Infectious (Septic) Arthritis: Causes and Symptoms

Complete Guide to Septic Arthritis (Infectious Arthritis)

By Dr. Mannu Bhatia in Orthopaedics & Joint Replacement

Feb 20 , 2024 | 5 min read

What is Septic Arthritis? 

Septic arthritis, also known as infectious arthritis, is a joint infection that arises when bacteria spreads through the bloodstream from another body part. It can also occur if an injury, like an animal bite or trauma, directly introduces bacteria, leading to bacterial arthritis or sepsis arthritis, into the joint.

This condition is more common in infants and older people. Individuals with artificial joints are also at higher risk. While knees are often affected, septic arthritis can also impact hips, shoulders, and other joints. The infection can rapidly and significantly harm the joint's cartilage and bone, making immediate arthritis treatment vital.

Symptoms of Septic Arthritis

Infectious arthritis manifests through several distinct symptoms:

  • Pain and tenderness: Individuals often experience pain and tenderness in the affected joint.
  • Swelling and warmth: Swelling and warmth are commonly observed in the joints affected by septic arthritis.
  • Limited range of motion: A reduced range of motion is a prevalent symptom, challenging regular joint movement.
  • Reluctance to Use or move the joint: Patients may exhibit reluctance or an aversion to using or moving the affected joint.
  • Fever: A fever is another indicative symptom of septic arthritis.

Causes of Septic Arthritis 

Septic arthritis arises from an infection, caused by bacteria, fungi, mycobacteria, viruses, or/and other pathogens. The disease originates in some other part of the body, and then spreads through the bloodstream to the joints. Specifically, the following organisms are known to cause septic arthritis:

  • Staphylococcus aureus (Staph): This bacterium, known as staph, is the leading cause of septic arthritis in children and adults.
  • Methicillin-resistant staphylococcus aureus (MRSA): MRSA, a resistant strain of staph infection, poses a heightened risk for individuals using intravenous (IV) drugs, those with HIV (human immunodeficiency virus infection), or individuals with diabetes.
  • Groups A and B streptococci: Streptococci, a type of bacteria, increase the risk of septic arthritis, particularly in elderly individuals and those with chronic conditions such as diabetes and cirrhosis.
  • Neisseria gonorrhoeae: This bacterium, causing gonorrhoea (a sexually transmitted infection), may lead to gonococcal arthritis, a form of septic arthritis.
  • Neisseria meningitidis (Meningococcus): While rare, this bacterium, responsible for meningitis, can potentially cause septic arthritis. Meningitis involves inflammation of the protective membranes covering the brain and spinal cord.
Read more- Inflammatory Arthritis: Types, Causes and Diagnosis

Risk Factors of Septic Arthritis

Factors that elevate the risk of developing septic arthritis include:

  • Existing joint conditions: Conditions like osteoarthritis, gout, rheumatoid arthritis, or lupus, which impact the joints, can heighten the risk. Previous joint surgeries and injuries are also risk factors.
  • Artificial joints: Joint replacement surgery might introduce bacteria, or germs might reach the artificial joint through the bloodstream from another part of the body.
  • Rheumatoid arthritis medication: Individuals with rheumatoid arthritis are at increased risk due to their immune-suppressing medications, which make infections more likely. Diagnosing septic arthritis in these patients is challenging due to overlapping symptoms.
  • Skin vulnerability: Easily damaged and slowly healing skin can allow bacteria entry into the body. Skin conditions like psoriasis, eczema, and infected skin wounds raise the risk. Regular drug injection sites also pose a higher infection risk.
  • Compromised immune system: A weakened immune system, as seen in conditions like diabetes, liver and kidney problems, or due to immune-suppressing drugs, increases susceptibility to septic arthritis.

Septic Arthritis Diagnosis

Diagnosing septic arthritis typically involves a combination of clinical evaluation, laboratory tests, and imaging studies. The process usually includes:

Medical history and physical examination 

The doctor will start with a thorough medical history and physical exam, focusing on symptoms and any recent injuries, surgeries, or infections.

Joint fluid analysis

A critical diagnostic step is the aspiration and analysis of fluid from the affected joint (arthrocentesis). The fluid is examined for white blood cells, crystals, and bacteria. A culture of the fluid can help identify the specific bacteria causing the infection.

Blood tests 

Blood tests are performed to look for signs of infection, such as an elevated white blood cell count or increased C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), which are markers of inflammation.

Imaging tests 

X-rays, MRI, or ultrasound can be used to view the affected joint. While these imaging tests cannot confirm septic arthritis, they can rule out other conditions and assess the extent of joint damage.

Other tests

If the source of the infection is unclear, further tests might be conducted to identify the primary site of infection. These could include chest X-rays or urine tests.

Septic Arthritis Treatment

Treatment for bacterial arthritis primarily involves draining the infected joint fluid and administering antibiotics. In some cases, physiotherapists play a crucial role in the rehabilitation process, helping to restore joint function and strength after the infection has been treated. The septic arthritis treatment includes:

Draining the infected joint 

  • Needle aspiration: A needle can sometimes extract the infected fluid directly from the joint.
  • Arthroscopic surgery: This procedure involves inserting a camera-equipped tube into the joint through a small incision. Additional small incisions allow for suction and drainage.
  • Open surgery: Open surgery may be necessary for adequate drainage for joints like the hip, which are harder to access.

Antibiotic treatment 

  • Initial therapy: Identifying the infection-causing bacteria is crucial to choose the appropriate antibiotic. Initially, antibiotics are usually administered intravenously.
  • Oral antibiotics: After a period, the treatment may shift to oral antibiotics.
  • Duration and side effects: Treatment typically lasts 2-6 weeks. Side effects include nausea, vomiting, diarrhoea, and potential allergic reactions. It's important to discuss possible side effects with a doctor.

Management of infected artificial joints

  • Joint removal and replacement: If an artificial joint is infected, it may need to be removed and replaced with a spacer made of antibiotic cement. A new joint replacement can occur several months later.
  • Joint preservation: In cases where the artificial joint cannot be removed, it may be cleaned and damaged tissue removed while keeping it in place. Long-term oral antibiotics may follow intravenous treatment to prevent the recurrence of the infection.
Read more- Rheumatoid Arthritis: Symptoms, Diagnosis and Treatment

Septic Arthritis Complications 

If left untreated, sepsis arthritis may cause joint degeneration and permanent damage. Complications such as loosening or dislocation may arise when an artificial joint is affected.

Prevention of Septic Arthritis

To reduce the risk of septic arthritis, you can take several preventive measures, including:

  • Care for cuts and wounds properly: Clean skin cuts or wounds to avoid infection. If you notice signs of infection like redness, warmth, or pus, seek medical advice promptly.
  • Effectively manage chronic conditions: For those with long-term health issues, such as diabetes or AIDS, it's essential to manage them effectively to maintain overall health.
  • Engage in safe sexual practices: Use protective measures like condoms or dental dams during sexual activity, and have open discussions with your partner about STI history and previous partners.
  • Avoid drug misuse: Refrain from injecting drugs, and always use medications strictly as directed by your healthcare provider.


The Complete Guide to Septic Arthritis (Infectious Arthritis) provides an in-depth understanding of this severe joint infection, its causes, diagnosis, and treatment options. Max Healthcare remains committed to offering the highest standard of care for those facing septic arthritis. With a team of expert professionals, state-of-the-art facilities, and a patient-centric approach, we ensure that each patient receives personalised treatment and support, helping them navigate their journey towards recovery with expertise and compassion.