Psoriatic Arthritis Presentation & Treatment

Psoriatic arthritis is a chronic inflammatory, seronegative arthritis that develops in about 5% of the people who have psoriasis. Psoriasis is an autoimmune disorder that mainly affects skin leading to a characteristic rash.

About half of the patients of psoriatic arthritis have often human leukocyte antigen HLA B27 associated spondyloarthropathy. Psoriatic arthritis is considered as the seronegative spondyloarthropathy.

Most common type is oligoarthritis [involves few joints].

Distal joint involvement and arthritis mutilans [destruction of digits] are characteristic features of psoriatic arthritis but less common.

The peripheral joint disease occurs in 95% of patients with psoriatic arthritis, and the spine is involved in 5%.

Psoriatic arthritis is more frequent in patients with severe psoriasis. However, the severity does not relate to the pattern of joint involvement.

Psoriatic arthritis has been found to be associated with greater risk of hypertension, obesity, hyperlipidemia, type 2 diabetes mellitus, and cardiovascular events compared with psoriasis without arthritis.

Both the genders are equally affected [spine more affected in males]

Any age group can be affected but most cases are seen in group 35-55 years.

Types of Psoriatic Arthritis

The patterns of psoriatic arthritis involvement are as follows:

Asymmetrical oligoarticular arthritis
Symmetrical polyarthritis
Distal interphalangeal arthropathy
Arthritis mutilans
Spondylitis with or without sacroiliitis

Asymmetrical Oligoarticular Arthritis

Asymmetrical oligoarticular arthritis affects less than 5 joints. It affects fingers and toes first.

Inflammation of the flexor tendon and synovium occur at the same time. A large joint, such as the knee, is also commonly involved.

Symmetrical Polyarthritis

It is the most common type and the involvement is similar to rheumatoid arthritis. The hands, wrists, ankles, and feet are generally involved.

The condition can be differentiated from rheumatoid arthritis by being milder in nature and the involvement of distal interphalangeal joints.

The subcutaneous nodules are absent. The test for rheumatoid factor is negative.

Distal Interphalangeal Arthropathy

This involves the distal interphalangeal joint. This type occurs in only 5-10% of patients. Men are more commonly affected and are more common in men than in women.

Nail involvement in form of paronychia and swelling of the digital tuft may be prominent.

Arthritis Mutilans

It is quite rare [1-5% of patients]. The condition involves bone resorption and destruction of joint of digits. The peculiar destruction leads to a pencil in cup appearance in radiographs. It is also called pencil in cup deformity or pencil cup deformity.

Over the joint skin becomes redundant and a telescoping motion of the digit can be possible.

Spondylitis with or without Sacroiliitis

This is mostly found in males and affects about 5% of cases. It can occur along with other types of psoriatic arthritis.

There is an asymmetrical involvement of the vertebrae in contrast to ankylosing spondylitis where the involvement is symmetrical.

The characteristic finding in the spine is nonmarginal asymmetrical syndesmophytes [osteophytes from adjoining vertebrae joined together]. paravertebral ossification, and, vertebral fusion with disc calcification.

Risk factors of Psoriatic Arthritis

The exact cause is not known. Following factors are said to contribute

Genetics
- Positive family history
- HLA-B7, HLA-B27, HLA-DR4, HLA-38, and HLA-DR7 increase susceptibility
- Mechanism unclear
Immunologic factors
- Higher serum IgG A and IgG levels
- Decreased IgM levels may be normal or decreased.
- Autoantibodies against nuclear antigens, cytokeratins, epidermal keratins, and heat-shock proteins
- Decreased CD4 cells
Bacterial and viral infections
Trauma
Unclear environmental factors

Clinical Presentation

Patient commonly complain of the following symptoms

Painful and swollen fingers [dactylitis]
pain back
Pain in ankle [Achilles tendon insertion]*

*The term enthesopathy is used when there is pain at the insertion site of the tendons. Enthesopathy may occur in many other conditions too.

The symptoms may develop acutely or have an insidious development.

Often the patient has pre-existing psoriasis but arthritis can precede psoriasis in the minority of patients.

Other important symptoms include

Eye involvement [about thirty percent]
- Conjunctivitis
- Anterior uveitis
- Iritis
Sacroiliitis
Aortic valve inflammation
Tenosynovitis of the flexor tendon sheath
Nails changes
- Beau lines- transverse groove within the nail plate
- Leukonychia [white nails]
- Onycholysis [nail destruction]
- Subungual hyperkeratosis
- Splinter hemorrhages,
- Cracking of nail edges
Secondary amyloidosis [late stage]

The patients may have skin rash and scaly patches, typical of psoriasis.

Differential Diagnoses

Diagnosis

Lab Studies

There is no particular diagnostic test for psoriasis. Routine lab investigations are within normal limits.

Erythrocyte sedimentation rate (ESR) and C-reactive protein level are elevated in these patients.

90% of the cases are negative for the rheumatoid factor.

Serum IgA levels [a type of circulating antibody] are increased in 60% cases.

Synovial fluid aspiration shows increased cell count suggesting inflammation.

Imaging

X-rays

Pencil Cup Deformity in Psoriatic Arthritis Image Credit: ASSH

X-rays typically show the following changes interphalangeal, metatarsophalangeal, and metacarpophalangeal joints.

Joint space narrowing
Joint erosions
Complete joint destruction
Pencil-in-cup deformity
Fusiform soft-tissue swelling
Sacroiliitis

CT/MRI

These modalities may help in the early detection of synovitis, sacroiliitis, enthesitis, and erosions.

MRI can reveal inflammation in the small joints of the hands, the involvement of the collateral ligaments and soft tissues around the joint capsule [in contrast to rheumatoid arthritis].

CASPAR Diagnostics Criteria

The CASPAR criteria consist of established inflammatory articular disease with at least 3 from features given below

Current psoriasis (2)
A history of psoriasis if there is no current psoriasis (1)
A family history of psoriasis if there is no current psoriasis/ history of psoriasis (1)
Dactylitis (1)
Juxtaarticular new-bone formation (1)
Negative rheumatoid factor (1)
Nail dystrophy (1)

Treatment of Psoriatic Arthritis

The treatment aims at

Controlling the inflammation
Pain relief
Control and treatment of deformities.

The treatment is mainly medical. The patient should rest the joint in the acute stage.

Splints can be used for pain relief, especially for the hands, wrists, knees, or ankles.

Cold fomentation also decreases inflammation and provides pain relief.

The following drugs are used in the treatment of psoriatic arthritis

Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Oral
- Topical
Disease-modifying antirheumatic drugs (DMARDs)
- Methotrexate
- Sulfasalazine
- Cyclosporine
- Leflunomide
- Anti–TNF medications
  - Infliximab
  - Adalimumab
  - Certolizumab
  - Golimumab)
Intralesional corticosteroid injections in the joints or enthesopathy sites

For skin lesions, retinoic-acid derivatives and psoralen plus ultraviolet light are used in cases of severe skin disease.

New studies have also reported the effectiveness of ustekinumab, interleukin-12, and interleukin-23 antagonist, in symptom reduction of psoriatic arthritis.

Synovectomy is done in severe synovitis involving a single joint. An arthroscopic synovectomy is followed by physical therapy.

Arthrodesis is used to fuse the small joints. In the case of the large joint deformity, arthroplasty may be done.

Assistive devices may be needed in certain patients. The type of device used would depend on the region involved and the functional limitation. These may include

Orthotics
Gait assistance devices
- Walker
- Sticks

The patient may require to modify home for easier use. A change in vocation may be needed.

Physical therapy has an important role in treatment. After the acute stage has subsided, the following are begun

Isometric exercises
Active movements
Heat therapy for pain control
- Heat packs
- Paraffin wax
- Diathermy
- Ultrasound
Gait activities
Stretching exercises

Physical therapy should also be instituted after surgery.

The following can worsen psoriasis and need to be checked