A knee replacement is performed to alleviate knee pain caused by trauma or arthritis. The surgeon performs the procedure through a vertical incision on top of the leg. When the surgery is complete, the incision is usually closed by stitches, metal staples or a combination of both. Some surgeons use stitches internally followed by medical-grade glue to close the top-most layer of skin. Regardless of the technique used to close the wound, a scar develops as a result of the body’s healing process.
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Formation of the Scar
The knee replacement incision, like any wound, heals in a three part process. The inflammatory phase, the proliferative phase and the remodeling phase take place to close a wound and repair the underlying tissue. The scar begins to form in the proliferative phase when the wound grows smaller and new skin cell growth occurs. New skin cells are formed and migrate over the top of the incision to close the skin. Remodeling occurs when the newly formed connective tissue that makes up the scar is arranged in the direction of the stresses the scar receives.
Features of the Scar
In the early stages of healing, the knee replacement scar looks mottled and bumpy. It usually presents with a loss of sensation due to the nerves that were cut during surgery. As the nerves heal, feeling along the scar slowly returns, although many people report that it does not return to pre-surgery levels. The scar gradually becomes less uneven as time goes by, but it does continue to contract in the latter stages of the healing process.
Care of the Scar
A primary consideration in the early stages of knee replacement rehabilitation is to encourage the incision to heal quickly and without infection. A healthy diet and drinking plenty of water allows the body to repair itself as rapidly as possible. Frequent hand washing reduces the likelihood of infection. There is no elasticity to scar tissue, therefore, the scar must be elongated enough in the remodeling phase so that it will allow full knee flexion to occur. As the scar becomes fully formed, continuation of the stretching program set up by the physical therapist is essential to keep the scar from contracting so much that it limits knee flexibility. The therapist may also prescribe cross-friction massage along the length of the scar to improve the final alignment of the collagen fibers and optimize healing.
Scar tissue is not as strong or resilient as the tissue it replaces. It is easier to damage a scar than it is healthy skin. Care must be given when resuming work and recreational activities after the knee replacement surgery so that the scar doesn’t become injured or re-open. The scar must also be protected from too much exposure to the sun. It has less protection than normal skin and should be covered with clothing or sun block lotion when outdoors to avoid serious sun burn.
There is no way to avoid a scar with knee replacement surgery. Some surgeons, however, use less invasive techniques that leave a considerably smaller scar on the surface of the knee, which will, of course, heal a bit faster. Even with the smallest of surgery scars, it is important to remember that every person heals at a different rate. Some knee replacement patients demonstrate complete scar formation and remodeling in only a few months, while others take a much longer time. The effectiveness of scar minimizing creams or lotions has not yet been proven by clinical research and should be avoided unless specifically ordered by a physician. Usually the scar from the knee replacement surgery fades to a pale thin line approximately 4 to 6 months after surgery.