Broken Bones and Remodeling Flashcards
What two possible breaks can broken bones be?
Closed fractures and open fractures
What are closed fractures?
Breaks that do not pierce the skin
What are open fractures?
Breaks that do pierce the skin
What are the 5 type of fractures?
stress, greenstick, compression, complete, and comminuted
What are the three subtypes of complete fractures?
transverse, oblique, spiral
What is a stress fracture? Where is it most common? What is it also known as?
known as a hairline fracture; comes not from one severe trauma event, but extended overuse; common in athletes and in weight-bearing bones (tibia, femur, metatarsals)
What is a greenstick fracture? Who is it most common in?
come from an incomplete fracture through the bone; bone breaks much like a “green stick”: a piece splinters off, but part stays intact; it’s most common in patients under 10 yo (more cartilage, less ossification)
What is a compression fracture? Where do they occur? What is it caused by? Who is it common in?
part of the bone is “crushed” or caved in; almost always happens in vertebra; caused by osteoporosis (bones cannot support normal amount of weight b/c they have low mineral density); common in geriatric patients
What is a complete fracture? Where does it usually occur?
bone breaks all the way through; usually occur in long bones
What is a transverse fracture?
a complete fracture that breaks at a perpendicular angle
What is an oblique fracture?
a complete fracture that breaks at a non perpendicular angle
What is a spiral fracture?
A complete fracture that breaks at rotating angles aka a torsion fracture
What is a comminuted fracture? How do they occur? What do they require?
bone breaks into many fragments; occurs from high-speed or high-trauma events; often requires screws or plates to hold bone together
What are the four steps of the body healing fractures?
- Hematoma forms; 2. fibrocartilage callus forms; 3. bony callus forms; 4. bone remodels to a permanent patch
What happens after a bone breaks? What does this lead to? What happens to bone cells?
The blood vessels surrounding and inside the bone break, which leads to the swelling of the area called hematoma; the bones cells are deprived of their normal blood flow, and they die
What forms after hematoma? What two cells migrate to the damaged site? What do they make? What begins to redevelop? What cell removes some debris?
Fibrocartilage callus forms; fibroblasts and osteoblasts migrate to the damaged site, and they make fibrocartilage (cartilage matrix, bone matrix, and collagen); capillaries begin to redevelop; phagocytes (type of white blood cell) remove some debris
What forms after fibrocartilage callus? What does the fibrocartilage slowly start to do? Why? What is the break now full of?
Bony callus forms; fibrocartilage starts to ossify because more osteoblasts begin to arrive at the fracture site; the break is full of new immature spongy bone
What finally occurs after bony callus forms? What removes dead cells? What settles around the edges?
The bone remodels to a permanent patch; osteoclasts remove the dead cells; compact bone settles around the edges
What are osteoblasts?
cells that build bone (ossification)
What are osteoclasts?
cells that break bone apart (bone resorption)
What percent of the skeleton is replaced in a year?
ten percent
What two diseases are a part of the delicate process of the skeleton getting replaced?
osteoporosis and osteopetrosis
What is Wolff’s Law?
states that bone grows and remodels in response to the forces that are places upon it in a healthy person. Basically says that more stress on a bone creates a stronger one.
What is osteoporosis?
a bone disease where density and quality of bone are reduces; risk of fracture increases
What is osteopetrosis?
a bone disease that makes bones abnormally dense and prone to fractures
What is trabeculae?
lines of spongy bone that remodel to run parallel or perpendicular to stress
What happens to bones after age 30? What is it? What are the results? Which disease is most common in postmenopausal women?
bone resorption occurs, which is when osteoclasts break down tissues and release minerals from hydroxyapatite; the result is bones slowly getting less dense and weaker; osteoporosis
What is RANK Ligand?
when protein binds to and activates RANK receptors on osteoclast membranes and increases osteoclast activity
What does estrogen do during RANK Ligand?
Estrogen down-regulates RANK ligand production, which leads to less osteoclast activity, meaning less resorption
Estrogen also up-regulates osteoprotegrin (OPG) production. OPG then binds to RANK ligand and blocks it from binding to RANK receptors, which leads to less osteoclast activity, which leads to less resorption
What happens to estrogen during menopause? Why is this bad?
Estrogen production dramatically decreases, which leads to osteoclast activity and bone resorption increase
