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Septic Arthritis: Symptoms, Causes, Treatments, and More

Septic arthritis is estimated to occur in 2 to 10 cases per 100,000 individuals per year in the general population. The prevalence of septic arthritis is higher in individuals with joint prostheses (artificial joints), particularly those who have undergone joint replacement surgery. In these cases, the prevalence may range from 1% to 2%.

What is Septic Arthritis?

Septic arthritis, also known as infectious arthritis or bacterial arthritis, is a serious medical condition that affects the joints. This condition occurs when bacteria, viruses, or fungi enter a joint, leading to inflammation, pain, and potentially severe joint damage. The bacteria can reach the joint through various means, such as through the bloodstream, direct injury, or following a surgical procedure. When bacteria infiltrate a joint, they trigger an immune response, causing the joint to become inflamed. The inflammation can lead to the destruction of the joint’s cartilage and bone if not treated promptly, resulting in long-term disability and pain. Septic arthritis requires prompt medical attention to prevent long-term complications. 


The symptoms of septic arthritis can vary in intensity and may develop suddenly or progress over time. It’s important to note that septic arthritis can affect any joint in the body, but it most commonly occurs in the knees, hips, shoulders, and elbows. The severity of symptoms can vary depending on the causative agent, the patient’s overall health, and how quickly treatment is initiated. Common signs and symptoms of septic arthritis include:

  • Joint Pain: the affected joint is typically painful, with the pain often described as severe and sharp. The pain may worsen with movement and become constant as the condition progresses.
  • Swelling: the affected joint becomes swollen, warm to the touch, and tender. The swelling can be significant and noticeable, leading to joint deformities in severe cases.
  • Limited Range of Motion: due to the pain and swelling, the joint’s range of motion is often restricted. This limitation can impede everyday activities.
  • Fever: many people with septic arthritis develop a fever, which is often a sign of a systemic infection. The fever may be accompanied by chills and sweating.
  • Fatigue: the body’s response to infection can cause fatigue and a general feeling of illness.
  • Redness of the Skin: the skin overlying the affected joint may appear red and feel warm to the touch.

Summary: Symptoms of septic arthritis involve pain, swelling, redness, and difficulty moving the affected joint along with systemic symptoms of fever and fatigue.


Septic arthritis is primarily caused by the introduction of infectious agents into a joint. The most common culprits are bacteria, particularly Staphylococcus aureus and Streptococcus species. However, other bacteria, viruses, or fungi can also be responsible. Here’s how these infectious agents can infiltrate the joint:

  • Hematogenous Spread: bacteria can enter the bloodstream through an infection in another part of the body and travel to a joint, causing septic arthritis. This is the most common route of infection.
  • Direct Inoculation: trauma or surgery can introduce bacteria directly into a joint, leading to infection.
  • Adjacent Infection: in some cases, an infection in a nearby tissue or bone can spread to a neighboring joint.
  • Prosthetic Joints: people with joint prostheses (e.g., knee or hip replacements) are at a higher risk of developing septic arthritis because bacteria can adhere to prosthetic materials and form biofilms, making them difficult to eradicate (1).

Risk Factors

Certain factors can increase an individual’s risk of developing septic arthritis. These risk factors include:

  • Age: infants and the elderly are at a higher risk of septic arthritis due to weakened immune systems.
  • Gender: males are more commonly affected than females.
  • Existing Joint Conditions: people with pre-existing joint conditions, such as rheumatoid arthritis or osteoarthritis, are more susceptible to septic arthritis (2).
  • Weakened Immune System: conditions that weaken the immune system, such as diabetes, HIV/AIDS, or cancer, increase the risk of infection (3).
  • Intravenous Drug Use: people who inject drugs are at a higher risk of bloodstream infections that can lead to septic arthritis.
  • Recent Joint Surgery or Injections: surgical procedures involving the joint or joint injections can introduce bacteria into the joint.
  • Prosthetic Joints: as mentioned earlier, individuals with prosthetic joints are at an increased risk due to the potential for bacterial biofilm formation.
  • Skin Infections or Wounds: skin infections and open wounds can provide a pathway for bacteria to enter the bloodstream and reach a joint.

Summary: Risk factors for septic arthritis include having a weakened immune system, IV drug use, recent surgery or infection, and having a history of joint replacement.


Prompt and accurate diagnosis of septic arthritis is crucial for effective treatment. To diagnose septic arthritis, healthcare providers typically employ a combination of the following methods:

  • Physical Examination: the doctor will examine the affected joint, checking for signs of swelling, redness, tenderness, and limited range of motion.
  • Medical History: information about the patient’s recent injuries, surgeries, or illnesses can help pinpoint the source of the infection.
  • Blood Tests: blood tests, such as a complete blood count (CBC) and erythrocyte sedimentation rate (ESR), can reveal signs of infection and inflammation.
  • Joint Fluid Analysis: a sample of synovial fluid is collected from the affected joint through a procedure called joint aspiration. The fluid is then analyzed for the presence of bacteria, white blood cells, and other markers of infection.
  • Imaging: X-rays, ultrasound, or magnetic resonance imaging (MRI) may be used to assess the extent of joint damage.
  • Microbiological Culture: joint fluid or tissue samples may be cultured to identify the specific causative organism and guide antibiotic treatment.


The treatment of septic arthritis typically involves a combination of medical therapies aimed at eradicating the infection and managing pain and inflammation. The specific treatment plan will depend on the severity of the infection and the causative organism. Here are the primary components of treatment:

  • Antibiotics: intravenous (IV) antibiotics are administered to combat the infection. The choice of antibiotics is determined by the identified bacteria and their sensitivity to antibiotics. Treatment may initially start with broad-spectrum antibiotics until culture results are available.
  • Joint Aspiration: the infected joint may be aspirated multiple times to remove accumulated pus and reduce pressure within the joint. This can help alleviate pain and improve the effectiveness of antibiotic treatment.
  • Immobilization: rest and immobilization of the affected joint are essential to prevent further damage. The use of a splint or brace may be recommended.
  • Pain Management: pain relief is a critical aspect of treatment. Over-the-counter pain relievers or prescription medications may be prescribed to manage pain and discomfort.
  • Physical Therapy: after the acute phase of treatment, physical therapy can help restore joint function, improve range of motion, and strengthen the affected area.
  • Surgery: in severe cases where the joint is extensively damaged or if there is an abscess that cannot be drained through aspiration, surgical intervention may be necessary. Surgical options include joint debridement (removing infected tissue) or, in some cases, joint replacement (https://pubmed.ncbi.nlm.nih.gov/32046824/).
  • Prosthetic Joint Removal: if a prosthetic joint is infected, it may need to be removed temporarily to clear the infection before a new joint can be implanted.
  • Adjunctive Therapies: in certain cases, depending on the severity of the infection and the patient’s overall health, additional treatments such as intravenous immunoglobulin (IVIG) therapy or immunosuppressive agents may be considered (4).

Summary: There are a variety of treatments for septic arthritis though it is always treated with antibiotics. Other treatments that may be used in combination with antibiotics include joint aspiration, immobilization, physical therapy, and in severe cases surgery may be required.


Septic arthritis is a serious condition that can cause significant joint damage and long-term disability if not promptly diagnosed and treated. Early recognition of symptoms, along with appropriate medical intervention, is crucial for a successful outcome. Anyone experiencing joint pain, swelling, and fever should seek medical attention as soon as possible, as prompt treatment can prevent complications and improve the chances of a full recovery. With timely and comprehensive care, many individuals with septic arthritis can regain joint function and lead a healthy, active life.