November 6, 2015 - Bone Biology

Question 1

Function of Bones

Answer 1

Support

Protection

Movement

Blood cell production

Storage of triglycerides

Mineral storage and release

Question 2

Hydroxylapatite

Answer 2

The main component of bone.

Question 3

Osteoclast

Answer 3

A specialized cell to break down bone. Formed from a conglomeration of macrophages (can be as many as 50) which are capable of releasing enzymes to degrade the bone.

These are important so old bone can be renewed.

About 10% of the adult skeleton is remodelled annually.

Question 4

RANK Ligand (RANKL)

Answer 4

RANK Ligand is needed for osteoclast activity.

Question 5

OPG

Answer 5

Needed for osteoblast activity.

Question 6

Vitamin D Production

Answer 6

Produced in response to UV light (need to get a slight burn)

Processed in the liver, therefore patients suffering from liver disease will get decreased levels of Vitamin D.

Question 7

Fragility Fractures

Answer 7

Bone fractures that occur from non-traumatic events.

Could be a fall from standing, from sitting, from laying down, or movement outside the typical plane of motion.

Question 8

Complications of Osteoporosis

Answer 8

Fractures

Poor fracture healing

Decreased independence

Decreased quality of life

Depression

Anxiety about future

Mortality

Question 9

Classification of Osteoporosis

Answer 9

Primary

Type I - postmenopausal

Type II - age related

Secondary

Caused by medications or underlying conditions

Question 10

DEXA

Answer 10

Dual-energy X-ray absorptiometry

Gold standard for bone mineral density

Question 11

Bone Mineral Density Classification

Answer 11

Normal: +2.5 to -1.0

Osteopenia: Between -1.0 and -2.5

Osteoporosis: Less than -2.5

Severe Osteoporosis: Less than -2.5 with Fragility Fracture

Question 12

Denosumab

Answer 12

A monoclonal antibody used for the treatment of osteoporosis.

Targets RANKL so that it cannot bind to the RANK receptors on the osteoclasts and they therefore do not become activated.