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Inflammation is a natural bodily response to injury and is the first part of the healing process. 

The response of our tissues to injury

To treat an injury best, it is important to understand the way the body responds to injury, the way it heals and the things which affect healing for good or ill.

The body has biological time scales for inflammation and healing, which we need to fit into to get the best result.

When injury occurs

When we suffer an injury, our body goes through an organised, consistent process at the site of damage as it attempts to heal the area. When an injury occurs, what gets damaged are the body’s cells and blood vessels.

In a sprain, strain, bruise or crush injury, the network of blood vessels in the area is damaged, and oxygenated blood can no longer reach the tissues. This, and the direct force of the injury, causes cells to die, releasing chemicals which cause pain and encourage the next stages of healing.

The injured area then consists of blood escaping from blood vessels, dead and dying cells and cell debris. It’s a challenging, low oxygen environment, with the process being essentially the same with an injury to a ligament, tendon or a muscle. The size and severity of the injury are more important factors in management.

There are three phases to healing:

  • Inflammation consists of the body’s reaction to the injury and preparation for the repair phases
  • Proliferation consists of the cells producing the materials to repair the injury.
  • Maturing and remodelling consists of the new replacement tissue settling down to its final form and the slow changes in it over time.

The phases, though they follow on from each other, are not completely defined and do overlap to some extent. The inflammatory phase lasts about six days until it gradually gives way to the next.

The signs of inflammation

  • Pain is an obvious first sign of damage and inflammation, although pain can be less than expected or take a day or so to develop as inflammation proceeds.

    The pain is caused by the chemicals released by dead and dying cells, acting on the pain nerve endings. As the swelling develops, the pressure it causes may also produce pain.

  • Swelling may occur quickly with a severe injury or bleeding, or come up over 24 hours or more (up to four days in some cases) as tissue fluid seeps from the leaky blood vessels in the area.

    The blood vessel walls become leaky in response to chemicals released by the damaged cells, and the fluid which passes out into the tissues is high in white cells and protein.

  • Heat is a sign of the body’s intense activity in the area as it goes through the healing process. Blood is diverted to the area as thousands of small blood vessels dilate, resulting in increased warmth. Blood flow slows down in the small vessels and by four hours after injury, white blood cells are travelling out of the blood vessels and into the damaged tissues.
  • Redness occurs due to the same processes which cause increased heat in the area.

All this frantic activity reminds me of a demolition squad, madly knocking down things and carting them off so something new can be put in its place.

The blood has clotted, the macrophages (white blood cells, “big eaters”), move in to clear up debris and digest particles of cell and any bacteria. The way is being prepared for the next stages of healing. Once the cleanup has been completed, healing can proceed.


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