Wrist involvement in rheumatoid swan-neck deformity

Area of Science:

• Orthopedics
• Rheumatology
• Hand Surgery

Background:

• Rheumatoid arthritis commonly causes hand deformities.
• Swan-neck deformity is a challenging complication affecting hand function.

Observation:

• Distraction of the rheumatoid wrist with correctable carpal collapse eased proximal interphalangeal joint flexion.
• This improved flexion was not observed in hands with boutonniere deformity or no deformity.
• X-ray review revealed carpal collapse in most rheumatoid patients with swan-neck deformity.

Findings:

• Carpal collapse and proximal migration of the carpal-hand unit impair the efficiency of extrinsic motor systems.
• This creates an imbalance, termed 'extrinsic-minus' phenomena.
• This 'extrinsic-minus' state is proposed as a significant factor in rheumatoid swan-neck deformity etiology.

Implications:

• Understanding the role of carpal collapse offers new therapeutic targets for swan-neck deformity.
• Wrist stabilization techniques may be crucial in managing rheumatoid hand deformities.
• This finding could refine surgical and non-surgical treatment strategies for rheumatoid arthritis patients.