Bone - 2 -- VTPP 435

Bone - 2 -- VTPP 435

SOST Mutation

-mutation that causes bone mass to be high

2 Mechanisms to Heal Bone

(1) Direct (Primary) Bone Healing
(2) Indirect (Secondary) Bone Healing

Direct Bone Healing

-keep fracture still
-put pressure to push bones together to heal bone directly without endochondral formation
-Bone Modeling but not remodeling since there is only formation and no bone resorption
-no fracture callus
-needs direct contact like surgical intervention

Indirect Bone Healing

-most common
-callus formation heals naturally to self-repair
-occurs within an unstable mechanical environment
-non-rigid fixation
-stabilize wound but still needs some movement

Stages of Indirect Healing

1) Intact Bone and Periosteum
2) Injury & Inflammation
3) Early Callus Formation
4) Maturing Callus
5) Cartilage Vascularization
6) Cartilage Replaced by Bone
7) Bony Union

1) Intact Bone and Periosteum

-highly vascularized
-bone is intact

2) Injury & Inflammation

-blood supply is disrupted
-hematoma forms
-inflammatory cytokines get to work

3) Early Callus Formation

-Periosteal expansion
-granulation tissue

4) Maturing Callus

-becomes mineralized
-intramembranous (woven) bone at margins forms & is well vascularized

5) Cartilage Vascularization

-blood vessels enter
-precursors recruited to remodel

6) Cartilage Replaced by Bone

-osteoclasts come into help remodel the woven bone
-woven bone replaces cartilage

7) Bony Union

-Callus is completely remodeled