What Is Boutonniere Deformity? Symptoms, Causes, and Treatment Options
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is boutonniere deformity?
Boutonniere deformity is a finger condition in which the middle joint stays bent and the fingertip joint bends upward, caused by damage to the central slip tendon, usually from injury. It is treated first with splinting and physical therapy, with surgery for severe cases. Most people treated promptly have good outcomes, though recovery can take many months. [1]
Key takeaways
Boutonniere deformity locks the middle finger joint (PIP) in a bent position while the tip joint (DIP) hyperextends upward. [1]
The root cause is usually a tear in the central slip extensor tendon. The tear looks like a "buttonhole" (boutonnière is French for buttonhole). [1]
Injury is the most common cause: jammed fingers, broken fingers, dislocations, and blunt or penetrating trauma. Athletes are at higher risk. [1]
Rheumatoid arthritis, burns, congenital hand differences, and connective tissue diseases are non-injury causes. [1]
Providers diagnose it by sight and confirm with Elson's test; X-rays help plan treatment. [1]
Early treatment is essential. The longer it goes untreated, the harder it is to correct, even with surgery. [1]
Most cases start with a splint for several months, then months of physical therapy; surgery is an option for severe cases. [1]
What the research says
Surgery for long-standing injuries gives good results in most patients, but not all. In a series of 13 patients with chronic, injury-related boutonniere deformity whose joints could still be corrected, central slip repair with suture-anchor augmentation reduced the average PIP extension lag from 43.5° by an average of 21.9°. About 77% (10 of 13) had excellent or good results, and 3 patients had a relapse of the deformity (Lee et al., Clin Orthop Surg, 2021) [2].
In rheumatoid arthritis, surgery can correct a boutonniere thumb. In 21 thumbs (18 patients) with rheumatoid arthritis, a modified tendon rerouting procedure improved the average MCP extensor lag from 62° to 17° over about 3.2 years of follow-up, and the deformity improved in 18 of 21 thumbs (Iwamoto et al., J Hand Surg Am, 2016) [3].
The right treatment depends on how far the joint has changed. A 2025 review of rheumatoid hand surgery notes that mild deformities that can be corrected by hand may need only orthoses or splints. When boutonniere deformity is present with joint structures that are almost intact, soft-tissue surgery without implants is preferred; severe joint destruction may need implant arthroplasty or fusion (Nakayama et al., J Clin Med, 2025) [4].
What Is Boutonniere Deformity?
Boutonniere deformity is a condition that affects your ability to straighten the middle joint of a finger (or, less commonly, a toe). Your middle joint gets stuck in a bent position and will not straighten. At the same time, the joint toward the tip of your finger or toe flexes upward. [1]
The condition starts with a tendon on top of your finger called the central slip. This is the tendon that allows you to straighten your finger at the middle joint. It runs over the top of your finger, and you might even be able to see it where it passes over your knuckles. [1]
If an injury stretches or tears this tendon, it creates a split in the fibers that looks like a buttonhole. The word boutonnière means "buttonhole" in French. If that tear is not repaired, the tendon will not work properly, and you will not be able to straighten your finger joints. [1]
Central slip injuries are the most common cause of boutonniere deformity, but arthritis can cause it too. Damage to the soft tissues in your finger may force the tendon out of place by stretching or weakening it, which has the same effect as a tear. [1]
Symptoms of Boutonniere Deformity
The primary symptom is the abnormal position of your finger joints. You will be unable to straighten the middle joint, medically called the proximal interphalangeal (PIP) joint. At the same time, the joint at the tip, the distal interphalangeal (DIP) joint, will be hyperextended. [1]
You may also experience pain and swelling in the joints, along with stiffness that gets worse with time. [1]
Symptoms may appear immediately after a finger injury or develop up to several weeks afterward. If you have arthritis of the hand, the deformity may develop very gradually. The first sign may simply be that your finger does not bend and straighten as easily as it should. [1]
Sign to watch for | What it looks like |
Bent middle joint | The PIP joint stays flexed and will not straighten |
Upward tip joint | The DIP joint at the fingertip hyperextends |
Joint pain and swelling | Aching and puffiness around the affected joints |
Progressive stiffness | Movement becomes harder over time |
Gradual onset | With arthritis, the finger slowly loses easy bending and straightening |
Causes and Risk Factors
Boutonniere deformity is usually the result of a traumatic injury to your central slip tendon. Anyone can get a central slip injury, but it is more common in athletes, who are prone to sports injuries. [1]
Traumatic cause | How it damages the central slip |
Jammed finger | Tears the tendon as well as ligaments |
Broken finger | The broken bone stretches or tears the tendon |
Dislocated finger joint | Stretches or tears the tendon |
Blunt or penetrating trauma | Direct damage to the finger and tendon |
Other possible causes are not injuries at all:
Non-injury cause | How it leads to deformity |
Rheumatoid arthritis | Constant inflammation and swelling in the hand weakens the tendon |
Burn injuries | Burns weaken the tendon and can sometimes cause rupture |
Congenital hand deformity | The deformity may be present at birth |
Connective tissue diseases | Certain genetic disorders weaken your connective tissues |
The mechanics behind the deformity come down to how your tendons work together. Your central slip tendon works with a network of other extensor tendons that extend your finger. If the central slip slackens or ruptures, it can no longer pull your PIP joint. It also affects the extensors that pull your DIP joint, making them pull more. That is why one bent joint creates two: a bent middle joint and a hyperextended fingertip. [1]
How Is Boutonniere Deformity Diagnosed?
A healthcare provider will examine your finger and ask about your symptoms and health history. The good news: boutonniere deformity is easy to recognize on sight once it has fully developed. [1] But if it is just starting to form, it might not be obvious yet.
For early or unclear cases, providers use a quick clinical check called Elson's test:
You curl your fingers around the edge of a table.
The provider gently presses down on the bone in your middle finger segment (middle phalanx).
You try to straighten your finger against their resistance.
If you cannot straighten it, the provider will know your central slip is impaired. Your provider might then order X-rays to evaluate the injury and plan your treatment. [1]
Diagnostic step | What it shows |
Visual exam | The bent PIP joint and hyperextended DIP joint are usually recognizable on sight |
Elson's test | Confirms whether the central slip tendon is impaired |
X-rays | Evaluate the injury and help plan treatment |
How Is Boutonniere Deformity Treated?
Most of the time, healthcare providers start with conservative (nonsurgical) treatments. But timing matters: it is important to treat boutonniere deformity sooner rather than later. The longer it goes untreated, the harder it may be to correct the deformity, even with surgery. [1]
Conservative (nonsurgical) treatment
If your condition is relatively recent, your healthcare provider will start by splinting your finger. The splint holds your PIP joint in an extended (straight) position for several months while the injured tendon heals. After the splint phase, you will have several months of physiotherapy to restore strength and movement. [1]
Surgical treatment
For severe injuries and older conditions that have failed to heal with conservative treatment, you might need surgery. [1] You might have scar tissue in your finger holding it in the wrong position, or your surgeon might need to put parts back where they belong.
Surgical option | When it is used |
Repair or reconstruct the central slip tendon | Restores the torn tendon's ability to straighten the middle joint |
Reposition or release tension in other extensor tendons | Rebalances the tendon network so the joints move correctly |
Repair or fuse the PIP joint | Considered when arthritis is involved |
After surgery, you will wear a finger splint for several weeks while your finger heals. After the first week, you will have hand exercises to practice as you recover. Your physiotherapist or hand therapist will guide your rehabilitation during the next few months. [1]
Treatment route | What it involves | Timeline |
Conservative | Finger splint holding the PIP joint straight | Several months |
Conservative | Physiotherapy to rebuild movement | Several months after splinting |
Surgery | Tendon repair, tendon rebalancing, or joint fusion | Splint for several weeks post-op |
Post-surgery | Hand exercises from week one, guided rehabilitation | Several months |
What Is the Outlook for Boutonniere Deformity?
Boutonniere deformity is treatable, but timing matters. If you get treatment right away after an injury, you may recover completely, with or without surgery. If it takes a while to recognize and treat your deformity, recovery may be more challenging. [1]
The cause of your deformity also matters. Chronic conditions like arthritis can interfere with healing and recovery. Severe injuries and congenital disorders may be harder to fix with surgery. Sometimes surgeons can restore some of your finger joint flexibility, but not all of it. [1]
Recovering from boutonniere deformity can take many months, and it requires active participation from you, especially when it is time to start exercising your finger. The encouraging part: most people who follow their healthcare team's guidance will have good outcomes. [1]
One important note: if you have injured your finger and cannot move it, have a healthcare provider look at it. Do not assume that because fingers are small, your injury is also minor. Fingers are complex and delicate, and an injury can do more damage than you might think. Damage to one tendon on top of your finger can affect other tendons connected to it, and the mechanics that let you move your finger can fall apart before you realize it. Recovery means rehabilitating these very small parts.
Conclusion
Boutonniere deformity may start small, a finger that will not quite straighten, but it is a real tendon injury that rewards quick action. The central slip that straightens your middle knuckle can tear or stretch from a simple sports injury, and the result is a bent joint that will not correct itself. The best outcomes belong to people who get diagnosed early, wear their splint faithfully, and commit to months of therapy.
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Frequently Asked Questions
What is boutonniere deformity?
Boutonniere deformity is a finger condition where the middle joint (PIP joint) stays bent and cannot straighten, while the fingertip joint (DIP joint) bends upward.
What does "boutonniere" mean?
The word is French for "buttonhole." The tear in the central slip tendon creates a split in the fibers that looks like a buttonhole, which gives the condition its name.
What is the central slip tendon?
The central slip is the tendon that runs over the top of your finger and straightens it at the middle joint. You might be able to see it where it passes over your knuckles.
Can boutonniere deformity affect toes?
Yes. While it most commonly affects fingers, it can also affect the toes, less commonly.
What are the main symptoms?
The primary symptom is the abnormal finger position: an inability to straighten the middle joint with an upward-bent fingertip joint. Pain, swelling, and progressively worsening stiffness may also occur.
Can you get boutonniere deformity from a jammed finger?
Yes. A jammed finger can tear the central slip tendon as well as ligaments, and is one of the most common traumatic causes.
Do broken fingers cause boutonniere deformity?
A broken finger can cause it when the broken bone stretches or tears the central slip tendon.
Is boutonniere deformity common in athletes?
Anyone can get a central slip injury, but it is more common in athletes because of their higher risk of sports injuries.
Can rheumatoid arthritis cause boutonniere deformity?
Yes. Constant inflammation and swelling in the hand can weaken the tendon, producing the same effect as a tear.
Can burns cause boutonniere deformity?
Yes. Burns can weaken the central slip tendon and, in some cases, lead to tendon rupture.
Can you be born with boutonniere deformity?
Yes. It can occur as a congenital hand deformity, present from birth, or result from genetic connective tissue diseases.
How do doctors test for boutonniere deformity?
Providers often diagnose it on sight. For early cases, they use Elson's test: you curl your fingers over a table edge while the provider presses on your middle phalanx; if you cannot straighten against the resistance, the central slip is impaired.
Do you need an X-ray for boutonniere deformity?
X-rays are not always required for diagnosis, but providers may order them to evaluate the injury and plan treatment.
What is the first-line treatment?
Most cases start with conservative treatment: a finger splint that holds the PIP joint straight for several months, followed by several months of physiotherapy.
When is surgery needed?
Surgery is considered for severe injuries and older conditions that failed to heal with conservative treatment. The surgeon may repair the tendon, rebalance extensor tendons, or fuse the joint if arthritis is involved.
Does boutonniere deformity heal completely?
With prompt treatment, many people recover completely, with or without surgery. Delayed treatment makes correction harder. Recovery takes many months and depends on active participation in exercises, but most people who follow their care team's guidance have good outcomes.
Related Reading
References
Cleveland Clinic. Boutonnière Deformity. Cleveland Clinic Health Library. Medically reviewed; last updated March 10, 2025. https://my.clevelandclinic.org/health/diseases/22094-boutonniere-deformity
Lee JK, Lee S, Kim M, Jo S, Cho JW, Han SH. Anatomic repair of the central slip with anchor suture augmentation for treatment of established boutonniere deformity. Clin Orthop Surg. 2021;13(2):243-251. PMID 34094016. https://doi.org/10.4055/cios20170
Iwamoto T, Sakuma Y, Momohara S, Matsumura N, Ochi K, Sato K. Modified extensor pollicis longus rerouting technique for boutonniere deformity of the thumb in rheumatoid arthritis. J Hand Surg Am. 2016;41(6):e129-e134. PMID 27118392. https://doi.org/10.1016/j.jhsa.2016.04.002
Nakayama M, Kiyota Y, Nakamura S, Yagi M. Trends in rheumatoid hand surgery: indications, techniques, and outcomes. J Clin Med. 2025;14(2):319. PMID 39860324. https://doi.org/10.3390/jcm14020319
Medical disclaimer
This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read in this article.
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