How Does Psoriatic Arthritis Affect the Knees?
One or both knees may be affected in people with psoriatic arthritis (PsA), a chronic inflammatory joint disease. PsA is a disease that presents with a diverse set of symptoms across the population affected by PsA.
In some individuals, PsA is asymmetrical, affecting only one side of the body. For example, PsA may involve the right knee while the left knee is unaffected. PsA can also be symmetrical, affecting both sides of the body.1,2
There are different ways to detect knee pain
In addition to affecting joints, PsA can also inflame the entheses, the attachment points of tendons and ligaments, and synovial tissue, the fluid-filled capsule found between the bones.
When one or both knees are involved in PsA, the joint may be compromised by inflammation in all of these structures.1
Imaging tools often used for diagnosing PsA in the knees include ultrasound and MRI (magnetic resonance imaging), which are more sensitive than x-ray to detect inflammatory changes in people with PsA.
Ultrasound is useful for detecting structural changes and abnormal blood flow. MRI allows for visualization of soft tissue as well as bony changes.1,2
What do knee symptoms from psoriatic arthritis look like?
There is no documented frequency for how often the knees are affected in PsA. PsA is a fluctuating disease, with periods of remission and flares, and can affect any joint in the body.
Symptoms of PsA in the knees include:
- Stiffness, especially first thing in the morning or after a period of rest
- Painful joints
- Reduced range of motion3,4
As a chronic, progressive disease, it can cause debilitating damage to the joints if left untreated. Minor pain and stiffness of mild PsA can be alleviated with non-steroidal anti-inflammatory drugs (NSAIDs). In addition, injections of corticosteroids may be used.5
There are many different treatment options
For moderate to severe disease, treatments that target joint disease in PsA can reduce symptoms and prevent disease progression, including deformity and loss of function. Recommended treatments include disease-modifying anti-rheumatic drugs (known as DMARDs).
The first step for treatments is usually DMARDs such as methotrexate, leflunomide, or sulfasalazine. Other treatments include medicines that target tumor necrosis factor (TNF), a chemical that produces a wide range of inflammation in PsA. Examples of TNF blockers include etanercept (Enbrel), adalimumab (Humira), infliximab (Remicade), golimumab (Simponi), and certolizumab pegol (Cimzia).
Other DMARDs that have proven effective in clinical trials include ustekinumab (Stelara), brodalumab (which is awaiting FDA approval), and secukinumab (Cosentyx).2
The FDA has also recently approved Inflectra (infliximab-dyyb), a biosimilar to infliximab, for the treatment of psoriatic arthritis.6
Are there any supplemental treatments?
Physical and occupational therapy can also be critical treatment approaches to both protect the involved joints and maintain function.5
A physical therapy program generally includes various exercises and stretches, applied heat and/or cold, orthotics, assistive devices for gait, and possible vocational readjustments.3Surgical care may be indicated for severe disease. Arthroscopic surgery to the synovial capsule has shown to be effective, and joint replacement or reconstructive surgery are occasionally necessary.3