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28 Cards in this Set
- Front
- Back
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What are the epiphysis, diaphysis, and metaphysis?
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Epiphysis: growth plate
Diaphysis: parallel cortices Metaphysis: non-parallel cortices, adjacent to epiphysis |
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Where should woven bone never be found?
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In adults
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What is the pathophysiology of achondroplasia?
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It is caused by a defect in cartilage formation impairing enchondral ossification. However, the flat bones formed by intramembranous processes like skull, sternum, and pelvis will be normal.
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What is Wilt's law?
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notion that bone will remodel itself based on the stress placed on it
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What causes osteogenesis imperfecta?
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This disease is caused by a failure of osteoblasts to normally synthesize collagen leading to a fragile skeleton.
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What is a characteristic sign of osteogenesis imperfecta?
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Blue sclerae due to collagen deficiency
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Is the bone in osteogenesis imperfecta hypo or hypercellular?
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The disease is caused by a lack of normal collagen production by osteoblasts. The bone's osteocytes become crowded as a result and the bone is actually HYPERcellular
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What is osteoporosis?
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increased porosity of the skeleton due to a reduction in bone mass, despite NORMAL mineralization
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What are two causes of primary osteoporosis and two causes of secondary osteoporosis?
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Primary: senile (age related) and postmenopausal osteoporosis
Secondary: endocrine disorders, neoplasia, GI factors, drugs, immobilization (reduced physical activity means there are fewer mechanical forces to stimulate normal bone remodeling) |
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What does menopause have to do with osteoporosis?
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Postmenopausal women have low estrogen which caused IL1 to be produced by monocytes in the blood. This cytokine release increases osteoclastic activity
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What is osteopetrosis?
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A disorder of osteoclast dysfunction that causes diffuse skeletal sclerosis and counterintuitively brittle bones (...marrow is replaced by lots of poorly organized fragile woven bone)
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What are some important complications of osteopetrosis?
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pinching of optic nerve (blindness), overgrowth of bone in inner ear (deafness), cranial nerve palsy, hydrocephalus
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By what age do people become skeletally mature?
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age 20
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What is Paget's disease (osteitis deformans)?
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This is a disorder of osteoblast dysfunction leading to excessive resorption of normal bone followed by excessive new bone formation of haphazard arrangement
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What causes Paget's disease?
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Infection by paramyxovirus, a retrovirus, that reduces the secretion of IL6 which usually recruits osteoclasts
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What labs might be expected in Paget's disease?
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The excessive osteoblastic activity causes high serum alkaline phosphatase levels
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What fatal complication of Paget's must be avoided?
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Secondary sarcomas
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What are the three stages of Paget's?
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1.) initial osteolytic stage
2.) mixed osteolytic-osteoblastic stage 3.) osteosclerotic stage |
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How can you treat Paget's?
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Calcitonin diphosphonates (counteracts PTH)
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What is osteomalacia? How does it relate to rickets
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metabolic defect of reduced vit D leading to increased UNmineralized bone, rickets is the childhood version
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What conditions can lead to ischemia that causes avascular necrosis?
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Steroid use, alcoholism, trauma, infection, sickle cell, lupus, RA, pressure dz of divers
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What characteristic shape does the necrotic region have in avascular necrosis? In what type of infarct?
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wedge shaped segment in subchondral infarct (tends to be geographic in medullary infarct)
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What happens to the overlying cartilage in avascular necrosis?
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It remains viable because it is receiving its nutrition from the synovial fluid.
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What is the crescent sign of avascular necrosis?
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It is the collapse of the articular surface due to weakened osteoclastic resorption at the margin of infarct. This causes the dead trabeculae to fracture beneath the subchondral plate.
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What kind of cells will be seen in a bone affected by osteomyelitis?
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It is a bone infection thus acute inflammatory cells - neutrophils!
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What are common bacterial causes of osteomyelitis and their preferred infecting demographic?
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Staph - most common
E. Coli, Klebsiella, Pseudomonas - pt with GU infxn, drug user H. flu, Group B strep - neonatal pt Salmonella - sickle cell pt |
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What is Pott's dz?
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Tuberculous osteomyelitis in the vertebrae caused by hematogenous spread from an active site of Tb infxn
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How does osteomyelitis present in syphilis?
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Occurs in tertiary stage of acquired syphilitic disease, presents as saber shins (periosteal rxn of tibia) or saddle nose deformity
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