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75 Cards in this Set
- Front
- Back
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How does endochondral bone formation work?
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cartilage first, then undergoes mineralization
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What is intramembranous bone formation?
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immature osteoid matrix laid down, then mineralizes
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What is woven bone?
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immature bone, irregular weave pattern
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What is lamellar bone?
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mature, stronger
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What does it mean if you see woven bone in an adult?
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new bone is laid down in response to injury
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What is achondroplasia?
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decreased chondrocytes in growth plate, decreased growth, decreased endochondral ossification, shortened bone length
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What is the mutation of achondroplasia?
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point mutation in FGFR3 gene, inhibits cartilage formation
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What does achondroplasia look like histologically?
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abnormal clusters of chondrocytes at growth plate
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How is achondroplasia inherited?
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autosomal dominant
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How does achondroplasia present?
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shortened proximal extremities with normal torso and enlarged forehead
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What is the defect in osteogenesis imperfecta?
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deficiency in synthesis of type I collagen
mutation in gene for alpha1 and alpha2 collagen chains |
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What organs are affected by osteogenesis imperfecta?
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bone, joints, eyes, ears, skin, teeth
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What are common signs of osteogenesis imperfecta?
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blue sclerae, dentinogenesis imperfecta, hearing loss
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What type of OI allows survival?
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type I, usually acquired
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What is the most common type of OI?
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type I
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What gene is mutated in Type I OI?
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COL-1-A1 gene
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What is the mtuation in OI Type II?
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COL-1-A1 and COL-1-A2 genes
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What happens with type II OI?
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increased osteocytes, sparse immature woven bone, abnormal growth plate, no cortical bone
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How do you treat OI?
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bisphosphonates, orthotic devices
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What is osteoporosis?
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increased porosity of skeleton due to reduction in bone mass, bone is susceptible to fracture
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What may be elevated with osteoporosis?
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urinary calcium, urinary hydroxyproline
alkaline phosphatase |
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What do you see microscopically with osteoporosis?
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osteoporotic trabeculae are thinned, lose interconnections
thinned cortical bone, widened Haversian canals |
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How do you treat osteoporosis?
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HRT, physical activity, Ca supplements
calcitrol, bisphosphonates, SERMs, calcitonin |
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What is osteomalacia?
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undermineralized bone
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What do you see histologically with osteomalacia?
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increased osteoid, less mineralized mature bone
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What can cause osteomalacia?
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vit D, Ca, PO4 deficiency
genetic abnormalities, systemic diseases that cause anorexia/malabsorption, drugs, metal poisoning, bone, soft tissue tumors |
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What is rickets?
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undermineralization of bone, causes bone deformities, affects growth plate
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How does rickets present?
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bowing of weight-bearing bones, short stature
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What can cause rickets?
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dietary deficiencies, hereditary
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How do you diagnose rickets?
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tetracycline uptake by the bone
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How do you treat rickets?
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vitamin and mineral replacement, supplements
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What does parathyroid hormone do to calcium?
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stimulates resorption, release from stored hydroxyapetite in bones
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What is osteitis fibrosa cystica?
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severe resportion of bone, includes loss of cortex and lamina dura of teeth
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What do you see on radiograph of osteitis fibrosa cystica?
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decrease in bone density in the fingers
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What do you see microscopically with osteitis fibrosa cystica?
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osteoclasts form railroad tracks
osteoclast-like giant cells, macrophages, fibrous tissue aggregate at microfractures |
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What is a Brown tumor?
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osteoclast-like giant cells, macrophages, fibrous tissue aggregate at microfractures
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What is Paget's Disease of Bone?
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increased rate of remodeling of bone
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How does Paget's Disease of Bone present?
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may be asymptomatic, one or many foci, can be progressive
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What are the phases of Paget's Disease of Bone?
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osteolytic, osteoclastic-osteoblastic phase, osteosclerotic phase
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What happens in the osteolytic phase of Paget's?
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abnormal large osteoclasts with up to 100 nuclei
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What happens in the osteoclastic-osteoblastic phase of Paget's?
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lining of osteoblasts around trabeculae, osteoclasts still present with loose connective tissue and vessels in marrow space, new bone formation
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What happens in the osteosclerotic phase of Paget's?
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larger coarse trabeculae, cortex is soft, porous, weak
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What is the radiographic lesion of Paget's?
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flame sign: lytic wedge advancing along the cortex
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What are the lab findings of Paget's?
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elevated alkaline phosphatase, increased urinary hydroxyproline and deoxypryidinoline
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What are the clinical findings of Paget's?
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can be mild or pain, chalk stick fractures, bowing of femur, tibia, compression of vertebrae resulting in kyphosis, femoral head involvement with secondary osteoarthritis
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What happens if Paget's involves the facial bones?
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thickening of cranium and facial bones
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What is leontiasis ossea?
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thickening of cranium and facial bones, can have deafness
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What happens if you have severe multifocal Paget's?
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high output heart failure due to hypervascularity
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What is Paget's sarcoma?
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high grade bone sarcoma like osteosarcoma or malignant fibrous hisstiocytoma in area affected by Paget's
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How do you treat asymptomatic Paget's?
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don't
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Why would you treat Paget's?
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bone pain, facial deformity, hearing loss, spinal cord compression, hypercalcemia
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How do you treat Paget's?
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bisphosphonates, calcitonin, surgery
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What are the initial post-fracture changes?
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formation of hematoma, fibrin mesh
platelets release PDGF, TGF-beta, FGF, IL's that activate bone progenitor cells and increase osteoblastic and osteoclastic activity |
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What happens a week after a fracture?
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soft tissue callus forms, remodeling fractured ends of bone, preparation for laying down of matrix
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What happens 2-3 weeks after a fracture?
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woven bone is deposited, forms fibrocartilage, undergoes endochondral ossification to form bony callus which then mineralizes
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What is osteonecrosis?
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infarction of bone and bone marrow due to ischemic event
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What can cause osteonecrosis?
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vessel injury due to fracture, radiation, corticosteroids, thrombosis/embolism, vasculitis, venous HTN, idiopathic
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How do subchondral infarcts present?
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pain and collapse of articular cartilage
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How do medullary infarcts present?
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asymptomatic
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What do subchondral infarcts look like grossly?
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wedge shaped pale yellow areas, new bone is not deposited quickly enough to prevent collapse of the area
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What is osteomyelitis?
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inflammation of the bone and bone marrow due to infection
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What are the common causes of osteomyelitis?
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bacteria and mycobacteria
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What is the pathogenesis of osteomyelitis?
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hematogenous spread, extension from contiguous site, direct implantation
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Which bacteria causes osteomyelitis by contiguous or hematogenous spread?
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Staph aureus
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Which bacteria cause osteomyelitis by UTI?
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E. coli, Pseudomonas, Klebsiella
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Which bacteria cause osteomyelitis by IV drug abusers?
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E. coli, Pseudomonas, Klebsiella
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How does osteomyelitis present?
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acute illness, fever, malaise, pain over involved area
fever of unknown origin or localized pain |
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Which patients commonly get osteomyelitis?
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orthopedic or interventional procedures, peripheral vascular disease, trauma patients
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How do you treat osteomyelitis?
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antibiotics and surgical drainage
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What is the pathology of osteomyelitis?
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inflammatory reaction, necrosis of entrapped bone, inflammation and bacteria spread through shaft, can spread through draining, cause arthritis
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What is sequestrum?
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dead bone entrapped in other bone
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What happens if osteomyelitis is chronic?
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inflammation causes increased osteoclastic bone resorption, reactive bone in periphery
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What is involucrum?
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sleeve of new bone around the sequestrum
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What are the late complications of osteomyelitis?
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squamous cell carcinoma in sinus or sarcoma
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Where does TB cause osteomyelitis?
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spine, hips, knees
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