1. Repair
DR: Gehan Mohamed

2. Types of cells
Conteniously dividing cells (Labile): e.g epithelium, haematopoietic (blood). Quiescent (Stable): e.g hepatic, kidney and pancreas as their cells divide when there is need. Non-dividing (Permanent): nerve cells and skeletal muscle cells

3. Repair (healing)
Definition : Tissue repair involves replacement of damaged tissue with new healthy living tissue.
Types
Usually involves two separate but coordinated components
Regeneration:
healing by the same type of tissue cells from surrounding healthy living cells, this occurs with in small damages of labile cells and stable cells for examples liver cirrhosis and bone fractures
B) Fibrosis (scar tissue):
healing by granulation tissue (fibroblast with new capillaries formed) which mature a vascular fibrous tissue (scar), this occurs in the healing process of permanent cells and stable cells with high damage. for example myocardial infraction and wounds

4. Introduction to wond healing
The adult wound healing process can be divided into 4 distinct phases:
The homeostasis phase
the inflammatory phase
the proliferative phase
the remodeling phase.

5. Sequence of events in healing
Initial phase - Hemostasis
Following vasoconstriction, platelets adhere to damaged endothelium and discharge adenosine diphosphate (ADP), promoting thrombocyte clumping, which dams the Wound
The inflammatory phase is initiated by the release of numerous cytokines by platelets.
Fibrinogen is cleaved into fibrin and the framework for completion of the coagulation process is formed. Fibrin provides the structural support for cellular constituents of inflammation.
This process starts immediately after the insult and may continue for a few days

6. Sequence of events in healing
Second phase - Inflammation
Within the first 6-8 hours, the polymorphonuclear leukocytes (PMNs) or PNLs “cleanse” the wound, clearing it of debris. The PMNs attain their maximal numbers in hours and commence their departure by hour 72
As the process continues, monocytes also exude from the vessels. These are termed macrophages. The macrophages continue the cleansing process and manufacture various growth factors during days 3-4.
Many factors influencing the wound healing process are secreted by macrophages. These include TGFs, cytokines and interleukin-1 (IL-1), tumor necrosis factor (TNF)

7. Sequence of events in healing
Third phase - Granulation
This phase consists of different subphases which are:
fibroplasia
matrix deposition
angiogenesis
and re-epithelialization
In days 5-7, fibroblasts have migrated into the wound, laying down new collagen of the subtypes I and III
Angiogenesis is theThe formation of new vasculature which requires extracellular matrix and basement membrane degradation followed by migration, mitosis, and maturation of endothelial cells
Re-epithelization occurs with the migration of cells from the periphery of the wound and adnexal structures. This process commences with the spreading of cells within 24 hours. Division of peripheral cells occurs in hours 48-72, resulting in a thin epithelial cell layer, which bridges the wound.
This succession of subphases can last up to 4 weeks in the clean and uncontaminated wound.

8. Sequence of events in healing
Fourth phase - Remodeling
After the third week, the wound undergoes constant alterations, known as remodeling,
This can last for years after the initial injury occurred. Collagen is degraded and deposited in an equilibrium-producing fashion
The collagen deposition in normal wound healing reaches a peak by the third week after the wound is created.
Contraction of the wound is an ongoing process resulting in part from the proliferation of the specialized fibroblasts termed myofibroblasts, which resemble contractile smooth muscle cells.

9. Types of healing

10. Types of healing

11. Types of healing

12. Complications of the healing process
This process can go wrong and produce an increase of fibroblastic proliferation with a resultant hypertrophic scar
Further exuberance can result in keloid formation where scar production extends beyond the area of the original insult. Conversely, insufficient healing can result in atrophic scar formation.

13. Complications of the healing process
Weak scar: this may lead to hernia
Cicatrisation: contracture of the size of the scar
Implantation epidermiod cyst
Stump neuroma: following amputation causing a painful coiled mass of nerves
Sinus: is a track of septic granulation tissue connecting a cavity to the outside and has one blind end e.g. pilonidal sinus
Fistula: is a tract of septic granulation tissue connecting 2 epithelial surfaces
Infection : leading to delayed healing
Rarely scars may develop squamous cell carcinoma
Ulcers: discontinuity of the covering epithelium or muscle membrane

14. Fractures: Definition :Break in the bone. TYPES: Simple / Compound .
Single - Horizontal, oblique, spiral,
Comminuted – multiple.
Greenstick is a partial fracture common in children.

15. Types of Fracture:

16. Stages of wound healing
Remodeling
Vessel regression, Collagen remodeling
Proliferation
Reepithelialization, Angiogenesis, Fibrogenesis,
Inflammation
PMNs, Macrophages, Lymphocytes
Hemostasis
Fibrin clot, platelet deposition
1D 3D wk wk wk
Time after injury

17. Healing in Bone: 1D - Hematoma formation (fibrin mesh)
3D - Inflammation
1W - Soft callus – granulation, matrix.
3-6W - Callus – ossification, woven bone
8+W - Re-modeling – absorb/deposit, strength, lamellate.

18. Complications: Delayed healing. Non healing.
Joint involvement - ankylosis
Abnormal position – arthritis.
Bone necrosis – nutrient artery
Pseudoarthrosis

19. Factors affecting Healing:
Local factors which delay healing:
Mobilization of the fractured ends.
Improper reduction – abnormal position.
Infection. Debris, dead tissue in wound.
Joint involvement.
Poor blood supply to area of injury.

20. Factors affecting repair:
General factors which delay healing :
-bad nutrition
Starvation
Diabetes
Corticosteroid therapy
Chronic deblitating disease as T.B,malignancy
Old Age of patient.