Boutonnière Deformity – A Comprehensive Medical Guide

Overview

Boutonnière deformity (pronounced “boo‑ton‑yay‑ray”) is a specific mal‑alignment of a finger in which the middle joint (proximal interphalangeal joint, or PIP) is flexed while the tip of the finger (distal interphalangeal joint, DIP) is hyper‑extended. The name derives from the French word for “buttonhole,” because the finger looks as if it were slipping through a buttonhole.

The condition most commonly affects the index, middle, or ring fingers of the dominant hand, but it can involve any finger. It may be present in children, adolescents, or adults, though the underlying causes differ by age group.

Who it affects

• Adults with traumatic finger injuries – up to 4–6% of closed finger lacerations develop a boutonnIère deformity if the central slip of the extensor tendon is disrupted.^[1]
• Patients with rheumatoid arthritis (RA) – approximately 10–15% of RA patients develop a boutonnière‑type contracture over the disease course.^[2]
• Rarely, congenital forms are seen in children with connective‑tissue disorders such as Ehlers‑Danlos syndrome.

While isolated cases are relatively uncommon, the deformity is a frequent complication after hand trauma or in inflammatory arthritis, making awareness essential for early treatment.

Symptoms

The presentation may be subtle at first but typically follows a predictable pattern:

• Flexion of the PIP joint – The middle joint bends toward the palm (usually 30°–90°).
• Hyper‑extension of the DIP joint – The fingertip points upward, often giving a “hooked” appearance.
• Loss of active extension at the PIP joint – The patient cannot straighten the middle of the finger without assistance.
• Pain or tenderness – Especially over the dorsal (back) surface of the PIP joint where the extensor tendon is injured.
• Swelling or bruising – Common after an acute injury.
• Difficulty gripping or performing fine motor tasks – The altered finger mechanics reduce strength.
• Visible “buttonhole” silhouette – The finger looks as if it is slipping through a buttonhole when viewed from the side.
• Progressive stiffness – Without treatment, the deformity can become fixed, limiting motion permanently.

In chronic cases (< 6–8 weeks), the joint capsule may contract, making the deformity rigid and more painful.

Causes and Risk Factors

Traumatic causes

• Central slip rupture – The most common mechanism; a forceful blow or laceration severs the central portion of the extensor tendon over the PIP joint.
• Avulsion injuries – The tendon pulls off a piece of bone (small fragment) at its attachment site.
• Contusion – Direct impact can cause a “staggered” tear of the tendon fibers.

Inflammatory causes

• Rheumatoid arthritis – Synovial inflammation gradually erodes the central slip and weakens the supporting ligamentous structures.
• Psoriatic arthritis – Similar mechanisms but less common.

Other contributing factors

• Connective‑tissue disorders (e.g., Ehlers‑Danlos, Marfan) that diminish tendon integrity.
• Repeated microtrauma – Athletes in rock climbing, gymnastics, or manual labor who repeatedly stress the DIP/PIP complex.
• Improper splinting or immobilization after a finger injury – If a splint holds the PIP in flexion for >2 weeks, the central slip may not heal properly.

Risk factors

• Male gender (slightly higher incidence in work‑related injuries).
• Age 15‑45 years for traumatic causes; >60 years for rheumatoid‑related cases.
• Occupations requiring heavy manual handling (construction, mechanics, musicians).
• History of prior finger injuries or surgeries.

Diagnosis

Diagnosis is primarily clinical, supplemented by imaging when needed.

Physical examination

• Observation of the classic “flexed PIP / hyper‑extended DIP” posture.
• Passive and active range‑of‑motion testing of the PIP and DIP joints.
• Tenodesis test – Extending the wrist while the hand is relaxed should cause passive extension of the fingers; lack of PIP extension suggests a central slip lesion.
• Palpation for tenderness over the dorsal PIP and assessing for a palpable gap in the extensor tendon.

Imaging studies

• Plain radiographs (X‑ray) – Rule out associated fractures, avulsion fragments, or joint degeneration.
• Ultrasound – Dynamic assessment of tendon continuity; useful in early trauma when the gap may be subtle.
• MRI – Gold standard for visualizing soft‑tissue injury, especially in chronic or rheumatologic cases.

Classification

Based on timing and severity, clinicians often categorize the deformity:

• Acute boutonnière – < 6 weeks from injury.
• Chronic boutonnière – >6 weeks; may be fixed.
• ‘Myerson’ classification – Grades severity (I‑IV) based on joint instability and contracture.

Treatment Options

Therapy aims to restore tendon continuity, prevent contracture, and regain functional motion. The approach differs for acute vs. chronic cases.

Non‑surgical management (typically for acute injuries)

1. Immobilization with a stacked‑splint – The PIP is held in slight extension (0‑10°) while the DIP is gently flexed. Splint is worn continuously for 4‑6 weeks.^[3]
2. Early controlled motion – After 4 weeks, supervised active‑assist exercises are introduced to prevent stiffness (e.g., “push‑up” exercises with a rubber band).
3. Physical therapy – Skilled hand therapists teach tendon gliding, scar mobilization, and strengthening.
4. Pharmacologic pain control – NSAIDs (ibuprofen, naproxen) for pain and inflammation; consider acetaminophen if NSAIDs are contraindicated.
5. Adjuncts – Cryotherapy for swelling, and elevation of the hand.

Surgical options (indicated when)

• Failure of conservative treatment after 6–8 weeks.
• Open central‑slip rupture or associated fracture.
• Chronic fixed deformity with joint contracture.

Procedures

1. Primary repair of the central slip – Direct suture of the torn tendon using microsurgical techniques; often combined with a temporary K‑wire or pull‑out wire to protect the repair.
2. Tenodermodesis (tendon‑to‑skin or tendon‑to‑bone graft) – Reinforces the central slip when tissue quality is poor.
3. Vince & Watson procedure – Uses a slip of the lateral band to augment the central slip.
4. Stage‑wise reconstruction – For chronic cases: (a) release of contracture, (b) tendon graft (palmaris longus or plantaris), (c) staged external fixation if severe stiffness.
5. Arthrodesis (fusion) – Rare, reserved for end‑stage arthritis with pain unresponsive to other measures.

Post‑operative care

• Immediate immobilization in a custom splint for 3–4 weeks.
• Gradual introduction of passive and active motion under therapist supervision.
• Regular follow‑up X‑rays to ensure joint alignment.

Management of rheumatoid‑related boutonnière

• Systemic disease control (DMARDs, biologics) per rheumatologist guidance.^[4]
• Occasional steroid injections into the tendon sheath for acute inflammation.
• Same splinting/therapy principles, but with heightened vigilance for infection.

Living with Boutonnière Deformity

Daily‑management tips

• Protect the finger – Use padded gloves during activities that place stress on the hand (gardening, woodworking).
• Ergonomic tools – Choose pens, keyboards, and utensils with larger grips to reduce required flexion.
• Warm‑up exercises – Before repetitive tasks, perform gentle tendon‑gliding (e.g., “straight‑hand”, “hook‑fist”) for 5 minutes.
• Ice & elevation – 15‑20 minutes post‑activity if swelling recurs.
• Splint at night – A low‑profile night splint keeps the PIP in neutral, preventing contracture progression.
• Regular therapist visits – Even after healing, periodic hand‑therapy sessions help maintain range of motion.
• Monitor for changes – New pain, increased stiffness, or loss of function warrants re‑evaluation.

Work‑place accommodations

Employers should consider:

• Modified duties that limit forceful gripping.
• Assistive devices (e.g., jar openers, button hooks).
• Scheduled breaks to perform stretching.

Prevention

• Protective equipment – Wear safety gloves when handling tools or during sports (rock climbing, martial arts).
• Proper splinting after finger injuries – Ensure the PIP is immobilized in extension, not flexion, and limit immobilization to ≤2 weeks when possible.
• Strengthening and flexibility program – Hand‑specific exercises 2‑3 times/week for at‑risk workers or athletes.
• Early treatment of tendon injuries – Prompt medical evaluation after a finger laceration or blow reduces the chance of a missed central slip rupture.
• Optimal rheumatoid‑arthritis management – Adherence to DMARD therapy, routine rheumatology follow‑up, and early hand‑specialist referral when joint changes appear.

Complications

If left untreated or inadequately managed, boutonnière deformity can lead to:

• Fixed flexion contracture – Permanent loss of PIP extension.
• Joint degeneration – Osteoarthritic changes secondary to abnormal biomechanics.
• Tendon adhesions – Scar tissue restricts motion and may require surgical release.
• Reduced grip strength – Impacts daily activities and occupational performance.
• Painful arthritic flare in rheumatoid patients, accelerating overall hand disability.
• Psychosocial impact – Visible deformity can affect self‑image and quality of life.

When to Seek Emergency Care

References

1. American Society for Surgery of the Hand. “Boutonnière Deformity.” Hand Clinics. 2022.
2. Mayo Clinic. “Rheumatoid arthritis – Hand problems.” https://www.mayoclinic.org/diseases‑conditions/rheumatoid‑arthritis/in‑depth/hand‑problems/art‑20045042 (accessed May 2026).
3. American Academy of Orthopaedic Surgeons. “Management of Acute Boutonnière Deformity.” AAOS Clinical Practice Guideline, 2021.
4. National Institute of Arthritis and Musculoskeletal and Skin Diseases. “Rheumatoid Arthritis Treatment.” https://www.niams.nih.gov (accessed May 2026).
5. World Health Organization. “Hand injuries: prevention and care.” WHO Fact Sheet, 2020.