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Flashcards in GK Deck (69):


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Original – A – Cervical or Neck Bones (7 in number). B – Dorsal or Thoracic Bones (13 in number, each bearing a rib). C – Lumbar Bones (7 in number).D– Sacral Bones (3 in number). E – Caudal or Tail Bones (20 to 23 in number).

Skeleton of a dog: A – Cervical or Neck Bones (7 in number). B – Dorsal or Thoracic Bones (13 in number, each bearing a rib). C – Lumbar Bones (7 in number).D – Sacral Bones (3 in number). E – Caudal or Tail Bones (20 to 23 in number). 1 – Cranium, or Skull. 2 – Maxilla. 3 – Mandible, or Lower jaw . 4 – Atlas. 5 – Axis. 6 – Scapula, or Shoulder-blade. 7 – Spine of scapula. 8 – Humerus. 9 – Radius. 10 – Ulna. 11 – Phalanges. 12 – Metacarpal Bones. 13 – Carpal Bones or Wrist-bones. 14 – Sternum, or Breast-bone. 15 – Cartilaginous part of rib. 16 – Ribs (13 in number). 17 – Phalanges. 18 – Metatarsal Bones. 19 – Tarsal Bones. 20 – Calcaneus (os calcu). 21 – Fibula. 22 – Tibia. 23 – Patella, or Knee-cap. 24 – Femur. 25 – Ischium. 26 – Pelvis, or Hip-bone.


When a white opacity is seen on a radiograph, what are the 5 most likely options?

Opacity is always relative to _____ structures or materials

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CHANG 1. Cyst 2. Hemorrhage 3. Abscess 4. Neoplasia 5. Granulation




How many views to interpret orthopedic rads

At least 2


Considerations for looking at bones?

1. Marination 2. Opacity 3. Geometry 4. Lesion distribution


Considerations for joint rads?

1. Alignment 2. Width of joint space 3. Peri articulate findings 4. Lesion distribution


Considerations for Soft Tissue Rads?

1. Thickness

2. Opacity


After looking at Rads, the next steps are?

1. Reassess based on clinical, physical and lab findings 2. Prioritize list of differential DX 3. Make "follow-up" rads



The less distinct the bone Marin, the more active and aggressive the Dz. Assess how easily the bone margin can be traced with a pencil to determine it's sharpness.


Sharpness of bone margin is/ is not the same as shape of bone boarder

is not


An irregular border does/does not equal an ill-defined margin and a smooth border does/does not equal a well defined margin.

Not Not


Opacity definition

Characteristic of a material to block (attenuate or absorb) x-rays. The more opaque a material, the more x-rays are blocked and the whiter the material appears on the radiograph.


Name the opacities of materials from least to most opaque.

1. Gas= black 2. Fat 2.5 Fluid 3. Soft tissue 4. Bone 5. Metal


The inherent opacity of a material is related to it's ______ Overall opacity of a material relates to it's ______

Density (atomic number and degree of compaction) Thickness


At least ____-____% of bone must be altered before a change is visible on rads



Active bone destruction may be visible in ___-___ days on a rad?



Active bone production may be visible in ___-____ days on rads?



Causes for decreased bone opacity?

1. Osteopenia 2. Osteolysis


Definition of Osteopenia? Reasons for seeing Osteopenia? 1. Bone to _____ ____ contrast is poor. 2. Vortices become _____ and _____ 3. Corgi medullary ______ is poor. 4. Trabecular in cancellous bone appear _____ and more _____ due to loss of fine bone structure. 5. A "_____ _____" may be visible due to intracorcortical resorption of bone.

"Too little bone" 1. Soft Tissue 2. Thin and Faint 3. Contrast 4. Larger and more porous (course trabecular pattern) 5. "Double cortical line"


What 2 types of Osteopenia are there and which bones do they effect first?

1. General Osteopenia (due to hyperparathyroidism, nutrition deficiency) vertebrae>mandible>long bones 2. Regional osteopenia (limb immobilization) tends to be more severe in distal portion of limb


What is Osteolysis?

An abnormal, localized area f active bone resolution caused by Dz. The pattern of Osteolysis reflects the aggressiveness if the disease process presents with less distinct bony margins, a longer zone of transition between moral and diseased bone, and more rapid rate of change on serial radiographs


Osteolytic patterns (3) and their aggressiveness

1. Geographic pattern (least aggressive) 2. Moth-eaten pattern (more aggressive) 3. Permeative pattern (Most aggressive)


Mixed patterns of Osteolysis are ________, especially with ________ diseases.

Common Aggressive As long as dz is unchecked, bone destruction will continue and bone margins will remain ill defined.


What is the hemipelvis?

The bony pelvis comprises the two hemi-pelvis bones which are bound anteriorly at the pubic symphysis and posteriorly at the sacroiliac joints.

As with other anatomical bone rings if a fracture is seen in one place a careful check should be made for a second fracture, or for disruption of the pubic symphysis or sacroiliac joints.

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The most important determinators in the analysis of a potential bone tumor are:

The morphology of the bone lesion on a plain radiograph

1. Well-defined osteolytic

ill-defined osteolytic


2. The age of the patient

It is important to realize that the plain radiograph is the most useful examination for differentiating these lesions. 
CT and MRI are only helpful in selected cases.

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Most bone tumors are ______. 
The most reliable indicator in determining whether these lesions are benign or malignant is the ____ of ____ between the lesion and the adjacent normal bone (1). 
Once we have decided whether a bone lesion is sclerotic or _____ and whether it has a well-defined or ill-defined margins, the next question should be: how old is the patient?
Age is the most important clinical clue. 
Finally other clues need to be considered, such as a lesion’s localization within the skeleton and within the bone, any periosteal reaction, cortical destruction, matrix calcifications, etc.


zone of transition


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What is the zone of transition?

In order to classify osteolytic lesions as well-defined or ill-defined, we need to look at the zone of transition between the lesion and the adjacent normal bone. 
The zone of transition is the most reliable indicator in determining whether an osteolytic lesion is benign or malignant (
The zone of transition only applies to osteolytic lesions since sclerotic lesions usually have a narrow transition zone.


What is a small zone of transition?

A small zone of transition results in a sharp, well-defined border and is a sign of slow growth. 
A sclerotic border especially indicates poor biological activity. 
In patients In patients > 30years, and particularly over 40 years, despite benign radiographic features, metastasis or plasmacytoma also have to be considered 

On the left three bone lesions with a narrow zone of transition. 
Based on the morphology and the age of the patients, these lesions are benign. 
Notice that in all three patients, the growth plates have not yet closed.

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What is a wide zone of transition?

An ill-defined border with a broad zone of transition is a sign of aggressive growth (1). 
It is a feature of malignant bone tumors. 
There are two tumor-like lesions which may mimic a malignancy and have to be included in the differential diagnosis. 
These are infections and eosinophilic granuloma. 
Both of these entities may have an aggressive growth pattern.

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Infections and eosinophilic granuloma are exceptional because they are benign lesions which may seem malignant due to their _____ ____behavior. 
These lesions may have ill-defined margins, but cortical destruction and an aggressive type of periosteal reaction may also be seen. 
EG almost always occurs in patients Infections have to be included in the differential diagnosis of any bone lesion at any age.

aggressive biologic 


What is a periosteal reaction?

A periosteal reaction is a non-specific reaction and will occur whenever the periosteum is irritated by a malignant tumor, benign tumor, infection or trauma.
There are two patterns of periosteal reaction: a benign and an aggressive type.
The benign type is seen in benign lesions such as benign tumors and following trauma.
An aggressive type is seen in malignant tumors, but also in benign lesions with aggressive behavior, such as infections and eosinophilic granuloma.

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What is a benign periosteal reaction?

Detecting a benign periosteal reaction may be very helpful, since malignant lesions never cause a benign periosteal reaction. 
A benign type of periosteal reaction is a thick, wavy and uniform callus formation resulting from chronic irritation. 
In the case of benign, slowly growing lesions, the periosteum has time to lay down thick new bone and remodel it into a more normal-appearing cortex.

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What is an aggressive periosteal reaction?

This type of periostitis is multilayered, lamellated or demonstrates bone formation perpendicular to the cortical bone. 
It may be spiculated and interrupted - sometimes there is a Codman's triangle. 
A Codman's triangle refers to an elevation of the periosteum away from the cortex, forming an angle where the elevated periosteum and bone come together. 
In aggressive periostitis the periosteum does not have time to consolidate.

Osteosarcoma with interrupted periosteal rection and Codman's triangle proximally. 
There is periosteal bone formation perpendicular to the cortical bone and extensive bony matrix formation by the tumor itself.

Ewing sarcoma with lamellated and focally interrupted periosteal reaction. (blue arrows)

Infection with a multilayered periosteal reaction. 
Notice that the periostitis is aggressive, but not as aggressive as in the other two cases.

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What is cortical distruction?

Cortical destruction is a common finding, and not very useful in distinguishing between malignant and benign lesions. 
Complete destruction may be seen in high-grade malignant lesions, but also in locally aggressive benign lesions like EG and osteomyelitis. 
More uniform cortical bone destruction can be found in benign and low-grade malignant lesions. 
Endosteal scalloping of the cortical bone can be seen in benign lesions like FD and low-grade chondrosarcoma.

The images on the left show irregular cortical destruction in an osteosarcoma (left) and cortical destruction with aggressive periosteal reaction in Ewing's sarcoma.

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What is cortical ballooning?

Ballooning is a special type of cortical destruction. 
In ballooning the destruction of endosteal cortical bone and the addition of new bone on the outside occur at the same rate, resulting in expansion. 
This 'neocortex' can be smooth and uninterrupted, but may also be focally interrupted in more aggressive lesions like GCT.

left: Chondromyxoid fibroma 
A benign, well-defined, expansile lesion with regular destruction of cortical bone and a peripheral layer of new bone.

right: Giant cell tumor 
A locally aggressive lesion with cortical destruction, expansion and a thin, interrupted peripheral layer of new bone. 
Notice the wide zone of transition towards the marrow cavity, which is a sign of aggressive behavior.

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What is cortical distruction?

In the group of malignant small round cell tumors which include Ewing's sarcoma, bone lymphoma and small cell osteosarcoma, the cortex may appear almost normal radiographically, while there is permeative growth throughout the Haversian channels. 
These tumors may be accompanied by a large soft tissue mass while there is almost no visible bone destruction.
The image on the left shows an Ewing's sarcoma with permeative growth through the Haversian channels accompanied by a large soft tissue mass. 
The radiograph does not shown any signs of cortical destruction.

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What kind of lesions will you find in the epiphysis?

Only a few lesions are located in the epiphysis, so this could be an important finding.
In young patients it is likely to be either a chondroblastoma or an infection.
In patients over 20, a giant cell tumor has to be included in the differential diagnosis.
In older patients a geode, i.e. degenerative subchondral bone cyst must be added to the differential diagnosis. 
Look carefully for any signs of arthrosis.

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What kind of lesions will you find in the metaphysis?

NOF, SBC, CMF, Osteosarcoma, Chondrosarcoma, Enchondroma and infections.

Differentiating between a diaphyseal and a metaphyseal location is not always possible. 
Many lesions can be located in both or move from the metaphysis to the diaphysis during growth.
Large lesions tend to expand into both areas.

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What kind of lesions will you find in the diaphysis?

Ewing's sarcoma, SBC, ABC, Enchondroma, Fibrous dysplasia and Osteoblastoma.

Differentiating between a diaphyseal and a metaphyseal location is not always possible. 
Many lesions can be located in both or move from the metaphysis to the diaphysis during growth.
Large lesions tend to expand into both areas.

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How do you tell if the lesion is centric - eccentric - juxtacortical?

Centric in long bone
SBC, eosinophilic granuloma, fibrous dysplasia, ABC and enchondroma are lesions that are located centrally within long bones.

Eccentric in long bone
Osteosarcoma, NOF, chondroblastoma, chondromyxoid fibroma, GCT and osteoblastoma are located eccentrically in long bones.

Osteoid osteoma is located within the cortex and needs to be differentiated from osteomyelitis.

Osteochondroma. The cortex must extend into the stalk of the lesion.
Parosteal osteosarcoma arises from the periosteum.

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What do you call mineralization w/in a bone lesion?

Calcifications or mineralization within a bone lesion may be an important clue in the differential diagnosis.
There are two kinds of mineralization: a chondroid matrix in cartilaginous tumors like enchondromas and chondrosarcomsa and an osteoid matrix in osseus tumors like osteoid osteomas and osteosarcomas. 

Chondroid matrix
Calcifications in chondroid tumors have many descriptions: rings-and-arcs, popcorn, focal stippled or flocculent.

left: Enchondroma, the most commonly encountered lesion of the phalanges.

middle: middle: Peripheral chondrosarcoma, arising from an osteochondroma (exostosis).

right: Chondrosarcoma of the rib.

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What is osteoid matrix?

Osteoid matrix
Mineralization in osteoid tumors can be described as a trabecular ossification pattern in benign bone-forming lesions and as a cloud-like or ill-defined amorphous pattern in osteosarcomas. 
Sclerosis can also be reactive, e.g. in Ewing’s sarcoma or lymphoma.

Cloud-like bone formation in osteosarcoma. 
Notice the aggressive, interrupted periosteal reaction (arrows).

Trabecular ossification pattern in osteoid osteoma. 
Notice osteolytic nidus (arrow).

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What constitute a multiple bone lesion?

Most bone tumors are solitary lesions. 
If there are multiple or polyostotic lesions, the differential diagnosis must be adjusted.

Polyostotic lesions 
NOF, fibrous dysplasia, multifocal osteomyelitis, enchondromas, osteochondoma, leukemia and metastatic Ewing' s sarcoma. 
Multiple enchondromas are seen in Morbus Ollier. 
Multiple enchondromas and hemangiomas are seen in Maffucci's syndrome.

Polyostotic lesions > 30 years 
Common: Metastases, multiple myeloma, multiple enchondromas. 
Less common: Fibrous dysplasia, Brown tumors of hyperparathyroidism, bone infarcts.

Mnemonic for multiple oseolytic lesions: FEEMHI: 
Fibrous dysplasia, enchondromas, EG, Mets and myeloma, Hyperparathyroidism, Infection.

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Name some spine lesions?



Multiple myeloma.

Plasmocytoma: vertebra plana.
This 'Mini Brain' appearance of plasmacytoma in the spine is sufficiently pathognomonic to obviate biopsy (9).

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Name some foot lesions?

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What is the average number of bones of a dog/cat?

Dogs: 320

Cats: 244

50 vertebrae, 26 ribs, 8 sternebrae, 41 skull bones, 9 hyoid bones, 45 bones in each pectoral limbm 48 bones in each pelvic limb, 1 os penis


Cortical (compact) bone forms the outer layer (cortex) of most bones (including all long bones), Rad appearance is dense, opaque, and ______. It makes up ___% of total bone mass. 




Calcellous or trabecular bone are found in the ____ of long bones, in vertebrae and in flat bones. Rad appearance is _______, spongy, or porous. It makes up ___% of total bone mass. Bony trabeculae are surrounded by ______. It provideds nearly ___ times the surface area of cortical bone. It si capable of high rates of remodeling, especially during growth and _____. 


trabeculated (any of various rod-shaped structures that divide organs into separate chambers)






What are the names of the different shape bones in the skeletal system?



What bones are classified as LONG bones?

Humerus, Ulna, Radius, Metacarpals, Phalanges, Femur, Tibia, Fibula, Metatarsals.


What bones are classified as SUTURAL bones?

Small irregular bones found between cranial bones.


What bones are classified as IRREGULAR bones?

Vertebrae, Sphenoid, Ethmoid, Facial bones.


What bones are classified as SHORT bones?

Carpals, Tarsals


What bones are classified as FLAT bones?

Frontal, Parietal, Occipital, Temporal, Hip, Ribs, Scapulae, Sternum.


What bones are classified as SESAMOID bones?

shaped like a sesame seed - Patella


What are the seven parts of a long bone?

1. Physis-

2. Diaphysis

3. Metaphysis

4. Epiphysis

5. Apophysis

6. Periosteum-

7.  Endosteum-

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Physis is what?

(growth plate, epiphyseal cartilage, or epipyseal plate). Present in immature animals. Separates the metaphysis from epiphysis or apophysis. composed of hyaline cartilage (appears as a less opaque band) In mature animals, the physis is absent and the metaphysis and epiphysis blend together. 

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What is ithe diaphysis?

("between physis")- middle portion or shaft of a long bone. Consists of cortical bone surrounding a less opaque medullary cavity.

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What is the Metaphysis?

 ("next to physis")- Wider portion located at either end of diahysis. contains cancellous bone. Functions as a zone of transformation where cancellous metaphyseal bone becomes cortical diaphyseal bone. (called the cut back zone)

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What is the epiphysis?

("upon physis")- Rounded end that supports  articular cartilage. Compsed of cancellous bone and a layer of dense subchondral bone.  

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What is the Apophysis?

("away or apart from physis")- A non articular epiphysis. Provides a prominence of bone for attachment of tendons and ligaments. Examples: femoral greater trochanter, tibial tuberosity, humeral greater tubercle. 

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What is the Periosteum?

 Completely covers all long bones except articular areas that are covered by cartilage). It consist of two layers: a) inner layer (cambium) produces bone via osteoprogenitor cells. b) outer layer is fibrous connective tissue. It is attached to the cortex by Sharpey's fibers. It blends continuously with tendons and ligaments at their attacements. Supplies nerves and blood vessels to underlying bone. It is responsible for circumferential growth of immature long bones. It provides the healing reponse when bone is damaged. 

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What is the endosteum?

Lines the medullary cavities of bones. It is similar to periosteum but thinner. 

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Dog body references

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What are the different types of bone classifications?

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Name the different types of collagen in making of bones?

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What are Sharpy's fibers?

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Illustration of a typical long bone showing the location of cancellous bone ("trabecular bone" on the image).

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Light micrograph of a decalcified histologic specimen of cancellous bone showing its bony trabeculae (pink) and marrow tissue (blue).

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There are 2 types of bone marrow, what are they and what defines them?

There are two types of bone marrow:

Red, or hematopoietic

Produces red blood cells, white blood cells and platelets

Gets its red color from the hemoglobin in the erythroid cells

Hematopoietic cells mature and migrate into sinusoids to enter the circulation when they are formed.

Highly vascular

Yellow, or stromal

Produces fat, cartilage, and bone

Gets its yellow color from the carotenoids in the fat droplets in the high number of fat cells

Paucity of vasculature

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