Psoriasis is a skin condition that causes skin cells to build up and form patches of itchy, dry skin called plaques.
If a person with psoriasis develops psoriatic arthritis as well, it may cause one or more joints, such as the knee, to become stiff, inflamed, and painful.
Psoriatic arthritis is a long-term inflammatory disease. Symptoms may get progressively worse over time without effective treatment.
It is possible, however, to slow the progress of the condition with the correct treatment. Early diagnosis is vital to minimize damage to the joints.
Image credit: Stephen Kelly, 2018.
How does psoriatic arthritis affect the knee?
Psoriatic arthritis does not follow the same pattern in everyone. The symptoms, such as stiffness and painful swelling, may appear differently in each person.
For example, some people with psoriatic arthritis of the knee will experience symptoms in one knee, while others will experience symptoms in both knees.
Psoriatic arthritis in the knee may also cause swelling in the ligaments, tendons, and synovial fluid in the surrounding area. Symptoms may also show up in the elbows, feet, and hands.
Some people may notice slight stiffness or pain in just one of their knees, whereas others may have severe pain in both knees that makes it difficult to walk.
Symptoms of psoriatic arthritis in the knee may vary from person to person. Common symptoms include:
- stiffness, especially after resting or sleeping
- swelling and inflammation in the knee and surrounding area
- pain in the joint, tendons, or ligaments
- feeling that the joint is stuck, difficult to move, or has a reduced range of motion
- warm or hot skin on the knee due to inflammation
A person may also experience other symptoms not confined to the knee, including:
- changes in the nails, such as pitting or separation
- pain and redness in the eyes
- swollen fingers or toes
- difficulty walking due to pain in the feet or Achilles tendon
- back pain
Symptoms may go through a pattern of relapses and remissions. A person may have a sudden attack where symptoms get worse over a short time.
After the flare-up, symptoms may improve as the condition goes into remission. The symptoms may stay away for a long time until the next flare-up.
The severity of a person's psoriasis symptoms does not always determine that of their psoriatic arthritis symptoms. For instance, a person may have severe psoriasis symptoms but only mild psoriatic arthritis symptoms.
Likewise, someone with only mild psoriasis may still experience more severe psoriatic arthritis.
Obesity may influence the development of psoriatic arthritis.
Psoriatic arthritis occurs because the body's immune system mistakenly attacks healthy cells and tissues.
In people with psoriasis, the faulty immune response causes the body to make new skin cells very quickly, which stack on top of each other and form plaques.
When the condition affects the joints, it leads to inflammation.
While there is no clear cause for psoriatic arthritis, researchers have found connections to both genetics and environment.
People whose close relatives have psoriatic arthritis may be more likely to also develop the condition.
A 2017 review that appears in The New England Journal of Medicine also noted other factors that may influence the development of psoriatic arthritis, such as:
- severe psoriasis
- nail disease
- traumatic injuries
The condition may occur at any age, but according to the National Psoriasis Foundation, most people with psoriatic arthritis first notice symptoms about 10 years after their psoriasis begins. Symptoms often begin between the ages of 30 and 50.
Not all people with psoriasis develop psoriatic arthritis. In fact, psoriatic arthritis only occurs in about 30 percent of people who have psoriasis.
Doctors can use imaging tools to help them diagnose psoriatic arthritis in the knee. Using MRI, X-rays, or an ultrasound of the knee may help them check for irregularities or signs of inflammation in the joint and surrounding tissues.
Doctors can use additional tests to rule out other common forms of arthritis, such as rheumatoid arthritis and osteoarthritis.
They may also order blood tests to check for inflammation and specific antibodies from other types of arthritis.
In some cases, they may remove some fluid from the joint to help eliminate the possibility of other underlying conditions, such as infections.
There is currently no cure for psoriatic arthritis. Treatment focuses on managing symptoms and increasing the person's quality of life.
Treatments for psoriatic arthritis of the knee may include:
Doctors may prescribe prescription-strength nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroid injections for the knee.
Doctors are cautious about using steroid injections, however, as they may cause long-term side effects.
Disease-modifying antirheumatic drugs
Disease-modifying antirheumatic drugs may also slow the progression of psoriatic arthritis. These drugs work best when a person starts taking them as early as possible.
Newer versions of these drugs are called oral small molecules.
They can take a while to build up in the body and be effective, so it is important to continue taking them even if symptoms do not immediately improve.
Immunosuppressants and biologics
Doctors may recommend immunosuppressant or biologic drugs such as tumor necrosis factor (TNF) inhibitors. These drugs may help block TNF, which has a key role in inflammation in the body.
Other promising biological agents called biologics may help put the disease into remission. These drugs work by blocking other chemicals in the blood that activate the immune system. This may halt an attack, prevent symptoms, and avert further joint and bone damage.
Biological agents may cause unwanted side effects in some people. Doctors will monitor a person for any adverse side effects.
Home remedies to ease inflammation
Taking NSAIDs may provide some relief from psoriatic arthritis.
Many people may find some relief from psoriatic arthritis in their knees using home remedies, including:
- taking over-the-counter NSAIDs such as ibuprofen (Advil) or naproxen (Aleve)
- alternating applying ice and heat packs
- gently exercising to promote range of motion
- gently stretching or taking yoga classes to help relax tight muscles
Doctors may also recommend that the person maintains a healthy weight through exercise and diet to reduce pressure and stress on their joints.
In some cases, wearing special shoes may help reduce symptoms in the feet and knees.
Psoriatic arthritis of the knee is a chronic condition. Successful treatment involves working closely with a healthcare provider to discuss any medications and their side effects to find a treatment for the pain and help stall the condition's progression.
Pain and inflammation from psoriatic arthritis in the knee can disrupt a person's everyday life. While there is currently no cure for psoriatic arthritis, there are many medications and home remedies available to help manage symptoms and reduce pain.