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14 Cards in this Set

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What is the main blood supply of growing bone?
Direct epiphyseal artery, which loses prominence when the growth plate closes. The intramedullary vessels don't reach the epiphysis in growing bone.
What are the four sources of blood supply to the long bones?
Nutrient artery, Metaphyseal artery, Epiphyseal artery, and Periosteal artery. Growing bone uses a direct epiphyseal artery which loses prominence as bone ages.
What is the main circulation in cortical bone?
Nutrient arteries which divide once they get to the medullary cavity. Some enter the cortex and supply the inner 2/3 of the Haversian system
Which arteries supply nutrition for active cells in enchondral ossification in growing bone?
Metaphyseal arteries, supplied by intraosseous vessels. These do not change throughout life, and do not cross the physis. Lots of branching in metaphyseal vessels mean there is one vessel for every column of cartilage.
What is the consequence of the limited collateral circulation in bone?
Trauma or disease can lead to necrosis b/c there isn't collateral circulation.
20 year old male presents with pain in his hip and limited ROM. How would the suspected avascular necrosis be confirmed?
MRI. If this is an early injury, you can try to restore anatomy, but an end stage injury would require a total hip replacement.
Pathogenesis of avascular necrosis?
Blood flow disruption initiates osteonecrosis, leads to death of osteocytes, which disappear from lacunae on histology. Then revascularization causes osteoporosis of living bone, and dead bone becomes more dense. As vessels approach, the osteoclasts are resorbed and the articular surface weakens, which leads to degenerative arthritis.
What is the difference b/w osteonecrosis and osteochondrosis?
Osteochondrosis is a vascular insult to growing bone. The epiphyseal blood supply is destroyed which results in epiphyseal necrosis and deprives the cartilage cells of nutrition. Longitudinal growth of the bone stops, and the growth plate will close if circulation is not restored. Osteonecrosis is a vascular insult to mature bone, most commonly idiopathic, common in femoral head. Fracture of dislocation can disrupt blood supply and cause death of the femoral head.
Blood supply of femoral head?
Medial femoral circumflex artery
Risk factors for osteonecrosis?
Idiopathic usually, but fracture, hemoglobinopathy, arterial thrombosis, steroids, EtOH abuse, Gaucher's disease
Treatment for osteonecrosis of femoral head?
Early- core compression, Later- bone grafting with vascularized fibula, later stages- osteotomy or total hip arthroplasty.
Osteochondritis dissecans
Vascular insufficiency of subchondral bone that can result in loss of support for overlying articular cartilage
Etiology and presentation for osteochondritis dissecans
Usually idiopathic, could be overuse. Presents as mild aching to severe pain with a joint effusion. Possible mechanical block.
Three most common sites of presentation for osteochondritis dissecans
distal humerus, distal femur, talus