Response of bone to injury, use, aging

Question 1

Differentiate between a pressure epiphysis and a traction epiphysis

Answer 1

Pressure epiphysis: located at the ends of long bones, serves as articulation for joints and contributes to longitudinal growth of bone

Traction epiphysis: centers of ossification, site of tendon or ligament attachments. contributes to shape but not length of bone
aka apophysis

Question 2

List the three zones of the growth plate

Answer 2

reserve zone
proliferative zone
hypertrophic zone

Question 3

Describe the reserve zone of the growth plate

Answer 3

Closest to the epiphysis, cells produce and store the cartilaginous matrix. Blood
supply is poor, cells do not actively divide.

Question 4

Describe the proliferative zone of the growth plate

Answer 4

• cells synthesize extracellular matrix, actively divide, and are stacked in columns to produce longitudinal growth.
• best blood supply, for cellular nutrition and hormonal signals necessary for growth plate function.

Question 5

Describe the hypertrophic zone of the growth plate

Answer 5

• prepares the matrix for calcification and initiates calcification
• anaerobic metabolism

Question 6

Injuries to the _____ in immature people are never minor

Answer 6

physis/ growth plate

Question 7

In response to stress, bone remodels and forms bone best suited for ________

Answer 7

weight bearing

Wolff’s law: bone is deposited in areas best positioned to resist stress/ loads

Question 8

Physeal fracture types III, IV, and IV are most likely to disturb ____

Answer 8

growth, poorer prognosis

Question 9

Differentiate complete growth arrest vs partial growth arrest with a physeal fracture

Answer 9

complete growth arrest–> shortened extremity

partial growth arrest –> angular deformity +/- shortening

Question 10

Describe primary bone healing

Answer 10

• rigid internal fixation of fracture
• primarily cortical healing
• no callus formation
• cutting cones lead the vascular ingrowth and eventually osteoblastic bone deposition
• very slow

Question 11

Describe secondary bone healing

Answer 11

• some motion at the fracture site during healing
• callus formation stabilizes the fracture site
  most common form of healing

Question 12

______ develop due to repetitive micro trauma that eventually exceeds bone’s ability to repair

Answer 12

stress fractures

Question 13

X rays will often be _____ at initial clinical evaluation for stress fractures

Answer 13

negative

diagnosis can be made on repeat radiographs when callus formation is seen

Question 14

___ peaks by age 30, then eventually starts to decline after the 5th decade

Answer 14

bone mass

Question 15

Describe changes in bone mass in women after menopause

Answer 15

Both men and women lose cortical bone mass at a similar rate, however women after menopause have a more rapid decline in trabecular bone mass than men.

Question 16

Differentiate osteopenia, osteomalacia, and osteoporosis

Answer 16

osteopenia: general term for decreased bone density on radiographs
osteomalacia: impaired mineralization of bone matrix, problem of bone quality not quantity
osteoporosis: decreased density of bone, problem of bone quantity not quality

Question 17

What can cause osteomalacia?

Answer 17

nutritional deficiencies, GI absorption defects, renal tubular defects, toxins