BSAVA MSK Flashcards
(278 cards)
What are the 3 inherent characteristics of tissue which influence Xray absorption?
1) Density (e.g. gas has low density so poor Xray absorber)
2) Physical thickness
3) Atomic number
If there is clinical concern for a fistula/sinus contacting the epidural or subarachnoid space what type of contrast media should be used?
Non-ionic
What are 3 mechanisms of muscle atrophy?
1) Disuse
2) Neurogenic
3) Long term sequel to myositis
Describe the location and appearance of calcinosis circumscripta? What age and breed(s) are predisposed?
- Young (< 2 yo) large breed dogs [especially GSDs]
- Usually solitary, well-marginated lesions
- Stippled calcified areas
- Typical locations = distal limbs, especially over prominencies; neck and tongue
- Boston Terriers & Boxers are predisposed to cheek & pinna lesions
Calcinosis cutis occurs secondary to what underlying disease conditions?
- Cushing’s
- Primary or secondary hyperparathyroidism
Metastatic mineralization occurs secondary to what underlying disease conditions?
Pathophysiology - systemic disturbance of calcium or phosphorus levels
- CKD
- Hypervitaminosis A
- Hypervitaminosis D
What is another term for pseudogout and where does it occur?
Chondrocalcinosis or calcium pyrophosphate deposition disease (CPDD)
- mineral deposits in or around joints
What is myositis ossificans?
- Benign bone formation WITHIN striated muscle & tendon
- Can occur after major surgery, secondary to chronic disease, or idiopathic
What condition appears similar to myositis ossificans and what are the differentiating features?
- Fibrodysplasia ossificans
- Occurs in cats
- Multiple symmetrical formations of bone within the soft tissues
- DISPLACES muscle but does not actually involve it
Bone is covered by periosteum everywhere except what locations?
Wherever there is articular cartilage
Most bones in the body develop by what route? And explain the process?
Endochondral ossification
- cartilage precursor converted to bone
How do flat bones of the skull form?
Intramembranous ossification directly from connective tissue
What is the preferred location for hematogenous osteomyelitis in immature animals and why?
- Metaphysis
- rich blood supply from nutrient foramen vessels
(physis is essentially avascular b/c metaphysis and epiphysis are supplied separately)
{Epiphyseal blood mainly via joint capsule}
In mature bones where does periosteal blood supply come from?
Vestigial supply via nutrient artery as well as metaphyseal arteries
What direction is medullary blood supply to the cortex?
-Centrifugal :: cortical venous drainage via periosteum & medullary drainage via nutrient foramen
What is the characteristic location for Panosteitis?
Diaphyseal in the Medulla of long bones, often starting in region of nutrient foramen
What are the two most common locations for marked growth abnormalities to occur? (
Distal radius & ulna (greatest contributors to overall bone length)
New medullary bone matrix production may be composed of what 3 things?
1) Osteoid (e.g osteosarcoma production; ivory like opacity with osteomas)
2) Fibrous tissue (results in woven bone production with ground glass appearance)
3) Cartilaginous tissue (stippled appearance which when replaced by endochondral bone develops circular/semicircular opacities—typical of Chondrosarcoma)
What disease processes can cause bone infarction? Which locations does it occur at?
-primary malignant neoplasia such as Osteosarcoma
-Feline leukemia
- affects all or most bones distal to mid femur
What are the 6 types of periosteal reaction from least to most aggressive?
1) Solid
-opacity indicative of duration
- indicate benign slow growing processes (e.g. callus, chronic osteomyelitis, Panosteitis)
2) Lamellar (parallel)
- periosteum lifted by subperiosteal exudate, hematoma, rarely Neoplastic cells
-usually indicate benign processes
3) Lamellated (onion like)
-indicates a fairly slow process but more aggressive than the above two
-caused by repeated sequential insults (e.g. fungal osteomyelitis, malignant neoplasia)
4) Brush-like
-osteoblastic activity along vertically oriented Sharpey fibers
- if thicker/palisading reaction is less aggressive/slower growing
-thinner rxn with acute hematogenous osteomyelitis, neoplasia, hypertrophic osteopathy
5) Sunburst
-indicates highly aggressive process (e.g. OSA)
-osteoblastic Sharpey fiber activity
6) Amorphous
-NOT periosteal reaction but Neoplastic new bone formation
-periosteum destroyed
-cotton wool or candy floss appearance
Where do Codman’s triangles tend to appear/what is their orientation?
-Usually present on diaphyseal side of metaphyseal lesion
-acts as buttress for partially/totally destroyed cortex adjacent to it
Radiographically when does osteoclast activity become evident (percent of bone loss & # of days)?
-After 30-50% of bone loss
- usually 7-10 days (May only see soft tissue changes)
What is the least aggressive form of bone lysis? Describe some of its characteristics.
- Geographic bone loss
-usually slower growing lesions - common in cancellous bone at extremities
-usually a sclerotic rim (No rim —> think more aggressive e.g. multiple myeloma/metastatic bone disease) - narrow lytic area & transitional zone
Describe some characteristics of moth eaten lysis.
-multiple separate lytic foci (~2-3mm)
- typically in cortex & usually endosteal in origin
- intermediate aggressiveness
-usually involve cortical destruction
-wide transitional zone