How is psoriatic arthritis different from osteoarthritis?
Psoriatic arthritis (PsA) and OA share some common symptoms, but there are also some key differences between the conditions.
What are the symptoms?
Symptoms of each include:
Psoriatic arthritis symptoms
People with PsA may have:
- painful, swollen joints
- stiffness (especially after rest)
- sausage-like fingers and toes
- pain in the tendons and ligaments
- thick, red, and scaly patches of skin
- nail changes
- reduced range of motion
- red, irritated eyes
- vision problems
Symptoms of PsA typically affect the:
- lower back
Below is a 3-D model of psoriatic arthritis.
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Symptoms of OA vary and depend on the part of the body that is affected. OA symptoms generally include:
- painful and stiff joints (especially after rest or overuse)
- swollen joints
- reduced range of motion (that improves with movement)
- a clicking noise when a joint bends
- noticeable bony lumps near the affected joints
- changes in joint shape
OA can affect any joint but most commonly occurs in the:
- lower back
Differentiating between PsA and OA
The following key symptoms can help differentiate between PsA and OA:
- Skin symptoms: PsA is associated with psoriasis, a skin disease that causes itchy, red, and scaly skin rashes. The rash causes the skin to become thicker and redden; silvery-white patches may also be present. Skin changes are unique to PsA, which helps doctors to confirm the diagnosis.
- Nail changes: Psoriasis and PsA can cause the nails to become pitted or lift from the nail bed. At least 80% of those with PsA experience discolored, pitted, or thickened nails. People with OA will not have nail changes.
- Flares: PsA symptoms typically come and go and get worse over time. Although OA symptoms can flare, they are typically more consistent, eventually destroying the cartilage and resulting in deformities of the joints.
- Swollen fingers and toes: PsA is an inflammatory condition that causes swelling of the fingers and toes so that they can resemble sausages. Swelling is not a significant symptom of OA, although there tends to be some inflammation around the affected joints.
- Joint deformity: OA is associated with the growth of bone spurs (lumps of bone) at the affected joints, as well as inflammatory nodules at the small joints of the hands. Bone spurs in OA can cause the joint to appear misshapen or deformed. The arthritic joints also tend to cause a clicking or cracking sound when they move due to a lack of cartilage. Inflammation in PsA can affect the tendon insertions to bones.
- Eye symptoms: People with PsA may have inflamed and irritated eyes. Other eye symptoms include changes in vision and pain in the eye area.
What are the causes?
The causes of each are quite different:
Psoriatic arthritis causes
Those with psoriasis may be at increased risk of developing psoriatic arthritis.
PsA is an inflammatory autoimmune condition. This means that inflammation and other symptoms stem from a problem with the immune system.
Scientists do not yet know why this happens, however.
Genetic and environmental factors also play a role in this disease process.
PsA often affects those with the skin condition psoriasis. Around 30% of people with psoriasis will develop PsA. Skin symptoms usually develop before joint symptoms. Arthritis symptoms appear first in 15% of cases.
OA, on the other hand, is caused by the gradual breakdown of cartilage at the end of the bones. Cartilage is a flexible, slippery tissue that cushions and protects the ends of bones, allowing them to move against one another without friction.
If the cartilage completely wears away, the action of bone against bone results in pain, stiffness, and reduced range of motion. It also causes irreversible damage to both the joint and bones.
Psoriatic arthritis risk factors
Factors that increase the risk of getting PsA include:
- Age: PsA tends to occur in people aged 30 to 50, but it can affect any age group.
- Genes: Approximately 40% of people who get PsA have a family member with either PsA or psoriasis.
- Health status: PsA may be triggered by infections, injury, or extreme stress in people who are predisposed to psoriasis or other autoimmune conditions.
Osteoarthritis risk factors
Risk factors for OA include:
- Age: The likelihood of developing OA is higher in older adults.
- Genes: Some inherited traits may result in people developing OA, including problems in the body's collagen production or the way bones fit together.
- Sex: Females are more prone to OA.
- Weight: Being overweight or obese puts added stress on the joints, which contributes to OA development. Body fat can also produce proteins that cause joint inflammation.
- Joint damage: A history of injury or repetitive movements can increase the risk of OA. Athletes and people in professions that require long periods of standing or repetitive motions are more likely to experience cartilage degeneration than others.
What are the treatment options?
There is no cure for either PsA or OA, but treatment can relieve symptoms and help prevent further damage.
Treatment for PsA
Medication, including pain relievers and steroids, may be prescribed to treat PsA.
Treatments for PsA include:
The first-line treatment for most people with a new diagnosis of PsA is biologic therapy. These drugs target a specific part of the immune system to treat the underlying cause of PsA.
However, not everyone can use these drugs, as they can have adverse effects.
Alternatives include oral small-molecule drugs and disease-modifying antirheumatic drugs, both of which are systemic treatments that work throughout the body to reduce inflammation or suppress the immune system.
Treatments for symptoms and flares include:
- pain relievers
- steroid injections
- medications for skin and nail conditions
A surgeon may replace a joint with an artificial joint that is made from plastic and metal if it is severely damaged.
Some lifestyle modifications that may help include:
- Protecting the joints during everyday domestic activities by using kitchen gadgets to open jars and lifting items with both hands.
- Maintaining a healthful body weight helps reduce stress on the joints.
- Following an anti-inflammatory diet.
- Engaging in regular exercise to build up muscle and encourage joint flexibility.
- Getting enough sleep to counteract the fatigue caused by medications and chronic illness.
- Seeking emotional support if necessary.
Treatment for OA
OA symptoms can be managed through:
Pain can be alleviated with:
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- duloxetine (Cymbalta)
- injected medications
A doctor may recommend physical therapy and occupational therapy for people with OA.
A physical therapist can create an exercise program to reduce pain, strengthen the muscles, and increase the range of motion.
An occupational therapist teaches people how to reduce the pressure on their joints when carrying out everyday tasks.
Surgery may be necessary to replace severely damaged joints. A replacement joint is the last resort option.
Lifestyle changes that may help OA include:
- Doing regular exercise to strengthen the muscles around the joint.
- Maintaining a healthy body weight to reduce stress on the joint.
- Applying hot and cold compresses to reduce pain.
- Using an over-the-counter (OTC) pain cream for temporary symptom relief.
- Supporting weak joints with braces, shoe inserts, or taping techniques.
- Using equipment such as canes, walkers, and grabbing devices.
- Getting enough sleep to counteract the fatigue caused by medication and chronic pain.
- Seeking emotional support if necessary.
There is no cure for either PsA or OA, but symptoms can be managed with
- lifestyle changes
Joints that are severely damaged may require surgery.
People with painful, swollen, or stiff joints should see a doctor if symptoms persist for a few weeks. These conditions can be disabling and cause further joint damage without treatment.