How to Diagnose Septic Arthritis

Last Updated: July 19, 2022 References

Septic arthritis, also called infectious arthritis, is an infection of a joint.^{[1]
X
Expert Source

Siddharth Tambar, MD
Board Certified Rheumatologist
Expert Interview. 25 August 2020.} Bacteria or a virus that spreads to a joint or its surrounding fluid causes septic arthritis. In most cases, the infection starts in another part of the body and circulates through the bloodstream into the joint. People who develop septic arthritis usually have it in only one large joint such as the knee, hip or shoulder. You can diagnose septic arthritis by identifying its symptoms and seeking professional assessment.

Part 1

Part 1 of 2:

Determining Physical and Behavioral Symptoms

1
Recognize risk factors. Individuals of any age can develop septic arthritis. However, some people may be more susceptible to this condition. Children, older adults, and illegal drug users are more likely to have septic arthritis. Other risk factors include:^{[2]
X
Trustworthy Source
Johns Hopkins Medicine
Official resource database of the world-leading Johns Hopkins Hospital
Go to source}
- Having existing joint problems such as gout or lupus.
- Taking medication for rheumatoid arthritis.
- Having fragile skin that breaks easily.
- Having a weakened immune system.
- Having joint trauma such as animal bites or puncture wounds.
- Having recent surgery.^{[3]
  X
  Trustworthy Source
  MedlinePlus
  Collection of medical information sourced from the US National Library of Medicine
  Go to source}
- Taking immunosuppressants.
2
Watch for swelling. Septic arthritis generally comes on quickly.^{[4]
X
Trustworthy Source
MedlinePlus
Collection of medical information sourced from the US National Library of Medicine
Go to source} Symptoms are usually in one joint, though in rare cases may affect two or more areas.^{[5]
X
Trustworthy Source
Arthritis Foundation
Main organization devoted to arthritis support and education
Go to source} One of the most common symptoms of septic arthritis is swelling around the affected joint.^{[6]
X
Expert Source

Siddharth Tambar, MD
Board Certified Rheumatologist
Expert Interview. 25 August 2020.} This is caused by a buildup of infected fluid around your joint. Watching for swelling in one joint can help you diagnose septic arthritis.
- Pay attention to any warmth and redness that accompanies the swelling. This can also indicate septic arthritis.
Advertisement
3
Notice pain and immobility in the joint. The swelling caused by septic arthritis infection can also bring on mild to severe pain. It can also lead to an inability to fully move your joint.^{[7]
X
Expert Source

Siddharth Tambar, MD
Board Certified Rheumatologist
Expert Interview. 25 August 2020.} Watching for any pain and immobility in the joint can help you diagnose septic arthritis and seek prompt treatment.
- Recognize that your pain may get worse when you move the affected joint.
- Avoid forcing a painful joint to move. Septic arthritis may also lead to an inability to move the joint.^{[8]
  X
  Trustworthy Source
  MedlinePlus
  Collection of medical information sourced from the US National Library of Medicine
  Go to source}
- Listen for crying or whimpering in infants and small children when the joint is moved. This is a sign of pain and may indicate that the child is suffering from septic arthritis.
4
Check for a fever. Infections, including septic arthritis, are often accompanied by a fever and chills.^{[9]
X
Expert Source

Siddharth Tambar, MD
Board Certified Rheumatologist
Expert Interview. 25 August 2020.} This is a sign that something out of the ordinary is happening in the body.^{[10]
X
Trustworthy Source
Johns Hopkins Medicine
Official resource database of the world-leading Johns Hopkins Hospital
Go to source} Taking the temperature can indicate a fever which may be the result of septic arthritis.
- Recognize that chills, muscle aches, sweating, and headache are common symptoms of a fever.^{[11]
  X
  Trustworthy Source
  Johns Hopkins Medicine
  Official resource database of the world-leading Johns Hopkins Hospital
  Go to source} These may also accompany a fever with septic arthritis.
- Seek immediate medical attention if your fever is higher than 103 degrees Fahrenheit (39.4 degrees Celsius). In a small child, contact your doctor as soon as you realize they have even a slightly elevated temperature. This can indicate a serious infection.
5
Observe fatigue and weakness. Two symptoms that are common with a fever are fatigue and weakness.^{[12]
X
Research source} These can also accompany septic arthritis. If you experience fatigue and weakness along with other symptoms of septic arthritis, you may have the condition.
- Recognize typical symptoms of weakness and fatigue, which include: delayed or slow movement, muscle cramps, muscle twitching, and uncontrollable shaking. Feeling run down is the most common symptom of fatigue.
- Be aware that your fatigue and weakness may lead to a decreased appetite, which can also signal septic arthritis.
6
Detect irritability. Most symptoms of septic arthritis are physical. However, some may be emotional or behavioral, especially in infants and small children. Noticing if you or another person are irritable can indicate septic arthritis, especially when in conjunction with other symptoms.
- Look for fussiness in children and infants. This can accompany any irritability they have.^{[13]
  X
  Trustworthy Source
  MedlinePlus
  Collection of medical information sourced from the US National Library of Medicine
  Go to source}

Part 2

Part 2 of 2:

Seeking a Professional Diagnosis

1
Schedule an appointment with your doctor. Only your doctor can definitively diagnose septic arthritis. If you have sudden onset of severe pain in a joint or any other symptoms of septic arthritis, contact your doctor as soon as possible. Prompt diagnosis of septic arthritis can minimize potential joint damage, including degeneration.^{[14]
X
Trustworthy Source
Mayo Clinic
Educational website from one of the world's leading hospitals
Go to source}
- Schedule the first available appointment by letting the doctor’s staff know that you have the symptoms of septic arthritis.
- Seek emergency medical attention if your doctor is unable to see you. Emergency rooms and emergency care centers can also diagnose septic arthritis.
2
Undergo an examination. During your appointment or exam, explain to the doctor that you suspect you may have septic arthritis. Discuss any symptoms you are experiencing as well as other relevant information, such as if you recently had surgery or a puncture wound. Your doctor will consider this information while examining your joint for signs of septic arthritis.
- Answer any questions the doctor may have honestly. Remember the doctor is trying to make a proper diagnosis and formulate the best treatment plan to minimize the risk of more serious conditions. If you are an illegal drug user, this information could be important information for a diagnosis.
3
Get your blood and joint fluid tested. Depending on the examination, your doctor may order additional tests. These can give a more definitive diagnosis of septic arthritis.^{[15]
X
Trustworthy Source
Arthritis Foundation
Main organization devoted to arthritis support and education
Go to source} Your doctor may prescribe the following additional tests:
- Arthrocentesis, which requires inserting a small needle into the joint for a sample of the synovial fluid. This test can indicate the presence of bacteria.^{[16]
  X
  Expert Source
  
  Siddharth Tambar, MD
  Board Certified Rheumatologist
  Expert Interview. 25 August 2020.} It can also assess your white blood cell count. It can also help your doctor figure out what medications to prescribe as treatment.^{[17]
  X
  Trustworthy Source
  Mayo Clinic
  Educational website from one of the world's leading hospitals
  Go to source} Synovial fluid with greater than 50,000 white cells with a predominance of Polymorphonuclear Leukocytes (PMN) is significant for the disease and needs treatment. Other than the cell count, a doctor will do a gram stain of the synovial fluid as well as a culture of the fluid. This will help guide treatment.
- Blood culture, which requires taking blood with a small needle.^{[18]
  X
  Trustworthy Source
  MedlinePlus
  Collection of medical information sourced from the US National Library of Medicine
  Go to source} A blood culture can determine what signs of infection are in your blood.^{[19]
  X
  Trustworthy Source
  Mayo Clinic
  Educational website from one of the world's leading hospitals
  Go to source} This test can help your doctor figure out the severity of infection in your joint.
4
Have imaging tests. In addition to joint fluid and blood tests, your doctor may also call for imaging tests. These can confirm the presence of infection as well as if your joint is damaged.^{[20]
X
Trustworthy Source
Mayo Clinic
Educational website from one of the world's leading hospitals
Go to source} Imaging tests often used for diagnosing septic arthritis include:
- X-rays.
- MRI scans.
- CT scans.
- Bone scans.
- Ultrasound.
5
Receive a diagnosis. Based on the outcome of an examination and any testing, your doctor may diagnose you with septic arthritis. Your doctor will talk to you about the results of your testing, including any damage in your joint. Your doctor will also discuss your treatment options.
- Ask your doctor any questions you may have about the diagnosis or treatment.
- If you have a MRSA infection you will need to treated with IV antibiotics such as vancomycin. This is the safest option for treatment given the prevalence of MRSA in hospitals and the community.

Expert Q&A

Question

Can a blood test detect septic arthritis?

Siddharth Tambar, MD
Board Certified Rheumatologist
Dr. Siddharth Tambar, MD is a board certified rheumatologist at Chicago Arthritis and Regenerative Medicine in Chicago, Illinois. With over 19 years of experience, Dr. Tambar specializes in Regenerative Medicine and Rheumatology, with a focus on platelet rich plasma and bone marrow derived stem cell treatments for arthritis, tendinitis, injuries, and back pain. Dr. Tambar holds a BA in Economics from State University of New York at Buffalo. He earned his MD from State University of New York at Syracuse. He completed his Internship, Residency in Internal Medicine, and his Rheumatology Fellowship at Northwestern Memorial Hospital. Dr Tambar is board certified in both rheumatology and internal medicine. He also holds Musculoskeletal Ultrasound Diagnostic and Interventional certifications from the American College of Rheumatology and the American Institute of Ultrasound in Medicine.

Siddharth Tambar, MD

Board Certified Rheumatologist

Expert Answer

It may, but more likely your doctor will test a small sample of the fluid in your affected joint.