Swan Neck Deformity

Swan neck deformity is a musculoskeletal condition that primarily affects the fingers, particularly the proximal and distal interphalangeal joints. It is characterized by a distinct and recognizable posture: hyperextension of the proximal interphalangeal (PIP) joint and flexion of the distal interphalangeal (DIP) joint, giving the finger a shape that resembles the long, curved neck of a swan. This deformity can significantly impair hand function, making it difficult to perform daily activities such as writing, gripping, or handling small objects. It may arise from a range of underlying disorders, including inflammatory, traumatic, or congenital causes. Understanding its symptoms, causes, and treatment options is crucial for timely intervention and improved patient outcomes (1).

Symptoms

The hallmark symptom of swan neck deformity is the abnormal positioning of the finger joints (1):

• Hyperextension of the PIP joint: This leads to a backward bend in the middle joint of the finger.
• Flexion of the DIP joint: The fingertip bends downward, often causing difficulty in straightening or extending the finger completely.
• Stiffness and pain: Some individuals may experience pain and stiffness, particularly in the early stages or in cases linked with inflammatory diseases.
• Loss of function: The deformity can hinder the ability to make a fist, grasp objects, or perform fine motor tasks.
• Swelling or tenderness: Particularly in cases associated with rheumatoid arthritis or trauma.
• Progressive worsening: Without appropriate treatment, the deformity may become more pronounced and less responsive to conservative management (1).

Causes

Swan neck deformity can be caused by a variety of conditions, often related to damage or imbalance in the tendons, ligaments, or joints of the finger (2). Common causes include:

• Rheumatoid arthritis (RA): The most frequent cause, RA leads to chronic inflammation of the joints, weakening ligaments and causing joint instability.
• Trauma: Injuries to the volar plate (a ligament that prevents the PIP joint from hyperextending), tendons, or bones can precipitate the deformity.
• Ligament laxity: Inherited or acquired conditions resulting in loose ligaments can make joints more susceptible to deformity.
• Cerebral palsy: Muscle imbalances due to neurological conditions can result in swan neck posture.
• Psoriatic arthritis or systemic lupus erythematosus (SLE): These autoimmune diseases can also cause joint deformities.
• Untreated mallet finger: A flexion deformity of the DIP joint, if not properly managed, can progress into a swan neck deformity due to imbalances in tendon pull.

Risk Factors

Several factors may increase the likelihood of developing swan neck deformity:

• Chronic inflammatory diseases: Especially rheumatoid arthritis, which commonly affects hand joints.
• Previous finger injuries: Ligament tears or fractures can predispose an individual to joint instability.
• Genetics: A family history of connective tissue disorders or arthritis can increase susceptibility.
• Occupational stress: Jobs that require repetitive hand movements or fine motor control may contribute to joint wear.
• Age and gender: Swan neck deformity is more prevalent in middle-aged to older adults and is more common in females, particularly in relation to autoimmune conditions.
• Neuromuscular disorders: Conditions affecting muscle tone and coordination may lead to joint imbalances.

Diagnosis

Diagnosing swan neck deformity typically involves a combination of clinical examination and imaging studies (3):

• Physical examination: A healthcare provider will inspect the hand, noting the alignment of the PIP and DIP joints and testing range of motion and strength.
• Medical history: Identifying underlying diseases like rheumatoid arthritis or recent trauma helps determine the cause.
• X-rays: These reveal joint alignment, bone integrity, and signs of arthritis or previous fractures.
• Ultrasound or MRI: These can assess soft tissue structures like ligaments, tendons, and cartilage, especially in early or complex cases.
• Laboratory tests: In suspected autoimmune causes, blood tests like rheumatoid factor (RF), anti-CCP antibodies, or ESR/CRP may be ordered.

Early diagnosis is critical to prevent progression and implement appropriate treatment strategies.

Treatment Options

Treatment of swan neck deformity depends on its underlying cause and severity.

Options may include (2):

Conservative Treatments

• Splinting: Finger splints can help maintain proper alignment, especially in early stages. PIP extension block splints are commonly used.
• Physical therapy: Exercises to strengthen the hand muscles, improve joint mobility, and correct tendon imbalances.
• Anti-inflammatory medications: NSAIDs or corticosteroids can reduce inflammation in cases associated with arthritis.
• Disease-modifying antirheumatic drugs (DMARDs): For autoimmune causes like RA, DMARDs (e.g., methotrexate) help control the underlying disease process.

Surgical Treatments

Surgery is typically considered for advanced or functionally limiting cases (2):

• Soft tissue reconstruction: To correct tendon imbalances or repair ruptured ligaments.
• Joint fusion (arthrodesis): Involves fusing the PIP or DIP joint in a functional position to relieve pain and improve stability.
• Joint replacement (arthroplasty): In cases with severe joint damage, prosthetic implants may restore mobility.
• Tendon transfers: Re-routing tendons to restore balance and correct deformity.

Postoperative rehabilitation is essential to regain function and prevent recurrence.

Living With or Prevention

Living With Swan Neck Deformity

Individuals with swan neck deformity can lead productive lives with proper management and adjustments (3):

• Occupational therapy: Helps patients adapt daily tasks and improve hand function using assistive devices.
• Regular monitoring: Especially important for those with underlying autoimmune conditions.
• Pain management: Combining medication, splinting, and heat/cold therapy can ease discomfort.
• Psychological support: Chronic conditions affecting hand function can lead to frustration or emotional distress, making mental health support valuable.

Prevention

While not all cases are preventable, certain strategies can reduce risk (3) :

• Early treatment of mallet finger or hand injuries to prevent deformity progression.
• Control of systemic inflammatory diseases through medication and lifestyle changes.
• Protective hand gear in occupations prone to hand trauma.
• Routine hand exercises to maintain strength and flexibility, especially in at-risk populations.

References

1. Lane R, Nallamothu SV. Swan-Neck Deformity. 2025 May 21. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 30247845.
2. Rode MM, Mullen BL, Zhu AQ, Helsper EA, Moran SL. Surgical Management of Swan Neck Deformity Following Mallet Finger Injury: A Review of 25 Patients Over 20 Years. Hand (N Y). 2025 Mar;20(2):197-202. doi: 10.1177/15589447231205616. Epub 2023 Oct 23. PMID: 37872782; PMCID: PMC11833895.
3. Hahn AK, Corvi JJ, Hammarstedt JE, Palmer B. Swan Neck Deformity: An Unusual Complication Following Trigger Finger Release. J Orthop Case Rep. 2023 May;13(5):20-23. doi: 10.13107/jocr.2023.v13.i05.3630. PMID: 37255647; PMCID: PMC10226641.