Ulnar Deviation Syndrome – Causes, Symptoms and Treatment

What is Ulnar Deviation Syndrome?

Ulnar deviation syndrome refers to a characteristic hand deformity in which the fingers permanently deviate toward the ulnar side of the hand (toward the little finger). This deviation occurs at the metacarpophalangeal (MCP) joints, which are the knuckle joints at the base of the fingers. It is a hallmark sign of advanced inflammatory joint disease, most notably rheumatoid arthritis. The condition can significantly impair hand function and reduce the quality of life of those affected.

Causes

The most common underlying cause of ulnar deviation syndrome is rheumatoid arthritis, a chronic autoimmune inflammatory disease that primarily targets the joints. Persistent inflammation damages the joint capsule, ligaments, and tendons surrounding the MCP joints. This leads to joint instability, causing the extensor tendons of the fingers to slip toward the ulnar side and pulling the fingers in that direction.

• Rheumatoid arthritis: The most frequent cause, due to chronic joint inflammation and connective tissue destruction
• Other inflammatory arthropathies: Such as psoriatic arthritis or systemic lupus erythematosus
• Traumatic injuries: Damage to the ligaments and tendons of the hand can also result in ulnar deviation
• Degenerative joint disease: Advanced osteoarthritis may rarely cause similar deformities

Symptoms

Ulnar deviation syndrome presents with a combination of visible deformity and functional impairment of the hand.

• Ulnar drift of the fingers: A visible shift of the fingers toward the little finger
• Pain and tenderness: Particularly at the MCP joints
• Swelling of the knuckle joints: Inflamed, swollen, and sometimes reddened joints
• Impaired grip function: Difficulty grasping, holding, and carrying objects
• Hand muscle weakness: Loss of strength due to tendon and muscle displacement
• Stiffness: Most pronounced in the morning or after periods of rest

Diagnosis

The diagnosis of ulnar deviation syndrome is primarily clinical, based on a careful physical examination. Imaging studies are used as supplementary diagnostic tools.

• Physical examination: Assessment of finger alignment, joint range of motion, tenderness, and grip strength
• X-ray of the hand: Evaluation of joint structure, bone erosions, and the extent of the deformity
• Ultrasound: Assessment of tendons, ligaments, and signs of inflammation at the joints
• MRI (Magnetic Resonance Imaging): Detailed visualization of soft tissues, tendons, and early cartilage damage
• Laboratory tests: Inflammatory markers (CRP, ESR), rheumatoid factor, and anti-CCP antibodies to confirm rheumatoid arthritis

Treatment

Treatment of ulnar deviation syndrome is guided by the underlying cause, the severity of the deformity, and the degree of functional impairment. Both conservative and surgical approaches are available.

Conservative Treatment

• Medication: Anti-inflammatory drugs (NSAIDs), disease-modifying antirheumatic drugs (DMARDs), and biologics for rheumatoid arthritis to slow disease progression
• Occupational therapy: Targeted exercises to improve hand function, joint protection training, and adaptation of assistive devices for daily activities
• Physical therapy: Heat applications, cryotherapy, and manual therapy for pain relief
• Orthoses and splints: Custom-made finger orthoses or wrist splints to stabilize the joints and correct the deformity

Surgical Treatment

• Synovectomy: Removal of the inflamed joint lining to slow further joint destruction
• Tendon reconstruction: Repositioning of the displaced extensor tendons to correct finger alignment
• Arthroplasty: Joint replacement using silicone implants for severely destroyed MCP joints to restore function and alignment
• Arthrodesis: Surgical joint fusion as a last resort in cases of severe instability

Prognosis and Course

The progression of ulnar deviation syndrome is closely linked to the course of the underlying disease. With early and consistent treatment of rheumatoid arthritis, the progression of the deformity can be slowed or halted. Advanced cases often require surgical intervention to restore hand function. Long-term follow-up by a combined rheumatology and orthopedic team, together with occupational therapy support, is essential for maintaining quality of life.

References

1. Smolen JS et al. - Rheumatoid arthritis. Nature Reviews Disease Primers, 2018. https://www.nature.com/articles/nrdp201869
2. Trieb K. - Treatment of the wrist in rheumatoid arthritis. Journal of Hand Surgery, 2008. PubMed PMID: 18984327
3. American College of Rheumatology - Rheumatoid Arthritis Clinical Guidelines, 2021. https://www.rheumatology.org