Bone Remodeling and Bone Repair
Bone Remodeling
Remodeling is process of creating new bone and removing old bone.
Bone remodeling is lifelong process where mature old bone tissue is removed from skeleton (bone resorption) and new bone tissue is formed (ossification).
These process also control reshaping or replacement of bone following injuries like fractures, microdamage.
Remodeling occurs in response to new stress applied to bone, increasing bone strength.
Remodeling occurs during repair of broken bones.
Bone Healing
Bone healing or fracture healing is proliferative physiological process in which body facilitates repair of bone fracture.
In fracture, the broken end of bone are joint by deposition of new born.
Bone healing occurs in Three primary stage;
1. Inflammatory stage
2. Repair stage
3. Remodeling stage
1. Inflammatory stage
In inflammatory stage haematoma develops with fracture site during first few hours and days between ends of bone and in surrounding soft tissues.
Inflammatory cells (macrophages, monocytes, lymphocytes) accumulate and fibroblast migrate to site; granulation tissue and new capillaries develop.
2. Repair stage
This is stage where fracture get healed, i.e bone ends becomes joined and stabilized.
During repair stage, fibroblasts begin to supporting framework that helps support vasular in growth.
In this stage new blood vessels for new growth are also developed.
New bone forms as large number of osteoblasts secrete spongy bone, which unites broken ends, and is protected by outer layer of bone and cartilage; these new deposits of bone and cartilage are called soft callus.
The hardening of cartilage begins at each end of fracture, bony or hard callus, forming a bridge of woven bone between fracture fragment.
All of woven bone and cartilage of original fracture callus is replaced by trabecular bone, restoring most of bone's original strength. This stage can last 1-2 months after fracture.
3. Remodeling stage
Fracture healing is completed during remodeling stage in which healing bone is restored to it's original shape, structure and strength.
Adequate strength is typically achieved in 3 to 6 months.
1. Infled area; haematoma and bone fragments
2. Phagocytosis of clot and debris.
Growth of granulation tissue begins.
3. Osteoblast begins to form new bone (callus).
4. Mineralization of callus to bridge gap.
5. Bone almost healed, osteoclasts reshape and new bone formed.
0 Comments