Monoarthritis refers to the inflammation of one joint rather than multiple joints. It involves typical symptoms of arthritis, including joint pain, swelling, and stiffness.

According to a 2022 research article, sudden-onset monoarthritis may occur due to infections, Lyme disease, crystal-induced arthritis, or trauma. In other cases, there may be a gradual onset. For example, a person may experience a few early symptoms of osteoarthritis in just one joint. Later, symptoms may affect multiple joints.

Doctors base a diagnosis on medical history, a physical exam, lab tests, and imaging. The extent of the condition can help guide whether conservative or surgical intervention is necessary. Treatment is likely to entail using antibiotics or anti-inflammatory medications.

Keep reading to learn more about monoarthritis, including symptoms, causes, diagnosis, treatment, and when to seek medical attention.

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Monoarthritis refers to the inflammation of a single joint. Inflammation may go on to affect other joints later.

People can have acute or chronic monoarthritis. A condition is acute if it develops quickly and is short-term. A chronic condition develops more gradually but is long-term.

The specific joints involved vary with the cause. It may affect the:

  • knee
  • hip
  • ankle
  • wrist
  • shoulder

It may also affect other joints.


The symptoms may include having a fever and experiencing the following in a joint:

The condition can also lead to a loss of the range of motion in the joint.

Some acute causes include:

Chronic arthritis usually manifests in more than one joint but may first manifest in a single joint. Some of the conditions that can lead to chronic arthritis include:

  • osteoarthritis, a type of arthritis that causes cartilage around the bone ends to deteriorate
  • rheumatoid arthritis, which happens when the immune system attacks tissues in the joints and other parts of the body
  • spondyloarthritis, a condition that causes inflammation where tendons and ligaments attach to bones


Septic arthritis is joint inflammation due to an infection. Each year, it affects around 20,000 people in the United States.

Although most of these infections result from bacteria, fungi, viruses, and other organisms can sometimes cause them. Typically, septic arthritis affects one major joint — such as the knee or hip — but it may also involve multiple smaller joints.

Although septic arthritis is uncommon, it poses an orthopedic emergency because it can produce considerable joint damage.

Learn more about septic arthritis.

Lyme disease

Lyme arthritis can be due to chronic infection in a joint or a post-reactive immune process without an ongoing infection.

The bacteria that causes Lyme disease can get into a joint and produce inflammation. It most often affects the knees but may also affect other large joints, such as the:

  • elbow
  • shoulder
  • wrist
  • jaw
  • ankle
  • hip

Research indicates that 27.5% of people with Lyme disease develop arthritis.

Crystal-induced arthritis

Crystal-induced arthritis occurs when deposits of crystals in joints lead to inflammation.

A 2020 study notes that two main types include gout and pseudogout. Crystals of monosodium urate cause gout, while crystals of calcium pyrophosphate cause pseudogout.

Gout most often affects the big toe. Pseudogout affects the knee more often. Additionally, this form of arthritis may affect the hands, wrists, shoulders, and ankles. Episodes commonly resolve within a few days but may last up to 3 weeks in some people.


Joint injury or overuse can contribute to osteoarthritis. Trauma is also a risk factor for monoarthritis, which can cause direct damage to the joint and surrounding structures.

Diagnosing monoarthritis involves the following components:

  • Personal and medical history: This includes asking a person about factors such as:
  • Physical exam: This involves noting signs of inflammatory arthritis, such as swelling and warmth in a joint.
  • Lab tests: These can involve the following:
  • Imaging: This may include:

Treatment options depend on the cause and severity. Generally, goals involve controlling pain and reducing joint damage.

For septic arthritis

Doctors treat septic arthritis using various means of joint fluid drainage. They may also prescribe IV antimicrobial medication to prevent the infection from spreading to nearby tissue.

Options may include ceftriaxone (Ceftrisol Plus), an antibiotic effective against Neisseria gonorrhea, a sexually transmitted infection that is the most common cause of monoarticular arthritis in young, sexually active individuals.

Another option is nafcillin (Nallpen) an antibiotic effective against Staphylococcus aureus, the most common cause of nongonococcal infections.

For Lyme disease

Treating arthritis from Lyme disease involves oral antibiotics, such as:

If symptoms persist, doctors may recommend administering a second course of antibiotics through a vein. In such cases, ceftriaxone (Ceftrisol Plus) is the drug of choice.

Crystal-induced arthritis

Standard treatment includes:

Trauma arthritis

Treatment of arthritis that follows a trauma can pose challenges, according to a 2016 study.

Surgery may be necessary to stabilize and restore the joint. Additionally, treatment may include:

The outlook of a person with monoarthritis depends partly on how quickly they receive a diagnosis and start treatment.

For this reason, if an individual experiences symptoms such as those this article lists, they should immediately make an appointment with a doctor or rheumatologist.

Monoarthritis refers to inflammation that affects a single joint instead of multiple joints. It may manifest in joint pain, swelling, and stiffness.

Acute causes include infections, Lyme disease, crystal-induced arthritis, and trauma. Chronic causes include osteoarthritis, rheumatoid arthritis, and spondyloarthritis. It can help to begin treatment early. For a better outlook, a person with symptoms should not delay seeing a doctor.

Treatment methods vary and aim to address the underlying cause. For example, treatment of arthritis due to an infection will involve using an antibiotic or other antimicrobial agent.