What Is Psoriatic Arthritis of the Knee?

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Psoriatic arthritis (PsA) is a type of inflammatory arthritis that develops in people who have psoriasis. PsA may affect many joints, including the knees.

Psoriasis is a chronic, autoimmune skin disorder that causes skin cells to build up and form plaques—dry, itchy patches of skin. Both PsA and psoriasis—together called psoriatic disease—are chronic, long-term diseases, which means you will have them for the rest of your life.

There are no studies on the frequency of PsA in the knees. Symptoms of both conditions will get progressively worse for people who are not effectively treated. Early diagnosis is vital to minimize joint damage. Fortunately, a variety of treatments can slow down psoriatic disease. Learn more about its symptoms, causes, diagnosis, and treatment.

Psoriatic arthritis of the knee

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Symptoms

PsA does not present the same for everyone. Even its primary symptoms, such as stiffness and swelling, can affect people differently.

For example, some people who have knee PsA might only have mild symptoms in one knee, while other individuals have severe symptoms in both knees. Yet someone else might have severe pain that affects their ability to walk.

Most people with PsA—whether PsA affects their knees or not—will experience pain, skin symptoms, and systemic (whole-body) symptoms.

Pain

It is hard to predict how much pain someone with PsA will experience or how PsA pain will affect a person’s life. For some, the condition progresses quickly and causes more severe symptoms, including pain. For other people, changes may occur at a slower pace, or they may only experience a mild disease course with little pain, swelling, and stiffness.

PsA pain in the knee starts slowly or can appear suddenly. You might notice stiffness and pain upon waking in the morning or after being inactive for a long period.

You might have pain while climbing steps, trying to stand, or kneeling to pick something up. You might hurt from activity or while doing absolutely nothing. In addition to pain, an affected knee might be red and warm to the touch. 

Additional symptoms associated with PsA knee pain include the following.

Stiffness and tenderness: PsA will cause stiffness and tenderness in an affected knee. It can also cause swelling as inflammation accumulates around the joint or because of bone spurs—pieces of bone that develop at the edges of bones where cartilage has depleted.

Decreased range of motion: Damage to bone and cartilage in your knee can make it harder for the knee joints to move smoothly. You may find it painful to bend or flex the knee. You might need a cane or walker to help you keep your balance and move safely.

Cracking and popping of the knee: Much like other types of arthritis, including rheumatoid arthritis (RA) and osteoarthritis (OA), PsA can cause cartilage damage. Cartilage damage makes it harder to bend or straighten your knee. You may also notice a grinding feeling or a cracking or popping sound—a symptom doctors call crepitus.

Buckling and locking: Knee buckling and locking of the knee are signs of joint instability and damage. Both can increase your risk for a fall. Knee buckling or locking might affect you as you stand up from a sitting position or when you attempt to bend your knees. You might also feel pain at the front of the knee.

Damage associated with buckling and locking is found in both tendon and cartilage. The tendons are the places where muscles join to the bone. Cartilage has many functions, including coverage for joint surfaces so that bones slide smoothly over each other. Tendon damage is called tendinitis, while damage to the area where tendons or ligaments insert into the bone is called enthesitis.

Early diagnosis and treatment can ease pain and other PsA symptoms as well as slow down joint damage. It is important to tell your doctor about worsening PsA symptoms, severe knee pain, and if your medications don’t seem to be helping.

Skin Symptoms

Skin symptoms of PsA will appear as psoriasis skin patches of silvery or gray plaques on the knees. These spots can also appear on the scalp, elbows, and lower spine. Plaques can be painful, and they can itch and burn. Scratching them might put you at risk for a skin infection.

You may have small, round spots called papules on your knees, arms, legs, or torso. Skin symptoms of PsA can come and go. They can be triggered by stress, an injury, or an infection.

But not everyone with psoriasis will have PsA, and not everyone with PsA will have skin symptoms. In fact, according to the National Psoriasis Foundation, only 30% of people with psoriasis also have PsA.

Systemic Symptoms

PsA is a systemic disease, which means it causes inflammation that affects more than just the joints and skin.

Systemic symptoms of PsA include:

  • Inflammation of the spine
  • Tendon and ligament pain
  • Muscle pain and weakness
  • Uveitis (eye inflammation)
  • Chronic fatigue
  • Depression
  • Digestive symptoms such as abdominal pain, bloating, constipation, and diarrhea
  • Scalp psoriasis—patches resembling dandruff that appear on the scalp that can be red, itchy, and painful
  • Nail psoriasis—pitted, deformed, or discolored nails
  • Organ damage from inflammation to the heart, lungs, or kidneys

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Causes

PsA results when the body’s immune system mistakenly attacks healthy cells and tissues. With PsA, the immune system attacks the joints.

In people with psoriasis, a faulty immune system response leads to skin cells growing too quickly and then stacking up on top of each other to form plaques. Both joint and skin symptoms start because of a chronic inflammatory response.

There are no confirmed causes for PsA, but researchers think genetic and environmental triggers might lead to the body’s faulty immune system response. People who have close family members with PsA are also more likely to have the condition. 

A 2017 report in the journal Current Rheumatology Reports discusses other factors that might contribute to the development of PsA. These include:

  • Having severe psoriasis
  • Nail disease
  • Obesity
  • Traumatic injuries
  • Smoking
  • Overconsumption of alcohol
  • Chronic stress
  • Infection

Anyone of any age can develop PsA, and, according to the National Psoriasis Foundation, most people with PsA are diagnosed about 10 years after they start having symptoms of psoriasis.

Diagnosis

A diagnosis of psoriatic arthritis can be made by physical exam, lab testing, and imaging.

Physical Examination

During a physical exam for PsA, your doctor will closely exam your joints for swelling and tenderness. They will also check your skin for signs of a PsA rash and psoriasis skin plaques. Your doctor may also examine your fingernails to look for pitting, discoloration, and other nail abnormalities.

For knee symptoms, your doctor will examine the knee to look for joint swelling, stiffness, and tenderness. Your range of motion is also checked, and your doctor will want to see how you walk and how you bend your knees.

Lab Tests

Laboratory testing for PsA might include a test for the protein HLA-B27, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and rheumatoid factor blood work as well as joint fluid testing.

  • HLA-B27: A blood test for this protein can help diagnose people who have a family history of psoriatic disease. However, not everyone who is HLA-B27-positive will have psoriatic arthritis (up to 10% of Caucasians are HLA-B27 positive).
  • Erythrocyte sedimentation rate and C-reactive protein: ESR and CRP are inflammation-promoting proteins. They are signs of elevated inflammation levels throughout your body.
  • Rheumatoid factor: This is an antibody present in people with RA, but it is not often found in people with PsA. The purpose of testing for it is to distinguish between the two conditions and reach a correct diagnosis. Your doctor might also request an anti-cyclic citrullinated peptide, or anti-CCP, test to rule out RA. It is an antibody that is 97% specific for the diagnosis of RA.
  • Joint fluid test: Using a needle, your doctor will take a small sample of fluid from one or more joints to send for testing. This is often done on an inflamed knee.

Imaging

Your doctor might use imaging tools to aid in finding the source of knee symptoms or diagnosing PsA. They may use X-rays. magnetic resonance imaging, and ultrasound to check the knees, other joints, bones, ligaments, and tendons for inflammation and damage.

Treatment

Treatment goals for PsA are to control disease progression and relieve symptoms and pain. Treatment can include medicines to manage pain and reduce the effects of PsA, including disease-modifying anti-rheumatic drugs (DMARDs), biologics, immunosuppressants, complementary therapies like physical therapy, and, as a last resort, surgery.

Pain Management 

According to the Cleveland Clinic, arthritis knee pain can be treated with nonsteroidal anti-inflammatory drugs, including ibuprofen and naproxen. Corticosteroid injections can be used to treat ongoing inflammation in a single joint, including a chronically inflamed knee.

Topical pain relievers can be helpful for numbing pain in affected joints, including the knees. However, according to the Arthritis Foundation, people with PsA should use these products with caution. The organization suggests that if a product irritates your skin, you stop using it. You should also avoid using these products on inflamed skin or open scales.

Disease-Modifying Anti-Rheumatic Drugs

DMARDs can slow down disease progression in PsA and reduce the potential for joint and tissue damage. The most common DMARDs are methotrexate and sulfasalazine.

While these medications can be effective for treating PsA, long-term use can lead to serious side effects, including increased risk for serious infection, liver damage, and bone marrow problems.

Biologic Drugs

Biologics are a newer type of DMARD. These medications target the parts of your immune system that trigger inflammation. Common biologics include Humira (adalimumab), Orencia (abatacept), and Cosentyx (secukinumab). A major side effect of biologics is that they can significantly increase your risk for infection.

Immunosuppressive Drugs

Immunosuppressive drugs can calm down an overactive immune system, which is characteristic of PsA. Examples of immunosuppressive drugs are azathioprine and cyclosporine. Because these medications suppress your immune system, however, they can increase your vulnerability to infection.

Physical Therapy

Your doctor might recommend physical therapy to ease knee pain and help you to move and function better. A physical therapist can design a plan for you to improve your range of motion and flexibility and to strengthen leg muscles.

Surgery

If your knee has been severally damaged by PsA, your doctor might recommend joint replacement surgery. Knee replacement surgery involves replacing a knee joint with an artificial joint called a prosthesis.

Coping

Your doctor may recommend ways to help you to cope with PsA and knee symptoms of PsA. Changes to your lifestyle, the use of assistive devices, and other home remedies can help you to better cope and manage pain and inflammation.

Lifestyle Changes

Changes to your lifestyle can protect your knees and reduce the effects of PsA. These might include:

  • Minimizing activities that make symptoms worse, such as frequently going up and down steps
  • Switching from high-impact exercise to low-impact activities to reduce stress on your knee joint—for example, switching out jogging for brisk walking or swimming
  • Losing weight to take stress off your knees, which will also help reduce pain and improve mobility

Assistive Devices

A cane, walker, brace or knee sleeve, or more comfortable shoes can reduce pain and make it easier to move around. 

  • A cane or walker can be helpful because you use it to transfer weight off your knee, which can reduce your pain.
  • A brace or knee sleeve can keep the joint in place, which means less pain.
  • Comfortable shoes or shoe inserts can lessen impact and strain on the knee joint.

Home Remedies 

Other home remedies, including heat and cold treatments and meditation, may also be helpful to managing PsA of the knee.

  • Heat treatment: Heat treatment can include warm baths, a heating pad, or an electric blanket to ease stiffness, swelling, and tenderness.
  • Cold treatment: Cold treatment includes gel ice packs or the use of a bag of frozen vegetables to relieve pain and swelling. (Never apply ice directly to the skin.)
  • Meditation or relaxation breathing: Meditation and relaxation breathing can reduce pain, lower stress, and help you cope. Less stress and better coping skills can, in turn, reduce triggers of PsA that might lead to a flare-up of symptoms.

A Word From Verywell

Psoriatic arthritis is a chronic condition, and knee symptoms associated with it can adversely affect your quality of life. Work with your doctor to find the best ways to manage PsA and knee pain symptoms that might affect your ability to walk, climb steps, lift, and perform daily tasks.

Even if your knee pain is mild, it can get worse over time, especially if it is not addressed. Talk to your doctor about the best ways to treat knee symptoms so that you can continue to keep moving and enjoying your life. 

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