Originally scheduled for publishing, September 1996
Karen Holzer
Following injury, be it acute or chronic, the tissue involved, regardless of it’s type, must undergo a process of repair in order to reduce the symptoms and regain function. This often involves the development of scar tissue, if significant tissue disruption has occurred which replaces the damaged tissue. The functional implications of the scar tissue depends on
- the tissue involved
- the function of the tissue
- the degree of organization or disorganization of the scar tissue
- the stresses applied to the tissue
Injuries can be classified according to the tissue type in which they occur.
These include
- the soft tissues, involving skin and deep fascia
- hard tissues, involving bone
- specialized tissues or organ injuries, eg the brain and nervous system, the thoracic, abdominal and pelvic organs, the eyes, nose, sinuses and teeth.
There are three phases of repair that can be applied to all tissue types. These are
Stage 1 The acute, inflammatory response
This occurs 0-72 hours post injury.
Immediately following tissue injury there is cell death and subsequently a uniform vascular response to the injury occurs.
Damage to the capillaries within the tissue leads to haemorrhage followed by short-lasting reactionary narrowing of the blood vessels known as vasoconstriction.
A subsequent vasodilation occurs with a leakage of plasma from the damaged vessels. This deposits blood-clotting factors including fibrin, within the damaged tissue, which acts to plug the damaged capillaries as well as blocking the lymphatic drainage from the area.
image of a fibronogen alpha chain
The combination of the vasodilation and decreased lymphatic drainage from the injured area results in the classical signs of
- redness
- swelling
- heat
Pain occurs as a result of local tissue pressures and release of special mediators of inflammation from the damaged cells.
The mediators include
- Prostoglandins, which act to stimulate the vascular system. Increase the permeability and stimulate lymphatic flow
- Growth factors which act to promote the formation of fibrous tissue as well as attracting white blood cells into the area which remove the damaged tissue. The white blood cells release further growth factors important for the progression of the repair process.
Stage 2 Matrix and cellular proliferation phase
This occurs 72 hours – 6 weeks post injury.
This phase is characterized by the proliferation of capillaries and fibroblasts, specialized cells, which together synthesize the “granulation tissue” the specialized connective tissue used to replace the damaged tissue.
Stage 3 The re-modeling and maturation phase
This occurs approximately 6 weeks –several months post injury.
This phase involves the contraction, re-orientation and maturation of the laid down granulation/scar tissue.
The scar tissue never has identical properties to that of the original tissue.
This is particularly noted within specialized tissues such as ligaments and tendons where the scar tissue has reduced strength and elastile properties, particularly if a large amount of disorganized tissue with adhesions occurs. The degree of organization/disorganization thus, has long-term functional implications for the involved tissue structure.
In order to optimize tissue healing and repair it, it is important to minimize the formation of disorganized scar tissue. This involves the early application of the RICE regime in conjunction with local physiotherapy and non-steroidal anti-inflammatory drugs following the immediate phase, in order to minimize the uncontrolled bleeding and oedema.
Over the next 3-6 weeks a graduated mobilization program is important, which acts to allow for organized connective tissue repair and re-modeling, ultimately resulting in an oriented load-bearing repair without adhesions.
Both excessive mobilization and prolonged immobilization adversely affects tissue healing and thus the long-term functional consequences of the injury.
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