Understanding the Physiological Stages of Healing Process – What’s really going on beneath the surface?
The process of recovery from traumatic physical injury depends on a number of factors, including injury type, severity, and location. Physical trauma disrupts the balance of normal cellular function and triggers the beginning of complex physiological repair processes. In some cases, this repair ultimately leads to normal or almost normal function. In others, the result may be lingering pain or impaired function of the damaged tissue. Some areas of the body can perform near normal after scar tissue repair, but others may perform less optimally.1 Understanding the process that occurs following an injury can give you more control over the pain and healing process, which may seem slow at times.
On initial injury, the protective membrane around some of the cells may break open, leading to the death of these cells. Other cells may be physically compromised, but less severely. Injury may also lead to disruption of blood supply to the tissue, which can cause depletion of oxygen to certain cells. Without oxygenated blood, affected cells may not be able to produce enough ATP, which is the energy the body needs to recover.
The process of healing begins almost immediately after the injury occurs and is categorized by three phases. These are:
Healing Process Phase 1 – Initial Inflammation
During the first phase, the body initiates processes to form blood clots in the injured area and begin acute inflammation. After injury to a blood vessel, the body releases chemicals near the site of the injury that trigger an immediate tightening of the vessel via a process called vasoconstriction. Chemicals also trigger blood platelets to adhere to exposed parts of the tissue in order to create a plug. Then, through a series of transformations triggered by enzymes, blood coagulation factors are activated and this promotes the formation of protein fibers that further strengthen the clot.1
This inflammatory period in the healing process can last several days. During this time, white blood cells are attracted to the area through chemical signals, such as leukotrienes. Fluid from blood vessels leaks into the surrounding tissue and triggers the characteristic signs of acute inflammation and injury: redness, swelling, and warmth.1,3
Local nerve cells are also triggered during this process and work to send pain signals to the spinal cord and brain. Depending on the injury, immune cells may be triggered, leading to other symptoms, such as fever. At the end of the inflammatory period, cells known as monocytes arrive and work to clean up dead cells and any foreign matter at the site of the injury.1,3
Healing Process Phase 2 – Rebuild & Repair
Platelets in the blood also release chemicals that help initiate the longer-term processes of healing that occur during the reparative phase. These chemicals attract cells to the site of the injury. These cells begin the process of rebuilding by producing the cells that make up the extracellular barrier, as well as large amounts of collagen that make up scar tissue.1,3 The length of time and success of this reparative process depends largely on the location and severity of the injury. For example, in an ankle tendon that has been injured through a sprain, this reparative phase can take up to three to six weeks. The reparative period may be shorter in parts of the body with better blood flow.2
Healing Process Phase 3 – Remodeling & Strength Training
The final remodeling phase of healing may last several weeks, months or even years. During this time, the muscles around the injured area should be challenged with strength training. Stressing the muscles and connective tissues stimulates growth and improved function, and is therefore essential to recovery. For example, in the process of healing an ankle tendon the original tissue used to heal the injury begins as very fibrous and then transforms to a stronger scar tissue during the final remodeling phase. Collagen tissue fibers, originally arranged somewhat haphazardly in the rush of healing the injured tendon, are reorganized in order to better support the tension of muscles.2
Given this step by step process of healing, it probably makes sense that until all three phases are complete, the tendon or injured area may be more easily re-injured. The tissue used during the repair is simply not as strong as it was originally, prior to the injury, and may never be.2 In some cases, such as for ankle tendons, this can contribute to chronic instability of the joint. At other times, acute injury can evolve into a chronic low-level inflammation causing unresolved pain and irritation in the area.1
If chronic pain and/or dysfunction do develop, different treatments can be applied to help re-stimulate the area and re-initiate the stages of healing. Deep tissue massage or electrical muscle stimulation (such as H-Wave) can reignite the inflammation phase by increasing circulation and lymphatic flow. Stretching, exercise and physical therapy can also assist with rehabilitation. Knowing what’s happening on a cellular level should give you insight to the healing processes that your body goes through, and hopefully prepare you for a faster, safer and more effective recovery from injury.
References:
- Kumar V, Abbas A, Fausto N. Pathologic Basis of Disease. 7th ed. Philadelphia, PA: Elsevier Saunders; 2005.
- Robi K, Jakob N, Matevz K, Matjaz V. The physiology of sports injuries and repair processes. In: Hamlin M, Draper N, Kathiravel Y, eds. Current Issues in Sports and Exercise Medicine. InTech. DOI: 10.5772/56649.
- Scott A, Khan KM, Roberts CR, Cook JL, Duronio V. What do we mean by the term “inflammation”? A contemporary basic science update for sports medicine. Br J Sports Med. 2004;38:372–380. DOI: 10.1136/bjsm.2004.011312.
- Herb CC, Hertel J. Current concepts on the pathophysiology and management of recurrent ankle sprains and chronic ankle instability. Curr Phys Med Rehabil Rep. 2014; 2:25–34. DOI 10.1007/s40141-013-0041-y.