Knee Replacement Infection Symptoms

Knee replacement surgery involves replacing a damaged knee joint with an artificial joint. As with any surgery, knee replacement poses risk for post-surgical infection 1. The American Association of Orthopedic Surgeons states that fewer than 2 percent of knee replacement surgeries become infected; however diligence in watching for symptoms of post-knee replacement infection is vital for early treatment should an infection occur 1. Infection symptoms can often be detected around the incision and may present as a single symptom, or grouping of symptoms.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Clear fluid may drain in small amounts from the incision after a knee replacement. This usually subsides within one to two days after the procedure and may cause crusting around the incision staples. Drainage which is colored, bloody or contains pus can indicate infection. Pus appears as cloudy, yellow or green-tinged drainage and may be thick or watery in appearance. Foul-smelling drainage, with or without the presence of pus, may also indicate an infection.

Skin Changes

Skin around the incision after a knee replacement can become red, irritated or inflamed if infected. The incision may become swollen along the skin edges or around the staples and have a red or flushed appearance. Additionally, skin over or around the incision can feel hot and may be painful to touch. Swelling may occur beneath or around the incision, causing the skin to feel hard or firm. These skin changes can be accompanied with pus or foul-smelling drainage.


Pain is common after a knee replacement due to the invasive disruption of bone and tissue. Discomfort in the knee may last for several weeks after surgery. However, pain can also be caused by a post-surgical infection and can cause a throbbing or sharp pain which is persistent. Infection-related pain may cause night waking and will not be relieved with rest. Pain may be difficult to assess immediately after knee replacement surgery if pain medications are used, however any pain which persists even with medication, or does not get better over time should be suspect for infection.


A fever may appear before other symptoms; indicating that the body is fighting infection. Fever may rise in conjunction with other symptoms of post-surgical infection. Chills or feeling unusually cold or flushed may also accompany a fever. Columbia University Medical Center advises that an oral temperature higher than 101.5 Fahrenheit is considered a fever and warrants medical attention.