A knee infection occurs when bacteria accumulate in the knee joint. It will therefore contaminate the synovial fluid that lubricates the knee joint. Knee infections may result from surgeries, inflammation, or other reasons.

How do you know if you are having a knee infection?

You will experience:

  • Severe pain while moving the knee joint
  • Restriction in the knee movement due to pain and stiffness
  • Nausea and chills
  • Fever that extends for more than a day
  • Swollen knee
  • Irritation and inflammation of the knee

Knee infection causes

Common conditions causing knee infection are listed below.

  • Soft tissue infection: Also known as cellulitis, it is caused by staph bacteria. The bacteria usually habitats on the skin, and will enter into the knee joint through an open wound. Immunosuppressants and diabetic medications will increase the risk for this infection.
  • Knee infection post-surgery: Infection may arise at the site of artificial implants of knee replacement surgeries. As artificial implants are made of metal or plastic, their immune capability to combat bacteria will be low and could give rise to infections. Surgeries for repairing tendons or cartilage, meniscus repair, ACL, or PCL repair will also result in infections.
  • Bacterial joint inflammation: Also known as septic arthritis, it may result from a puncture wound, animal bite, or existing infection in the knee. Rheumatoid arthritis and immune suppressants will also increase the risk of infections.
  • Knee bursitis: Inflammation that affects the knee bursae, the fluid-filled sacs that protect and pad the knee. bacteria will enter into these sacs and develops into an infection.
  • Osteomyelitis: Infections that arise in the knee bursae and other knee parts will reach the bones. Also, traumatic injuries expose the bone to the air developing an infection. They are serious but rare infections.


Treating the infection at home could spread the infection into the bloodstream causing severe complications.

Medications: Your doctor will prescribe antibiotics to work on the bacteria, and reduce the infection. Antibiotics are also given intravenously to improve the infection. Oral antibiotics are to be taken until the infection is cleared completely.

Surgery: Arthroscopy is a surgical procedure where the infected fluid around the joint is removed. In minor cases, fluid is removed with the help of a large needle. In serious conditions, open surgery is needed to remove the fluid and damaged tissue.