Arthritis, Infectious

Septic arthritis is a painful infection in a joint. It happens when germs, like bacteria, get into the joint. These germs can travel to the joint through your bloodstream from another part of your body that's already infected. Alternatively, germs can enter the joint directly through a wound or injury, like a dog bite or a fall.

Babies and older adults are more prone to getting septic arthritis. People who have had artificial joints are also at higher risk. The knee is the most common joint affected, but septic arthritis can also affect the hip, shoulder, or other joints. The infection can quickly damage the cartilage and bone within the joint, making it crucial to get treatment right away. This damage can lead to long-term problems if not treated properly.

Treatment usually involves draining the infected fluid from the joint using a needle, or in some cases, surgery. Antibiotics are also typically necessary to kill the germs causing the infection. Early and appropriate treatment is vital to prevent long-term joint damage and other complications.

Septic arthritis is a serious condition that causes significant pain and makes it hard to move the affected joint. The joint might become swollen, red, and feel warm to the touch. You might also have a fever.

If septic arthritis develops in an artificial joint (like a knee or hip replacement), the symptoms can be different and may not appear right away. Sometimes, mild pain and swelling might not show up for months or even years after the surgery. This type of infection can also cause the artificial joint to loosen, leading to pain when you move the joint or put weight on it. The pain often goes away when you're not using the joint. In severe cases, the joint might come completely out of place (dislocate).

If a joint suddenly hurts badly, see your doctor right away. Getting treatment quickly can help prevent the joint from getting damaged.

If you have a replacement joint (like a hip or knee replacement), see your doctor if you feel pain when using it.

Septic arthritis is a joint infection. It can happen when bacteria, viruses, or fungi get into a joint. The most common cause is bacteria, like Staphylococcus aureus (often called staph). Staph bacteria are often found on healthy skin.

This infection can spread to a joint from another part of your body. For example, a skin infection or a urinary tract infection can sometimes spread through the bloodstream to a joint. Less frequently, an injury like a puncture wound, a drug injection, or surgery near a joint (such as joint replacement surgery) can introduce germs directly into the joint.

Joints don't have much natural protection against infections. When an infection occurs, your body's response—including inflammation—can lead to problems. Inflammation can increase pressure inside the joint and reduce the flow of blood to the area. This can further damage the joint.

Septic arthritis is a serious joint infection. Several things can increase your chances of getting it.

Joint Issues: If you already have joint problems like osteoarthritis, gout, rheumatoid arthritis, or lupus, you're more likely to develop septic arthritis. Past joint surgeries or injuries can also make you more vulnerable. This is because any existing damage or inflammation in the joint can provide a place for bacteria to grow.

Artificial Joints: Artificial joints, like hip or knee replacements, are at risk of infection. Bacteria can get into the joint during surgery, or they can travel there through the bloodstream from another part of the body.

Rheumatoid Arthritis Medications: People with rheumatoid arthritis often take medications to control their condition. Some of these medications weaken the immune system, making infections, including septic arthritis, more likely. This can make it hard to diagnose septic arthritis in people with rheumatoid arthritis because the symptoms can be similar to those of their underlying condition.

Skin Problems: If your skin is easily broken or doesn't heal well, bacteria can enter your body more easily. Skin conditions like psoriasis or eczema, infected skin wounds, and injection drug use all increase your risk of this kind of infection.

Weakened Immune System: A weakened immune system makes you more susceptible to infections. Conditions like diabetes, kidney problems, liver disease, and certain medications that suppress the immune system can put you at higher risk for septic arthritis.

Joint Injuries: Injuries to joints, like animal bites, puncture wounds, or cuts near a joint, can introduce bacteria into the joint space and increase the risk of infection.

Multiple Risk Factors: Having a combination of these risk factors significantly increases your likelihood of developing septic arthritis, compared to only having one risk factor. The more risk factors you have, the more important it is to be aware of the signs of infection and seek medical attention promptly.

Delayed treatment of septic arthritis can significantly harm the joint. This condition, where a joint becomes infected, can cause the joint to break down and become permanently damaged. If the infection affects a joint replacement (artificial joint), it could lead to the replacement loosening or even coming out of place.

Doctors use several tests to diagnose septic arthritis (a joint infection). These tests help them understand what's wrong and how best to treat it.

Checking the Joint:

• X-rays and other imaging scans: These pictures of the affected joint can show if there's damage to the joint itself, or if an artificial joint has become loose. This is important because a loose joint can be a sign of infection.
• Special scans (bone scans): If a doctor thinks you might have an infection in an artificial joint, especially if it's been more than a year since the surgery, a special scan might be used. This scan involves swallowing or injecting a small amount of a special radioactive substance. The scan helps highlight areas of infection.

Analyzing Joint Fluid:

• Joint fluid sample: The fluid inside your joints can change if you have an infection. Doctors can take a small sample of this fluid with a needle. A lab test of this fluid can identify the type of germ causing the infection. This helps doctors choose the right medicine to fight the infection.

Checking Your Blood:

• Blood tests: These tests look for signs of infection in your bloodstream. A small sample of blood is taken from a vein with a needle. This helps doctors see if the infection has spread beyond the joint.

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Treating Septic Arthritis: A Guide for Patients

Septic arthritis is a serious infection in a joint. Doctors typically use a combination of draining the infected joint fluid and taking antibiotic medications to treat it.

Removing the Infected Fluid is Key:

The first step is to remove the infected fluid from the joint. There are several ways to do this:

• Needle: A needle is inserted into the joint to drain the fluid. This is often a first option for less complex cases.
• Arthroscopy: A small incision is made, and a thin tube with a camera at the end (called an arthroscope) is inserted into the joint. Suction tubes are also used to remove the fluid. This method is often used for joints that are easier to access.
• Open Surgery: For some joints, like the hip, a larger incision might be needed to drain the fluid. This is a more invasive procedure, but sometimes necessary to get a thorough cleaning.

Antibiotic Treatment:

To choose the best antibiotic, doctors need to identify the specific germ causing the infection. Initially, antibiotics are usually given through a vein (IV). Once the infection is under control, the patient may be able to take the antibiotic by mouth (orally).

Treatment typically lasts from two to six weeks. While antibiotics are very effective, they can cause side effects like nausea, vomiting, diarrhea, or allergic reactions. It's important to talk to your doctor about possible side effects and how to manage them.

Artificial Joint Infections:

If an artificial joint is infected, the treatment plan often involves removing the infected joint and temporarily replacing it with a spacer. This spacer is a small device that helps keep the area clean and allows for antibiotic treatment. After several months, a new replacement joint can be put in.

If removing the artificial joint isn't possible, a doctor might clean the joint and remove damaged tissue while keeping the artificial joint in place. In this case, intravenous (IV) antibiotics are followed by oral antibiotics for several months to prevent the infection from returning.

Important Considerations:

It's essential to follow your doctor's instructions carefully throughout the treatment process. If you experience any unusual symptoms or side effects, contact your doctor immediately. Early and thorough treatment is crucial to prevent complications and ensure a full recovery.