Introduction
Before going into what causes psoriatic arthritis (PsA) and its manifestations (symptoms), a brief overview would help you understand what we are dealing with here.
Arthritis Psoriasis is an autoimmune disease, an inflammatory spondyloarthropathy, without cure and characterized by chronic inflammation of the joints and usually also the skin.
Studies have indicated that up to 42% of patients who suffer from psoriasis develop psoriatic arthritis (PsA), an inflammatory spondyloarthropathy.
In 70% of psoriasis cases, the skin psoriasis appears first before the onset of joint inflammation (the gap could be months or years). Again, in 15% of the cases, psoriasis of the skin and psoriatic arthritis appear simultaneously. In 15% of the cases, joint involvement may appear before the skin symptoms.
It was only in 1960 that psoriatic arthritis was clinically diagnosed and distinguished from rheumatoid arthritis.
PsA can affect any joint of the body, small or big, but it mostly affects the peripheral and spinal joints. These include the joints of the fingers and the joints of the vertebrae in the spine.
Depending on the area of the body where this type of arthritis has developed, psoriatic arthritis is classified into five different types, each with its typical symptoms and degree of prevalence
Peripheral joints are diseased in 95% of the cases while axial spine involvement is seen in the balance 5% of the cases. It is characterized by pain in the affected joints, stiffness, and swelling.
As in skin psoriasis, this joint condition can be mild or severe and exhibits periods of remission and flare-ups. This disease can be disabling if left untreated.
Causes of psoriatic arthritis
Just as the etiology of psoriasis remains unclear, the exact cause of psoriatic arthritis is not known. What is known is that it occurs due to a disorder in the immune system, which inadvertently attacks the healthy cells and tissues of the body.
This causes inflammation of joints in psoriatic arthritis and the excessive production of skin cells in psoriasis – a skin condition with red patches topped with silvery scales.
Besides the disorder in the immune system, there are other associated reasons. Many of the psoriatic patients have a family history of psoriasis or psoriasis arthritis. Research has discovered certain genetic markers, which are associated with this form of arthritis.
Physical trauma, infectious agents, and some environmental factors act as trigger factors, especially in persons with a family history.
Factors that increase the risk of PsA
- Psoriasis. Having psoriasis is the single largest factor that increases your risk of psoriasis arthritis. Existing psoriasis of the nails especially, largely enhances that risk.
- Family history. Having a parent or a sibling with this disease puts you at a higher risk.
- Age. Psoriatic arthritis often appears between the ages of 30 years and 50 years. Its onset after the age of 60 years can be very severe and the outcome can be destructive.
Symptoms
Symptoms and signs of psoriatic arthritis can develop slowly or can have a rapid and severe onset. This disease is characterized by periods of remission and flare-ups. This type of arthritis more commonly involves the knees, ankles, and the small joints of the feet.
Most of the psoriatic arthritis patients already have pre-existing skin psoriasis, symptoms of which also exist. It is important that this condition be diagnosed early to prevent damage to joints in the later stages.
Fatigue is a common generalized symptom. Besides, some specific symptoms pertaining to joints can include:
- Swelling, pain, and tenderness of one or more joints
- Stiffness of the joints, which is typically more in the mornings causing morning stiffness.
- Joints become red and feel warm on the touch.
- Reduced mobility of the joints
- Lowermost back pain over the sacrum (tailbone) due to inflammation (spondylitis) of the joints of the spine. This inflammation occurs between the joints of the vertebrae and the joints between the spine and the pelvis.
- Similarly, pain can occur in the neck and the upper back due to inflammation of the joints of the upper spine.
- Similarly, inflammation of the joints of the breastbone and the ribs (costochondritis) can cause chest pain.
Other non-arthritic symptoms of PsA can include:
- Fatigue
- Thirty percent of psoriasis arthritis patients develop conjunctivitis and iritis (inflammation of the iris).
- Acne is common in patients with this type of arthritis.
Symptoms of psoriatic arthritis of the hands (fingers)
Psoriatic arthritis of the fingers mostly affects the distal joints closest to the nails. The fingers become swollen and can be confused with gout. This condition could be worse on the one hand while it may be milder on the other hand.
- The finger and the hand joints become painful, stiff, and tender.
- The whole finger becomes swollen and takes the shape of a sausage.
- Fingernails get pitted.
- There is a reduced range of movement of the finger joints.
Symptoms of psoriatic arthritis of the ankles and toes
The patient experiences pain over the areas of attachments of the tendons and ligaments to the joints, more commonly at the back of the heel and the sole of the foot. The former is called Achilles tendonitis and the latter is called plantar fasciitis. This can cause pain while walking.
There is sausage-like swelling of the toes due to swelling of the entire digit caused by the inflammation of the joint of that digit. This is called dactylitis
Psoriatic arthritis of the nails
There is the pitting of the nails, the appearance of yellow spots, and their separation from the nail bed. This happens usually when the distal joints of the fingers and the nails are affected. Nail abnormalities develop in 80% of psoriatic arthritis cases.
Complications of psoriatic arthritis
- Psoriatic arthritis can result in inflammation of the conjunctiva and the iris of the eyes resulting in conjunctivitis and iritis. If not treated, this can result in blindness. This complication is treated by injecting corticosteroids into the eyes to reduce inflammation.
- The patient with psoriatic arthritis can develop inflammation of the pleura of the lungs (pleuritis). This can cause chest pain on deep breathing and shortness of breath.
- PsA can cause inflammation of the aorta (aortitis). This can lead to leakage in the valves of the aorta, which can lead to heart failure and shortness of breath.
- A small percentage of PsA patients develop arthritis mutilans, which is a severely disabling form of psoriatic arthritis. Over time, this can destroy the small bones of the fingers and cause permanent disability.
Though there is no cure for this condition, early diagnosis and prompt treatment will help in the prevention of complications and give symptomatic relief to the patient.
Prevalence in the United States
- There is a considerable variation in the prevalence of psoriatic arthritis in different populations.
- According to the National Psoriasis Foundation, 30% of the people who have skin psoriasis, develop psoriatic arthritis.
- In the U.S. this condition affects 2% of the Caucasian (white) population.
- About one million people in the U.S. have psoriatic arthritis.
- It is less commonly seen in Native Americans and African Americans.
- Psoriatic arthritis is usually seen between the ages of 30 tears to 50 years
- Males and females are equally at risk to have psoriasis arthritis.
- In males, the spine is more commonly affected (spondylitis form) while in women, involvement of multiple joints is seen (rheumatoid form).