Septic Arthritis

What is septic arthritis? 

Septic arthritis, also called infections arthritis, is a quick-developing infection that occurs in the joint fluid and tissues. The infection causes intense pain and inflammation in the joints, requiring immediate medical attention to drain the infection and employ antibiotics to keep the infection from spreading. Cases of septic arthritis are rare and affect roughly 20,000 people in the United States each year. 

While anyone can get septic arthritis, the condition is most common in infants, young children, and older adults. The infection can cause lasting damage if not treated promptly, so you should seek emergency medical attention if you notice symptoms of an infection in your joints.

What causes septic arthritis?

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Septic arthritis is caused by fungi, bacteria, or other viral infection that enters the body, travels the bloodstream, and settles in the joints. The resulting infection creates the symptoms of septic arthritis and contributes to the damage to the joints and surrounding tissue. The main sources of the infection are the following:

  • Staphylococcus aureus: Commonly known as staph, this bacterium is the most common bacteria at the root of septic arthritis. Staph is a normal presence on the outside layers of skin, making a staph infection much more likely to occur when there is damage to the skin and open wounds. 
  • Neisseria meningitidis (meningococcus): While rare, septic arthritis can result from the bacterium that causes meningitis, which results in inflammation of the brain and spinal cord. 
  • Methicillin-resistant Staphylococcus aureus (MRSA): HIV and conditions that require IV treatments can be vulnerable to septic arthritis caused by MRSA, which is resistant to some types of antibiotics. 
  • Groups A and B streptococci: These types of bacteria are common in a variety of different diseases. Older people are more likely to develop septic arthritis because of bacteria of streptococci origin. 
  • Neisseria gonorrhoeae: This bacterium that causes the STD gonorrhea also can cause a case of septic arthritis if the infection is already within the body. 

Germs and bacteria can enter the body through injuries to the joints, other injuries or wounds across the body that invite outside infection, preexisting infection, or medical treatments that require surgery or injections. Given the multiple causes of septic arthritis, it is important to properly dress wounds and monitor for signs of infection to detect septic arthritis and seek immediate treatment.

What are symptoms of septic arthritis?

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The symptoms of septic arthritis can resemble the symptoms of other forms of arthritis and common conditions, so an accurate diagnosis can confirm if the symptoms are resulting from septic arthritis. Most cases of septic arthritis occur in one knee, but symptoms can appear in other joints, like the shoulder, elbow, hip, finger, and wrist. Common symptoms including:

  • Intense pain one or more joints that worsens 
  • Fever
  • Noticeable swelling in one or more joints 
  • One or more joints that are warm to the touch and red
  • Weakness or fatigue 
  • High heart rate 
  • Limited movement and range of motion in the joints 
  • Loss of appetite 

The core symptoms of septic arthritis can vary from person to person, depending on a number of risk factors along with any prescription medications a person takes. Symptoms can develop over a period of a few hours to a few days, and symptoms tend to get worse over time. Be sure to speak with a doctor as soon as you notice any symptoms of infection or inflammation in the joints that are out of the ordinary as you could be in the early stages of a case of septic arthritis.

Are there any risk factors or groups for septic arthritis?

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There are risk factors and groups who face a higher likelihood of septic arthritis. If you find yourself at a higher risk for septic arthritis, you should see your doctor regularly and inform them of any new or worsening symptoms impacting your joints to try and prevent the onset of an infection. The following risk factors make a person more likely to develop the condition. 

Weakened immune system: People with conditions that result in a weakened immune system like diabetes or kidney problems lessen the body’s ability to fight off infection and could allow a septic arthritis infection to fester with more speed. 

Preexisting joint conditions: Gout, rheumatoid arthritis, and lupus are all examples of existing joint conditions that make a joint infection more likely. Since the joints are already weakened from these conditions, the body has an even harder time fighting off infection in the vulnerable joint areas. 

Recent joint damage or joint surgery: Any new wounds or injuries that are not fully healed or properly dressed leave the body susceptible to an outside infection that can cause septic arthritis. Repeated injuries increase the risk more. 

Medical treatments: Medical treatments that are immunosuppressants or that are administered via IV pose a higher risk for a joint infection. 

Artificial joints: People with artificial joints may experience mild symptoms of septic arthritis and may not detect an infection until more fully manifested. In addition, the surgery to replace the joint introduces bacteria both through the procedure and from the artificial joint itself if it is not cleaned properly.

How is septic arthritis diagnosed?

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Septic arthritis is diagnosed by a doctor or medical professional who assesses the joint and conducts tests to identify what may be causing the infection. Your doctor may also review your medical history to see if there are any risk factors that could signal septic arthritis. There are tests that doctors will use to diagnose a case of septic arthritis, including:

  • Aspiration: During an aspiration test, the doctor inserts a needle into the inflamed joint to collect a sample of the synovial joint fluid. The fluid is then lab tested where the analysis of the sample of fluid provides information on what bacteria is causing the infection.
  • Blood test: A blood sample is used to check for white blood cell counts to indicate the presence and severity of an infection. 
  • Imaging tests: Imaging tests like X-rays and MRIs can be useful in identifying the scope and precise location of the infection in the joint. In addition, imaging tests help doctors assess the damage to the joints and surrounding tissues. 

The information from these tests helps your doctor rule out other conditions and confirm a septic arthritis diagnosis to begin to form a treatment plan.

How is septic arthritis treated?

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Treating septic arthritis more likely than not will involve a stay in the hospital to ensure the infection does not spread to other areas of your body or create other complications. During a hospital stay, you will be given a course of IV antibiotics which will work quicker to fight the infection in the joint. Depending on the infection, part of the treatment will be to drain the joint of excess fluid to restore movement and remove any infected fluid. In many cases, surgery is required to access the joint to clear away damaged tissue or bone and replace the joint. 

After the more intense course of treatment with IV antibiotics and surgery, doctors will often prescribe physical therapy to help the joints recover and build back strength after the infection. In addition, your doctor may prescribe oral antibiotics or pain relievers to manage the lingering symptoms of the infection and the pain of the healing process.  

Should you see a doctor for septic arthritis?

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If you think you have an infection in one or more of your joints, you should see a doctor or emergency medical professional as soon as you can. Septic arthritis is cause for immediate concern and needs aggressive and prompt treatment to resolve. The only way to diagnose septic arthritis definitively is by lab tests to confirm the source and location of the infection. 

As soon as you notice the symptoms of a joint infection, take action to be able to start a course of antibiotics to limit damage and start seeing improvement of your symptoms. After treating a case of septic arthritis, be sure to routinely visit your doctor for a checkup to make sure any new infections are detected early and that no complications occur.

What is the outlook for people living with septic arthritis?

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Septic arthritis is treatable if caught early enough. A rigorous and aggressive course of treatment can resolve the infection and limit damage to the surrounding areas. Treatment will improve symptoms and let you return to your normal life. Catching the infection too late or not treating the infection at all can result in serious, sometimes life-threatening complications that put you at risk of widespread infection and significant damage to your joints. 

Generally, with the right medical attention, a person who has had septic arthritis will heal completely and notice their pain subside with physical therapy and regular exercise. Each person’s outlook will depend on their likelihood of developing septic arthritis another time or experiencing more serious complications of a resolved infection. Be sure to closely monitor your symptoms after an infection has been treated to ensure the infection does not recur.