BONE HEALING

Ketan D Deshpande Dept. of Orthopedics ESIPGIMSR MGM Hospital

Bone Histology

Cells in Bone

Bone Histology

Periosteum & Endosteum

BONE

Two forms of bone tissue

Cortical or compact bone Cancellous or trabecular bone

Two types of bone formation in healing(mechanical & biological properties)

Woven or immature bone Lamellar or mature bone

WOVEN BONE

More rapid rate of deposition & resorption Irregular woven pattern of matrix collagen fibril Four times the number of osteocyte per unit volume Irregular pattern of matrix mineralization

Less stiff & more easily deformed

FRACTURE HEALING

Sequence of fracture healing

Inflammation Repair Remodeling

Fracture HealingInflammation

Fracture damages the bone, blood vessels, bone matrix and surrounding soft tissue

Haematoma Inflammatory mediators

- Dilatation blood vessel- Plasma exudat- inflammatory cells- PMN lecocytes- Macrophages- Lymphocytes

Release byplatelets inj.cells

FRACTURE HEALING

Inflammation

MacrophageDegranulating platelets release

- Cytokines (PDGF, TGF ß )- Interleukin 1 & 6- Prostaglandin E2 (PGE2)

Invitiation of the repair process

FRACTURE HEALING

INFLAMMATION

Inflammatory Necrosis Tissue and Exudate Resorbed

Fibroplasty & Chondrocytes Appears

Produce new matrix(The fracture callus)

BONE HEALING

REPAIR

Growth factors Fibroblast Growth factor Angiogenesis Osteoclast Osteoblast Bone formation Mesenchymal cells Hard callus intramembranous bone Soft callus endochondral ossification Fracture callus matrix glycosaminoglycans, proteoglycans and collagen type I & III

BONE HEALING

REPAIR

Bone Healing

First phase of woven bone formation

Later phase in woven bone formation

Bone Healing

Chronology of mineralization in subchondral bone

BONE HEALING

Remodelling

Replacement of woven bone by lamellar bone Resorption of unneeded callus mechanical Stability

BONE HEALINGREMODELING

Remodeling of bone trabecula

Accretion and remodeling of bone

BONE HEALING

BONE HEALING

Fracture healing with rigid stabilization

* Healing with primary bone healing mechanism Gap healing Haversian remodeling

Osteoclast resorb fracture line deposition osteoblast

Blood vessels formation

new bone matrix + osteocytes form new Haversian

Systems or primary osteons

Bone Healing

Direct bone formation in stabilized gap bone

Courtesy AO Risert laboratory

BONE HEALING

Variables Influence Fracture Healing

INJURY VARIABLES

* Open Fractures

Impeding or preventing formation # Hematoma Delaying formation repair tissue Risk of infection

* Severity of Injury

Retard fracture healing

* Intra articular fractures

If the alignment & congruity joint surface is not restored Delayed healing or non union Joint stiffness

* Segmental fractures

* Soft tissue interposition

* Damage to the blood supply

INJURY VARIABLES

BONE HEALING

BONE HEALING

Variables Influence Fracture Healing

Patient Variables

* Age* Nutrition

Healing process needs

- Energy- Proteins & carbohydrates

WOLFF’s Law

The principle that every change in the form and the Function of a bone or in the Function of the Bone alone leads to changes in its Internal Architecture and in

its External Form

T H A N K Y O U !