Definition: Complex dynamic biochemical and physiological process to restore structure and function of damaged tissue.
Pathologic type of healing
Healing in humans is by regeneration or reparation. In regeneration there is regrowth of original tissue eg as occurs in bone, liver, epithelium. In reparation there is scar or fibrous tissue formation as occurs in muscle.
Historical perspectives (Eras in care of wound)
Era of laudable pus
Era of masterly inactivity
Era of active attempt to promote healing
Elements of healing
- Epithelialization: Epithelial lining regenerate from basal cells
- Connective tissue formation: Granulation to bridge gap
- Contraction: Pulling together of wound edges by myofibroblasts to reduce defect
Phases of healing
There are 3 phases of healing and each phase has phase has 3 components: Vascular, Cellular and Humoral
- Lag and migratory phase (AKA inflammatory or preparatory or demolition or substrate or exudative)
- Proliferative or Fibro-plastic
- Remodeling or Maturation
TYPES HEALING (3 types: primary, secondary and tertiary)
Primary (healing by primary intention): edges apposed at time of wounding, minimal granulation and contraction, fine scar/fibrous tissue
Secondary (healing by secondary intention): edges not apposed, granulation fill defect, wide and thick scar tissue
Delayed primary (healing by tertiary intention): wound edges apposed after 3-5 days of wounding before granulation formation, less thick fibrous tissue
CLINICAL TIME TABLE OF HEALING (for healing by primary intention)
(less variable timing)
Day 1: dolor, calor, rubor, tumor and loss of function, clot and fibrin glue
Day 2: epithelialization completed
Day 3-4: dolor, calor, rubor tumor, subsiding
Day 5-6: pain absent or limited immediate edge of wound
Day 6-10: pain absent, tensile strength high enough to remove sutures, presence of healing ridge-thickening beneath and around scar
Up to 12months: healing ridge present, scar pink, blanches, firm & raised, pulling and itching sensation
>12months: healing ridge disappear, no blanching, scar pale, flat and soft
Gaining of tensile strength
3.0% at 7 days (1week)
20% at 20 days(3 weeks)
40%% at 40 days(6weeks)
60% at 90days(12weeks)
80% at 1year (42 weeks
FACTORS THAT AFFECT HEALING:
- Factors that delay( Drugs/Disease, Emissions Local events Anoxia, Years(age)
- Factors that accelerate or promote healing : re-wounding , topical growth factors, cartilage derivative application, vitamin A, hyperbaric oxygen , ultraviolet light, electrostimulation
Complications of wound healing( early and late
Healing in specialized tissue
- Fetus: low TGF-beta in fetus for scarless healing, low inflammation
- Mesothelium: by metaplasia
- Bone(hematoma, traumatic inflammation and demolition, granulation, callus formation ,lamella bone formation , remodeling)
- Muscle: regeneration and fibrosis
- Tendon: regeneration and fibrosis
- Nerves: wallerian degeneration
- Intestine: regeneration of mucosa and fibrosis of deeper layers
- Cartilage: regeneration and osteogenesis
- Vascular endothelium: regeneration
- Fat cells: fibrosis
Assessment of wound healing
- Clinical : physical observation of symptoms and signs
- Biochemical : cytokine and growth factors , wound
- Laboratory : light microscopy, xenon perfusion, tensiometry, planiometry
Conclusion and Future trend: knowledge invaluable for surgeons that create wounds, application of growth factors and neutralizing antibodies to wound, attempts at scar-less healing as seen in fetus
