Definition

Septic arthritis (SA) is a joint infection. The joint reacts to it by filling with pus. It may also become swollen.

Causes

Bacteria is the most common cause of this infection. Viruses and fungi can also cause infection.

The infection may be started by an organism:

• That has entered the blood from an infection somewhere else in the body
• That entered the blood from IV drug use
• That is outside the body and entered through a wound or incision from surgery

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Risk Factors

This problem is more common in older adults. Things that may raise the risk in adults are:

• Taking medicines or having health problems that weaken the immune system, such as HIV
• A history of joint problems or having other types of arthritis
• Joint replacement or organ transplant surgery
• Long-term health problems, such as diabetes
• Recent joint injections
• A history of IV drug use

This problem is also more common in children who are male and those who are under 3 years old. Things that may raise the risk in children are:

• Trauma
• A weakened immune system
• Respiratory distress syndrome
• Having an umbilical artery catheter
• History of a urinary tract infection

Symptoms

The knee, hip, shoulder, ankle, elbow, and wrist are the most common sites in adults. Problems may be:

• A warm, red, painful joint
• Joint swelling
• Problems moving the joint or limb
• Fever

The knee and hip are the most common sites for SA in children. Problems may be:

• Crying when a joint is moved, such as during a diaper change
• Warmth and redness
• Swelling
• Problems moving a joint or limb
• Problems walking
• Fever

Diagnosis

You will be asked about you or your child’s symptoms and health history. A physical exam will be done. Your doctor may refer you to a specialist.

Tests may be done to look for signs of infection. This can be done with:

• Joint fluid tests
• Blood tests

Images of the area may be taken. This can be done with:

• X-rays
• MRI scan

Treatment

The goal is to treat the infection. This is done with antibiotics.

Fluid may be removed to ease pressure in the joint. This may be done with a needle or through surgery.

Prevention

There are no known guidelines to prevent this problem.