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what part of the bone seen on xray when viewed in profile
cortex
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define a tumor
just a mass
- -Not all tumors are neoplasms, but all neoplasms are tumors
- -e.g. an intramuscular hematoma is a tumor (lump/mass) but not a neoplasm
- - e.g. even soft tissue swelling following trauma could be considered a tumor!
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what are Lytic Lesions
lesions which result in bone destruction to some extent and produce a defect or hole in the bone.
-creates a lucency
-tumor may destroy bone or stimulate osteoclasts to resorb bone
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what are Blastic legions
lesions that present as radiographic areas of increased bone density or radioopacity
-tumor that stimulates bone production by osteoblasts or produces bone by itself or the tumor undergoes a degree of calcification
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Geographic margins (type I)
Focal areas of bone destruction
-May be well-defined sclerotic margins, well-defined non-sclerotic margins, or indistinct margins
-tend to be benign, indolent lesions
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Moth-eaten Margins
(Type II)
Multiple holes in either cortical (hard) or medullary bone
Each hole may be relatively well defined or not
-tend to be more aggressive
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Permeative margins (type III)
Tumor infiltrates hard and/or spongy bone
difficult to identify extent of bone lysis
the more poorly defined the lesion is, the more permeative it is
e.g. ewings sarcoma
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osteoid matrix
calcification
matrix produced by osteoblasts, if present it tells you that the tumor is making bone; looks like cotton ball dipped in barium!
described as:
-solid, dense
-ivory-like
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Chondroid matrix calcification
calcification produced by chondroblasts; has discrete structure and features, if present it tells you that the tumor is making cartilage. looks like calcified popped popcorn!
described as:
-stippled
-flocculent
-rings and arcs
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- calcification produced by fibroblasts; has discrete structure and features, if present it tells you that the tumor is making cartilage; looks like frosted beer stein (smudgy or hazy)
- -doesn't have the structure of the chondroid matrix or the density of the osteoid matrix
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define the Periosteum
Layer of dense connective tissue that surrounds the exterior of bones
- -not visible on a radiograph unless stimulated
- -will then produce new bone through the actions of osteoblasts
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Periosteal new bone production
- -When the periosteum is stimulated to produce new bone through the action of osteoblasts (not an inflammatory response- do not call it periostitis)
- -The new bone is added to the surface of the bone- the underlying cortex may or may not remain intact
- -smooth, solid, uninterrupted--> slow growing, benign, indolent
- -lamellated, interrupted, spiculated, Codman's triangles--> fast-growing, malignant, agressive
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Cortex-
A layer of compact (hard) bone that completely envelopes a less dense medullary cavity that contains cancellous bone arranged as trabeculae
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Cancellous bone
- One of two types of osseous tissue that form bones
- -also known as spongy or trabecular bone
- -less dense and more flexible than cortical bone
- -found at the ends of long bones, proximal to joints and within the interior of vertebrae
-red bone marrow is found here
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Avascular necrosis
(aka ischemic necrosis, aseptic necrosis, osteonecrosis)
- Pathophysiology: cellular death and collapse of bone due to lack of blood supply
- -caused by sickle cell anemia, trauma, anything that blocks blood vessels
- Density changes: Focal increase in density
- -Devascularized bone becomes denser
- -medullary bone infarcts appear as dense amorphous deposits of bone within the medullary cavities
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what are the hallmarks of Hyperparathyroidism
- - subperiosteal bone resorption on radial side of middle phalanges of index and middle fingers
- -erosion os distal clavicles
- -well-circumscribed lytic lesions in the long bones called brown tumors
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What is the orientation of trabeculae determined by?
mechanical forces
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What secretes collagen and calcium salts?
Osteoblasts
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What are the 3 most common sites of avascular necrosis?
Scaphoid bone (waist fracture), femoral head, humeral head.
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three criteria for strongly recommended osteopenia/osteoporosis therapy
- osteopenia or low bone mass and history of fragility fracture of the hip or spine;
- T score of -2.5 or less in the spine, femoral neck, total hip, or 33% radius;
- T-score between -1 or -2.5 in spine, femoral neck, total hip, or 33% radius, if the FRAX 10-y probability for major fracture is >20% or 10-y probability of hip fracture is >3%
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diagnostic criteria for diagnosis of osteoporosis in postmenopausal women (4)
- T-score -2.5 or below in lumbar spine, femoral neck, total, and/or 33% radius;
- low-trauma spine or hip fracture;
- osteopenia or T-score between -1 and -2.5 with fragility fracture of proximal humerus, pelvis, or distal forearm;
- low bone mass or osteopenia and high FRAX fracture possibility
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active calcium transport occurs here (2)
duodenum, jejunum (depends on vitamin D) (15% passive diffusion in jejunum and ileum)
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form of calcium supplement that should be taken with meals for best absorption
calcium carbonate
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form of calcium supplement that should be taken on empty stomach for best absorption
calcium citrate
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four bisphosphonates agents
- Alendronate (Fosamax, generic) oral
- Ibandronate (Boniva) oral, IV
- Risedronate (Actonel) oral
- Zoledronic acid (Reclast) IV
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what do bisphosphonates do (detailed)
drug class that inhibits osteoclast function & bone resorption; strong affinity for hydroxyapatite crystals on bone surface; Decreases osteoclast maturation, number, recruitment, and life span (increased apoptosis)
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define bone mineral
deposited as hard, brittle crystals in flexible collagen and gives bone its rigidity and strength
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vertebroplasty
a minimally invasive procedure for managing acute painful cerebral fractures; this involves injecting bone cement into the fractured vertebra under fluoroscopic guidance
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balloon kyphoplasty
a minimally invasive procedure that can reduce back pain and restore vertebral body height and spinal alignment; involved reducing the vertebral compression and injecting the cement into this space created within the vertebral body using fluoro guidance
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body composition
can be measured as fat and fat-free mass in specific measurements by performing a DXA whole body scan
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Where are there fewer trabeculae?
- Midshaft (diaphysis)
- --vs metaphysis or epiphysis
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