Bone Disorders

Question 1

Bone disorders

Answer 1

Imbalances between bone deposition and bone resorption underlie nearly every disease that affects the human skeleton
3 major types:
- osteomalacia and rickets
- osteoporosis
- paget’s disease

Question 1

Osteomalacia

Answer 1

• bones are poorly mineralized
• osteoid is secreted, but calcium salts are not adequately deposited
• result: soft/weak bones + pain with weight bearing

Question 2

Rickets

Answer 2

• osteomalacia in children
• cause: deficiency in Vitamin D or insufficient dietary calcium
• Result: bowed legs or other bone deformities

Question 3

Osteoporosis

Answer 3

• groups of diseases when bone resorption > bone deposit (bones breakdown faster than they build up)
• bone matrix remains normal, but bone mass declines
• bones become porous and light - very likely to fracture under minimal stresses (holes within bone)
• bones most susceptible to fracture are the neck of the femur and the vertebrae (high weight bearing stress)

Question 4

Kyphoplasty

Answer 4

• kyphosis: hunchback that develops in elderly
• vertebrae become brittle (more likely to fracture) so common activities can cause them to fracture
• inject bone matrix in bone to cover up cracks to heal

Question 5

Risk factors for osteoporosis

Answer 5

• older post menopausal women are most affected (decrease in estrogen which stimulates bone growth)
• men are less affected bc testosterone plays a protective role
  Additional risk factors:
• insufficient excercise
• Diet poor in calcium + protein
• smoking and alcohol use
• genetics
• hormone-related conditions
• hyperthyroidism
• diabetes mellitus
• use of certain medications-especially steroids

Question 6

Treating osteoporosis

Answer 6

• calcium and vitamin d supplements
• regular weight bearing exercise
• hormone replacement therapy-can slow bone loss but can increase of heart attack, stroke, and cancer

Question 7

Prevention Techniques for osteoporosis

Answer 7

• plenty of dietary calcium in early adulthood
• reduced consumption of carbonates beverages and alcohol
• plenty of weight bearing exercise

Question 8

Paget’s disease

Answer 8

• excessive or haphazard bone deposit and resorption; causes bone to grow quickly and poorly
• high ratio of spongy to compact bone with reduced mineralization
• typically occurs in spine, pelvis, femur, or skull
• rarely occurs before age 40
• affects about 3% of elderly people in North America
• cause is unknown-possibly triggered by a viral infection
• treatment: biphosphates and calcitonin (which beings down calcium levels)

Question 9

Developmental Timeline of Bone

Answer 9

• children/adolescents: bone formation exceeds resorption; males tend to have greater overall bone mass
• young adults: bone formation = bone resorption
• adults: bone resorption exceeds formation
  Changes in bone density are largely determined by genetics-a single gene that codes for Vitamin D’s cellular docking site
• beginning in the 4th decade of life, bone mass, bone mineralization, and bone’s ability to repair decreases

Question 10

Developmental Aspects of bone

Answer 10

• embryonic skeleton ossifies predictably so fetal age can be easily determined on x-ray / sonogram
• most long bones being ossifying by 8 weeks - primary ossification centers are well developed by 12 weeks
• at birth, most long bones are well ossified - except the epiphyses (bones still need growth)
• epiphyseal plates persist through childhood and adolescence
• by age ~25, all bones are completely ossified and skeletal growth ceases