6 - Fractures Flashcards
List the 3 cell types involved in the maintenance and remodelling of bone.
- Osteoblasts
- Osteoclasts
- Osteocytes
What is osteomalacia?
Softening of the bone; caused by INSUFFICIENT MINERALIZATION
List 3 medical conditions associated with low trauma fractures.
- Osteoporosis
- Osteopenia
- Cancer
What type of collagen would you find in reticular fibres?
Type III
Remember: THREE is in reTHREEcular fibres
List 4 pharmacological treatments for osteoporosis.
- Bisphosphonates
- Calcium supplements
- Vitamin D supplements
- Hormone replacement therapy (in younger women)
What is the impact of steroids on bone cells?
INHIBIT OSTEOBLASTS
What type of connective tissue forms bone?
Dense connective tissue
Where does vitamin D come from?
- Sun exposure (70%)
2. Diet (30%)
List 2 activities signalled by calcium ions.
- Muscle contraction
2. Cellular secretion
What type of collagen would you find in bone?
Type I
Remember: ONE is in bONE
What is the major protein of bone?
Type I collagen
What does the T-score indicate?
Number of standard deviations above or below mean bone density for a healthy 30-year-old
What type of bone cells break down matrix and release minerals?
Osteoclasts
Which cells produce collagen?
Fibroblasts
Compact bone tissue organizes in concentric layers called ___ to form osteons.
Lamellae
What percentage of bone is replaced each year?
10%
Why is old age a risk factor for osteoporosis?
Bone mass declines with age
What is kyphosis?
Outward curvature of the upper back
Remember: Hunchback of Notre Dame
Compare the cartilage and bone changes in osteoarthritis.
Cartilage: thins and cracks
Bone: rubs against bone; may form osteophytes
Why is collagen abundant in connective tissue, bone, cartilage, tendons, etc.?
Provides strength
Which hormone stimulates osteoclast activity?
PTH
How does PTH raise blood calcium?
Stimulates osteoclast activity
Where would you find type IV collagen?
Basal lamina
Remember: FOUR is in the FLOOR
Compare a primary and secondary tumor.
Primary: at site of origin
Secondary: travelled from site of origin
How does a dramatic dip in estrogen hormones affect bone homeostasis in postmenopausal women?
Causes the amount of bone broken down by osteoclasts to exceed the amount of bone formed by osteoblasts
What is osteopenia?
Early stage bone density loss; precursor to osteoporosis
What causes calcium stones?
High calcium levels in the urine
What is the most common site of osteoporosis-related fracture?
Spine
What type of connective tissue forms bone?
Dense connective tissue
List 2 methods of identifying those at risk of osteoporosis.
- Presence of risk factors
2. DEXA scan (bone density screening)
At what age is peak bone mass reached?
25-30
You are performing a thyroidectomy. Why is it important to leave the parathyroid gland behind when the thyroid gland is removed?
Thyroid hormones are replaceable, but it is difficult to manage lost PTH
Bone is made up of calcium salts (mainly calcium hydroxyapatite) embedded in a(n) ___.
ECM
Compare a normal fracture and a pathological fracture.
Normal: huge force applied to normal bone
Pathological: small force applied to weakened bone
Describe how menopause increases risk of osteoporosis.
Low estrogen ->
Decrease in osteoblast activity +
Increase in osteoclast activity ->
Net bone loss
A patient has poor calcium and vitamin D intake early in life. How will this increase their risk of developing osteoporosis down the line?
Reduced peak bone density makes it easier for bone to wear down with age
What are the 4 stages of bone remodelling?
- Hematoma (blood clot)
- Fibrocartilaginous callus formation (fibres and cartilage)
- Bony callus formation (spongy bone)
- Remodelling (compact bone)
Why is spongy (a.k.a. trabecular) bone more susceptible to fractures from osteoporosis?
Osteoporosis weakens trabeculae
You suspect septic arthritis and decide to aspirate the joint in question. What features of the aspirate would support your diagnosis?
Pus
When is osteoporosis usually detected? (Hint: unfortunate timing.)
After first fracture
When does bone remodelling occur?
All times; process is constant
Where is collagen found in the bone?
ECM