Bone Formation

Question 1

What are examples of intramembranous ossification?

Answer 1

1) embryonic flat bone formation (skull, maxilla, mandible, pelvis, clavicle, subperiosteal surface of long bone)
2) distraction osteogenesis bone formation
3) blastem bone (occurs in children with amputations)
4) fracture healing with rigid fixation (compression plate)
5) one component of healing with intramedullary nailing

Question 2

Which genetic disorder results in a defect in intramembranous ossification?

Answer 2

Cleidocranial dysplasia

Mutation in CBFA1 (also known as Runx2) on Ch 6

Question 3

What direction does physeal growth occur?

Answer 3

From the epiphysis to the metaphysis

Reserve zone-proliferative zone-hypertrophic zone-primary spongiosa (metaphysis)

Question 4

Sustained compression applied to a growth plate under experimental conditions has what effect?

Answer 4

Deceleration of longitudinal growth; Hueter-Volkman Law

Question 5

Which disease processes affect which area of the physis?

Answer 5

1) Reserve zone: Gaucher’s, diastrophic dysplasia
2) Proliferative zone: MHE, achondroplasia
3) Hypertrophic zone: SCFE, MED/SED, Salter-Harris fx (zone of provisional calcification), Rickets
4) Primary spongiosa: scurvy, corner fx

Question 6

What are the roles of the groove of Ranvier and perichondral ring of La Croiux in the physis?

Answer 6

Groove of Ranvier is responsible for apositional growth, perichondral ring is responsible for stability

Question 7

What region of the physis does collagen type X play a prominent role?

Answer 7

Zone of hypertrophy; important for collagen calcification