Tissue Mechanics - Bone

Question 1

What are the phases of callus formation?

Answer 1

1. Hematoma Formation (immediately) - inflammatory phase with hematoma (blood outside vessels)
2. “Soft” Callus (0-2wk) - Fibrocartilage spans fracture ends, layer of woven bone is laid adjacent to periosteal layer and bone fragments
3. “Hard” Callus (2wk-2mth) - soft callus is resorted and calcifies, callus of immature bone forms
4. Bone Remodelling (2mth-2yr) - Hard callus is remodelled, callus replaced with lamellar bone. Evidence is erased in kids but may persist in adults

Question 2

What is the typical Elastic Modulus for callus?

Answer 2

1GPa

Question 3

What is one issue with rigid fixation?

Answer 3

Inhibits the production of large amounts of callus

Question 4

How is callus formation impacted by external fixation?

Answer 4

Higher formation than rigid internal fixation but less than a cast