Broken Bones and Remodeling

Question 1

What two possible breaks can broken bones be?

Answer 1

Closed fractures and open fractures

Question 2

What are closed fractures?

Answer 2

Breaks that do not pierce the skin

Question 3

What are open fractures?

Answer 3

Breaks that do pierce the skin

Question 4

What are the 5 type of fractures?

Answer 4

stress, greenstick, compression, complete, and comminuted

Question 5

What are the three subtypes of complete fractures?

Answer 5

transverse, oblique, spiral

Question 6

What is a stress fracture? Where is it most common? What is it also known as?

Answer 6

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)

Question 7

What is a greenstick fracture? Who is it most common in?

Answer 7

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)

Question 8

What is a compression fracture? Where do they occur? What is it caused by? Who is it common in?

Answer 8

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

Question 9

What is a complete fracture? Where does it usually occur?

Answer 9

bone breaks all the way through; usually occur in long bones

Question 10

What is a transverse fracture?

Answer 10

a complete fracture that breaks at a perpendicular angle

Question 11

What is an oblique fracture?

Answer 11

a complete fracture that breaks at a non perpendicular angle

Question 12

What is a spiral fracture?

Answer 12

A complete fracture that breaks at rotating angles aka a torsion fracture

Question 13

What is a comminuted fracture? How do they occur? What do they require?

Answer 13

bone breaks into many fragments; occurs from high-speed or high-trauma events; often requires screws or plates to hold bone together

Question 14

What are the four steps of the body healing fractures?

Answer 14

1. Hematoma forms; 2. fibrocartilage callus forms; 3. bony callus forms; 4. bone remodels to a permanent patch

Question 15

What happens after a bone breaks? What does this lead to? What happens to bone cells?

Answer 15

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

Question 16

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?

Answer 16

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

Question 17

What forms after fibrocartilage callus? What does the fibrocartilage slowly start to do? Why? What is the break now full of?

Answer 17

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

Question 18

What finally occurs after bony callus forms? What removes dead cells? What settles around the edges?

Answer 18

The bone remodels to a permanent patch; osteoclasts remove the dead cells; compact bone settles around the edges

Question 19

What are osteoblasts?

Answer 19

cells that build bone (ossification)

Question 20

What are osteoclasts?

Answer 20

cells that break bone apart (bone resorption)

Question 21

What percent of the skeleton is replaced in a year?

Answer 21

ten percent

Question 22

What two diseases are a part of the delicate process of the skeleton getting replaced?

Answer 22

osteoporosis and osteopetrosis

Question 23

What is Wolff’s Law?

Answer 23

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.

Question 24

What is osteoporosis?

Answer 24

a bone disease where density and quality of bone are reduces; risk of fracture increases

Question 25

What is osteopetrosis?

Answer 25

a bone disease that makes bones abnormally dense and prone to fractures

Question 26

What is trabeculae?

Answer 26

lines of spongy bone that remodel to run parallel or perpendicular to stress

Question 27

What happens to bones after age 30? What is it? What are the results? Which disease is most common in postmenopausal women?

Answer 27

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

Question 28

What is RANK Ligand?

Answer 28

when protein binds to and activates RANK receptors on osteoclast membranes and increases osteoclast activity

Question 29

What does estrogen do during RANK Ligand?

Answer 29

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

Question 30

What happens to estrogen during menopause? Why is this bad?

Answer 30

Estrogen production dramatically decreases, which leads to osteoclast activity and bone resorption increase