Psoriatic Arthritis

Seronegative inflammatory Arthritis and Spondyloarthropathy seen in up to 30% of Psoriasis patients

Distal Interphalangeal Arthritis (Classic, 5% of cases)
1. Adjacent nails may show psoriatic pitting and Onycholysis
2. Progressive bony erosions occur
3. May be associated with Dactylitis
Arthritis mutilans (1-5% of cases)
1. Severe osteolysis
  1. Phalanges
  2. Metatarsals
  3. Metacarpals
2. "Opera glass" Digit
  1. Telescoping of skin over resorbed joint
Symmetric Polyarthritis (15-25%)
1. Rheumatoid Arthritis similarities
  1. Prominent Metacarpal disease
  2. Prominent proximal interphalangeal joint disease
2. Rheumatoid Arthritis differences
  1. Milder course than Rheumatoid Arthritis
  2. No Extra-articular Rheumatoid Arthritis signs
    1. No Subcutaneous Nodules
    2. No Vasculitis
    3. No pulmonary involvement
  3. Rheumatoid Factor Seronegative
Oligoarthritis (>50-70% of cases)
1. Asymmetric joint involvement (<4 joints)
2. Often presents as Arthritis in one knee
Psoriatic Spondylitis
1. Ankylosing Spondylitis type spine involvement
2. Less associated with HLA-B27
3. Atypical axial skeleton involvement
4. Lumbar Spine most commonly affected
5. Sacroiliitis (30%)

See above for signs specific to various Arthritis forms
Careful skin exam for signs of Psoriasis (concurrent with Arthritis in 80% of patients)
Inflammatory Arthritis
1. Asymmetric distal joint involvement
2. Joint Pain and tenderness to palpation
3. Peripheral joint and spine stiffness
  1. Occurs >30 minutes in morning and after inactivity
Skin lesions consistent with Psoriasis (60-80%)
1. Arthritis may precede psoriatic dermatitis (20%)
2. Classic psoriatic Plaques (See Psoriasis)
  1. Look at typical sites on extensor knee and elbow
  2. Examine scalp, ears, perineum, Umbilicus
3. Psoriatic Nail Pitting (80% of patients, see Psoriasis)
  1. Onycholysis
Other Skin changes: Keratoderma blennorrhagica
1. Hyperkeratotic Papules on plantar foot surface
2. Also seen in Reactive Arthritis (Reiter's Disease)
Sausage-shaped fingers and toes
1. Also seen in Reactive Arthritis (Reiter's Disease)
Enthesitis (ligament, tendon insertion inflammation)
1. Also seen in Reactive Arthritis (Reiter's Disease)
2. Achilles Tendonitis
3. Plantar Fasciitis
4. Patellofemoral Syndrome
Other musculoskeletal involvement
1. Sternoclavicular joint involvement
2. Temporomandibular Joint involvement
Ophthalmic changes
1. Uveitis (may be chronic and bilateral)

Major criteria (must be present)
1. Established articular disease (peripheral Arthritis, Spondyloarthropathy or enthesitis)
Minor Criteria (3 points or more present out of the following 5 categories)
1. Psoriasis
  1. Psoriasis currently active with skin or scalp disease (2 points) OR
  2. Psoriasis history in past (1 point) OR
  3. Psoriasis in a first or second degree relative (1 point)
2. Typical psoriatic Nail Dystrophy with pitting, Onycholysis or hyperkeratosis (1 point)
3. Rheumatoid Factor negative by any method other than latex (1 point)
4. Dactylitis
  1. Entire digit currently swollen (1 point) OR
  2. Dactylitis history as diagnosed previously by a rheumatologist (1 point) OR
  3. Hand or Foot XRay with new bone formation (not osteophytes) near joint margins (1 point)
5. Radiographic evidence on plain film XRay Hand or Foot
  1. Juxtarticular new bone formation as an ill-defined ossification near joint margin AND
  2. Excludes osteophyte formation
References
1. Taylor (2006) Arthritis Rheum 54(8): 2665-73 [PubMed]

Rheumatoid Factor (RF) negative
Erythrocyte Sedimentation Rate (ESR) increased
Complete Blood Count (CBC)
1. Mild normocytic normochromic Anemia
Uric Acid elevated (Hyperuricemia) in severe Psoriasis
Synovial Fluid Exam
1. Synovial Fluid WBC 2,000 to 15,000 per mm3
2. High Synovial Fluid WBC count seen in large effusions
Serum Hemolytic complement elevated
Serum electrophoresis
1. Hypergammaglobulinemia

XRay of involved joints
1. Bony erosions
2. Pencil-in-a-cup deformity at DIP joints
  1. Whittling of proximal phalanx
  2. Expanded base of distal phalanx
Spine XRay (Cervical, Thoracic or Lumbar)
1. Unilateral asymmetric syndesmophytes in skip pattern
2. Bamboo spine of Ankylosing Spondylitis rarely occurs
3. Asymmetric Sacroiliitis
4. Asymmetric paravertebral ossification

Treat underlying Psoriasis
Physical Therapy
1. Learn to protect affected joints
2. Perform strengthening and range of motion Exercises
First-Line
1. NSAIDs (sufficient in mild cases)
Second-Line
1. Intra-articular Corticosteroids for Oligoarticular disease
Disease modifying agents in moderate to severe cases
1. TNF-a inhibitor
  1. Adalimumab (Humira)
  2. Etanercept (Enbrel)
  3. Infliximab (Remicade)
  4. Ustekinumab (Stelara)
2. Interleukin-17 Inhibitors
3. Sulfasalazine (Azulfidine)
4. Methotrexate (avoid in HIV Infection)
5. Leflunomide
Other agents historically used in severe cases
1. Cyclosporine (avoid in HIV Infection)
2. Azathioprine (Imuran) (avoid in HIV Infection)
3. Gold Salts
4. Penicillamine