Why Does Healing of a Soft Tissue Injury Take Up to Twelve Months or More?

Recent research done in Australia1 and the U.S.2 indicates that the healing of a soft tissue injury (muscles, ligaments, tendons, etc.) may take up to twelve months or more and occurs in three phases:

Phase I: Inflammation: This initial phase lasts seventy-two hours or more. The impact of the injury ruptures the tissues, particularly the capillaries, resulting in debris-strewn gaps between the healthy tissues. With the oxygen carrying capillaries damaged, an oxygen poor environment is created. The immediate cellular response is from the cells that require little oxygen such as mast cells, macrophages, and granulocytes. (These are all immune system “clean-up” cells.) Visible signs such as swelling, redness, and pain may or may not be present at this time.

Phase II: Repair / Regeneration: This phase lasts up to six weeks or more. The early part of this phase is concerned with capillary restoration and the clean up of the debris. Macrophages and granulocytes devour debris (similar to the cleaning crew on a construction site) as the capillary system regenerates and brings oxygen and nutrients back into the injured area. Once there is available oxygen, collagen proteins are necessary to bridge the gaps in the soft tissue created by the injury and clean up. Unfortunately, instead of being a strong flexible criss-cross pattern of the original tissue, this repair tissue is characterized by a weaker, stiffer, and more pain sensitive rope-like pattern.

Phase III: Remodeling: This final phase of healing lasts up to twelve months or more. In this phase, collagen is remodeled to increase functional capabilities in the healing region. It is important that controlled motion be introduced during this phase. When motion is introduced the collagen fibers will slowly arrange themselves more like the original pre-injury tissue. Motion also minimizes the weakness, stiffness and pain sensitivity of the healing tissue. Each of the three types of motion (active- the patient moves, passive- someone else moves the area and para physiological – the end range of motion) has a role in the remodeling process. The more complete the remodeling process, the less likely the patient will suffer future aggravations or exacerbation of the injured areas.