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100 Cards in this Set
- Front
- Back
Osteology
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Study of bone
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Skeletal system
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Bone, cartilage, ligament
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Ligaments
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Attach bone to bone
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Tendons
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Attach muscle to bone
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Skeleton functions
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Support, protection, movement, electrolyte balance, acid-base balance, blood formation
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Bone/osseous tissue
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Connective tissue with the matrix hardened by calcium phosphate and other minerals
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Mineralization/calcification
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The hardening process of bone
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Flat bone
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Protect soft organs, curved but wide and thin
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Long bone
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Longer than it is wide, rigid levers for muscles
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Short bone
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Equally long and wide, glide across each other in multiple directions
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Irregular bone
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Elaborate shapes that don’t fit into other categories
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Compact/dense bone
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Outer shell of long bone
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Diaphysis/shaft
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Cylinder of compact bone providing leverage
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Medullary/marrow cavity
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Space within diaphysis of long bone, containing bone marrow
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Epiphyses
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Enlarged ends of long bone
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Spongy/cancellous bone
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Covered by more durable compact bone
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Location of spongy bone
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Ends of long bones, middle of most others
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Fraction bone type by weight
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¾ compact, ¼ spongy
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Articular cartilage
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Hyaline cartilage layer covering joint surface between bones
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Nutrient foramina
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Minute holes in bone surface allowing blood vessels to penetrate
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Periosteum
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External sheath covering bone, except where articular cartilage
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Periosteum’s outer fibrous layer of collagen
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Sharpey fibers, strong attachment from muscle-->tendon-->bone
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Periosteum’s inner osteogenic layer
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Bone forming cells, important to growth and repair
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Endosteum
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Layer of reticular connective tissue lining marrow cavity. Deposits or dissolves osteous tissue.
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Epiphyseal plate
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Growth plate. Hyaline cartilage between marrow spaces of epiphysis and diaphysis
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Purpose of epiphyseal plate
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Growth in bone length
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Epiphyseal line
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In adults. Bony scar marks former site of growth plate.
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Diploe
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Spongy layer in cranium
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Principal types of bone cells
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Osteogenic, osteoblasts, osteocytes, osteoclasts
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Osteogenic cells
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Stem cells in endosteum, periosteum, and central canals. Multiply continuously to produce osteoblasts
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Origin of osteogenic cells
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Mesenchyme
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Osteoblasts
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Form bone. Nonmitotic. Synthesize soft organic matter of matrix, which is hardened by mineral deposition
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Osteocalcin
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Secreted by osteogenic cells. Structural protein of bone.
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Osteocytes
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Former osteoblasts trapped in matrix they deposited
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Lacunae
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Tiny cavities where osteocytes reside
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Canaliculi
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Channels connecting lacunae
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Cytoplasmic processes
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Reach into canaliculi
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Osteoclasts
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Bone-dissolving cells on bone surface
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Origin of osteoclasts
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Same bone marrow stem cells as blood cells
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Ruffled border
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Side facing bone surface. Deep infolding of plasma membrane for surface area/resorption efficiency
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Resorption bays/Howship lacunae
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Pits on bone surface where osteoclasts reside
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Remodeling
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From combined action of osteoclasts and osteoblasts
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Organic matter in matrix
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Synthesized by osteoblasts. GAGs, proteoglycans, glycoproteins
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Inorganic matter in matrix
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85% hydroxyapatite, 10% calcium carbonate, other minerals
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Composite
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Combination of a ceramic and a polymer
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Rickets
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Soft bones due to deficiency of calcium salts
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Osteogenesis imperfecta (brittle bones)
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Excessively brittle bones due to lack of protein, collagen
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Parts of spongy bone
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Spicules, trabeculae, red bone marrow
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Location of trabeculae
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Along lines of stress
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Bone marrow
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Soft tissue in marrow cavity of long bone and among trabeculae in spongy bone
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Red marrow (myeloid tissue)
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Hemopoietic tissue--produces blood cells.
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Location of red marrow
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Nearly every bone in children. In adults, skull, vertebrae, ribs, sternum, pelvic girdle, proximal heads of humerus and femur
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Yellow marrow
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In adults. Does not produce blood. Fatty.
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Ossification/osteogenesis
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Formation of bone
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Methods of bone development in infant
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Intramembranous ossification, endochondral ossification
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Metaphysis
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Zone of transition facing the marrow cavity
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Interstitial growth
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Bones increase in length via cartilage growth within epiphyseal plate
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Appositional growth
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Bones increase in width throughout life. New bone deposited at surface.
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Bone remodeling
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Throughout life. 10% per year.
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Wolff’s law of bone
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Architecture of bone determined by mechanical stresses placed on it
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Achondroplastic dwarfism
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Long bones stop growing in childhood; failure of cartilage growth in metaphysis. Normal torso, short limbs.
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Pituitary dwarfism
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Lack of growth hormone. Normal proportions, short stature.
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Is mature bone metabolically active?
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Yes
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Mineral deposition/mineralization
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Calcium phosphate and other ions taken from blood and deposited in bone tissue
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Process of mineral deposition
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Osteoblasts produce collagen fibers that spiral the length of the osteon, fibers become encrusted with minerals that harden matrix
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Inhibitors
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Prevent most tissue from being calcified, neutralized by osteoblasts
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Abnormal calcification/ectopic ossification
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Calcification of tissue other than bone (arteriosclerosis, etc)
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Calculus
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Calcified mass in otherwise soft organ such as lung
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Mineral resorption
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Dissolving bone, releasing minerals into blood. Done by osteoclasts at ruffled border.
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Hydrogen pumps
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Secrete hydrogen into space between osteoclast and bone surface, dissolving bone
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How braces work
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Osteoclasts dissolve bone ahead of tooth, osteoblasts form new bone behind
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Calcium homeostasis levels
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1,100g in adults
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Normal calcium concentration in blood plasma
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9.2 to 10.4 mg/dL
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Causes of hypocalcemia
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Vitamin D deficiency, diarrhea, thyroid tumors, underactive parathyroid, pregnancy, lactation
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Hormones regulating calcium homeostasis
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Calcitrol, calcitonin, parathyroid hormone
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Calcitrol
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Form of vitamin D, raises blood calcium concentration
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How calcitrol is formed
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Epidermal keratinocytes convert 7-dehydrocholesterol to previtamin D3, liver adds hydroxyl group converting to calcidiol, kidneys add hydroxyl group converting to calcitrol
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Diseases from inadequate vitamin D
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Rickets, osteomalacia
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Location of calcitonin secretion
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C cells in thyroid
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Use of calcitonin
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Lowers blood calcium levels by inhibiting osteoclasts and stimulating osteoblasts
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Calcitonin in adults vs children
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Weak in adults, important in children
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Parathyroid hormone (PTH)
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Secreted by parathyroid, raises blood calcium levels
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Mechanisms for PTH
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Bind receptors on osteoblasts, stimulating them to secrete RANKL. Promote calcium reabsorption. Promote final step of calcitrol synthesis in kidneys. Inhibit collagen synthesis.
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Normal plasma concentration of phosphate
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3.5 to 4 mg/dL
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Two forms of phosphate
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HPO4(-2) and H2PO4(-)
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Percent phosphate in bones
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85-90%
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Problems with anabolic steroids
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Close epiphyseal plate, abnormally short stature
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Orthopedics
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Prevention and treatment of injury and disorder of bone, joint, muscle
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Stress fracture
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Caused by abnormal trauma to bone (falls, athletics, combat)
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Pathological fracture
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Break in bone weakened by disease (bone cancer, osteoporosis, etc)
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Ways to classify fractures
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Direction of fracture line, break in skin, number of pieces
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Closed reduction
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Bone fragments put in position without surgery
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Open reduction
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Surgical exposure of bone and use of plates, screws, or pins to realign
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Cast
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Stabilize and immobilize healing bone
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Traction
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Treat femur fractures in children. Override thigh muscles but risk long-term confinement to bed
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Electrical stimulation
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Suppresses effects of parathyroid hormone
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Osteoporosis
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Severe loss of bone density. Most common
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Kyphosis (widow’s hump)
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Deformity of spine due to vertebral bone loss
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Treatments for osteoporosis
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Estrogen replacement therapy, drugs, PTH, prevention
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Greatest risk group for osteoporosis
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Postmenopausal white women
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