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纽扣畸形

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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 2026
指端呈纽扣孔畸形的示意图——中间关节弯曲，指尖向后倾斜。
纽扣畸形：中指关节保持弯曲，指尖向后倾斜。 Kieran Hirpara 4.0

本页面由机器翻译，尚未经临床医生审核。英文版本为权威版本。

您的感受

您可能会注意到中指关节向内弯曲，而指尖关节向外翘起。这种形态改变称为纽扣孔畸形（boutonniere deformity）。当手指背侧的肌腱移位时，就会发生这种情况。您可能会在手指与手掌连接的基部感到疼痛。疼痛也可能位于手指本身的中间关节处。

日常活动往往变得困难。向后伸手扣内衣可能很困难。塞衬衫时可能会感到别扭或疼痛。您可能难以握紧拳头。简单的抓握动作可能会引起不适。即使尝试轻柔拉伸或休息，畸形也可能持续存在。

症状常在活动后加重。早晨刚醒来时，您可能会感到僵硬。夜间疼痛是可能的，尤其是如果您侧卧睡觉时。手部受压会刺激受损的肌腱。如果您患有类风湿关节炎，该病症随时间推移可能遵循不同的病程。若无关节炎或创伤史，约 13% 的人会出现此问题。

准确了解您的症状非常重要。真正的纽扣孔畸形与一种称为假性纽扣孔畸形（pseudoboutonniere）的类似损伤外观不同。您的外科医生需要区分二者以选择合适的治疗方案。了解您的具体症状有助于我们制定治疗计划。我们希望恢复您手部的功能和舒适度。

如果您患有天鹅颈畸形（swan neck deformity），指尖可能会随时间推移向下弯曲得更明显。这种进展可能是逐渐发生的。早期了解您的症状可带来更好的预后。我们将仔细检查您的手部。我们将观察关节的活动情况以及疼痛的具体位置。这有助于我们判断您是否需要夹板固定或其他治疗。

实际发生了什么

您的手指拥有一套复杂的肌腱系统，它们像绳索一样帮助您弯曲和伸直手指。在手指的中节指间关节处，有一条特定的肌腱，称为中央束。这条肌腱位于关节上方，有助于将您的手指拉直。当这条肌腱受伤或发炎时，可能会撕裂或松弛。

当中央束失效时，手指内的力量平衡发生改变。手指两侧的肌腱拉力过大，导致中节指间关节向内弯曲。同时，手指末端可能会向外弯曲。这会在手指上形成可见的弯曲，即我们所说的纽扣畸形（Boutonnière deformity）。该问题的最关键因素在于这些肌腱及相关结构发生的变化，尤其是在早期阶段。

这种情况可能由直接损伤引起，例如切割伤或挫伤。它也可能自然发生，特别是在类风湿关节炎患者中，炎症会磨损关节。在某些情况下，它会在没有明显创伤或关节炎的情况下出现，在这些情况下影响约 13% 的人群。治疗的主要目标是保持关节对齐，恢复稳定性，并让您重新活动关节。

如果您患有这种畸形，您可能会发现很难完全伸直手指。非手术治疗，如夹板或石膏固定，可以帮助将您的活动范围提高一到两个等级。然而，即使经过专门的保守治疗，畸形仍可能持续存在。这就是为什么准确诊断至关重要。我们需要将真正的纽扣畸形与一种类似的问题——假性纽扣畸形（pseudoboutonniere）区分开来，因为两者的管理方法不同。了解这些力学机制有助于我们为您的康复选择正确的路径。

我们能采取的措施

基兰·希尔帕拉（Kieran Hirpara）医生是麦特私人医院（Mater Private Hospital Rockhampton）的上肢外科医生，他在我们诊所采用的方法侧重于将治疗方案与手指畸形的具体病因相匹配。我们首先需要确定您是否患有真正的纽扣畸形（boutonniere deformity），还是类似的问题，称为假性纽扣畸形损伤（pseudoboutonniere injury）。这一区分至关重要，因为它会改变您的护理管理方式。我们从全面评估开始，包括病史、体格检查，并在必要时进行影像学检查，以了解问题的解剖结构和分期。

对于许多患者，我们从非手术治疗开始。这通常涉及系列石膏固定以帮助伸直手指，随后使用相对运动屈曲矫形器三个月。这种特殊的夹板允许您活动手指，同时保护愈合的组织。物理治疗旨在改善您的活动范围并减少僵硬。通过这种专门的保守管理，您可以期望获得一到两个等级的活动改善。然而，请注意，即使经过这种治疗，畸形仍可能持续存在。如果疼痛是一个显著问题，我们可能会讨论止痛药或抗炎选项。在某些情况下，会使用可的松或透明质酸等注射剂来减轻炎症并提供缓解，尽管效果持续时间因人而异。

当保守治疗未能带来足够的改善，或者问题是结构性且急性的时，我们会考虑手术。我们寻找软组织或肌腱发生永久性变化的迹象。如果建议手术，这是基于您的目标和畸形的具体分期而做出的共同决定。对于慢性病例，肌腱移植等手术可以纠正排列。在类风湿关节炎中，由于长期软组织重建的结果可能不可靠，如果畸形复发，我们可能会讨论挽救性手术。目标是恢复功能并有效解决畸形。在继续进行之前，我们确保您了解预期的结果。

预期情况

您的预后取决于畸形存在的时间长短，以及是否与类风湿关节炎相关。在许多情况下，该病症不会自行缓解。非手术治疗可实现一到两个等级的关节活动度改善，尽管经过专门的保守治疗后，畸形仍可能持续存在。

如果您的病例属于慢性期，我们通常会尝试连续石膏固定以实现充分伸展，随后佩戴相对活动度屈曲支具3个月，然后再考虑手术。这种方法产生的结果与其他方法相似，应在手术干预之前尝试。在此期间，您可能会注意到手指关节的活动度增加。然而，类风湿关节炎中畸形的自然病程往往难以预测。类风湿关节炎患者 boutonniere 畸形（纽扣孔畸形）软组织重建后的长期结果不可靠。复发性或持续性畸形最好通过补救性手术进行治疗。

对于需要手术的患者，成功的手术结果取决于完善的术前检查、畸形的正确分期以及治疗时机的把握。我们不对所有畸形使用同一种技术。我们在干预前确定真正的原因。例如，Y形肌腱移植是矫正慢性 boutonniere 畸形的一种有用手术，在一项报道的系列病例中，18例患者中有16例取得了良好或极佳的效果。

您应了解，区分真正的 boutonniere 畸形与假性 boutonniere 损伤对于确定临床管理至关重要。无类风湿关节炎或创伤史的 boutonniere 畸形患病率约为13%。这意味着大多数病例与其他因素有关。您的外科医生将指导您进行这些区分。

康复是一个过程，而非即时修复。您最初可能会经历僵硬或活动受限。通过正确的分期和时机把握，许多患者能看到有意义的改善。如果保守措施失败，手术提供了一条矫正途径。我们的目标是稳定性和功能。您应预期在数周至数月内逐渐恢复日常活动。您对治疗和支具使用的依从性在最终结果中起着重要作用。

何时就医

如果您发现手指中间关节持续弯曲且无法伸直，请咨询您的全科医生（GP）。如果出现持续疼痛且休息后未改善，或感觉手指无力或不稳定，请寻求专科医生评估。注意观察活动中是否出现卡顿或突然无力。如果症状影响您的睡眠或工作，或出现突然加重，请勿等待。准确诊断至关重要，因为区分真正的纽扣畸形（boutonnière deformity）与假性纽扣畸形（pseudoboutonniere injury）将改变您的治疗方案。早期评估有助于为您的特定损伤确定正确的治疗路径。

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.

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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NC NonCommercial — not for commercial use

Attribution-NonCommercial 4.0 International

Creative Commons Corporation ("Creative Commons") is not a law firm and does not provide legal services or legal advice. Distribution of Creative Commons public licenses does not create a lawyer-client or other relationship. Creative Commons makes its licenses and related information available on an "as-is" basis. Creative Commons gives no warranties regarding its licenses, any material licensed under their terms and conditions, or any related information. Creative Commons disclaims all liability for damages resulting from their use to the fullest extent possible.

Using Creative Commons Public Licenses

Creative Commons public licenses provide a standard set of terms and conditions that creators and other rights holders may use to share original works of authorship and other material subject to copyright and certain other rights specified in the public license below. The following considerations are for informational purposes only, are not exhaustive, and do not form part of our licenses.

Considerations for licensors: Our public licenses are intended for use by those authorized to give the public permission to use material in ways otherwise restricted by copyright and certain other rights. Our licenses are irrevocable. Licensors should read and understand the terms and conditions of the license they choose before applying it. Licensors should also secure all rights necessary before applying our licenses so that the public can reuse the material as expected. Licensors should clearly mark any material not subject to the license. This includes other CC- licensed material, or material used under an exception or limitation to copyright. More considerations for licensors: wiki.creativecommons.org/Considerations_for_licensors

Considerations for the public: By using one of our public licenses, a licensor grants the public permission to use the licensed material under specified terms and conditions. If the licensor's permission is not necessary for any reason--for example, because of any applicable exception or limitation to copyright--then that use is not regulated by the license. Our licenses grant only permissions under copyright and certain other rights that a licensor has authority to grant. Use of the licensed material may still be restricted for other reasons, including because others have copyright or other rights in the material. A licensor may make special requests, such as asking that all changes be marked or described. Although not required by our licenses, you are encouraged to respect those requests where reasonable. More considerations for the public: wiki.creativecommons.org/Considerations_for_licensees

Creative Commons Attribution-NonCommercial 4.0 International Public License

By exercising the Licensed Rights (defined below), You accept and agree to be bound by the terms and conditions of this Creative Commons Attribution-NonCommercial 4.0 International Public License ("Public License"). To the extent this Public License may be interpreted as a contract, You are granted the Licensed Rights in consideration of Your acceptance of these terms and conditions, and the Licensor grants You such rights in consideration of benefits the Licensor receives from making the Licensed Material available under these terms and conditions.

Section 1 -- Definitions.

a. Adapted Material means material subject to Copyright and Similar Rights that is derived from or based upon the Licensed Material and in which the Licensed Material is translated, altered, arranged, transformed, or otherwise modified in a manner requiring permission under the Copyright and Similar Rights held by the Licensor. For purposes of this Public License, where the Licensed Material is a musical work, performance, or sound recording, Adapted Material is always produced where the Licensed Material is synched in timed relation with a moving image.

b. Adapter's License means the license You apply to Your Copyright and Similar Rights in Your contributions to Adapted Material in accordance with the terms and conditions of this Public License.

c. Copyright and Similar Rights means copyright and/or similar rights closely related to copyright including, without limitation, performance, broadcast, sound recording, and Sui Generis Database Rights, without regard to how the rights are labeled or categorized. For purposes of this Public License, the rights specified in Section 2(b)(1)-(2) are not Copyright and Similar Rights.

d. Effective Technological Measures means those measures that, in the absence of proper authority, may not be circumvented under laws fulfilling obligations under Article 11 of the WIPO Copyright Treaty adopted on December 20, 1996, and/or similar international agreements.

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.

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