PRORehab Library

Understanding the Healing Process

Knowledge and understanding of the healing process is necessary in properly rehabilitating various musculoskeletal injuries. The progression of rehabilitation must be based primarily on how tissues respond physiologically to injury and how certain tissues heal. It is important for certified athletic trainers and physical therapists to be familiar with these processes in order to adequately supervise rehab progressions. Tissues follow a predictable sequence and time frame when subject to injury. Decisions on altering treatment plans are based primarily on the recognition of the signs and symptoms of this sequence. Although the healing process is a continuum, it can be broken down into 3 phases.
The first phase of the healing process is known as the inflammatory response phase. Once tissue is injured, the process of healing begins immediately. On a cellular level, metabolism is altered and certain symptoms occur. Redness, swelling, point tenderness, and increased temperature to the touch are some of the symptoms that characterize the inflammatory response. At this time, phagocytic cells arrive at the injured tissue and begin to dispose of injury-related waste products. A vascular response also occurs, which results in spasm, platelet plug formation, blood coagulation, and fibrous tissue growth. After an initial 5-10 minutes of vasoconstriction, a dilation of vascular tissue occurs. This increase of blood flow can last anywhere from 24-36 hours. This results in the release of chemical mediators. These mediators are responsible for exudates formation and the margination of cell walls. The next step in the initial inflammatory response is the formation of a clot. This helps to keep the response localized. This clotting starts at about 12 hours post-injury and is completed within 48 hours.
The second phase of the healing process is the repair phase. At this time, scar formation and repair of injured tissues occur. This is also referred to as fibroplasias, which begins within the first few hours after injury and can last up to 4-6 weeks. During this period, many of the signs and symptoms that characterize the initial inflammatory response have subsided. At this time, capillary buds begin to grow at the site of injury creating increases in blood flow and oxygen delivery. These increases are important for the arrival of nutrients necessary for the regeneration of tissue in the injured region. After a while, the clot begins to break down resulting in the formation of a very delicate form of connective tissue. This connective tissue is called granulation tissue. It consists of collagen, capillaries, and fibroblasts. Granulation tissue is necessary to fill in the gaps created by tissue injury. At 6-7 days post-injury, fibroblasts begin to randomly lay down scar tissue. This results in increased tensile strength and the beginning of the final phase of the healing process.
The final stage of healing is known as the maturation and remodeling phase. This long-term process features realignment of scar formation through added tensile forces. These forces result in increased strength of the scar matrix. By adding controlled stress loads, the scar formation begins to become parallel with these lines of tension. This produces maximum efficiency and the tissue slowly begins to appear normal and functional. Normally a strong scar exists by the end of 3 weeks. This final stage of remodeling and maturation can take up to several years to be totally complete.
There are some factors that can actually impede or slow down the healing process. Excessive edema or swelling can cause separation of tissues, inhibit neuromuscular control, and impede proper nutrition delivery to the injured area. Hemorrhaging also can have the same negative effects on tissue recovery. On the other, not enough blood to the area produces adverse effects. Tissues with poor vascular supply heal at a slower rate than other well vascularized tissues. Another impeding factor is muscle spasm and atrophy. Spasms cause traction on injured tissues and prevent approximation, while atrophy can limit strength gains. Infection is another way in which the healing process is slowed. The presence of bacteria can delay healing and cause excessive granulation tissue leading to scar deformity.
In conclusion, it is very important for the allied health care professional to understand the entire healing process. Rehabilitation programs must be designed in accordance with the stages of injury response. Certified athletic trainers and physical therapists must also be familiar with certain factors that impede healing. Avoiding these factors allows for timely return to the playing field or work place.

« back to complete listing