18th January 2024

Articular manifestations

RA typically presents with symmetrically swollen, painful and stiff small joints of the hand and feet. Morning stiffness is a sign of inflammatory arthritis and typically lasts over an hour. Classically, metacarpophalangeal (MCP), proximal interphalangeal joints (PIP), and metatarsophalangeal (MTP) joints are involved (The distal interphalangeal (DIP) joints and thoracic and lumbosacral spine are spared in RA). Other synovial joints which may be involved include wrists, knees, elbows, ankles, hips, shoulders and cervical spine (C1-C2).

RA onset can vary, and initial presentation may occur in the following ways:

• Insidious onset of symmetric polyarthropathy of small joints of the wrists, hands and feet is the commonest
• Insidious onset of monoarticular or oligoarticular arthritis similar to a seronegative spondyloarthropathy. Additional small joint and symmetric involvement can occur over time.
• Sudden onset polyarticular arthritis is less common
• Palindromic RA is characterised by brief, self-limited and recurrent episodes of mono/polyarthritis of various joints
• Systemic illness with extra-articular symptoms

Signs

There is inflammation early in the disease process, but usually no joint damage. With progressive inflammation and disease progression, damage to the joints and surrounding tendons can result in the classic deformities associated with RA (now rarely seen with earlier diagnosis and initiation of disease-modifying anti-rheumatic drug (DMARD) therapy.

The following signs are some of the characteristic findings associated with RA:

• ‘Zigzag’ deformity- ulnar deviation and palmar subluxation of the MCP joints and radial deviation of the wrist
• Swan neck deformities- PIP hyperextension and DIP flexion
• Boutonniere deformities- PIP flexion and DIP hyperextension
• Trigger finger- thickening of the tendon sheaths, causing the finger to lock in flexion
• Rupture of hand extensor tendons
• Carpal tunnel syndrome- tenosynovitis in the flexor tendon sheaths can cause median nerve impingement
• Claw toe deformities of the PIP joints due to plantar subluxation of the metatarsal heads
• Valgus and pes planus deformities.

Image Source: Wikimedia Commons (2014). Swan neck deformity in a 65 year old Rheumatoid Arthritis patient- 2014-05-27 01-49, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Swan_neck_deformity_in_a_65_year_old_Rheumatoid_Arthritis_patient-_2014-05-27_01-49.jpg  (Accessed: 24 November 2021).

Image Source: Wikimedia Commons (2021). RA hand deformity. Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:RA_hand_deformity.JPG (Accessed: 24 November 2021).

Image Source: Wikimedia Commons (2021). Luxierte Zehen bei Rheumatoidarthritis (praop), Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Luxierte_Zehen_bei_Rheumatoidarthritis_(pr%C3%A4op.)..jpg (Accessed: 24 November 2021).