What is the mechanism of inflammation in joint and soft tissue injuries treated with corticosteroid injections?

Updated: Mar 01, 2019
  • Author: Jess D Salinas, Jr, MD; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Answer

Answer

Inflammation is one of the body's first reactions to injury. Release of damaged cells and tissue debris occurs upon injury. These expelled particles act as antigens to stimulate a nonspecific immune response and to cause the proliferation of leukocytes. Local blood flow increases to transport the polymorphonuclear leukocytes, macrophages, and plasma proteins to the injured area. A redistribution of arteriolar flow produces stasis and hypoxia at the injury site. The resulting infiltration of tissues by the leukocytes, plasma proteins, and fluid causes the redness, swelling, and pain that are characteristic of inflammation.

Inflammatory muscle and joint injuries are associated with many causes, including the following:

  • Muscle strains

  • Polyarthritis

  • Connective tissue disease

  • Degenerative joint disease (DJD)

  • Neoplasm

  • Inherited congenital disorders

  • Miscellaneous systemic diseases

Initially, the inflammatory reaction serves several important purposes. The influx of leukocytes facilitates the process of phagocytosis and the removal of damaged cells and other particulate matter. Pain and tenderness remind the patient to protect the injured area; however, the inflammatory reaction eventually becomes counterproductive. The extravascular pressure exerted by the edema may retard blood flow into the area and delay healing. Sometimes, the debris coagulates and forms hard masses, scarring, and/or trigger points in the muscle or joint, preventing normal function from returning.


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