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function of bone protect organs, structural framework, mechanical support, house marrow, mineral homeostasis types of bone shapes long, flat, short, irregular, sesamoid Trabecular bone spongy bone, found at epiphyses (ends), network of plates and rods(strut), porous, bone marrow between pores, if stress is more load it will be more dense vice versa, also more dense in OA, lamellae are irregular in trabecular bone cortical bone compact bone found @ diaphysis periosteum outer layer of bone on all of bone except the ends, tendons attach to periosteum periostitis inflamation of periosteum inner layer of periosteum osteogenic layer containing osteoblasts/clasts outer layer of periosteum fibrous connective tissue endosteum located in wall of medullary cavity/surface of spongy bone/haversion canals/volksman canals, is also ostegenic (ostoblasts/clasts) growth plate hyaline cartilage in bone which separates the physes nutrient arteries nutrient foramen, inner 2/3 of bone blood supply periosteal outeries outer 1/3 of bone blood supply epiphyseal arteries @ both epiphyseal ends of bone Nerve supply to bone all periosteum is highly innervated Osteon primary structural feature of compact bone, think expanding sword, contains: lamellae, haversian cnals, lacunae, canaliculi volkmann's canal perpendicular to haversion canals connecting them to one another haversion canal blood supply in the middle of the steon lamellae rings of osteon (4-20), fiber direction differs based on load location of osteocytes inside lacunae inbetween lamellae lacunae where osteocytes reside in compact bone canaliculi microscopic tunnels connecting lacunae extracellular matrix of bone organic(30%): collagen 90%, Inorganic(70%): hydroxyapetite(calcium phosphate crystals), remaining tissue volume H2O primary bone cells osteoblasts, osteocytes, osteoclasts osteoblasts bone lining cells which lay down new matrix(collagen), originate from osteoprogenitor cells, located in deep layer of periosteum, lifespan/fate: 1/3 become osteocytes, bulk die, may live 1mo-1yr osteocytes mechano-sensing functional units located in lacunae, originate from osteoblasts, live for decades, sense load+communicate w/osteoblasts on how to lay bone down osteoclasts cells that reabsorb bone located in osteogenic regions of bone, originate from hematopoetic cells, live for 7wks bone regeneration in femur new every 5-6 months in young health adults relatively active wolff's law bone is deposited+resorbed in accordance w/ the stresses placed upon it, ^activity/loading = ^bone mass/density inorganic matrix of bone resists compressive loads, 70% of matrix organic matrix of bone good for resisting tensile loads, 30% of matrix Colles fracture fracture of styloid process of radius: fall on outstretched hand EXTENSION, most commonly fractured bone in UE, displaced posteriorly, may also have scaphoid fracture which usually occurs 1st Smith's fracture opposite of colles, fracture of styloid process of radius in FLEXION Jones fracture fracture of 5th metatarsal often seen in runners Monteggia's fracture fracture of ulna 1/3 length from humerus, w/ dislocation of radial head, in kids radial head sometimes not grown in to annular ligament, treated with fixation Avulsion fracture separation of small segment of cortical bone @ attachment site of tendon/ligament, treated w/ normal healing but often internal fixation Comminuted fracture bone fragments into 3 or more pieces, common in aged whose bones are more brittle, treatment will need screws/plates/etc. very messy Greenstick fracture bone breaks incompletely like fresh twig, only one side of the shaft splits the other side bends and stays intact, common in children their bones have more organic matrix and flexibility vs adults Compression fracture most common in lumbar spine, cancer also affects integrity of bone Stress fracture repeated loading greater than the bone can handle, common in female runners in the distal anterior medial tibia Compound fracture bone penetrates the skin, has a HIGH risk for infection Open Reduction Internal Fixation (ORIF) pins, screws, plate, nails or rod, further immobilized by cast/brace. wb restrictions External Fixation may be adjusted during the healing to change loads etc., risk 4 infection, risk for soft tissue injury osteoporosis systemic skeletal disease characterized by low bone mass and microarchitectual changes resulting in fractures, BMD 2.5SD below mean peak value of young adults types of Osteoporosis type l (postmenopausal): loss of trabecular bone after menopause, type ll (senile): loss of cortical and trabecular bone in men&women as the end result of age related bone loss risk factors for Osteoporosis caucasian/asian, family hx, female fair small boned short, sedentary life style, imoobilization, alcohol, smoking, lack of Calcium and vitamin D, estrogen & androgen deficiency, med use, diabetes, RA Skeletal risk factors low BMD, previous fracture, high bone turnover, family hx Non skeletal risk factors poor eyesight, poor hearing, poor balance, muscle weakness peak bone mass 70% of PBM during pubertal growth, achieved by age 30, bone loss declines exponentially after peak, rapid decline after menopause Osteoperosis in Women and men 50% women osteopenic after 50, 50% women will have osteoperosis, 20% are men bone w/ aging trabeulae becomes thin sparse rods, cortical bone becomes more porous resits torsional and bending loads bone loss after menopause 1-1.5% / year best exercise parameters for Ostegenic response High strains, daily repetitions, short duration, site-specific