A total knee replacement involves surgery to open up the knee and replace the knee bones. Like any other major surgery, knee surgery has risks. One of the most serious risks is postoperative infection, where bacteria on the skin and in the environment infect the surgical site. While infection is rare, knowing the signs and symptoms is important so the infection can be treated.
Redness and Swelling
When bacteria infect the surgical site, the immune system responds by sending white blood cells to the site of the infection. As the white blood cells fight the invading organisms, they release chemicals called cytokines that kill bacteria. Coincidentally, cytokines also destroy adjacent cells. That destruction results in redness and swelling.
The same cytokines that are used to fight the infection also trigger a rise in body temperature. Fever works to fight infection since the bacteria causing the infection are not able to survive in the higher temperature environment as their proteins begin to break down. Unfortunately, a sustained fever may cause damage to sensitive organs such as the brain. This is why a fever must be controlled with medication.
Some infections may not result in anything more than an exudate (pus) coming out of the surgical site. The exudate is made up of proteins secreted by the body and white blood cells and bacteria. While some oozing is normal after surgery, if the exudate is yellow or smells foul, it should be cause for concern.