Septic Arthritis: Symptoms, Diagnosis & Treatment

Septic arthritis is a bacterial infection that affects a joint. It can develop after surgery, as a result of injury, or due to an infection in another part of the body, such as a urinary tract infection or a skin wound.

The joints most often affected by septic arthritis are the knees and hips, although the infection can occur in any joint in the body.

Septic arthritis can be cured, but treatment must start in the hospital. It typically involves intravenous (IV) antibiotics and joint drainage using a needle. Afterward, physical therapy is needed to restore joint movement and prevent stiffness and pain.

Main symptoms

The main symptoms of septic arthritis include:

• Inability to move the affected joint;

• Severe pain when moving the affected limb;

• Swelling and redness in the joint;

• Fever above 100.4°F (38°C);

• Burning sensation in the joint.

Septic arthritis causes progressive damage to the joint and can lead to its destruction if not diagnosed and treated promptly.

The condition is more common in children and older adults with infected wounds near joints. It is also more frequent in people with autoimmune diseases or chronic conditions such as diabetes or cancer.

The knee and hip joints are the most commonly affected. Hip infections in children are especially serious because they can interfere with bone and joint development.

Symptoms of septic arthritis in children

The main symptoms of septic arthritis in babies and children include:

• Crying when the infected joint is moved;

• Mild fever, in some cases;

• Inability to move the affected limb;

• Irritability;

• Swelling and redness of the joint.

Septic arthritis is most common in children under 3 years old and typically affects the knee, hip, or ankle joints.

Confirming a diagnosis

Diagnosis of septic arthritis should be made by an orthopedic surgeon based on symptoms and medical history.

To confirm the diagnosis, the doctor may order tests such as X-rays, blood tests, and a joint aspiration, in which a sample of synovial fluid is taken from the joint to be analyzed in the lab. This helps identify the microorganism causing the infection in order to guide appropriate treatment.

Main causes

Septic arthritis occurs when bacteria infect the synovial fluid and tissues surrounding a joint. The main causes include:

• Infections in other parts of the body, such as skin or genital infections;

• Infected wounds;

• Foreign objects penetrating the skin;

• Open fractures;

• Skin injuries.

The bacteria most commonly associated with septic arthritis are Staphylococcus aureus, gram-negative bacilli, Streptococcus species, and Haemophilus influenzae.

Treatment options

Septic arthritis is considered a medical emergency. If it is suspected, it is important to seek hospital care immediately.

Treatment usually starts in the hospital, where tests are performed and medication is given to relieve pain. Once test results are available, intravenous antibiotics are started to help eliminate the infection.

Hospitalization continues until symptoms improve, but antibiotic treatment must often be continued at home for as long as prescribed by the doctor to ensure that all bacteria are fully eliminated.

Physical therapy

As recovery progresses, the doctor may recommend physical therapy to help restore movement in the affected limb. These exercises should continue until the joint regains normal mobility or as close to normal as possible.