Overview of joint involvement

The clinical course of joint involvement is extremely variable:

• may be a mild, self-limiting mono- or oligoarthitis
• often an insidious symetrical polyarthritis
• the most aggressive disease results in rapid disability with systemic inflammation and a high mortality rate

Often the disease begins in:

• proximal finger joints
• wrists

Later inflammation spreads to:

• elbows
• shoulders
• knees
• ankles
• feet

Characteristic joint deformities include:

• ulnar deviation of the fingers due to subluxation at the metacarpophalangeal joints
• loss of finger function due to hyperextension of the PIP joints with fixed flexion of the DIP joints 'swan neck deformity'
• fixed flexion of the PIP joints with hyperextension of the DIP joints 'boutonniere' or Z deformity of the thumb