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Boutonnière Deformity

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Extensor central-slip injury at the middle finger joint; early splinting prevents the zigzag deformity, established cases need surgery.

Updated Aug 20263 citations
Illustration of a finger with a boutonniere deformity — the middle joint bent and the fingertip tilted back.
Boutonniere deformity: the middle finger joint stays bent and the fingertip tilts back. Kieran Hirpara 4.0

What you're feeling

You may notice a change in how your finger looks and feels. A boutonnière deformity is a closed soft tissue injury affecting the extensor mechanism, which is the system of tendons and ligaments that helps you straighten your finger. This injury typically occurs in specific zones around the middle joint of your finger.

The most common symptom is pain at the middle joint of your finger. You might feel tenderness when you press on this area. The pain often worsens when you try to straighten your finger or when you use your hand for gripping tasks. You may find it difficult to fully extend the tip of your finger. Instead, the middle joint bends inward while the tip joint hyperextends. This creates a distinctive shape that can feel stiff and uncomfortable.

Daily tasks become challenging as the deformity progresses. Simple actions like typing on a keyboard, holding a cup, or buttoning a shirt may require extra effort or cause pain. You might notice that your finger catches on clothing or objects because of the altered joint position. The discomfort can flare up after periods of activity, such as gardening, typing for long stretches, or playing sports. Some people report increased stiffness when they first wake up in the morning.

It is important to understand that this condition can develop differently depending on the cause. In some cases, it results from trauma to the central slip of the tendon. In others, it may be associated with underlying conditions like rheumatoid arthritis. There is also a rare congenital form present from birth. Early recognition and treatment are crucial because addressing central slip injuries promptly can help prevent the deformity from becoming fixed.

If you suspect you have this injury, seeking professional evaluation is key. Differentiating between a true boutonnière deformity and a similar condition called pseudoboutonniere is critical for determining the right management plan. Your surgeon will assess the anatomy and clinical presentation to guide your treatment. Understanding the specific nature of your injury helps ensure optimal outcomes and restores function to your hand.

What's actually happening

Your finger has a complex system of tendons that act like ropes, allowing you to bend and straighten it. One key part is the central slip, a band of tissue in the middle of your finger joint. This slip helps keep your finger straight when you extend it.

When this central slip is injured, the balance of forces in your finger changes. The tendon can slip out of place, pulling the middle joint (PIP joint) into a bent position. At the same time, the tip joint may overextend. This creates the characteristic shape known as a boutonnière deformity.

You might notice snapping or catching at the middle joint. This happens because the damaged tendon is no longer gliding smoothly. Over time, progressive damage reduces your ability to straighten that joint fully. The asymmetrical position of your finger tip during extension is often a sign that the central slip is involved.

In some cases, the joint can become stuck in a bent position. This is called an irreducible dislocation. It occurs when the intact central slip gets trapped inside the joint space. Even though the joint is stuck, the prognosis is often better than if the tendon were completely torn. This is because the main structure is displaced rather than disrupted.

Early treatment is crucial. Addressing central slip injuries promptly can prevent this deformity from developing. If the condition is congenital, meaning you were born with a weaker tendon, a static hand brace can help keep the joint in extension. Understanding these mechanics helps your surgeon choose the right path to restore your finger’s function.

What we can do about it

Dr Kieran Hirpara, an upper-limb surgeon at Mater Private Hospital Rockhampton, starts with the least invasive options that suit your condition. We begin by trying to restore movement without surgery. You may be asked to wear a special splint that keeps your finger in a gentle curve. This is often used after a period of casting to help straighten the joint. If you start this therapy within 6 weeks of the injury, you are more likely to see an improvement in how far you can bend and straighten your finger. We aim to help you regain flexion by wearing a relative motion splint for 3 months. This approach works well if your joint can still be positioned with less than -20° of extension. The goal is to improve the movement in your fingertip and straighten the middle joint.

If pain or inflammation is part of your condition, we may discuss medical management. This can include pain medication or anti-inflammatory drugs to reduce swelling. Injections may also be offered to calm the joint. Cortisone injections can reduce inflammation for a limited time, helping you move more comfortably during therapy. Hyaluronic acid injections aim to lubricate the joint, while platelet-rich plasma (PRP) injections use your own blood components to support healing. The duration of relief varies, but these treatments are typically used to manage symptoms while you work on your hand function. We tailor the choice to what your specific injury requires.

When conservative care has not given enough improvement, or if the deformity is long-standing, we may consider surgery. This is usually recommended when the lateral bands of your tendon have slipped out of place and simple splinting cannot correct it. Surgical options include reconstructing the central slip or using a tendon graft to restore balance. In some cases, a simpler procedure to cut part of the tendon may be used to improve flexibility. The Y-shaped tendon graft provides good or excellent results in 16 of 18 patients in reported series. Cross-lateral band reconstruction is another option if the tendons are damaged. We discuss these options with you to decide the best path forward.

Patients are generally referred to our clinic by their GP; if a physiotherapist has suggested you see us, you will still need a referral from your GP in order to be eligible for the Medicare rebate. A clinic assessment, including history, examination, and imaging where needed, establishes the diagnosis. For degenerative or long-standing problems we usually try non-operative care — activity change, physiotherapy or hand therapy, splinting, and injections — and consider surgery when that has not given enough improvement. For structural or acute problems, surgery may be recommended straight away, without a preceding non-operative trial.

What to expect

Your outlook depends largely on whether this is a true deformity or a similar issue called pseudoboutonniere. Getting this distinction right is critical. It ensures you receive the correct care and avoid ineffective treatment. If you have rheumatoid arthritis, the condition tends to worsen over time. Without repair, the deformity progresses and causes increasing difficulty with your hand.

If the issue stems from an old central slip injury that was not treated properly, it can lead to significant disability. You may find it hard to bend your finger joint. This loss of movement can become marked if left uncorrected. However, treatment can make a real difference. Procedures such as extensor tenotomy can restore flexion to the distal joint. They also markedly lessen the disability you experience in daily life.

For chronic cases, surgical correction offers a clear path forward. In reported series, the Y-shaped tendon graft procedure provided good or excellent results in 16 of 18 patients. This suggests that with proper management, you can regain significant function and comfort.

It is also worth noting that this condition can occur in the thumb without any history of trauma or rheumatoid arthritis. In such cases, the prevalence is approximately 13%. Understanding the anatomy and treatment options helps your surgeon plan the best approach for your specific situation. Early intervention for central slip injuries can prevent the deformity from developing in the first place.

Your recovery involves regaining movement and reducing pain. While individual experiences vary, many patients find that correcting the deformity restores their ability to use their hand normally. We focus on helping you achieve the best possible function within your unique circumstances.

When to see someone

Ask for a specialist review if you have persistent pain that does not improve with rest. Seek care if you notice weakness or instability in your finger. Watch for locking or giving way during movement. Contact your doctor if symptoms interfere with sleep or work. Sudden worsening of pain is also a reason to seek help. Untreated injuries can lead to a permanent condition called boutonnière deformity. This involves damage to the extensor mechanism, the tendons that straighten your finger. Differentiating this from similar injuries is critical for proper management. Early assessment helps avoid inappropriate treatment and prevents long-term disability.

Advanced reading: the deeper science (optional)

This section goes further than you need for your own treatment decisions. Boutonnière deformity is worth the extra reading because the instinctive treatment for a painful, swollen, bent finger — rest it and keep it still — is the one thing the evidence specifically does not support.

Early mobilisation, not prolonged immobilisation

A systematic review of treatments for central slip injury found the evidence base limited, with the roles of different strategies for both open and closed injuries not well supported. Within that limitation, the evidence from individual studies tentatively supports early mobilisation and does not support prolonged immobilisation [1].

That is worth stating plainly because it runs against the reflex. The distinction is between protecting the healing central slip — which requires the middle joint to be held straight — and immobilising the whole finger, which allows the fingertip joint to stiffen in extension and the whole digit to become rigid. The splint is intended to hold one joint while the others keep moving.

Why the deformity gets worse rather than staying still

Boutonnière is a progressive deformity, which is unusual and worth understanding. The central slip attaches to the base of the middle bone and straightens the middle joint. When it fails, that joint drops into flexion — and the two lateral bands, which normally run above the joint's axis, slip below it.

Once they are below the axis, the same tendons that previously helped straighten the middle joint begin to bend it, while pulling the fingertip into hyperextension. The deformity therefore self-reinforces: every attempt to straighten the finger tightens the structures now holding it bent. This is why an injury that looked minor can produce a fixed deformity weeks later, and why the window for simple splinting is early.

The deformity that is not a boutonnière

A finger can adopt the same posture without a central slip injury at all, and the treatments differ entirely. Boutonnière and pseudoboutonnière deformities differ in pathoanatomy, diagnosis and management [2] — the pseudo variety arising from a volar plate injury at the middle joint, where the fingertip joint retains normal passive flexion rather than being drawn into hyperextension.

Distinguishing them at the bedside rests on the fingertip. In a true boutonnière the tip is held hyperextended and resists being bent, particularly with the middle joint straightened; in a pseudoboutonnière it flexes freely. Splinting a pseudoboutonnière as though it were the real thing addresses the wrong joint.

It belongs to a family of injuries defined by where the tendon fails

Boutonnière sits alongside mallet finger and sagittal band injury as one of three closed extensor mechanism injuries, categorised by the zone in which the mechanism fails [3]. All three can present as a swollen finger held abnormally within days of an injury, and each requires a different splint position — which is the practical reason a definite diagnosis is worth reaching before committing to weeks of splinting.

Reviewed by Dr Kieran Hirpara · 10 June 2026.

Talk to your treating clinician for advice specific to you.

For an appointment with the CQ Hand + Upper Limb team, ask your GP about a referral or visit www.cqupperlimb.com.

References for the advanced reading
  1. Geoghegan L, Wormald JCR, Adami RZ, Rodrigues JN. Central slip extensor tendon injuries: a systematic review of treatments. J Hand Surg Eur Vol. 2019;44(8):825-32.
  2. Hanson ZC, Thompson RG, Andrews JR, Lourie GM. Boutonniere versus pseudoboutonniere deformities: pathoanatomy, diagnosis, and treatment. J Hand Surg Am. 2023;48(5):489-97.
  3. Lin JD, Strauch RJ. Closed soft tissue extensor mechanism injuries (mallet, boutonniere, and sagittal band). J Hand Surg Am. 2014;39(5):1005-11.
Evidence & references

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

  • Differentiating a true boutonniere deformity from a pseudoboutonniere injury is critical in determining clinical management [2].
  • An understanding of the anatomy, clinical presentation, treatment options, and expected outcomes is crucial for optimal treatment of posttraumatic boutonnière and swan neck deformities [4].
  • The paper outlines the anatomy, pathoanatomy, and treatment concepts for boutonniere deformity, emphasizing that early treatment of central slip injuries can prevent the deformity [7].
  • The natural history of the boutonnière deformity in rheumatoid arthritis is outlined, and a simple method of repair is described [3].
  • The case extends understanding of congenital boutonniere deformity as various embryonic developmental failures and suggests a reliable surgical option involving central slip reconstruction [8].

Anatomy & Pathophysiology

  • A finite element model successfully replicated the behavior of the digit under specific scenarios, including the extension of the DIP joint during Elson's test [12].
  • Injury to the extensor mechanism, specifically the central slip, can lead to snapping or catching at the PIP joint [24].
  • Progressive damage to structures involved in Boutonniere deformity results in decreased extension of the PIP joint [25].
  • A release procedure based on precise anatomy redistributes forces acting on the interphalangeal joints to restore full extension and flexion [26].
  • Asymmetrical position of the distal phalanges during extension suggests a central slip lesion, while symmetrical position indicates the lesion is unlikely [28].
  • Irreducible volar dislocation of the PIP joint can be caused by interposition of the intact central slip [31].
  • In irreducible volar dislocations, the prognosis is better than in reducible dislocations because the extensor mechanism is displaced rather than disrupted [31].
  • Congenital hypoplasia of the extensor tendon central slip can be treated successfully with a static hand brace to keep the PIP joint in extension [35].

Classification

  • The boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the proximal interphalangeal (PIP) joint [15].
  • Anterior dislocation of the PIP joint is associated with ruptures of the central slip of the extensor mechanism and results in boutonniere deformity unless repaired [16].
  • Early treatment of central slip injuries can prevent the development of boutonniere deformity [7].
  • The natural history of boutonniere deformity in rheumatoid arthritis is distinct from other etiologies [3].
  • Congenital boutonniere deformity results from various embryonic developmental failures [8].
  • Boutonniere deformity can occur in the thumb without rheumatoid arthritis or trauma [11].
  • The prevalence of boutonniere deformity without rheumatoid arthritis or trauma is approximately 13% [11].

Clinical Presentation

  • Boutonniere deformities are closed soft tissue injuries of the extensor mechanism in zones I, III, and V [14].
  • Elson's test involves extension of the distal interphalangeal (DIP) joint [12].

Investigations

  • This article summarizes current concepts relating to the presentation and treatment of closed soft tissue injuries of the extensor mechanism in zones I, III, and V, commonly known as mallet finger, boutonniere deformities, and sagittal band injuries [14].
  • The article discusses injuries to the central slip (boutonniere) and annular pulleys in elite athletes, emphasizing the importance of anatomic knowledge, accurate diagnosis, and balancing early return to play with long-term risks [18].
  • The boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the PIP joint [15].
  • Anterior dislocation of the proximal interphalangeal joint is associated with ruptures of the central slip of the extensor mechanism and results in boutonnière deformity unless repaired [16].
  • Treating swan neck and boutonniere deformities of the PIP joint is a difficult challenge that requires understanding the cause, biomechanical changes, and articular status [17].
  • The study developed and validated a finite element model that successfully replicated the behavior of the digit under specific scenarios, including the extension of the DIP joint during Elson's test observed in cadaveric studies [12].

Treatment

Non-Operative Management

  • Serial casting for adequate extension followed by 3 months of relative motion flexion (RMF) orthotic use should be attempted prior to surgical intervention for chronic boutonniere deformity [1].
  • Chronic boutonniere deformity responds to relative motion flexion splinting if serial casting places the proximal interphalangeal joint in less than -20° extension and the patient actively uses the hand in a relative motion flexion orthosis for 3 months to recover flexion [5].
  • The use of relative motion flexion orthoses (RMFO) is effective in increasing active distal interphalangeal joint flexion and improving proximal interphalangeal joint extension in patients with Burton stage 1 chronic boutonniere deformity [23].
  • Improvement in digit range of motion is associated with the initiation of nonoperative treatment within 6 weeks [20].
  • The type or length of conservative treatment is not associated with differences in outcomes for nonoperative treatment of boutonniere deformity [20].

Operative Management

  • The natural history of boutonniere deformity in rheumatoid arthritis has been outlined, and a simple method of repair is described [3].
  • The Y-shaped tendon graft is a useful procedure for the correction of chronic boutonniere deformity, providing good or excellent results in 16 of 18 patients in a reported series [6].
  • When lateral bands are deficient or damaged in chronic boutonniere deformity, cross-lateral band reconstruction using palmaris longus autograft is a treatment option with satisfactory results [9].
  • Extensor tenotomy to correct a long-standing boutonniere deformity markedly lessens disability with restoration of flexion of the distal joint [10].
  • Transection of the terminal extensor tendon is a useful salvage procedure for boutonniere deformity [13].
  • Central slip reconstruction is a reliable surgical option for congenital boutonniere deformity [8].

Complications

  • Chronic boutonniere deformity may result from untreated or inadequately treated central slip injuries [7].
  • Differentiating a true boutonniere deformity from a pseudoboutonniere injury is critical to avoid inappropriate clinical management [2].
  • The natural history of boutonnière deformity in rheumatoid arthritis involves progressive deformity requiring repair [3].
  • Boutonnière deformity can occur in the thumb without underlying rheumatoid arthritis or trauma, with a prevalence of approximately 13% in such cases [11].
  • Chronic boutonniere deformity can lead to marked disability and loss of flexion of the distal joint if left uncorrected [10].

Recovery

  • The Y-shaped tendon graft is a useful procedure for correcting chronic boutonniere deformity, providing good or excellent results in 16 of 18 patients in a reported series [6].
  • Extensor tenotomy can correct long-standing boutonniere deformity by markedly lessening disability and restoring flexion of the distal joint [10].

Key Evidence

  • [L4] Similar results occurred for chronic boutonniere deformity using serial casting for adequate extension followed by 3 months of RMF orthotic use, which should be attempted prior to surgical intervention. [1] (10.1016/j.jht.2023.02.005)
  • [L5] Differentiating a true boutonniere deformity from a pseudoboutonniere injury is critical in determining clinical management. [2] (10.1016/j.jhsa.2022.10.019)
  • [L4] The natural history of the boutonnière deformity in rheumatoid arthritis is outlined, and a simple method of repair is described. [3] (10.2106/00004623-196951070-00009)
  • [L5] An understanding of the anatomy, clinical presentation, treatment options, and expected outcomes is crucial for optimal treatment of posttraumatic boutonnière and swan neck deformities. [4] (10.5435/jaaos-d-14-00272)
  • [L4] Chronic boutonniere deformity will respond to relative motion flexion splinting if serial casting can place the proximal interphalangeal joint in less than -20° extension, and the patient actively uses the hand in a relative motion flexion orthosis for 3 months, recovering flexion. [5] (10.1097/sap.0000000000002307)
  • [L4] The Y-shaped tendon graft can be a useful procedure for the correction of chronic boutonniere deformity; in our patient series, this provided good or excellent results in 16 of 18 patients. [6] (10.1016/j.jhsa.2021.01.003)
  • [L5] The paper outlines the anatomy, pathoanatomy, and treatment concepts for boutonniere deformity, emphasizing that early treatment of central slip injuries can prevent the deformity. [7] (10.1016/s0749-0712(21)00060-3)
  • [Case_report] The case extends understanding of congenital boutonniere deformity as various embryonic developmental failures and suggests a reliable surgical option involving central slip reconstruction. [8] (10.1016/j.jhsa.2014.05.030)
  • [L4] In chronic boutonniere deformity, when the lateral bands are deficient or damaged, the cross-lateral band reconstruction technique using palmaris longus autograft is a treatment option with satisfactory results. [9] (10.1016/j.jhsa.2017.04.010)
  • [L3] The prevalence of boutonnière deformity without rheumatoid arthritis or trauma is approximately 13%. [11] (10.1177/1753193417704610)
  • [L5] The study developed and validated a finite element model that successfully replicated the behavior of the digit under specific scenarios, including the extension of the DIP joint during Elson's test observed in cadaveric studies. [12] (10.1186/s13018-025-06329-3)
  • [L4] Transection of the terminal extensor tendon is a useful procedure for salvage of the boutonniere deformity. [13] (10.1016/s0749-0712(21)00065-2)
  • [L5] This article summarizes current concepts relating to the presentation and treatment of closed soft tissue injuries of the extensor mechanism in zones I, III, and V, commonly known as mallet finger, boutonniere deformities, and sagittal band injuries. [14] (10.1016/j.jhsa.2013.11.018)
  • [L5] The boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the PIP joint. [15] (10.1016/j.jhsa.2017.07.011)
  • [L4] Treating swan neck and boutonniere deformities of the PIP joint is a difficult challenge that requires understanding the cause, biomechanical changes, and articular status. [17] (10.1016/j.hcl.2017.12.006)
  • [Paper] The article discusses injuries to the central slip (boutonniere) and annular pulleys in elite athletes, emphasizing the importance of anatomic knowledge, accurate diagnosis, and balancing early return to play with long-term risks. [18] (10.1016/j.hcl.2012.05.044)
  • [L3] Improvement in digit ROM was associated with initiation of treatment within 6 weeks, but not with any particular type or length of conservative treatment. [20] (10.1016/j.jht.2025.02.013)
  • [L4] The use of RMFO is effective in increasing active distal interphalangeal joint flexion and improving PIP extension in patients with Burton stage 1 chronic boutonniere deformity. [23] (10.1016/j.jhsa.2022.08.007)
  • [Case_report] Hand surgeons should be aware that injury to the extensor mechanism and specifically the central slip can lead to snapping or catching at the PIP joint in the finger. [24] (10.1177/15589447221081876)
  • [Paper] Extension of the PIP joint decreases as these structures are progressively damaged. [25] (10.1016/s0363-5023(12)60014-8)
  • [L5] Asymmetrical position of the distal phalanges during extension suggests a central slip lesion, while symmetrical position indicates the lesion is unlikely. [28] (10.1177/175899830601100402)
  • [L4] The prognosis is far better after irreducible than after reducible volar dislocations because the extensor mechanism is displaced, not disrupted. [31] (10.2106/00004623-197860010-00023)
  • [L4] Congenital hypoplasia of the central slip can be treated successfully by using a static hand brace to keep the PIP joint in the extension position, especially with the frequent application of the hand brace. [35] (10.1177/1753193416676410)

References

[1] The relative motion concept in acute and chronic boutonniere deformity: Invited commentary. Journal of Hand Therapy. 2023. DOI: 10.1016/j.jht.2023.02.005

[2] Boutonniere Versus Pseudoboutonniere Deformities: Pathoanatomy, Diagnosis, and Treatment. The Journal of Hand Surgery. 2023. DOI: 10.1016/j.jhsa.2022.10.019

[3] Correction of the Rheumatoid Boutonnière Deformity. The Journal of Bone & Joint Surgery. 1969. DOI: 10.2106/00004623-196951070-00009

[4] Posttraumatic Boutonnière and Swan Neck Deformities. Journal of the American Academy of Orthopaedic Surgeons. 2015. DOI: 10.5435/jaaos-d-14-00272

[5] A Paradigm Shift in Managing Acute and Chronic Boutonniere Deformity. Annals of Plastic Surgery. 2020. DOI: 10.1097/sap.0000000000002307

[6] Y-Shaped Tendon Graft—A Technique in the Reconstruction of Posttraumatic Chronic Boutonniere Deformity. The Journal of Hand Surgery. 2021. DOI: 10.1016/j.jhsa.2021.01.003

[7] BOUTONNIERE DEFORMITY. Hand Clinics. 1995. DOI: 10.1016/s0749-0712(21)00060-3

[8] Restoration of the Central Slip in Congenital Form of Boutonniere Deformity: Case Report. The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2014.05.030

[9] Chronic Boutonniere Deformity: Cross-Lateral Band Technique Using Palmaris Longus Autograft. The Journal of Hand Surgery. 2017. DOI: 10.1016/j.jhsa.2017.04.010

[10] Extensor Tenotomy for Chronic Boutonniere Deformity of the Finger: REPORT OF TWO CASES.. The Journal of Bone and Joint Surgery. American Volume. 1965.

[11] Thumb boutonnière deformity without rheumatoid arthritis or trauma. Journal of Hand Surgery (European Volume). 2017. DOI: 10.1177/1753193417704610

[12] Assessment of the ligamentous stress distribution in the pathomechanics of the boutonniere deformity through a computational 3D model. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-06329-3

[13] TREATMENT OF THE CHRONIC BOUTONNIERE DEFORMITY BY EXTENSOR TENOTOMY. Hand Clinics. 1995. DOI: 10.1016/s0749-0712(21)00065-2

[14] Closed Soft Tissue Extensor Mechanism Injuries (Mallet, Boutonniere, and Sagittal Band). The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2013.11.018

[15] Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2018. DOI: 10.1016/j.jhsa.2017.07.011

[16] Anterior dislocation of the proximal interphalangeal joint. A cause of rupture of the central slip of the extensor mechanism.. The Journal of bone and joint surgery. American volume. 1970.

[17] Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities. Hand Clinics. 2018. DOI: 10.1016/j.hcl.2017.12.006

[18] Boutonnière and Pulley Rupture in Elite Athletes. Hand Clinics. 2012. DOI: 10.1016/j.hcl.2012.05.044

[20] Nonoperative treatment of the Boutonniere deformity: Is there a difference in outcomes?. Journal of Hand Therapy. 2025. DOI: 10.1016/j.jht.2025.02.013

[23] The Use of Relative Motion Flexion Orthoses for Chronic Boutonniere Deformity. The Journal of Hand Surgery. 2024. DOI: 10.1016/j.jhsa.2022.08.007

[24] Longitudinal Tear of the Central Slip Causing Painful and Unusual Snapping of the Finger: A Case Report. HAND. 2022. DOI: 10.1177/15589447221081876

[25] Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2012. DOI: 10.1016/s0363-5023(12)60014-8

[26] Redistribution of Forces in the Correction of the Boutonniere Deformity.. The Journal of Bone and Joint Surgery. American Volume. 1967.

[28] A Modification Of Elson's Test For The Diagnosis Of An Acute Extensor Central Slip Injury. The British Journal of Hand Therapy. 2006. DOI: 10.1177/175899830601100402

[31] Irreducible volar dislocation of the proximal interphalangeal joint of a finger caused by interposition of the intact central slip. The Journal of Bone & Joint Surgery. 1978. DOI: 10.2106/00004623-197860010-00023

[35] Successful conservative treatment outcomes and clinical characteristics of congenital hypoplasia of the extensor tendon central slip. Journal of Hand Surgery (European Volume). 2016. DOI: 10.1177/1753193416676410

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e. Exceptions and Limitations means fair use, fair dealing, and/or any other exception or limitation to Copyright and Similar Rights that applies to Your use of the Licensed Material.

f. Licensed Material means the artistic or literary work, database, or other material to which the Licensor applied this Public License.

g. Licensed Rights means the rights granted to You subject to the terms and conditions of this Public License, which are limited to all Copyright and Similar Rights that apply to Your use of the Licensed Material and that the Licensor has authority to license.

h. Licensor means the individual(s) or entity(ies) granting rights under this Public License.

i. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. For purposes of this Public License, the exchange of the Licensed Material for other material subject to Copyright and Similar Rights by digital file-sharing or similar means is NonCommercial provided there is no payment of monetary compensation in connection with the exchange.

j. Share means to provide material to the public by any means or process that requires permission under the Licensed Rights, such as reproduction, public display, public performance, distribution, dissemination, communication, or importation, and to make material available to the public including in ways that members of the public may access the material from a place and at a time individually chosen by them.

k. Sui Generis Database Rights means rights other than copyright resulting from Directive 96/9/EC of the European Parliament and of the Council of 11 March 1996 on the legal protection of databases, as amended and/or succeeded, as well as other essentially equivalent rights anywhere in the world.

l. You means the individual or entity exercising the Licensed Rights under this Public License. Your has a corresponding meaning.

Section 2 -- Scope.

a. License grant.

1. Subject to the terms and conditions of this Public License, the Licensor hereby grants You a worldwide, royalty-free, non-sublicensable, non-exclusive, irrevocable license to exercise the Licensed Rights in the Licensed Material to:

a. reproduce and Share the Licensed Material, in whole or in part, for NonCommercial purposes only; and

b. produce, reproduce, and Share Adapted Material for NonCommercial purposes only.

2. Exceptions and Limitations. For the avoidance of doubt, where Exceptions and Limitations apply to Your use, this Public License does not apply, and You do not need to comply with its terms and conditions.

3. Term. The term of this Public License is specified in Section 6(a).

4. Media and formats; technical modifications allowed. The Licensor authorizes You to exercise the Licensed Rights in all media and formats whether now known or hereafter created, and to make technical modifications necessary to do so. The Licensor waives and/or agrees not to assert any right or authority to forbid You from making technical modifications necessary to exercise the Licensed Rights, including technical modifications necessary to circumvent Effective Technological Measures. For purposes of this Public License, simply making modifications authorized by this Section 2(a) (4) never produces Adapted Material.

5. Downstream recipients.

a. Offer from the Licensor -- Licensed Material. Every recipient of the Licensed Material automatically receives an offer from the Licensor to exercise the Licensed Rights under the terms and conditions of this Public License.

b. No downstream restrictions. You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, the Licensed Material if doing so restricts exercise of the Licensed Rights by any recipient of the Licensed Material.

6. No endorsement. Nothing in this Public License constitutes or may be construed as permission to assert or imply that You are, or that Your use of the Licensed Material is, connected with, or sponsored, endorsed, or granted official status by, the Licensor or others designated to receive attribution as provided in Section 3(a)(1)(A)(i).

b. Other rights.

1. Moral rights, such as the right of integrity, are not licensed under this Public License, nor are publicity, privacy, and/or other similar personality rights; however, to the extent possible, the Licensor waives and/or agrees not to assert any such rights held by the Licensor to the limited extent necessary to allow You to exercise the Licensed Rights, but not otherwise.

2. Patent and trademark rights are not licensed under this Public License.

3. To the extent possible, the Licensor waives any right to collect royalties from You for the exercise of the Licensed Rights, whether directly or through a collecting society under any voluntary or waivable statutory or compulsory licensing scheme. In all other cases the Licensor expressly reserves any right to collect such royalties, including when the Licensed Material is used other than for NonCommercial purposes.

Section 3 -- License Conditions.

Your exercise of the Licensed Rights is expressly made subject to the following conditions.

a. Attribution.

1. If You Share the Licensed Material (including in modified form), You must:

a. retain the following if it is supplied by the Licensor with the Licensed Material:

i. identification of the creator(s) of the Licensed Material and any others designated to receive attribution, in any reasonable manner requested by the Licensor (including by pseudonym if designated);

ii. a copyright notice;

iii. a notice that refers to this Public License;

iv. a notice that refers to the disclaimer of warranties;

v. a URI or hyperlink to the Licensed Material to the extent reasonably practicable;

b. indicate if You modified the Licensed Material and retain an indication of any previous modifications; and

c. indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License.

2. You may satisfy the conditions in Section 3(a)(1) in any reasonable manner based on the medium, means, and context in which You Share the Licensed Material. For example, it may be reasonable to satisfy the conditions by providing a URI or hyperlink to a resource that includes the required information.

3. If requested by the Licensor, You must remove any of the information required by Section 3(a)(1)(A) to the extent reasonably practicable.

4. If You Share Adapted Material You produce, the Adapter's License You apply must not prevent recipients of the Adapted Material from complying with this Public License.

Section 4 -- Sui Generis Database Rights.

Where the Licensed Rights include Sui Generis Database Rights that apply to Your use of the Licensed Material:

a. for the avoidance of doubt, Section 2(a)(1) grants You the right to extract, reuse, reproduce, and Share all or a substantial portion of the contents of the database for NonCommercial purposes only;

b. if You include all or a substantial portion of the database contents in a database in which You have Sui Generis Database Rights, then the database in which You have Sui Generis Database Rights (but not its individual contents) is Adapted Material; and

c. You must comply with the conditions in Section 3(a) if You Share all or a substantial portion of the contents of the database.

For the avoidance of doubt, this Section 4 supplements and does not replace Your obligations under this Public License where the Licensed Rights include other Copyright and Similar Rights.

Section 5 -- Disclaimer of Warranties and Limitation of Liability.

a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.

b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.

c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.