Skip to content

Patients › Knee

前交叉韧带重建

PDF Evidence Consent
Updated Sep 2026
Illustration: knee

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。

为何建议进行此手术

诸如 MRI 等扫描检查有助于确认前交叉韧带撕裂，该韧带是膝关节内部的一条组织带，可防止胫骨过度向前滑动。

前交叉韧带无法自行愈合，因此重建手术会使用一段新的肌腱来重建该韧带。我们通常向年轻或活跃人群，或膝关节出现不稳（打软腿）的患者提供此手术。治疗方案将根据您的年龄、活动水平、膝关节的不稳定程度以及其他任何损伤进行个性化调整。许多人首先尝试物理治疗以恢复关节活动度并增强大腿肌肉力量，若改善效果不足，则随后进行手术。目标是使膝关节感觉稳定，从而让您能够自如活动并保持活跃状态，而不会出现膝关节不稳的情况。

手术前

在手术前的几周里，您将配合物理治疗师进行训练，使膝关节能够完全伸直和弯曲，并增强大腿肌肉力量。提前进行这些训练有助于使术后恢复更加顺利。您还将接受影像学检查以协助手术规划，例如X光或磁共振成像（MRI）。手术当天，请在术前七小时停止进食和饮水；我们要求比标准的六小时稍长一些，以便在手术排期提前时能够提前进行您的手术。您的外科医生会告知您哪些药物需要暂停服用。请安排他人驾车送您回家，并携带一份您目前正在服用的药物清单。穿着宽松、舒适的衣物。如果您有其他基础疾病，可能需要进行血液检查或接受麻醉医生的评估。

手术当天

您抵达医院的手术入院单元，在此办理入院手续并进行术前准备。您将见到麻醉师，即负责让您入睡并在手术期间保持您舒适状态的医生。本手术在全身麻醉下进行。有时会追加区域神经阻滞以缓解术后疼痛；麻醉师将在当天就此与您讨论。

随后，您将被带入手术室进行手术。术后，您将在复苏区苏醒，护士会在此监护您，直至麻醉消退。一旦您的生命体征稳定，根据手术类型及恢复情况，您将被转入病房或当天出院。

手术内容

重建手术会用一段新的肌腱（称为移植物）来替换撕裂的韧带。移植物可取自患者自身，通常取自膝关节前方或大腿后侧的腘绳肌腱，也可取自供体组织。您的外科医生会根据您的膝关节状况、年龄以及您希望恢复的活动类型，选择最适合的移植物。

手术通过膝关节周围的小切口进行，使用一种称为关节镜的细径摄像头，使外科医生能够观察关节内部。医生会确认撕裂的韧带，并检查膝关节是否存在其他损伤，例如软骨撕裂。随后，在小腿骨（胫骨）和大腿骨（股骨）上钻出小隧道，将新的移植物穿过这些隧道，使其位于原韧带所在的位置。移植物随后通过螺钉或纽扣固定，以便其在愈合过程中与骨骼结合。

切口用缝合线关闭，并覆盖敷料。您将收到关于伤口护理的书面说明。

部分撕裂可以通过修复而非重建来处理，但这仅适用于少数患者，通常是指韧带从骨骼上干净利落地撕裂且组织质量良好的情况。如果您的情况适合修复，您的外科医生会告知您。

术后

麻醉苏醒后，您将被安置在复苏区，待生命体征平稳后，您将被转入病房或回家。您的医疗团队会告知您是当天回家还是住院一晚。护士会确保您的舒适度，并根据需要为您止痛。您的膝关节伤口处将覆盖敷料，可能会使用支撑绷带而非支具。大多数患者在手术当天即可在物理治疗师的协助下，借助助行器或拐杖站立并行走几步。请安排有人在您回家后最初24小时内陪伴您。敷料通常保留约10天；除非我们告知您，否则请勿在此之前拆除。我们将在复诊时为您更换或拆除敷料。

恢复

最初几天以舒适和轻柔活动为主。您的膝关节会疼痛、肿胀，并可能感觉发热。休息、冰敷以及医疗团队开具的止痛药均有助于缓解症状。坐着或躺下时，请抬高腿部。肿胀通常在最初几天达到高峰，随后在接下来的几周内逐渐消退。

手术后不久，您将接受物理治疗师的指导，并在膝关节恢复过程中持续与其合作。早期练习的重点是使膝关节完全伸直，每天逐渐增加屈曲角度，并重新激活大腿肌肉。行走初期需使用拐杖或助行器，并根据物理治疗师的建议逐步对腿部施加重量。您可能使用支持性绷带而非支具。一旦感觉稳定，您即可在家中进行大多数活动：在屋内走动、准备餐食以及小心地上下楼梯。在膝关节准备好之前，请避免扭转、旋转或跪姿。

随着肿胀消退和活动能力恢复，练习难度将逐渐增加。您将增强大腿肌肉力量，并练习平衡与控制。后期阶段旨在为您恢复期望的活动做准备，例如跑步、跳跃或改变方向。部分患者在获得无限制运动许可前，还会在常规物理治疗之外完成结构化的重返运动项目。

恢复情况因人而异。您的时间线可能有所不同，外科医生和物理治疗师将在每个阶段为您提供指导。

可能出现的并发症

大多数患者恢复良好，但偶尔可能出现一些问题。您的外科医生和医疗团队会密切监测您的状况，以便尽早发现任何问题。

膝关节僵硬。 部分患者会出现关节紧绷，限制膝关节弯曲或伸直的范围。您可能会注意到膝关节感觉被锁住，或者即使用力也无法完全伸直。在手术前进行锻炼并恢复完全的活动度可以降低这种风险。如果膝关节无法伸直，请告知您的物理治疗师或致电诊所。

感染。 这种情况并不常见，但请留意以下症状：简单的止痛药无法缓解的深层搏动性疼痛、伤口周围扩散的红肿，或发热及身体不适感。膝关节可能会变得发热、肿胀且触痛明显。如果您注意到上述任何迹象，请立即致电诊所或前往急诊科。感染通常通过关节冲洗和抗生素治疗，移植物通常可以保留在原位。

新韧带再次撕裂。 移植物可能会像原始韧带一样再次撕裂。这通常发生在扭伤或跌倒时，感觉像是膝关节再次失稳，常伴有肿胀。如果发生这种情况，请联系诊所。可以进行第二次手术以重建韧带，但第二次手术后的恢复通常较慢，且结果不如第一次手术可预测。

另一侧膝关节韧带受伤。 您另一侧膝关节的韧带也可能撕裂，尤其是在重返运动的年轻人中。在重返运动前，按照重返运动计划循序渐进地进行训练，可以保护双侧膝关节。

膝关节前部疼痛。 如果移植物取自膝关节前部，该区域可能会持续疼痛，特别是在跪姿时，且大腿肌肉恢复力量可能较慢。如果这影响了您的活动，请在复诊时提及。

本页中的并发症表格列出了典型的发生率，如果您想了解具体数据，请参阅该表格。

何时联系我们

大多数问题都会早期显现，我们更希望尽早得知。如果您出现发热，伤口周围皮肤变得更红或开始渗出液体，或膝关节变得发热、肿胀且疼痛加剧，请致电我们。如果您出现突发剧烈疼痛、小腿肿胀或呼吸困难，请立即前往急诊，因为这些可能提示血栓形成。如果您的腿部出现麻木、感觉发冷或颜色改变，或无法活动，也请立即前往急诊。

Reviewed by AI synthesis (v2) — pending human review · 9 September 2026.

Want the clinical detail? Read the clinician version.

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.

Anatomy & Pathophysiology

Epidemiology & Risk Factors

  • ACL injury accounts for between 40% and 50% of all knee ligament injuries [6, 7].
  • Female athletes have a two to eight times higher risk of ACL tear than male athletes [6, 7].
  • The increased risk in female athletes is thought to occur because women have different landing biomechanics, specifically greater total valgus knee loading in landing and landing more erectly [6, 7].
  • Female athletes have increased quadriceps-to-hamstring strength, which causes greater anterior shear [6, 7].
  • Proposed additional risk factors for ACL injury include smaller notches, smaller ligaments (reduced area in cross section), greater generalized ligament laxity, increased knee laxity, and absence of the COL5A1 gene [6, 7].
  • Skiing, soccer, basketball, and football are the highest-risk sports for ACL injury [6, 7].

Mechanism & Biomechanics

  • The mechanism of ACL injury is typically a valgus load with internal tibial rotation and anterior tibial translation while the knee is in almost full extension [6, 7].
  • The in situ force of the ACL is highest at 30 degrees of flexion in response to anterior tibial load [6, 7].
  • The anteromedial bundle of the ACL provides anterior restraint and is evaluated by Lachman and anterior drawer tests [6, 7].
  • The posterolateral bundle of the ACL provides rotatory restraint and is evaluated by the pivot shift test [6, 7].

Associated Injuries

  • Associated injuries are common with ACL tears [6, 7].
  • Acute lateral meniscal tears are more common than acute medial tears, whereas medial tears occur more often with chronic ACL deficiency [6, 7].
  • MCL injuries occur in approximately 25% of cases and are typically treated nonoperatively [6, 7].
  • PLC injuries occur in approximately 10% of cases [6, 7].
  • Lack of recognition of a PLC injury has been cited as a common cause of ACL reconstruction failure [6, 7].
  • Chronic ACL deficiency is associated with higher incidences of both complex meniscal tears not amenable to repair and chondral injury [6, 7].

Pathophysiology & Long-term Outcomes

  • Currently there is no high-level evidence to suggest that ACL reconstruction reduces the risk of development of arthritis [6, 7].
  • Chondral and meniscal injuries that occur at the time of initial ACL rupture have been demonstrated to be the main predictors of arthritic change [6, 7].
  • The most common reasons for failure to return to play or sport after ACL reconstruction are pain and fear of reinjury [6, 7].
  • Primary repair of ACL tears is not currently recommended because myofibroblasts “coat” the ends of the ACL stumps, making primary healing unlikely [1, 2].
  • Arthrofibrosis is the most common complication following ACL reconstruction and often occurs with reconstruction for acute ACL tears [1, 2].
  • The risk of arthrofibrosis is minimized by the achievement of full range of motion prior to surgery [1, 2].
  • In skeletally immature patients, the most common complications after ACL reconstruction include arthrofibrosis, growth disturbance, and secondary injury of the same or the contralateral ACL [3].
  • An overall incidence of arthrofibrosis of 8.3% was reported in a cohort of 902 young patients (average age = 15 years) treated with ACL reconstruction [3].
  • Risk factors for arthrofibrosis in young patients include female sex, older age, the use of bone–patellar tendon–bone autograft, and concomitant meniscal repair [3].
  • Growth arrest can occur after ACL reconstruction in skeletally immature patients despite efforts to avoid this complication [3].
  • Clinically important growth disturbances, including tibial recurvatum and genu valgum, have been reported after transphyseal ACL reconstruction using physeal-respecting techniques [3].
  • Focal physeal bone bridges were noted in five knees in a review of 43 patients who underwent transphyseal ACL reconstruction using soft-tissue graft, although no patient had resultant limb deformity [3].
  • Growth disturbance has been reported with physeal-sparing techniques, with one patient in a series of all-epiphyseal ACL reconstructions developing clinically significant growth arrest [3].
  • The incidence of second ACL injury in young athletes (average age = 17 years) within 2 years of the index surgery is more than five times greater than that of healthy control athletes [3].
  • Nearly 30% of young athletes sustained a second ACL injury within 24 months of return to sports, with approximately one-third of the injuries occurring in the ipsilateral knee and two-thirds in the contralateral knee [3].
  • Patients younger than 20 years at the time of ACL reconstruction had a 29% chance of sustaining a second ACL injury (either knee) within 5 years of the index surgery [3].
  • In a cohort of 85 patients younger than 18 years, 32% sustained a second ACL injury, with later return to sport being protective against new ACL injury [3].
  • Athletes younger than 25 years who return to sports had a secondary rate of ACL injury (ipsilateral or contralateral knee) of 23% [3].

Clinical Evaluation

  • Young athletes with ACL tears frequently report the sudden onset of knee pain that may be accompanied by a popping sensation after a noncontact, twisting-type injury [4].
  • Difficulty bearing weight and hemarthrosis are commonly present in acute ACL tears [4].
  • Clinical tests for ACL deficiency include the Lachman, anterior drawer, and pivot shift tests [4].
  • Results of clinical tests for ACL deficiency should be compared with similar tests performed on the contralateral, unaffected knee, particularly in young, anxious patients [4].
  • The presence of associated meniscal injuries may be established by evaluating for tenderness of the joint line and decreased passive knee motion [4].
  • Injuries of the collateral ligaments may be evaluated by varus and valgus stress testing of the knee performed at 0° and 30° of flexion [4].
  • MRI of the knee has a sensitivity of 95% and specificity of 88% for confirming an ACL tear [4].
  • MRI is helpful for elucidating additional injuries and assessing physeal patency in skeletally immature patients [4].
  • A bone age study is generally performed for skeletally immature patients to estimate the amount of remaining skeletal growth before surgical treatment [4].
  • Standing hip-to-ankle alignment radiographs may be obtained to evaluate for preexisting angular deformity or limb-length discrepancy before surgical intervention [4].

Clinical Presentation

History and Symptoms

  • Young athletes with ACL tears frequently report the sudden onset of knee pain after a noncontact, twisting-type injury [4].
  • The onset of knee pain in young athletes with ACL tears may be accompanied by a popping sensation [4].
  • Difficulty bearing weight is commonly present in young athletes with ACL tears [4].
  • Hemarthrosis is commonly present in young athletes with ACL tears [4].

Physical Examination

  • Initial evaluation includes inspecting the soft tissues of the affected limb [4].
  • Initial evaluation includes performing passive motion of the ipsilateral hip, knee, and ankle [4].
  • Initial evaluation includes carefully palpating the entire affected limb [4].
  • Initial evaluation includes assessing neurovascular status [4].
  • Clinical tests for ACL deficiency include the Lachman test [4].
  • Clinical tests for ACL deficiency include the anterior drawer test [4].
  • Clinical tests for ACL deficiency include the pivot shift test [4].
  • Clinical tests for ACL deficiency may be difficult to perform and/or interpret in a young, anxious patient [4].
  • Results of clinical tests for ACL deficiency should be compared with similar tests performed on the contralateral, unaffected knee [4].
  • Clinical tests for ACL deficiency may need to be repeated in a young, anxious patient [4].
  • The presence of associated meniscal injuries may be established by evaluating for tenderness of the joint line [4].
  • Decreased passive knee motion may indicate a meniscal injury with displacement [4].
  • The dial test can be performed to evaluate the posterolateral corner of the knee [4].
  • The posterior drawer test can be performed to evaluate the posterior cruciate ligament [4].
  • Limb alignment and lengths are assessed clinically if ACL injury is suspected in a skeletally immature patient [4].
  • The patient’s degree of physiologic maturity may be gauged by use of Tanner staging of sexual maturation in skeletally immature patients [4].

Imaging

  • Orthogonal radiographs of the affected knee should be obtained [4].
  • Additional radiographs should be obtained as suggested by the physical examination findings [4].
  • MRI of the knee has a 95% sensitivity for confirming an ACL tear [4].
  • MRI of the knee has an 88% specificity for confirming an ACL tear [4].
  • MRI of the knee is helpful for elucidating additional injuries [4].
  • MRI of the knee is helpful for assessing physeal patency [4].
  • A bone age study is generally performed for skeletally immature patients before surgical treatment to estimate the amount of remaining skeletal growth [4].
  • A bone age study consists of a PA radiograph of the left hand compared with the Greulich and Pyle atlas of normal standards [4].
  • Standing hip-to-ankle alignment radiographs may be obtained to evaluate for preexisting angular deformity before surgical intervention [4].
  • Standing hip-to-ankle alignment radiographs may be obtained to evaluate for limb-length discrepancy of the lower limbs before surgical intervention [4].

Investigations

  • In young, anxious patients, results of clinical tests for ACL deficiency should be compared with similar tests performed on the contralateral, unaffected knee and may need to be repeated [4].
  • If ACL injury in a skeletally immature patient is suspected, limb alignment and lengths are assessed clinically [4].
  • The patient’s degree of physiologic maturity may be gauged by use of Tanner staging of sexual maturation [4].
  • Orthogonal radiographs of the affected knee should be obtained, with additional radiographs obtained as suggested by the physical examination findings [4].
  • MRI of the knee is helpful for elucidating additional injuries and assessing physeal patency [4].
  • Before surgical treatment, a bone age study (a PA radiograph of the left hand compared with the Greulich and Pyle atlas) is generally performed for skeletally immature patients to estimate the amount of remaining skeletal growth [4].
  • Standing hip-to-ankle alignment radiographs may be obtained to evaluate for preexisting angular deformity or limb-length discrepancy of the lower limbs before surgical intervention [4].
  • A thorough workup of failed ACL reconstruction should include acquiring prior imaging and considering all causes of graft failure, including technical issues, unrecognized concomitant ligament injuries, coronal or sagittal malalignment, biological failure of graft incorporation, and other patient-related issues [1].

Treatment

Non-Operative Management

  • Initial management of ACL injury consists of physical therapy to restore motion [1].
  • Immobilization is avoided in the initial management of ACL injury [1].
  • Full range of motion (ROM) and good quadriceps control should be achieved prior to surgery [1].
  • Treatment should be individualized based on age, activity level, instability, associated injuries, and other medical factors [1].

Surgical Technique

  • Primary repair of ACL tears is not currently recommended [1].
  • Myofibroblasts "coat" the ends of the ACL stumps, making primary healing unlikely [1].
  • Single-bundle reconstruction is the most commonly performed ACL reconstruction technique [1].
  • There is currently no difference in patient-reported outcomes between single-bundle and double-bundle ACL reconstruction techniques [1].
  • Independent femoral tunnel drilling techniques focus on placing a more horizontal femoral tunnel (10- or 2-o’clock position) to center the graft in the middle of the femoral ACL footprint [1].
  • A more horizontal graft position may reduce rotational instability [1].
  • Graft selection for ACL reconstruction depends on patient factors and surgeon preference [1].
  • Common graft choices for ACL reconstruction include bone–patellar tendon–bone (BPTB) autograft, four-strand hamstring autograft, quadriceps tendon autograft, and allograft [1].
  • BPTB autograft demonstrates faster incorporation into bone tunnels than hamstring autograft [1].
  • BPTB autograft is often the graft of choice for patients who desire an early return to sports activity [1].
  • Several studies have demonstrated a higher incidence of arthritis associated with the use of BPTB autograft than with hamstring autograft 5 to 7 years after ACL reconstruction [1].
  • BPTB autograft harvest carries the risk of anterior knee pain, pain with kneeling, loss of extension, and poorer recovery of quadriceps strength [1].
  • Hamstring autograft is similar in strength to the native ACL but is less stiff [1].
  • Hamstring autograft harvest carries the risk of weakness of knee flexion and internal rotation, along with injury to branches of the saphenous nerve [1].
  • Both BPTB and quadriceps tendon with bone block grafts carry the risk of patellar fracture [1].
  • Use of allograft with ACL reconstruction in younger, more active patients is associated with a higher rate of rerupture [1].
  • Chemically processed and irradiated allografts have demonstrated higher rates of failure than fresh frozen allografts [1].
  • Allografts have been demonstrated to incorporate into bone tunnels more slowly than autografts [1].
  • Use of allograft includes infection risk with Clostridium species, hepatitis, and human immunodeficiency virus (HIV), although rates are low at 1:1.6 million [1].
  • Preimplantation culture of allografts is not widely recommended [1].

Postoperative Rehabilitation

  • Most postoperative rehabilitation protocols encourage early motion with an emphasis on extension and weight bearing [1].
  • Exercises that do not endanger the ACL graft are dominated by the hamstrings, such as isometric hamstrings [1].
  • Exercises that do not endanger the ACL graft involve active knee ROM between 35 and 90 degrees of flexion [1].
  • Closed kinetic chain rehabilitation and compressive loading are emphasized because they allow physiologic cocontraction of the muscles around the knee [1].
  • Open kinetic chain extension exercises, particularly with the knee near full extension, place increased stress on the reconstructed ACL and should be avoided for the first 6 weeks [1].
  • No difference in outcome has been found between accelerated and nonaccelerated rehabilitation programs [1].
  • Postoperative bracing has not proved beneficial after ACL reconstruction except in downhill skiers [1].
  • Early progressive eccentric exercise has yielded good initial results in terms of muscle size and function after ACL reconstruction [1].

Complications

  • The most common technical error leading to graft failure is tunnel malposition [1].
  • Vertical graft placement results in decreased rotational stability [1].
  • Anterior placement of the femoral tunnel results in flexion loss [1].
  • Arthrofibrosis is the most common complication following ACL reconstruction [1].
  • Arthrofibrosis often occurs with reconstruction for acute ACL tears [1].
  • The risk of arthrofibrosis is minimized by the achievement of full ROM prior to surgery [1].
  • Aberrant hardware placement, defined as interference screw divergence of >30 degrees for femoral tunnels or >15 degrees for tibial tunnels, can result in complications [1].
  • Infection occurs in less than 1% of ACL reconstruction cases [1].
  • Irrigation and débridement with graft retention are successful in up to 85% of post-ACL reconstruction infection cases [1].

Revision ACL Reconstruction

  • Causes of graft failure in revision ACL reconstruction include technical issues, unrecognized concomitant ligament injuries, coronal or sagittal malalignment, biological failure of graft incorporation, and other patient-related issues [1].
  • A thorough workup of failed ACL reconstruction should include acquiring prior records [1].

Complications

General Complications

  • Graft failure is a complication of ACL reconstruction [1].
  • Irrigation and débridement with graft retention are successful in up to 85% of infected ACL reconstruction cases [1].

Skeletally Immune Patients

  • The most common complications occurring after ACL reconstruction in skeletally immature patients include arthrofibrosis, growth disturbance, and secondary injury of the same or the contralateral ACL [3].
  • In a retrospective case series of 902 young patients (average age 15 years) treated with ACL reconstruction, the overall incidence of arthrofibrosis was 8.3% [3].
  • Female sex, older age, the use of bone–patellar tendon–bone autograft, and concomitant meniscal repair are additional risk factors for arthrofibrosis in skeletally immature patients [3].
  • Growth arrest can occur after ACL reconstruction in skeletally immature patients despite the use of physeal-respecting techniques [3].
  • In a case series of four patients (average age 14.2 years) who underwent transphyseal ACL reconstruction using physeal-respecting techniques, clinically important growth disturbances including tibial recurvatum and genu valgum developed [3].
  • In a retrospective review of 43 patients (average age 14.8 years) who underwent transphyseal ACL reconstruction using soft-tissue graft, focal physeal bone bridges were noted in five knees, although no patient had resultant limb deformity [3].
  • Growth disturbance has been reported with physeal-sparing techniques, including one patient in a series of all-epiphyseal ACL reconstructions who developed clinically significant growth arrest [3].
  • In a 2014 cohort study of young athletes (average age 17 years), nearly 30% sustained a second ACL injury within 24 months of return to sports [3].
  • In the same 2014 cohort study, approximately one-third of second ACL injuries occurred in the ipsilateral knee and two-thirds in the contralateral knee [3].
  • In a 2014 case-control study, patients younger than 20 years at the time of ACL reconstruction had a 29% chance of sustaining a second ACL injury within 5 years of the index surgery [3].
  • In a cohort of 85 patients younger than 18 years who underwent primary ACL reconstruction with autograft, 32% sustained a second ACL injury [3].
  • A systematic review and meta-analysis found that athletes younger than 25 years who return to sports had a secondary rate of ACL injury (ipsilateral or contralateral knee) of 23% [3].

References

[1] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > 1. ACL injury > Treatment.

[2] Miller S Review Of Orthopaedics. 1. ACL injury > Treatment.

[3] Orthopaedic Knowledge Update. Ligamentous Knee Injuries > ACL Injuries > Complications.

[4] Orthopaedic Knowledge Update. Ligamentous Knee Injuries > ACL Injuries > Evaluation.

[6] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > 1. ACL injury > Introduction.

[7] Miller S Review Of Orthopaedics. 1. ACL injury > Introduction.

Creative Commons BY-NC 4.0

CC Creative Commons licence
BY Attribution — you must credit the source
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.

Creative Commons may be contacted at creativecommons.org.