Does septic arthritis cause knee swelling?

Septic arthritis occurs when germs enter the fluid and tissues of a joint. The immune response can produce extra fluid, causing the knee to look puffy and feel tight. Pain, warmth, tenderness, redness, and marked difficulty bending or bearing weight may occur as well. Fever, chills, or feeling generally unwell can accompany the joint symptoms, but their absence does not safely rule out infection.

Knee swelling has many possible explanations, including injury, osteoarthritis, crystal arthritis, or another inflammatory condition. Swelling alone cannot establish the cause. A clinician may examine the joint and arrange blood tests or take a sample of joint fluid to check for infection and guide treatment.

If the knee became swollen over a short time, especially with severe pain, warmth, fever, or trouble walking, contact an urgent medical service today. Keep weight off the knee as much as practical while arranging care. Do not try to drain the swelling yourself, and do not use leftover antibiotics; the wrong medicine can delay the correct diagnosis and treatment. Tell the clinician about recent wounds, injections, surgery, infections, bites, or medicines that affect your immune system.

Seek emergency help if knee swelling is accompanied by confusion, fainting, severe weakness, breathing difficulty, or rapidly worsening illness. Arrange same-day assessment for a hot, red, very painful swollen knee; a new inability to move or bear weight; or fever or chills with joint symptoms. Septic arthritis can damage the joint if treatment is delayed, so do not wait for the swelling to settle on its own.

You could ask: What findings make infection more or less likely? Do I need joint-fluid testing or blood tests? What symptoms should prompt emergency care? Which pain-relief options are suitable for me while the cause is being checked?