Boutonniere deformity is a condition of the hand characterized by an abnormal finger position in which the middle joint bends downward while the end of the finger bends backward. This deformity affects the finger joints, particularly the proximal interphalangeal joint and the distal interphalangeal joint, disrupting normal finger alignment and function.
The finger joints rely on a coordinated system of tendons, ligaments, and bones to provide smooth motion and stability. Boutonniere deformity most commonly occurs when the central slip of the extensor tendon is injured. The central slip is responsible for extending the proximal interphalangeal joint. When this tendon is torn or stretched, the middle joint bends downward (flexion) while the distal interphalangeal joint bends backward (hyperextension), creating the characteristic appearance often referred to as a “buttonhole deformity.”
The extensor mechanism includes several important structures that support finger movement and stability, including the lateral bands, triangular ligament, and terminal tendon. Damage to any of these components can disrupt normal finger mechanics, contributing to the development of the deformity and limiting the finger’s ability to straighten properly.
Your Guide to Boutonniere Deformity
Causes
The deformity may develop immediately after injury or may appear gradually over several weeks. Early recognition and treatment are important to restore normal finger position and function.
Individuals with rheumatoid arthritis are also at higher risk for boutonniere deformity. Chronic inflammation can weaken the soft tissues and tendons around the finger joints, leading to structural changes over time.
The thumb is typically not affected by this condition.
Common causes of boutonniere deformity include:
- Rheumatoid arthritis: Chronic inflammation can damage tendons, ligaments and bones, leading to finger deformities.
- Trauma or injury: Lacerations, jammed fingers or penetrating injuries can damage the central slip tendon.
- Forceful blows or severe sprains: Direct trauma to the finger can disrupt the tendon or supporting ligaments.
- Cuts or lacerations: A cut across the top of the finger may tear the underlying extensor tendon.
- Dislocations or fractures: Bone injuries involving the finger joints may contribute to deformity.
The central slip injury is sometimes subtle in “jammed finger” injuries, making careful clinical evaluation important for accurate diagnosis.
Symptoms
Signs and symptoms of boutonniere deformity may include:
- Swelling and tenderness
- Pain in the affected finger
- Visible finger deformity
- Difficulty or inability to straighten the finger
- Stiffness in the finger joint
- Limited range of motion
Symptoms may appear immediately after injury or develop over several days to weeks.
Diagnosis
Diagnosis typically involves a physical examination and imaging studies.
Clinical Evaluation May Include
- Assessment of finger alignment and joint motion
- Evaluation of tenderness and swelling
- Functional testing of the extensor tendon mechanism
Imaging Tests May Include
- X-rays: Used to detect fractures or joint abnormalities
- Elson test: A clinical test used to identify a central slip injury before the deformity becomes obvious
Radiographs may also be used to evaluate for associated fractures or joint damage.
Treatment
Treatment depends on the severity of the injury and how early the deformity is identified.
Non-Surgical Treatment
Many cases can be treated without surgery, particularly when diagnosed early.
- Ice therapy: Applying ice during the first 24 to 48 hours can reduce swelling and pain.
- Medications: Anti-inflammatory medications may help relieve pain and inflammation.
- Splinting: The affected finger is often splinted in full extension for approximately six weeks to allow the tendon to heal.
- Exercises: After immobilization, stretching and strengthening exercises help restore motion and function.
- Taping: Athletes may use protective taping during sports after recovery to help prevent reinjury.
Surgical Treatment
Surgery may be recommended if:
- The injury is severe
- The tendon is significantly damaged
- Conservative treatment fails
Surgical procedures may involve repairing the central slip tendon, reconstructing damaged structures or stabilizing the joint. In advanced cases, joint fusion may be considered to improve stability and reduce pain.
After surgery, patients typically wear a splint for several weeks and participate in hand therapy to restore strength and mobility.
Early treatment improves the likelihood of restoring normal finger function and preventing permanent deformity.
Prognosis and Complications
The outlook for boutonniere deformity depends largely on how quickly treatment begins. When treated early, many patients regain good function and alignment of the finger.
If left untreated, the deformity may become permanent and lead to complications such as:
- Persistent stiffness
- Reduced range of motion
- Chronic pain
- Post-traumatic arthritis
In some cases, untreated boutonniere deformity may contribute to other finger alignment problems over time.
Management and Rehabilitation
Rehabilitation is an important part of recovery. Hand therapy helps restore motion, flexibility and strength in the affected finger.
Treatment plans may include:
- Splinting to maintain proper joint alignment
- Guided exercises to improve flexibility and strength
- Occupational or hand therapy to restore function
For patients with rheumatoid arthritis, managing the underlying condition is also important to prevent further tendon damage and deformity.
When to Seek Care
If you notice swelling, pain or difficulty straightening a finger after an injury, seek medical evaluation promptly. Early diagnosis can prevent long-term deformity and improve treatment outcomes.
