Septic arthritis

Written by Dr Sheila Strover on March 14, 2025

Septic arthritis in deep infection within the knee joint. It is a dreaded complication of knee injury or surgery.

What causes septic arthritis?

Infection of the knee joint may occur as a result of infection elsewhere in the body, eg gonorrhoea, but is often the consequence of penetration of the joint either during injury or after surgical operation.

Back to top

What organisms are involved in septic arthritis?

There are many different organisms that can infect the knee - bacteria, viruses and fungi. Acute infections may be 'hospital acquired' such as staphylococcus. Chronic infections may be due to tuberculosis. Whatever the cause, the physician must send as aspirate to the laboratory to exactly identify the organisms involved and treatment must be specific to the infecting organism.

Back to top

Clinical signs of septic arthritis

Local signs of infection in the knee include swelling and heat. The skin may be red and shiny. The patient is also likely to have a temperature and feel very unwell.

Back to top