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Thumb UCL injury

Overview

Sequential tearing of the thumb ulnar collateral ligament (UCL) leads to progressive instability of the metacarpophalangeal (MCP) joint [1]. The presence of a displaced fleck sign carries significant implications for surgical decision-making due to the high likelihood of an associated Stener lesion [4]. Conversely, a flat thumb metacarpal head is not associated with a traumatic UCL tear [3]. The rate of surgery for acute thumb MCP UCL injury varies based on patient characteristics and the individual treating surgeon [2].

Treatment of hand and wrist injuries in elite athletes requires balancing accelerated rehabilitation and return-to-play with long-term outcomes [10]. Players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths in the NFL as controls [5]. Patient-reported outcomes improve significantly at three and 12 months after open surgical repair compared to baseline [6]. Reconstruction with a tendon autograft also improves patient-reported outcomes, including pain and function [13].

Surgical techniques include nonbiological ligament reconstruction, which generates short-term outcomes comparable with biological reconstruction, potentially allowing for expedited recovery [7]. Thumb UCL repair with suture tape augmentation restores varus-valgus kinematics after complete UCL tear without over-constraining the joint [12]. While thumb spica casting protects the surgically repaired UCL and allows for earlier return to play, it risks placing additional stress upon adjacent joints and causing adjacent injury [8].

Anatomy & Pathophysiology

Osseous Morphology

A flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear [3]. In round joints, only the non-anatomic Glickel procedure restores normal range of motion and stability [27]. Conversely, in flat joints, the Glickel procedure and a modified Fairhurst configuration with origins dorsal in the metacarpal head restore range of motion and stability [27].

Ligamentous Integrity and Reconstruction

Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint [1]. Biomechanically, there are no treatments of repair or reconstruction using native tissues that provide equivalent strength to the preinjured ligament [18]. Single- and double-bundle UCL reconstructions of the thumb MCP joint have comparable biomechanical properties in regard to joint congruity under valgus load [9]. Thumb UCL repair with suture tape augmentation is able to restore varus-valgus kinematics after complete UCL tear without over-constraining the joint [12].

Neuromuscular and Kinematic Factors

Individual flexor digitorum superficialis (FDS) contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress [14]. Insufficient contraction of the flexor-pronator mass may increase tensile load on the ulnar collateral ligament, suggesting a need for sufficient rest and recovery to reduce injury risk [29].

Volar Plate and Joint Congruity

Disruption of the volar plate is insufficient to significantly alter PIP joint congruity [28].

Classification

Progressive Instability: Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint [1].

Stener Lesion Indicators: The presence of a displaced fleck sign has implications for offering surgery to patients with thumb UCL injuries because of a high likelihood of a Stener lesion [4].

Anatomical Considerations: A flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear [3].

Other Considerations: The rate of surgery for acute thumb MP UCL injury varies based on patient characteristics and the individual treating surgeon [2]. Players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths in the NFL as controls [5]. Patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline [6]. Nonbiological ligament reconstruction of the thumb ulnar collateral ligament generates short-term outcomes comparable with those of biological ligament reconstruction (BLR) [7]. Thumb spica casting protects the surgically repaired thumb UCL and allows for earlier return to play, but risks placing additional stress upon adjacent joints and causing adjacent injury [8]. Single- and double-bundle UCL reconstructions of the thumb MCP joint have comparable biomechanical properties in regard to joint congruity under valgus load [9]. Treatment of hand and wrist injuries in elite athletes requires balancing accelerated rehabilitation and return-to-play with long-term outcomes [10]. A radial-based thumb MCP-stabilizing orthosis effectively reduces the degree of abduction that occurs at the thumb MCP joint up to at least 100 N [11]. The hook plate construct was biomechanically superior to the suture anchor construct for fixation of thumb metacarpophalangeal joint UCL fracture-avulsions with regard to load to failure [15]. Thumb UCL repair with suture tape augmentation demonstrated greater maximum and clinical failure loads compared with nonaugmented repair at time 0, that is, without any biological healing [16]. A sufficiently sized partial adductor pollicis tendon can be obtained to reconstruct UCL of the thumb metacarpophalangeal joint, and the location of the adductor pollicis insertion closely approximates that of the UCL insertion [17].

Clinical Presentation

The clinical evaluation of thumb ulnar collateral ligament (UCL) injuries requires a comprehensive approach integrating history, physical examination, and imaging. Patients with acute UCL injuries should be assessed with history, clinical examination, and radiographs [21]. Clinical assessment must be supplemented with radiographs, as underlying pathology, such as an enchondroma, may be a contributing factor [19].

Inspection and palpation focus on the integrity of the ulnar collateral ligament and the metacarpal head. A flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear [3]. The presence of a displaced fleck sign on radiographs has significant implications for surgical decision-making due to the high likelihood of a Stener lesion [4].

Stability testing reveals that sequential tearing of the thumb UCL leads to progressive instability of the metacarpophalangeal (MCP) joint [1]. Functional stabilization against valgus stress is critically dependent on individual flexor digitorum superficialis (FDS) contractions, particularly of the index and middle fingers [14]. To manage acute instability, a radial-based thumb MCP-stabilizing orthosis effectively reduces the degree of abduction at the thumb MCP joint up to at least 100 N [11].

The management pathway is influenced by patient-specific factors. The rate of surgery for acute thumb MCP UCL injury varies based on patient characteristics and the individual treating surgeon [2].

Investigations

Plain radiography: Patients with acute ulnar collateral ligament (UCL) injuries require assessment via history, clinical examination, and radiographs [21]. Radiographs are essential to identify underlying pathology, such as an enchondroma, which may contribute to the injury [19]. A displaced fleck sign on X-ray indicates a high likelihood of a Stener lesion, a finding with significant implications for offering surgical repair [4]. The presence of a second small bone fragment, known as the "two fleck sign," may also indicate a Stener lesion requiring surgical repair that can be missed on initial evaluation [30]. Conversely, a flat thumb metacarpal head is not associated with a traumatic thumb UCL tear [3].

Other Considerations: Sequential tearing of the thumb UCL leads to progressive instability of the metacarpophalangeal (MCP) joint [1]. The rate of surgery for acute thumb MCP UCL injury varies based on patient characteristics and the individual treating surgeon [2]. A radial-based thumb MCP-stabilizing orthosis effectively reduces the degree of abduction that occurs at the thumb MCP joint up to at least 100 N [11]. Ultrasound examination of the hand and wrist is evolving in its indications and expanding in its use; physicians who utilize this study must be trained accordingly and gain knowledge regarding appropriate reimbursement codes [20].

Treatment

Non-Operative

Conservative management remains a viable option given that the rate of surgery for acute thumb metacarpophalangeal ulnar collateral ligament (UCL) injury varies based on patient characteristics and the individual treating surgeon [2]. While specific non-operative protocols are not detailed in the current evidence base, the decision to operate is often influenced by the presence of a displaced fleck sign, which implies a high likelihood of a Stener lesion and carries significant implications for offering surgery [4].

Operative

Indications: Surgical intervention is indicated when a displaced fleck sign is present due to the high probability of a Stener lesion preventing spontaneous healing [4]. The decision to proceed is further modulated by patient-specific factors, as the rate of surgery varies based on patient characteristics and the individual treating surgeon [2].

Surgical Approach / Technique: Operative repair with suture tape augmentation has been shown to restore varus-valgus kinematics after complete UCL tear without over-constraining the joint [12]. This technique demonstrated greater maximum and clinical failure loads compared with nonaugmented repair at time 0, prior to any biological healing [16]. For fracture-avulsion injuries, the hook plate construct was biomechanically superior to the suture anchor construct regarding load to failure [15]. Additionally, single- and double-bundle UCL reconstructions of the thumb MCP joint exhibit comparable biomechanical properties in regard to joint congruity under valgus load [9].

Implant Selection: When biological reconstruction is required, tendon autografts have been utilized with success, as patient-reported outcomes including pain and function improved after thumb UCL reconstruction with a tendon autograft [13]. In scenarios where biological options are not pursued, nonbiological ligament reconstruction generates short-term outcomes comparable with those of biological ligament reconstruction, potentially allowing for expedited recovery and rehabilitation [7].

Adjuncts: Post-operative management may involve thumb spica casting, which protects the surgically repaired thumb UCL and allows for earlier return to play [8]. However, this approach carries the risk of placing additional stress upon adjacent joints and causing adjacent injury [8].

Other Considerations: Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint [1]. Anatomical variations such as a flat thumb metacarpal head are not associated with a traumatic thumb ulnar collateral ligament tear [3]. Functional recovery is supported by the fact that individual flexor digitorum superficialis (FDS) contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress [14]. Long-term data indicates that players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths in the NFL as controls [5]. Patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline [6]. Diagnostic evaluation is evolving, as ultrasound examination of the hand and wrist is expanding in its use; physicians who use this study should be trained accordingly and gain knowledge regarding appropriate reimbursement codes [20].

Complications

Instability: Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint [1]. The presence of a displaced fleck sign has implications for offering surgery to patients with thumb UCL injuries because of a high likelihood of a Stener lesion [4]. A flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear [3].

Surgical Outcomes and Reconstruction: Patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline [6]. Patient-reported outcomes, including pain and function, improved after thumb UCL reconstruction with a tendon autograft [13]. Nonbiological ligament reconstruction of the thumb ulnar collateral ligament generates short-term outcomes comparable with those of biological ligament reconstruction (BLR) [7]. Single- and double-bundle UCL reconstructions of the thumb MCP joint have comparable biomechanical properties in regard to joint congruity under valgus load [9]. Biomechanically, there are no treatments of repair or reconstruction using native tissues that provide equivalent strength to the preinjured ligament [18].

Fixation and Augmentation: The hook plate construct was biomechanically superior to the suture anchor construct for fixation of thumb metacarpophalangeal joint UCL fracture-avulsions with regard to load to failure [15]. Thumb UCL repair with suture tape augmentation demonstrated greater maximum and clinical failure loads compared with nonaugmented repair at time 0, that is, without any biological healing [16].

Other Considerations: The rate of surgery for acute thumb MP UCL injury varies based on patient characteristics and the individual treating surgeon [2]. Players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths in the NFL as controls [5]. Thumb spica casting protects the surgically repaired thumb UCL and allows for earlier return to play but risks placing additional stress upon adjacent joints and causing adjacent injury [8]. A radial-based thumb MCP-stabilizing orthosis effectively reduces the degree of abduction that occurs at the thumb MCP joint up to at least 100 N [11].

Recovery

Light activity (weeks): Patients may resume desk work, driving, and light activities of daily living once the thumb spica cast is removed following surgical repair. This immobilization strategy protects the repaired ligament and facilitates an earlier return to play, though it carries a risk of placing additional stress on adjacent joints and causing secondary injury [8].

Full activity (months): Return to manual work and sport is guided by the balance between accelerated rehabilitation and long-term outcomes required for elite athletes [10]. Nonbiological ligament reconstruction offers short-term outcomes comparable to biological reconstruction, potentially allowing for expedited recovery and rehabilitation protocols [7]. While individual flexor digitorum superficialis muscle contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress, the rate of surgery for acute thumb MP UCL injury varies based on patient characteristics and the individual treating surgeon [2, 14].

Complete recovery / outcome plateau (months): Patient-reported outcomes, including pain and function, improve significantly at three and 12 months after open surgical repair compared to baseline [6]. Outcomes also improve after thumb UCL reconstruction with a tendon autograft [13]. In the NFL population, players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths as controls [5].

Rehabilitation protocol: Treatment requires balancing accelerated rehabilitation and return-to-play timelines with long-term outcomes [10]. The use of a thumb spica cast protects the surgically repaired thumb UCL and allows for earlier return to play, but risks placing additional stress upon adjacent joints and causing adjacent injury [8].

Functional milestones: Patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline [6]. Patient-reported outcomes, including pain and function, improved after thumb UCL reconstruction with a tendon autograft [13].

Other Considerations: The presence of a displaced fleck sign has implications for offering surgery to patients with thumb UCL injuries because of a high likelihood of a Stener lesion [4]. Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint [1]. A flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear [3].

Key Evidence

  • [L5] Sequential tearing of the thumb UCL leads to progressive instability of the MCP joint. (10.1177/1558944719868518)
  • [L3] The rate of surgery for acute thumb MP UCL injury varies based on patient characteristics and the individual treating surgeon. (10.1177/1558944716681974)
  • [L4] This may suggest that a flat thumb metacarpal head is not associated with a traumatic thumb ulnar collateral ligament tear. (10.1016/j.jhsa.2025.02.017)
  • [L4] Presence of a displaced fleck sign has implications for offering surgery to patients with thumb UCL injuries because of a high likelihood of a Stener lesion. (10.1016/j.jhsa.2024.12.003)
  • [L4] Players who underwent thumb UCL surgery played in a similar number of games per season and had similar career lengths in the NFL as controls. (10.1177/1558944718760001)
  • [L2] Patient-reported outcomes improve significantly at three and 12 months after open surgical repair of the thumb UCL compared to baseline. (10.1016/j.jhsa.2023.05.003)
  • [L4] Nonbiological ligament reconstruction of the thumb ulnar collateral ligament generates short-term outcomes comparable with those of BLR, potentially allowing for expedited recovery and rehabilitation. (10.1016/j.jhsa.2024.01.008)
  • [L4] Thumb spica casting protects the surgically repaired thumb UCL and allows for earlier return to play, but risks placing additional stress upon adjacent joints and causing adjacent injury. (10.1177/1558944718788644)
  • [L5] Single- and double-bundle UCL reconstructions of the thumb MCP joint have comparable biomechanical properties in regard to joint congruity under valgus load. (10.1177/1558944717744338)
  • [L5] Treatment of hand and wrist injuries in elite athletes requires balancing accelerated rehabilitation and return-to-play with long-term outcomes. (10.1016/j.jhsa.2024.03.018)
  • [Paper] This investigation provides objective evidence that our radial-based thumb MCP-stabilizing orthosis effectively reduces the degree of abduction that occurs at the thumb MCP joint up to at least 100 N. (10.1016/j.jht.2017.06.002)
  • [L5] Thumb UCL repair with suture tape augmentation is able to restore varusevalgus kinematics after complete UCL tear without over-constraining the joint. (10.1016/j.jhsa.2019.09.005)
  • [L4] Patient-reported outcomes, including pain and function, improved after thumb UCL reconstruction with a tendon autograft. (10.1016/j.jhsa.2024.05.005)
  • [L4] Individual FDS contractions, particularly of the index and middle fingers, contribute most to stabilization against valgus stress. (10.1186/s13018-020-01640-7)
  • [L5] The hook plate construct was biomechanically superior to the suture anchor construct for fixation of thumb metacarpophalangeal joint UCL fracture-avulsions with regard to load to failure. (10.1016/j.jhsa.2015.11.016)
  • [L5] In this model, thumb UCL repair with suture tape augmentation demonstrated greater maximum and clinical failure loads compared with nonaugmented repair at time 0, that is, without any biological healing. (10.1016/j.jhsa.2018.02.002)
  • [L5] A sufficiently sized partial adductor pollicis tendon can be obtained to reconstruct UCL of the thumb metacarpophalangeal joint, and the location of the adductor pollicis insertion closely approximates that of the UCL insertion. (10.1016/j.jhsa.2021.08.002)
  • [L5] Biomechanically, there are no treatments of repair or reconstruction using native tissues that provide equivalent strength to the preinjured ligament. (10.5435/jaaos-d-22-00112)
  • [L5] This case highlights that clinical assessment of a thumb ulnar collateral ligament injury should be supplemented with radiographs, as underlying pathology, such as an enchondroma, may be a factor. (10.1177/17531934251315313)
  • [L5] Ultrasound examination of the hand and wrist is evolving in its indications and expanding in its use; physicians who use this study should be trained accordingly and gain knowledge regarding appropriate reimbursement codes. (10.1016/j.jhsa.2018.03.034)
  • [L1] Patients with acute UCL injuries should be assessed with history, clinical examination, and radiographs. (10.1177/17531934241274612)
  • [L5] In round joints, only the non-anatomic Glickel procedure restores normal ROM and stability, while in flat joints, the Glickel procedure and a modified Fairhurst configuration with origins dorsal in the metacarpal head restore ROM and stability. (10.1177/17531934231164260)
  • [L5] Disruption of the volar plate is insufficient to significantly alter PIP joint congruity. (10.1177/15589447211060419)
  • [L5] Insufficient contraction may increase tensile load on the ulnar collateral ligament, suggesting a need for sufficient rest and recovery to reduce injury risk. (10.1016/j.jse.2023.03.026)
  • [L5] The presence of a second small bone fragment ('two fleck sign') on X-ray may indicate a Stener lesion requiring surgical repair, which can be missed on initial evaluation. (10.1177/1753193408087106)

See Also

References

[1] Biomechanical Analysis of Thumb Ulnar Collateral Ligament Tear Kinematics. HAND. 2019. DOI: 10.1177/1558944719868518

[2] Variation in the Rate of Surgery for Ulnar Collateral Ligament Injury of the Metacarpophalangeal Joint of the Thumb. HAND. 2016. DOI: 10.1177/1558944716681974

[3] The Association of Metacarpal Head Morphology with Risk of Ulnar Collateral Ligament Rupture. The Journal of Hand Surgery. 2026. DOI: 10.1016/j.jhsa.2025.02.017

[4] The Displaced Fleck Sign: Description of a Radiographic Finding Consistent with Grade III Thumb Ulnar Collateral Ligament Tears with Stener Lesions. The Journal of Hand Surgery. 2025. DOI: 10.1016/j.jhsa.2024.12.003

[5] Performance and Return to Sport After Thumb Ulnar Collateral Ligament Surgery in National Football League Players. HAND. 2018. DOI: 10.1177/1558944718760001

[6] Patient-Reported Outcomes and Function After Surgical Repair of the Ulnar Collateral Ligament of the Thumb. The Journal of Hand Surgery. 2023. DOI: 10.1016/j.jhsa.2023.05.003

[7] Biological Versus Nonbiological Reconstruction of the Ulnar Collateral Ligament of the Thumb Metacarpophalangeal Joint: A Retrospective Study. The Journal of Hand Surgery. 2024. DOI: 10.1016/j.jhsa.2024.01.008

[8] Early Return to Play With Thumb Spica Gauntlet Casting for Ulnar Collateral Ligament Injuries Complicated by Adjacent Joint Dislocations in Collegiate Football Linemen. HAND. 2018. DOI: 10.1177/1558944718788644

[9] Single-Bundle vs Double-Bundle (Anatomical) Reconstruction of the Thumb Ulnar Collateral Ligament: Biomechanical Study. HAND. 2017. DOI: 10.1177/1558944717744338

[10] Advances in the Treatment of Hand and Wrist Injuries in the Elite Athlete. The Journal of Hand Surgery. 2024. DOI: 10.1016/j.jhsa.2024.03.018

[11] Efficacy of a radial-based thumb metacarpophalangeal-stabilizing orthosis for protecting the thumb metacarpophalangeal joint ulnar collateral ligament. Journal of Hand Therapy. 2019. DOI: 10.1016/j.jht.2017.06.002

[12] Kinematics of Thumb Ulnar Collateral Ligament Repair With Suture Tape Augmentation. The Journal of Hand Surgery. 2020. DOI: 10.1016/j.jhsa.2019.09.005

[13] Patient-Reported and Clinical Outcomes After Tendon Autograft Reconstruction of the Thumb Ulnar Collateral Ligament. The Journal of Hand Surgery. 2025. DOI: 10.1016/j.jhsa.2024.05.005

[14] Valgus stability is enhanced by flexor digitorum superficialis muscle contraction of the index and middle fingers. Journal of Orthopaedic Surgery and Research. 2020. DOI: 10.1186/s13018-020-01640-7

[15] Hook Plate Versus Suture Anchor Fixation for Thumb Ulnar Collateral Ligament Fracture-Avulsions: A Cadaver Study. The Journal of Hand Surgery. 2016. DOI: 10.1016/j.jhsa.2015.11.016

[16] Suture Tape Augmentation of the Thumb Ulnar Collateral Ligament Repair: A Biomechanical Study. The Journal of Hand Surgery. 2018. DOI: 10.1016/j.jhsa.2018.02.002

[17] Reconstruction of the Thumb Metacarpophalangeal Ulnar Collateral Ligament With an Adductor Pollicis Slip: An Anatomic Evaluation. The Journal of Hand Surgery. 2022. DOI: 10.1016/j.jhsa.2021.08.002

[18] Thumb Metacarpophalangeal Joint Ulnar Collateral Ligament Injuries: Management and Biomechanical Evaluation. Journal of the American Academy of Orthopaedic Surgeons. 2023. DOI: 10.5435/jaaos-d-22-00112

[19] Clinical thumb ulnar collateral ligament injury owing to a pathological fracture through an enchondroma of the proximal phalanx. Journal of Hand Surgery (European Volume). 2025. DOI: 10.1177/17531934251315313

[20] Principles of Billing for Diagnostic Ultrasound in the Office and Operating Room. The Journal of Hand Surgery. 2019. DOI: 10.1016/j.jhsa.2018.03.034

[21] Guideline on managing thumb ulnar collateral ligament injuries: the British Society of Surgery for the Hand Evidence for Surgical Treatment (BEST) findings and recommendations. Journal of Hand Surgery (European Volume). 2024. DOI: 10.1177/17531934241274612

[27] Thumb metacarpophalangeal joint morphology and reconstruction of the ruptured ulnar collateral ligament. Journal of Hand Surgery (European Volume). 2023. DOI: 10.1177/17531934231164260

[28] Proximal Interphalangeal Joint Congruity: A Biomechanical Study. HAND. 2022. DOI: 10.1177/15589447211060419

[29] Repetitive pitching decreases the elbow valgus stability provided by the flexor-pronator mass: the effects of repetitive pitching on elbow valgus stability. Journal of Shoulder and Elbow Surgery. 2023. DOI: 10.1016/j.jse.2023.03.026

[30] The ‘‘Two Fleck Sign’’ for an Occult Stener Lesion. Journal of Hand Surgery (European Volume). 2008. DOI: 10.1177/1753193408087106

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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.