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Small Animal Skeleton Radiology of Bone

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sihirlifil's version from 2017-09-08 00:25

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Question Answer
How many views should you take?At least 2 orthogonal views trying to reproduce 3D structure (+/- additional views)
Where should you place the marker?In primary beam (not occluding area of interest) along DORSAL/CRANIAL / LATERAL aspect of limb
Order of bone anatomy from end  middleEpiphysis --> (Physis in immature) --> Metaphysis --> Diaphysis
Apopshysis starts from outside, doesn’t contribute to bone length
Components of normal long bone (4)Cortex
Medulla, bone marrow
Periosteum/Endosteum
Nutrient foramen
Describe blood supply to the bone2/3 is centrifugal from medullary artery
Periosteal vessels from soft tissue
Epiphyseal vessles present in skeletally immature
Woven bone: what does it look like? Formed when?Hapharzard, less organized
Formed in fetal life, and during skeletal repair (fracture callus)
Lamellar bone: what does it look like? Formed when?Cortical and cancellous/trabecular bone
Orderly, slower rate of formation. Osteocytes within lacunae, organized collagen fibers
Late in fracture healing, remodeling
Cancellous/trabecular (spongy) bone: what does it look like? Example?Less radiodense, trabeculated with marrow spaces
Subchondral bone (shock absorption for joints); navicular bone
Compact/cortical bone: what does it look like? Example?Uniform and radiodense plates & cylinders
Flexor cortex of navicular bone
How do flat bones develop?Intramembranous ossification
What’s going on during intramembranous ossification?Mesenchymal cells differentiate directly into osteogenic cells that form bone tissue (no cartilage)
Periosteal membrane around tubular (diaphyseal) bone lays down concentric laminae
What’s going on during endochondral ossification?Bones preformed in cartilage tissue at the physis, differentiate along chondrogenic pathway
Where is the physeal plate?Between epiphysis and metaphysis
Where is the epiphyseal secondary center of ossification?Beneath surface of articular cartilage
What is special about blood supply to the bone in immagure animals?Separate supply to epiphysis
4 zones of endochondral ossification (from epiphysis to diaphysis)Resting cartilage
Proliferation
Hypertrophy
Calcification
Where is the primary center of ossification for long bones?Midpoint of developing bone organ (diaphysis)
Where is the secondary center of ossification for long bones?Ends of developing bone organ (cartilage tissue in growth plates)
Tertiary center of ossification for long bones aka?Apophyseal center
What is the cut-back zone?Metaphysis starts flared, its width decreases drastically to the width of the diaphysis as it grows shaftward, has roughened periosteal border that is NORMAL in growing animal
What are the sites of attachment of tendons?Apophyseal centers
T/F Apophyseal centers contribute to the length of long bonesFalse
(Examples of tertiary centers of ossification (8)(Supraglenoid tubercle of scapula
Deltoid tuberosity of humerus
Olecranon
Medial epicondyle of humerus
Trochanter tertius femoris
Tibial apophysis
Tuber calcis
Tuber coxae)
Important to know apophyseal centers becauseDon’t want to mistake them for avulsion fractures
How do carpal / tarsal bones form?Round cartilaginous templates ossify from the center, become more square
Physeal scar =Faint radiodense line left over from the physis closing
What can a defect / trauma to the distal ulnar physeal plate lead to?Premature closure --> shortened ulna, overgrowth of radius --> cranial bowing of radius --> 2ry elbow joint problems
What is the periosteum like in young animals?More active & responsive, have loose periosteal attachment
Which species have more reactive periosteum?Bovine & equine
Types of periosteal reaction (5)Smooth, well defined, solid
Parallel/lamellar
Brush-border, columnar, palisading, specular
Radiating (sunburst)
Amorphous
Smooth solid periosteal reaction: examples?Fracture callus
Chronic osteomyelitis
Panosteitis
Chronic exostosis
Lamellar periosteal reaction: examples?Fungal osteomyelitis
Malignant neoplasia
Lamellar vs. lamellated periosteal reaction?Lamellar = thin layer lifted by exudate, hematoma, neoplastic cells --> repeated process --> lamellated (multilayered)
Palisading periosteal reaction: what does it look like? Examples?New bone forming at right angle like toothbrush bristles
Hypertrophic osteopathy, acute hematogenous osteomyelitis, neoplasia
Is Marie’s disease uni or bilateral? Aggressive or not?(Hypertrophic osteopathy) Bilaterally symmetrical. Slower growing lesions make bigger ‘bristles’
Radiating periosteal reaction: example? How does it behave?Osteosarcoma
Active and aggressive lysis
Amorphous periosteal reaction: what does it look like?No pattern recognized
What is the Codman triangle?Often found in association with bone neoplasia. Wedge of periosteal reaction around advancing tumor margin, which destroys periosteal new bone before it ossifies
What do you have to keep in mind when assessing soft tissue changes?May need to increase exposure to not underexpose bone tissue
Examples of soft tissue changes?Calcification, gas, foreign body, shift fascial planes
Distinct zone of transition suggests what kind of lesion?Benign / non-aggressive
Indistinct zone of transition suggests what kind of lesion?Malignant / aggressive
What is the zone of transition?Interface between area of destruction/production and surrounding healthy bone
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