front 28

why is it important to biopsy a suspected humeral osteomyelitis?

Back 28

because it could be a primary bone infection, tumor, etc.

Front 29

why do surgical implants commonly cause a chronic infection?

Back 29

because a glycocalyx/biofilm adheres to the implant and is resistant to antibiotic treatment

Front 30

what antibiotic do you use for osteomyelitis?

Back 30

that must be determined by culture and susceptibility testing

Front 31

what are four basic radiographic assessments used to determine the agressiveness of a lesion?

Back 31

1. Bone lysis
2. zone of transition
3. osteogenesis
4. margins

Front 32

describe the differences in incidence and presentation osteosarcoma between small-breed and large-breed dogs. Also compare the incidence of metastatic bone neoplasia.

Back 32

- 20x less likely in small breed dogs
- small breed axial:appendicular 1:1, whereas 1:5 in large breed
- 24% of bone tumors in small breed dogs are metastatic carcinomas, whereas they comprise only 5% in large breeds

Front 33

list the five most common sites of osteosarcoma in order of predilection

Back 33

1. distal radius (23.1%)
2. proximal humerus (18.5%)
3. distal femur (8.5%)
4. distal tibia (8.2%)
5. proximal tibia (7.5%)

Front 34

what are the three types of osteosarcoma based on where on the bone they are located?

Back 34

1. endosteal
2. parosteal
3. periosteal

Front 35

how does amputating a limb with osteosarcoma correlate with pulmonary metastasis?

Back 35

- lowest incidence of pulmonary metastasis without amputation
- highest incidence with amputation and no chemotherapy
- intermediate incidence with amputation & chemo

Front 36

after amputating a limb with osteosarcoma, how does treatment with cisplatin correlate with metastasis to other bones?

Back 36

- lower (5%) if no cisplatin used
- very high (47%) if cisplatin is used

Front 37

with osteosarcoma, what is the MST for
- no treatment
- amputating the limb
- amputating the limb and also treating with cisplatin?

Back 37

- 101-175 days with no treatment and with amputation
- 262-325 days with amputation & cisplatin

Front 38

what are three differentials for metastatic bone disease?

Back 38

1. carcinoma (most common)
2. multiple myleoma
3. osteosarcoma

Front 39

a radiograph shows geographic lysis at the distal humeral metaphysis (monostotic), a moderate zone of transition, and an aggressive periosteal reaction. What are four differentials. What are two tests to make a DDx?

Back 39

1. osteosarcoma
2. metastatic carcinoma
3. osteomyelitis (fungal/bacterial)
4. other primary bone tumor (e.g. multiple myeloma)
- two tests: biopsy (best) and bone scan

Front 40

why should you do a bone scan and/or biopsy before performing a limb spare surgery to treat osteosarcoma?

Back 40

to rule out other conditions such as metastatic neoplasia.

Front 41

when an aggressive bone lesion is found on a limb, what other radiographic tests should be performed?

Back 41

a 3-view thorax (to look for pulmonary metastases, etc.)

Front 42

in aggressive toe lesions in the dog, what are five most common diferentials in order of incidence?

Back 42

1. squamous cell carcinoma
2. pododermatitis
3. melanoma
4. metastatic sarcoma
5. osteosarcoma

Front 43

what is pododermatitis?

Back 43

osteomyelitis of the nail bed

Front 44

what is the difference between osteomyelitis and septic arthritis?

Back 44

osteomyelitis is outside the joint capsule, whereas septic arthritis is inside the joint capsule

Front 45

how long does it take for a periosteal reaction to form on a bone lesion?

Back 45

10-14 days

Front 46

what is your main differential for an excessive periosteal reaction accompanying a fracture?

Back 46

osteomyelitis

Front 47

what is the big difference between a hematogenous osteomyelitis and one that was caused by a puncture wound/surgery (in most cases)?

Back 47

it is polyostotic

Front 48

fungal osteomyelitis:
- mono or polyostotic?
- non-radiographic clinical signs
- age predilection
- with a hematogenous infection, what part of the bone is most affected?

Back 48

- usually polyostotic, but can be mono
- fever, lymphadenopathy, pulmonary infiltrates
- affects younger animals
- hematogenous → mainly metaphyseal region

Front 49

coccidiomycotic osteomyelitis:
- geographic location
- mono or polyostotic?
- parts of the bone affected
- describe the lesion
- non-radiographic clinical signs

Back 49

- SW US ("Valley Fever")
- usually MONostotic
- affects diaphysis and metaphysis
- proliferative lesion
- hilar lymphadenopathy

Front 50

what is the difference between mycotic osteomyelitis caused by Histoplasma and Blastomyces?

Back 50

Blastomyces has a high incidence of bone involvement, whereas Histoplasma osteomyelitis is rare

Front 51

what dog breed is predisposed to mycotic osteomyelitis caused by Aspergillus?

Back 51

German Shepherd Dog

Front 52

Osteomyelitis caused by Aspergilla, Nocardia, Cryptococcus, Actinomyces, Sporotrichosis:
- bones affected
- why they cause osteomyelitis

Back 52

- long bones, sternebrae, discospondylitis
- usually associated with immunocompromized

Front 53

with regards to osteomyelitis what is a
- sequestrum?
- involucrum?
- cloaca?

Back 53

- sequestrum: sharply marginated, avascular piece of bone
- involucrum: area of radiolucency surrounding a sequestrum
- cloaca: draining tract

Front 54

area of radiolucency surrounding a sequestrum

Back 54

involucrum

Front 55

a draining tract caused by osteomyelitis

Back 55

cloaca

Front 56

what are five diseases in which hypertrophic osteopathy commonly occurs as a sequela?

Back 56

1. thoracic mass
2. granulomatous disease
3. heartworm disease
4. parasites
5. abdominal mass

Front 57

periosteal proliferation of bone along the diaphysis of limb bones that is usually symmetrical; it is a rare disease occurring mostly in the dog.

Back 57

hypertyrophic osteopathy

Front 58

what is the pathogenesis of hypertrophic osteopathy?

Back 58

secondary to systemic disease, the primary mass stimulates increased vascular perfusion to the periosteum by an unknown mechanism.

Front 59

a radiographic lesion, characterized by aggressive periosteal new bone formation, progressing up the limb, that "skips over" some bones and joints is probably what?

Back 59

hypertyrophic osteopathy

Front 60

where on the skeleton does hypertrophic osteopathy often begin? How does the disease progress?

Back 60

- Begins on the outer aspect of the 2nd/5th digits
- skips cuboidal bones and joints
- progresses proximally up the limb

Front 61

how is hypertrophic osteopathy differentiated from osteomyelitis radiographically?

Back 61

the periosteal new bone formation skips bones and joints as it moves proximally up the leg

Front 62

if you are suspicious of hypertrophic osteopathy, what is the sequence of tests that should be performed?

Back 62

1. DP of the painful metacarpus
2. 3-view thorax (to look for masses, HW disease, etc.)
3. CBC and blood chemistry to look for predisposing factors (such as heartworm)
4. abdominal ultrasound (to look for masses)

Front 63

what are three basic pathological processes that cause an aggressive joint lesion?

Back 63

1. joint-associated tumor (mono-articular)
2. septic arthritis
3. erosive polyarthritis

Front 64

what are the three descriptive categories used for fractures?

Back 64

1. open/closed
2. type
3. displacement

Front 65

what are three non-infectious complications of a fracture repair?

Back 65

1. delayed union
2. nonunion
3. malunion

Front 66

what is required to repair articular fractures?

Back 66

surgery

Front 67

describe proper radiographic positioning for a fracture?

Back 67

- orthogonal radiographs
- joints above and below fracture
- ± obliques

Front 68

what are five descriptive terms for a fracture location?

Back 68

1. articular
2. non-articular
3. epiphysis
4. metaphysis
5. diaphysis

Front 69

what are nine types of fractures?

Back 69

1. incomplete
2. transverse
3. oblique
4. spiral
5. comminuted
6. avulsion
7. segmental
8. pathologic
9. Salter-Harris

Front 70

what are two good radiographic indicators for an open fracture?

Back 70

- air lucency
- penetrating foreign object(s)

Front 71

what two breeds of dogs are predisposed to articular fractures?

Back 71

Spaniels and min pins

Front 72

fracture where only one cortex is involved

Back 72

incomplete / greenstick

Front 73

what group most commonly gets incomplete/greenstick fractures?

Back 73

immature animals

Front 74

when repairing a spiral fracture, what must you be careful of?

Back 74

there may be fissures past the margins of the fracture, which could cause the screws/plates to fail

Front 75

what is the difference between a comminuted fracture and a segmental fracture?

Back 75

in a comminuted fracture, the fracture lines interconnect, in a segmental fracture, they don't

Front 76

what is an avulsion fracture, and what causes them?

Back 76

- fracture of a bony prominence at the origin/insertion of tendon, ligament, or muscle
- caused by violent contraction

Front 77

what is a Salter-Harris Type I fracture?

Back 77

separation of metaphysis from epiphysis

Front 78

what is a Salter-Harris Type II fracture?

Back 78

fracture line travels through growth plate for a variable distance then extends into the metaphysis

Front 79

what is a Salter-Harris Type III fracture?

Back 79

fracture line travels through growth plate for a variable distance then extends through epiphysis into articular surface

Front 80

what is a Salter-Harris Type IV fracture?

Back 80

metaphyseal fracture line extending through the physis and epiphysis to exit through the articular cartilage

Front 81

what is a Salter-Harris Type V fracture?

Back 81

compression of growth plate resulting from crushing force transmitted through physis

Front 82

what is a common location for a Salter-Harris Type IV fracture?

Back 82

a break between the trochlea and capitulum of the femoral head

Front 83

a fracture fragment that usually occurs at the corner of an articular margin.

Back 83

chip fracture

Front 84

what usually causes chip fractures?

Back 84

direct bone trauma or hyperextension

Front 85

an articular fracture that extends from one articular margin to another

Back 85

slab fracture

Front 86

what is a slab fracture?

Back 86

an articular fracture that extends from one articular margin to another

Front 87

if you suspect a fracture, but can't visualize it on radiographs, how would you find where it is?

Back 87

nuclear medicine. Approximately 90% of fractures will show increased uptake within 24 hours with greater than 98% of fractures being hot at 48 hours

Front 88

a fracture that has not and is not going to heal

Back 88

nonunion

Front 89

what often accompanies a nonunion fracture, which may be the cause of the nonunion?

Back 89

disuse muscle atrophy and lameness

Front 90

what are the two classifications of nonunion fractures?

Back 90

1. viable (hypervascular)
2. non-viable (avascular)

Front 91

how long does a fracture take to develop a bony callus?

Back 91

2 weeks

Front 92

what do you see on a radiograph of a viable nonunion fracture that you don't see in a non-viable nonunion fracture?

Back 92

sclerosis of the fracture ends (looks like a bony callus "wants" to develop, but they can't touch each other)

Front 93

what do you see on a radiograph of a non-viable nonunion fracture that you don't see in a viable nonunion fracture?

Back 93

intramedullary sclerosis

Front 94

how is a fracture displacement described?

Back 94

the distal part relative to the proximal part

Front 95

how does the blood supply differ in an immature bone versus a mature bone?

Back 95

immature bone: diaphyseal and epiphyseal have separate blood supplies; mature bone, they fuse

Front 96

what are the five types of forces at a fracture site?

Back 96

1. tension
2. compression
3. shear
4. bending
5. rotation (torsion)

Front 97

a wire that wraps entirely around the bone

Back 97

full cerclage wire

Front 98

what are three indications for using a full cerclage wire?

Back 98

1. supplementary support to a primary fixation
2. fragment reduction
3. protection of fissures

Front 99

full cerclage wire:
- fracture types
- comment on obliquity
- when do you place the wires relative to primary fixation?
- how many wires minimum?
- minimum distance of wires from each other
- how far from the fracture ends should they be?

Back 99

- only used in long oblique or spiral fractures
- obliquity should be at least twice the diameter of the bone
- bone must be reconstructed with the wires placed before primary fixation
- must use at least two wires
- wires must be a minimum of 1 cm apart from each other
- place wires at least 5 mm from fracture ends do the wires don't slip into the fracture

Front 100

what is the correct technique for twisting a full cerclage wire?

Back 100

the wire must be under tension. Pull up on the wire and push down on the bone while twisting

Front 101

why must a fracture be fully reconstructed before placement of a full cerclage wire?

Back 101

(barrel analogy) interfragmentary compression holds the fracture together. Otherwise, the wire could cause the fragments to collapse upon each other

Front 102

what are the three methods for tightening a cerclage wire?

Back 102

1. twist (pliers, wire twister)
2. single loop (tensioning device)
3. double-loop (tensioning device, twice as tight, twice as strong)

Front 103

what is the purpose of a hemicerclage?

Back 103

counteracts shear and rotational forces in transverse and short oblique fractures and may improve bony alignment

Front 104

what are disadvantages of a hemicerclage?

Back 104

- adds little mechanical stability to the fracture
- holes in bone can weaken the fracture ends

Front 105

what is used to prevent rotation of short oblique or transverse fractures in flat or non-weight bearing bones (such as the mandible)?

Back 105

interfragmentary wire

Front 106

what are two aspects of cerclage wire placement so as to prevent damage to the periosteal blood supply?

Back 106

1. the wire should be parallel to the axis of the bone, so the blood supply is not crushed
2. the wire must be tight so it does not slide up and down, damaging the blood supply

Front 107

for what force placed on a fracture is an IM pin most effective? Lest effective?

Back 107

- most effective: bending
- least effective: rotation

Front 108

what are three fixation options to use in conjunction with an IM pin to counteract rotational forces?

Back 108

1. external fixator
2. plate
3. cerclage wires

Front 109

what is the maximum diameter of an IM pin?

Back 109

one that fills 70% of the bone diameter at its narrowest point

Front 110

what is the purpose of stacked IM pins?

Back 110

provides additional bending strength, but does not provide axial or rotational stability

Front 111

why should an IM pin not be used without other additional fixation in a comminuted fracture?

Back 111

because they cannot withstand axial, rotational, and compression forces, so collapse and instability will result

Front 112

what is the most common IM pin and point type?

Back 112

Steinmann pins with a trocar point

Front 113

what is retrograde pin insertion

Back 113

an IM pin inserted from fracture site and driven through the epiphysis

Front 114

what is normograde pin insertion?

Back 114

an IM pin inserted at the epiphysis and driven through the fracture line

Front 115

IM pin in the femur:
- type of insertion
- landmarks
- complications

Back 115

- retrograde or normograde
- trochanteric fossa and directed laterally
- damage to the sciatic nerve

Front 116

IM pin in the tibia:
- type of insertion
- landmarks

Back 116

- always normograde
- pin at the medial aspect of the tibial tuberosity

Front 117

why should you not insert an IM pin into the tibia in a retrograde fashion?

Back 117

because the tip may come out at the articular surface. It needs to come out at the tibial tuberosity so that it will not damage the stifle joint

Front 118

IM pin in the humerus:
- type of insertion
- landmarks

Back 118

- retrograde or normograde
- exit or start distal to the greater tubercle on the lateral aspect → direct into medial aspect of condyle

Front 119

IM pin in the radius:
- type of insertion
- landmarks

Back 119

you can't put an IM pin in the radius because both sides are joint surfaces and the oval shape does not stabilize

Front 120

what are seven complications of an IM pin?

Back 120

1. pin migration
2. nonunion
3. osteomyelitis
4. delayed union
5. damage to joint
6. fracture collapse
7. nerve entrapment

Front 121

what is an interlocking nail?

Back 121

it is an IM pin with holes in it for screws to be placed laterally

Front 122

interlocking nail:
- nail size
- how far from fracture should the screws be placed?
- how many screws
- with what technique is the pin placed?

Back 122

- choose the biggest nail possible
- screws should be at least 2 cm away from the fracture
- try to use four screws; at least one screw must be at the end of each bone
- pin is placed normograde

Front 123

what are four indications for an external skeletal fixator?

Back 123

1. long bone fractures
2. corrective osteotomies
3. joint arthrodesis
4. temporary joint immobilization (e.g. skin grafts)

Front 124

what are the three main components of an external skeletal fixator?

Back 124

1. fixation pins
2. external connectors (bars)
3. linkage devices (clamps)

Front 125

what is the advantage of using threaded pins in an external fixator as opposed to smooth pins?

Back 125

threaded pins are stronger because they resist being pulled out

Front 126

what is the maximum pin size for an external skeletal fixator?

Back 126

pins ≤ 25% of bone diameter

Front 127

what are the maximum and minimum number of pins to be used in an external skeleton fixator?

Back 127

- maximum of 4 pins per bone fragment
- minimum of 2 pins per bone fragment

Front 128

comment on the pin location in an external skeleton fixator?

Back 128

- close to fracture, but no closer than 5 mm
- close to bone ends
- they should span the entire length of the bone

Front 129

comment on the pin length in an external skeletal fixator

Back 129

you want the shortest distance possible between the bone and the clamp for maximal stiffness

Front 130

how do connecting bars affect the stiffness of an external skeletal fixator?

Back 130

increasing strength and stiffness with increasing size and number

Front 131

what are the four configurations of an external skeletal fixator and a brief description of each?

Back 131

1. Type Ia - unilateral, uniplanar
2. Type Ib - unilateral, biplanar
3. Type II - bilateral, uniplanar
4. Type III - bilateral, biplanar

Front 132

Type Ia external skeletal fixator: comment on placement on the
- radius
- tibia
- femur
- humerus

Back 132

- radius and tibia: craniomedial
- humerus and femur: lateral; Type Ia is usually not strong enough and needs other fixation (e.g. IM pin)

Front 133

Type Ib external skeletal fixator:
- which bones?
- directionality of placement

Back 133

- radius and tibia
- one bar placed craniomedial and one placed craniolateral

Front 134

Type II external skeletal fixator:
- which bones?
- directionality of placement

Back 134

- radius and tibia (can't be used on femur and humerus because of the anatomic restrictions of the axillary and inguinal regions)
- placed in the mediolateral plane

Front 135

Type III external skeletal fixator:
- which bones?

Back 135

- radius and tibia (can't be used on femur and humerus because of the anatomic restrictions of the axillary and inguinal regions)

Front 136

external skeletal fixator pins: comment on the penetration of a half pin versus a whole pin

Back 136

a half pin only penetrates one skin surface, whereas a full pin penetrates both skin surfaces. HOWEVER, BOTH BENETRATE THROUGH BOTH CORTICES

Front 137

what are five materials used to construct external skeletal fixator connecting bars? Which ones are most common

Back 137

1. stainless steel (common)
2. titanium alloy
3. carbon fiber (common)
4. acrylic (PMMA) (common)
5. aluminum

Front 138

what advantage does a carbon fiber external fixator connecting bar have over the metal ones?

Back 138

it is radiolucent

Front 139

what are five indications for using a circular (ring) fixator?

Back 139

1. fractures (stabilize, compress, distract)
2. transport bone segments
3. correct angular deformities**
4. arthrodesis
5. bone lengthening**

Front 140

circular fixators are best suited for fractures where?

Back 140

below the elbow and stifle

Front 141

what is the basic construction of a circular fixator?

Back 141

-4 rings
- 4 small diameter, tensioned wires for each ring
- threaded rods to connect the rings to each other

Front 142

what is the most important prognosticator of using an external bone fixator?

Back 142

owner and patient selection

Front 143

regarding an external fixator, what is a staged disassembly?

Back 143

disassembling the fixator in steps to gradually increase loading on fracture; this stimulates bone healing and remodeling

Front 144

what are some complications of using external fixators?

Back 144

- drainage from pin tracts (movement of soft tissues; infection)
- loosening of fixation pins (usually secondary to infection)
- fracture of bone through fixation pin holes
- requires maintenance (repeated vet visits, pin track cleaning by clients, patient temperament)

Front 145

true or false, an external fixator placed on the humerus or femur should be stabilized with another fixator such as an IM pin

Back 145

true

Front 146

casts are best suited for fractures where?

Back 146

below the elbow and stifle

Front 147

true or false, casts ensure there is no movement at the fracture site because they conform to the limb?

Back 147

false - there is movement at the fracture site because the cast does not provide direct stabilization of the fracture

Front 148

what are some indications of when a cast would be appropriate verus a fixator?

Back 148

- closed fracture
- below elbow or stifle
- fracture can be reduced closed
- fracture will be stable after reduction
- bone will heal quickly

Front 149

what are three specific fractures that a cast would be indicated?

Back 149

1. greenstick
2. impaction fracture
3. young animals with intact periosteum

Front 150

what are the four principles of fracture treatment?

Back 150

1. anatomic reduction
2. stable fixation
3. preservation of blood supply
4. return to function

Front 151

what is the most difficult aspect of fracture treatment?

Back 151

anatomic reduction

Front 152

what are five aspects that affect bone healing?

Back 152

1. vascularity
2. stability
3. distance between fragments
4. location of the fracture
5. age of the animal

Front 153

what is the primary blood supply to a bone

Back 153

principle nutrient artery

Front 154

what supplies blood to the periosteum?

Back 154

surrounding musculature

Front 155

what supplies blood to the proximal and distal apsects of a long bone?

Back 155

metaphyseal arteries

Front 156

what are three blood supplies to an immature bone?

Back 156

1. principal nutrient artery
2. separate metaphyseal and epiphyseal blood supply
3. perforating longitudinal periosteal arteries

Front 157

if, in a fracture, the nutrient artery is disrupted, what takes over as the blood supply?

Back 157

periosteal arteries

Front 158

what three things happen to the blood supply during early fracture healing?

Back 158

1. initially, disruption of medullary circulation
2. enhancement of existing periosteal blood supply
3. increased extraosseus blood supply from the surrounding soft tissues

Front 159

what three things happen to the blood supply during late fracture healing?

Back 159

1. progressive stability
2. reestablishment of medullary blood supply
3. nutrient artery reestablishes itself as the main blood supply

Front 160

what happens if fragments are incoroporated into the callus?

Back 160

- if they are vascularized they will become incorporates into the tissue
- if not, they will become a sequestrum or reabsorbed

Front 161

describe healing of a fracture under stable conditions.

Back 161

- direct apposition of bone
- direct or primary bone healing

Front 162

describe and name the basic process of healing of a fracture under unstable conditions

Back 162

- connective tissue → fibrocartilage → bone
- indirect or secondary bone healing

Front 163

why does stability allow for primary healing of a fracture?

Back 163

stability allows vessels and cells to cross fracture line effectively

Front 164

what are the three primary determinants of callus size during bone healing?

Back 164

1. distance between fragments
2. vascularity
3. stability

Front 165

what are the four stages of bone healing?

Back 165

1. coagulation-fracture hematoma
2. inflammation-clean up
3. granulation-repair
4. maturation-remodeling/modeling

Front 166

why is a hematoma at the fracture gap important?

Back 166

it provides cells that are necessary for healing, e.g. fibroblasts, osteoblasts, and platelets

Front 167

what is the most important inflammatory cell in the inflammation-cleanup stage of fracture healing and why?

Back 167

macrophages, because they clean up and also recruit fibroblasts to the site

Front 168

in fracture healing, what is the first cell of bone origin that comes into the fracture site?

Back 168

osteoclast

Front 169

what is the process of granulation-repair of bone?

Back 169

1. fibroblasts produce fibrous tissue
2. chondrocytes produce fibrocartilage
3. osteoblasts produce bone

Front 170

how is a fracture aged radiographically?

Back 170

by the smoothness of the bone and fracture margins

Front 171

what is the most important requisite for direct (primary) bone healing?

Back 171

stability

Front 172

what are four requisites for direct (primary) bone healing?

Back 172

1. contact between fragments
2. gap < 1 mm
3. stability (most important)
4. good blood supply

Front 173

what are three steps in the process of direct (primary) bone healing?

Back 173

1. osteoclasts create tunnels across the fracture line
2. vessels follow
3. osteoblasts fill in the tunnel in concentric rings

Front 174

describe the direct (primary) healing process if the gap is < 200 μm

Back 174

- hematoma in gap
- blood vessels and mesenchymal cells
- blood vessels deposit lamellar bone
- little remodeling

Front 175

describe the direct (primary) healing process if the gap is > 200 μm but < 1 mm

Back 175

- hematoma in gap
- blood vessels and mesenchymal cells
- osteoblasts deposit bone haphazardly
- later remodeling

Front 176

which is better: direct or indirect fracture healing?

Back 176

- after they are healed, there is no difference
- the only difference is that with indirect the callus may impair function; direct may heal more slowly

Front 177

what type of healing is required for articular fractures?

Back 177

direct

Front 178

in fracture repair, how does fibrocartilage convert to bone?

Back 178

endochondral ossification

Front 179

by what process does a trabecular (metaphyseal) fracture heal?

Back 179

intramembranous ossification

Front 180

what is a big difference in the healing process between a diaphyseal and a metaphyseal (trabecular) fracture?

Back 180

trabecular fractures often have no callus and the trabaculae may heal before the cortical shell

Front 181

at what age is a fracture plate typically not used?

Back 181

< 3 months

Front 182

how does age affect fracture repair?

Back 182

the older the animal, the longer it takes (up to about 1 year)

Front 183

what are four uncontrollable factors that may delay fracture healing?

Back 183

1. older patients
2. highly comminuted fracture
3. soft tissue injury (vascularity)
4. systemic or local bone disease (e.g. pathologic fracture, bone disease)

Front 184

what are four controllable factors that may delay bone healing?

Back 184

1. poor fracture reduction
2. inadequate immobilization
3. excessive operative trauma
4. lack of aseptic technique