chp 6

• What is osteosarcoma? Who does it affect?

  Bone cancer

  10-25 year olds
• What causes rickets?

  Inadequate vitamin D in diet

  Inadequate sun exposure
• What are rickets? Who does it occur in?

  Bones are inadequately mineralized

  Children
• What is osteomalacia? Who does it occur in?

  Bones are inadequately mineralized

  Adults
• How is osteoporosis treated?

  1. Vitamin D

  2. Anti-resorptive drugs

  3. Anabolic agents

  4. Estrogen replacement therapy

  5. Drugs that block osteoclast formation/function
• Why does cancer accelerate bone loss?

  Cancerous tissues release osteoclast-activating factor
• Why does bone loss in women accelerate after menopause?

  Estrogens and androgens help maintain bone mass by inhibiting osteoclast activity
• What percentage of men and women over 45 does osteoporosis occur in?

  30% postmenopausal women

  20% men
• What is osteoporosis?

  Severe bone loss that affects normal function
• How is osteopenia treated?

  No specific medications

  Sometimes given medications for osteoporosis
• When does osteopenia typically begin and how much bone mass does each gender lose per decade?

  Between ages 30-40

  Women: 8%

  Men: 3%
• What is osteopenia?

  Bone mineral density (BMD) is lower than normal peak but not low enough to be osteoporosis
• What is a Potts fracture?

  Variety of bimalleolar ankle fractures

  Caused by combined abduction external rotation from an eversion force
• What is a Colle's fracture?

  Distal portion of radius bone

  Typically from breaking fall with hand
• What is a displaced fracture?

  Bone is off original axis
• What is a transverse fracture?

  Bone breaks at diagonal angle
• What is a greenstick fracture?

  Bone breaks incompletely

  Common in children
• What is a depressed fracture?

  Bone is pressed inward

  Common in skull
• What is an epiphyseal fracture?

  Epiphysis separates from diaphysis along epiphyseal plate

  Common where cartilage cells are dying and calcification of matrix is occuring
• What is a spiral fracture?

  Ragged break from excessive twisting

  Common in sports
• What is a compression fracture?

  Bone is crushed

  Common in porous bones subjected to trauma

  Vertebrae
• What is a comminuted fracture?

  Three or more pieces

  Common in aged (brittle bones)
• What happens in bone remodeling in fracture repair?

  Osteoblasts and osteoclasts lay down spongy and compact bone that can be BETTER than the original for a couple months
• What happens in bone callus formation in fracture repair?

  In a week, osteoblasts replace cartilage with spongy bone via endochondral ossification

  Trabeculae span callus to reunite bone
• What happens in fibrocartilaginous callus formation during a fracture repair?

  New blood vessels form

  Osteoblasts and osteoprogenitor cells divide in periosteum and edosteum - invade clot ad form soft callus

  Cells make fibrocartilage and hyaline cartilage
• What happens in hematoma formation during a fracture repair?

  Blood clot forms fibrous network and bone cells nearby die
• What are the four main steps in fracture repaid?

  1. Hematoma formation

  2. Fibrocartilaginous callus formation

  3. Bone callus formation

  4. Bone remodeling
• What is open reduction?

  Bones joined surgically with pins and wires
• What is closed reduction?

  Bones coaxed into position by physician
• What is the general method for treating fractures?

  Reduction - realignment of broken ends
• How much calcium may enter or leave the adult skeleton each day?

  500 mg
• How often is compact bone replaced?

  Every 10 years
• How often is spongy bone with red bone marrow (cancellous bone) replaced?

  Every 3-4 years
• What is the process of bone remodeling?

  Bone matrix and osteocytes are continually removed and replaced by osteoclasts and osteoblasts
• Where does bone remodeling occur?

  At periosteal and endosteal surfaces
• What cells are involved in bone remodeling?

  Osteocytes - direct

  Osteoblasts - deposit

  Osteoclasts - resorb
• How do bones widen as they lengthen?

  Osteoblasts add tissue to external surface of diaphysis

  Osteoclasts remove bone from internal surface of diaphysis
• How do bones grow as adolescence draws to an end?

  Appositional growth - bones widen as they lengthen
• When do long bones stop lengthening?

  When diaphysis and epiphysis fuse
• What happens to bone growth as adolescence ends?

  Chondroblasts divide less often

  Epiphyseal plates become thinner (cartilage stops growing, replaced by bone tissue)