Table 1.

General Cellular Events Associated with a Muscle and/or Tendon Injury⁷²

Time Frame After Injury	Cellular Events
First 48 hours	Initial vasoconstriction and coagulation upon rupture of blood and lymphatic vessels Immediate swelling at injury site caused by cellular components (e.g., exudate) leaking from the blood and lymphatic vessels leaking into wound area Clot formation Hallmark signs associated with an acute injury: redness, warmth, pain, and swelling Chemical mediators attracted to the site to control the inflammatory process Vasodilation occurs shortly thereafter the initial injury Phagocytosis (removal injured/dead cellular material)
Day 2 to 4	Reduction in inflammation Reabsorption of clot Increase in granulation tissue (fibroblasts, myofibroblasts, and capillaries) Angiogenesis
Day 4 to 21	Scar formation Production of collagen, elastin, and ground substance Growth of scar ceases at the end of the phase
Day 21 to 60	Scar remodeling Collagen thickens and strengthens