Classification of Joint Involvement in Psoriatic Arthritis

Classification of Joint Involvement in Psoriatic Arthritis

What are the characteristic patterns of joint involvement in Psoriatic arthritis?

Approximately 95% of patients with PsA have peripheral joint disease (synovitis, tenosynovitis [dactylitis], enthesitis).

Another 5% have axial spine involvement exclusively. In 1973, Moll and Wright divided PsA into five broad categories. These categories overlap, creating a heterogeneous combination of joint disease. For instance, only 2% to 5% of PsA patients have predominantly DIP involvement, whereas over 50% of patients have DIP involvement in association with another pattern. As mentioned earlier, 5% of patients have only axial spine involvement but up to 40% of patients with one of the other patterns of PsA will also have coexistent axial involvement. Importantly, these patterns are not mutually exclusive.

Classification of Joint Involvement in Psoriatic Arthritis

Subtype%Typical Joints
1. Asymmetric oligoarticular disease15–20DIP and PIP joints of hands and feet. MCP joints, MTP joints, knees, hips, and ankles
2. Predominant DIP involvement2–5DIP joints
3. Arthritis mutilans5DIP joints, PIP joints
4. Polyarthritis “rheumatoid-like”50–60MCP joints, PIP joints, and wrists
5. Axial involvement (isolated)2–5Sacroiliac, vertebral

DIP , Distal interphalangeal; MCP , metacarpophalangeal; MTP , metatarsophalangeal; PIP , proximal interphalangeal.

What other features are associated with certain subtypes?

  • • Asymmetric oligoarthritis—dactylitis.
  • • Predominant DIP involvement—nail changes.
  • • Arthritis mutilans—osteolysis of involved joints, “telescoping” of digits.
  • • “Rheumatoid-like” disease—fusion of wrists.
  • • Axial involvement—asymmetric sacroiliitis and “jug handle”-like syndesmophytes.

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