Author(s): Marlena Rose Mueller, DO, Aldo Salgado Hernandez, MD, Jessica Bailey, DO, Travis Treml, BS
Originally published: January 30, 2014 Last updated: November 21, 2024
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Disease/Disorder

Definition

The posterior cruciate ligament (PCL) is the largest and strongest intra-articular ligament in the knee. As one of the four primary ligaments that helps stabilize the knee joint, the PCL functions as the counterpart to the anterior cruciate ligament (ACL). The primary role of the PCL is to prevent posterior tibial translation relative to the femur, while also serving as a secondary support to provide rotational stability for the knee.1

Etiology

Injury to the PCL is generally the result of a direct trauma, and seldom occurs in isolation.2 Because the PCL functions to prevent the tibia from translating posteriorly,3 the mechanism of injury is usually secondary to a direct anterior tibial blow while the knee is in flexion.4 Though multi-ligament injuries involving the PCL most commonly occur following high-velocity trauma such as motor vehicle accidents (MVAs), sports-related activities are more likely to result in an isolated PCL injury.2 PCL tears resulting from MVAs are typically due to direct impact from the knee striking the dashboard.5 In a sports context, these injuries typically arise when the knee strikes the ground, an opponent, or a piece of equipment while in a hyperflexed position. This is commonly seen in football, soccer, rugby, and skiing.6   Many individuals who have sustained an isolated PCL injury continue to participate in sports without functional limitations, thus lowering the reported incidence.7 Trauma with associated knee hyperextension can also result in a PCL injury.4

Epidemiology including risk factors and primary prevention

PCL injuries are most frequently associated with other ligament, meniscal, or chondral injuries, particularly those involving the posterior lateral corner (PLC) of the knee. The annual incidence of isolated complete PCL tears was found to be 2 in 100,000, which comprises approximately 1% of all acute knee injuries.1,8 

PCL injuries have a higher incidence in men, with the average age at time of injury ranging from 28 to 34 years.9 The severity of PCL and related ligamentous injuries varies significantly, influenced by individual patient characteristics and the mechanism of injury. In general, high-velocity trauma or activities are more likely to cause PCL injuries than low-velocity mechanisms.3

Given the relatively low incidence of isolated PCL injuries, there are no specific strategies or protocols reported for their prevention. The vast majority of sports-related knee injury prevention programs primarily focus on the ACL.

Patho-anatomy/physiology

The PCL is an hourglass-shaped ligament that originates from the lateral aspect of the medial femoral condyle and inserts onto the intercondylar fossa on the posterior tibial plateau. It is the largest intra-articular ligament in the knee and is surrounded by a robust synovium. This provides increased blood supply compared to the anterior cruciate ligament (ACL), providing better healing capacity in lower grade injuries.1 The vascular supply is primarily provided by the middle genicular artery, a branch of the popliteal artery. Secondary blood supply is derived from the inferior genicular arteries.10 Innervation is provided by the posterior articular nerve, a branch of the tibial nerve.11

The PCL is composed of two functional bundles, the anterolateral (AL) and posteromedial (PM) bundles. The AL bundle is the larger and stronger of the two, and is oriented more vertically, whereas the PM bundle has a more horizontal orientation. These bundles act co-dominantly, with the AL bundle acting as the primary restraint against posterior tibial translation during midrange flexion, while the PM bundle takes over this primary role with deep knee flexion and extension. The more horizontal orientation of the PM bundle also helps to provide additional rotational stability of the knee.1 

In addition to its primary function of resisting posterior tibial translation throughout knee range of motion, the PCL also helps provide knee rotational stability. This is especially true when the knee is flexed between 90 and 120 degrees.1 This secondary function includes resisting both internal and external knee rotation. 

PCL injuries are commonly only one component of multi-ligamentous knee injuries.12 PCL injuries are associated with ACL injuries in 46% of cases, medial collateral ligament injuries in 31% of cases, and injuries to the posterolateral corner in 62% of cases.13 The posterolateral corner of the knee is made up of three primary stabilizing structures including the popliteus muscle, the popliteofibular ligament, and the lateral collateral ligament. Secondary structures include the two heads of the biceps femoris, the lateral capsule, and the iliotibial band.14

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

Most acute PCL injuries result from trauma. Unlike many other knee ligament injuries, symptoms can be mild and nonspecific, and patients rarely report hearing a “pop,” which is common with ACL injuries. In cases of isolated PCL injuries, initial symptoms may include deep or posterior knee pain, a feeling of instability, and usually minimal to no significant swelling. Typically, following an event like an MVA or a sports-related contact injury to the knee, an initial physical examination and/or imaging is conducted, allowing for early diagnosis and discussion of operative vs. non-operative management.13 This is especially true with combined knee ligamentous injuries. However, in instances of lower-velocity trauma or delayed presentation to a healthcare provider, an acute PCL injury may remain undiagnosed. Some patients may present months later with only mild symptoms such as generalized knee discomfort and instability.13

Specific secondary or associated conditions and complications 

When an isolated PCL tear is missed or left untreated, a chronic tear may persist and can result in secondary problems within the knee joint. Ongoing symptoms may include chronic pain and joint instability. Long-term complications in knees with PCL insufficiency are generally related to altered knee biomechanics.1,8 The loss of stability provided by the PCL leads to increased contact pressures in both the patellofemoral and medial knee compartments, with associated posterior tibial subluxation. This has been associated with increased rates of medial femoral condyle cartilage degeneration.1 Patients with a history of isolated PCL tears have recently been shown to have a six-fold increase in the rate of knee osteoarthritis later in life.1,8 The rate of arthritis can potentially be reduced if patients undergo surgical PCL reconstruction.15

Essentials of Assessment

History

In any acute knee injury, understanding the mechanism of injury and type of trauma is crucial for establishing a differential diagnosis. In the case of an MVA, knowing the dashboard was struck can be informative. In sports-related injuries, the event is often witnessed, allowing for a clear description of the injury mechanism. It is essential to also assess for concurrent damage to other adjacent structures since isolated PCL injuries are rare. For all high-velocity trauma, the examiner should inquire about neurovascular symptoms to rule out concomitant nerve or vascular injury. 

Symptoms upon presentation may be highly variable depending on both chronicity and mechanism of injury. Patients with isolated, acute PCL injuries may complain of a mild knee effusion or posterior knee swelling, in addition to stiffness and pain in the posterior knee that is aggravated by squatting or kneeling. An antalgic gait or guarding of the knee with ambulation may also be seen.3,16   More significant complaints such as complete inability to bear weight, a large effusion, or significant instability after injury are more common in combined knee ligament injuries.

In the patient presenting with a chronic PCL tear, complaints of generalized pain and aching tend to be more localized over the anterior knee. Patients may describe symptoms of instability with associated pain that becomes more prevalent with acceleration and when descending, such as when using stairs or ramps.6 

Physical examination

Evaluation of PCL injuries should start with a general inspection of the knee. The examiner should look for signs of trauma such as edema, ecchymosis, or lacerations. This should be followed by a palpatory exam of the joint, evaluation of range of motion, neurovascular testing, and a gait assessment. Multiple special tests exist that can help evaluate both PCL integrity as well as concomitant injuries, however these may be difficult in the acute setting secondary to pain and guarding. Functional knee testing can also be considered in athletes after acute symptoms have resolved, which may include sports-specific evaluation of balance and stability.

Special tests that can assist in the evaluation of PCL injuries include the following:

  • Posterior Drawer Test: The patient lies supine with 45 degrees of hip flexion and 90 degrees of knee flexion. While stabilizing the foot, a posterior force is applied to the proximal tibia. This test is positive if the tibia is able to be translated posteriorly. Sensitivity ranges from .22-.89, with a specificity of .98.17
  • Posterior Sag Sign: The patient lies supine with 45 degrees of hip flexion and 90 degrees of knee flexion. Sagging of the tibia posterior to the femur suggests a PCL tear. Sensitivity ranges from 0.46-1.00, with a specificity of 1.00.17
  • Quadriceps Active Test: The patient lies supine with hips flexed to 45 degrees and knees flexed to 90 degrees. The foot and thigh are stabilized, and the patient is asked to contract the quadriceps muscles.  Anterior tibial translation can be seen in the setting of a PCL tear. Sensitivity ranges from 0.53-0.98, with a specificity range of 0.96-1.00.17
  • Dial test: The patient lies prone, and the degree of foot external rotation is compared side-to-side with the knees flexed at 30 degrees and then 90 degrees. More than 10 degrees of increased external rotation in both positions indicates a combined posterolateral corner and PCL injury. An increase at 30 degrees alone suggests an isolated posterolateral corner injury with an intact PCL.18  

Imaging

When evaluating a suspected acute PCL tear, X-rays with anteroposterior (AP) and lateral views should be obtained to evaluate for concomitant injuries such as occult fractures, avulsion injuries, and posterior tibial translation. In a suspected chronic PCL tear, weightbearing AP, lateral, and sunrise views should be obtained to evaluate for the above abnormalities as well as medial and patellofemoral compartment degenerative changes.19 More recently, lateral stress or kneeling stress radiography of the knee has been utilized to diagnose and quantify PCL lesions. A lateral stress view is obtained by applying posterior stress to the anterior tibia at 70 degrees of knee flexion, and asymmetric posterior tibial displacement indicates a PCL injury.20

Additional confirmation of PCL injuries can be obtained with an MRI, which has a high sensitivity and specificity for diagnosing acute PCL tears.21. MRI can also help further distinguish between full and partial tears, as well as evaluate for other associated soft tissue injuries. However, up to 57% of chronic PCL tears may appear near normal on MRI due to the inherent ability of the ligament to heal.22 Degenerative changes in the medial and patellofemoral compartments can also be suggestive of chronic PCL tears if the ligament appears intact on MRI.23 In this case, clinical correlation with signs and symptoms of chronic PCL tears is prudent to obtain an accurate diagnosis.23

Supplemental assessment tools

PCL injuries are classified into 3 grades based on the physical examination of the knee:

  • Grade I – Partial tear with 1 to 5 mm posterior tibial translation on exam
  • Grade II – Partial tear with 5 to10 mm posterior tibial translation on exam 
  • Grade III- Complete tear with >10mm of posterior tibial translation on exam 

Environmental

The National Collegiate Athletic Association (NCAA) Injury Surveillance system found that the rate of PCL tears sustained by Division I, II, and III American football players was roughly three times higher when games were played on artificial turf compared to natural grass.24

Professional issues

Return-to-play timing is often the first question posed by most athletes of all ages and abilities after a PCL injury. As a physiatrist, it is important to advocate for patients to receive an early and accurate diagnostic evaluation, appropriate imaging, and discussion of both surgical and non-surgical treatment options. This helps facilitate a faster return to the patient’s level of prior activity and avoid long-term complications. 

Rehabilitation Management and Treatments

Available or current treatment guidelines

Management of PCL injuries is highly dependent on the injury chronicity, concomitant injuries, and patient level of activity. As a general rule, acute grade I and II injuries can be managed non-operatively.25 Patients with isolated grade III injuries, especially those who participate primarily in low demand activities can typically forego surgical intervention as well, though most grade III PCL tears are associated with multiligamentous injuries.25 Referral to a knowledgeable orthopedic surgeon is indicated for PCL tears with combined ligamentous or significant soft tissue injuries. Surgical management should also be considered for acute grade II or III injuries with an associated avulsion injury, and for athletes who are unable to return to sport due to continued instability after a trial of non-operative management. Chronic PCL tears are generally only treated surgically in the case of functional knee instability. 20

Initial management of acute PCL tears: Many physicians are proponents of bracing the knee in full extension for approximately 2-4 weeks after injury to reduce posterior tibial lag and prevent hamstring activation during gait.26 Basic principles of all acute joint injuries also apply, including pain management with oral analgesics as needed, relative rest, protection, and compression or ice if needed for swelling. Crutches are not always required but can be used if initial weight-bearing is painful.

Rehabilitation of PCL injuries should begin relatively quickly after injury, when swelling has diminished and pain is controlled.27 Non-operative rehabilitation protocols have the same general principles as those used for postoperative management, but patients often progress more quickly than patients that have undergone PCL reconstruction.26 Key elements of the rehabilitation course should include progressive weight bearing, early quadriceps strengthening, and avoidance of open-chain hamstring exercise to prevent posterior tibial subluxation.7 These programs should be individualized based on each patient’s baseline functional status, activity level, and sport. Having a physical therapist or experienced athletic trainer supervise the rehabilitation process will help ensure the exercises are being performed correctly.27 Dynamic or functional PCL bracing is an emerging adjunctive treatment that shows promise in preliminary studies, with improved patient outcomes when incorporated into conservative management plans for PCL tears.28

All surgical repairs or reconstructions of PCL injuries should also be followed by a structured rehabilitation program. Similar to non-operative protocols, recovery begins with initial immobilization of the knee in full extension with gradual advancement of range of motion and weight bearing status. This is followed by a focus on quadriceps strengthening, proprioceptive training, and a gradual return to sports-specific exercises. In athletes, jogging and sport-specific activities are typically initiated around 6 months postoperatively. Criteria for returning to cutting and pivoting sports includes full knee range of motion, quadriceps strength of over 90 percent of the contralateral quadriceps, and a firm endpoint during posterior drawer testing. Full return to sports may take up to 12 months after surgery, although some high-level athletes have been reported to return sooner.26

Patient & family education

Patient and family education should be provided on the natural course of PCL injuries and should include a discussion that includes all available treatment options including both nonoperative and operative management and indications for each. The patient should be made aware that full return to sport after a surgical PCL reconstruction can take up to a year. A shared decision-making approach should be used to guide treatment after establishing the patient’s current and long-term functional goals. If the patient is an athlete, including coaches and training staff in the rehabilitation plan can help facilitate a multidisciplinary approach to recovery.

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

Though isolated PCL injury is relatively rare compared to other knee ligament injuries, it is important for clinicians to consider concomitant PCL injury when a patient presents with any history of knee trauma. Over 60 percent of acute PCL injuries are associated with additional capsuloligamentous lesions.1,9 Clinical decision making regarding treatment options should be individualized for each patient after a thorough physical exam and diagnostic workup of the knee. Treatment should be based on both the severity of the PCL injury as well as any associated cartilage, meniscus, or ligamentous injuries. Other considerations should include the social, professional, and athletic demands of the patient.9

First line treatment for isolated grade I and II PCL injuries should consist of non-operative management, which has been consistently reported to be highly successful in recent literature.9 The consensus for the optimal treatment of isolated grade III PCL injuries is more variable, and long-term outcomes following operative vs. non-operative management is an area of ongoing research. It is reasonable to refer grade III PCL tears to orthopedic surgery for an in-depth discussion of the pros and cons of operative vs. non-operative management, especially in patients who are very physically active. Though both treatment options yield good clinical outcomes, PCL reconstruction has been found to reduce residual laxity and reduce incidence of secondary osteoarthritis development when compared to conservative treatment alone.29 

Cutting Edge/Emerging and Unique Concepts and Practice

Diagnostic ultrasound is an emerging treatment for the diagnosis of intra-articular knee injuries, including the PCL. The advantages of ultrasound include its relatively low cost, absence of radiation risk, and convenience, as it can be performed during an office visit. A recent study found that a PCL thickness of >6.5mm on 2D ultrasound has a sensitivity of 90.6% and a specificity of 86.7% for the diagnosis of acute PCL injury. Ultrasound has significant potential for future healthcare cost reduction when used as an alternative to MRI, and remains an area for ongoing research in both acute and chronic PCL injuries.30

Regenerative medicine for the use of musculoskeletal injuries is on the rise, but there is limited data for isolated PCL injuries due to the relatively low incidence. However, a small randomized trial was recently published that suggests the use of platelet-rich plasma (PRP) in isolated PCL injury may facilitate earlier improvement in range of motion and faster return to sport.31 Larger trials are still needed to assess the role and efficacy of orthobiologic agents for the treatment of PCL injuries.

Gaps in the Evidence-Based Knowledge

Additional research is needed to compare long term outcomes of surgical versus conservative management of PCL injuries, particularly with respect to different patient populations. The optimal timing of both surgical reconstruction as well as initiation of both non-operative and post-operative rehabilitation programs following grade III PCL tears is still up for debate. More definitive research on these subjects may have a significant influence on initial treatment protocols, including the value of an initial trial of non-operative management with a formal rehabilitation program before proceeding with surgical reconstruction.9

References

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  2. Schlumberger M, Schuster P, Eichinger M, Mayer P, Mayr R, Immendörfer M, Richter J. Posterior cruciate ligament lesions are mainly present as combined lesions even in sports injuries. Knee Surg Sports Traumatol Arthrosc. 2020 Jul;28(7):2091-2098. doi: 10.1007/s00167-020-05919-4. Epub 2020 Mar 10. 
  3. Dowd GS. Reconstruction of the posterior cruciate ligament. Indications and results. J Bone Joint Surg Br. 2004;86(4):480-491.
  4. Brukner P, Clarsen B, Cook J, Cools A, Crossley K, Hutchinson M, McCrory P, Bahr R, Khan K. eds. Brukner & Khan’s Clinical Sports Medicine: Injuries, Volume 1, 5e. McGraw-Hill Education; 2017.
  5. Margheritini F, Mariani PF, Mariani PP. Current concepts in diagnosis and treatment of posterior cruciate ligament injury. Acta Orthop Belg. 2000;66(3):217-228.
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  7. Shelbourne KD, Benner RW, Ringenberg JD, Gray T. Optimal management of posterior cruciate ligament injuries: current perspectives. Orthop Res Rev. 2017;9:13-22.
  8. Sanders TL, Pareek A, Barrett IJ, Kremers HM, Bryan AJ, Stuart MJ, Levy BA, Krych AJ. Incidence and long-term follow-up of isolated posterior cruciate ligament tears. Knee Surg Sports Traumatol Arthrosc. 2017 Oct;25(10):3017-3023. doi: 10.1007/s00167-016-4052-y. Epub 2016 Feb 27. 
  9. Winkler PW, Zsidai B, Wagala NN, Hughes JD, Horvath A, Senorski EH, Samuelsson K, Musahl V. Evolving evidence in the treatment of primary and recurrent posterior cruciate ligament injuries, part 1: anatomy, biomechanics and diagnostics. Knee Surg Sports Traumatol Arthrosc. 2021 Mar;29(3):672-681. doi: 10.1007/s00167-020-06357-y. Epub 2020 Nov 17. 
  10. Arnoczky SP. Blood supply to the anterior cruciate ligament and supporting structures. Orthop Clin North Am. 1985;16(1):15-28.
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  12. Kim YM, Lee CA, Matava MJ. Clinical results of arthroscopic single-bundle transtibial posterior cruciate ligament reconstruction: a systematic review. Am J Sports Med. 2011;39(2):425-434.
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  14. Chahla J, Moatshe G, Dean CS, LaPrade RF. Posterolateral Corner of the Knee: Current Concepts. Arch Bone Jt Surg. 2016 Apr;4(2):97-103. 
  15. Strobel MJ, Weiler A, Schulz MS, Russe K, Eichhorn HJ. Arthroscopic evaluation of articular cartilage lesions in posterior-cruciate-ligament-deficient knees. Arthroscopy. 2003 Mar;19(3):262-8. doi: 10.1053/jars.2003.50037. 
  16. Margheritini F, Mariani PF, Mariani PP. Current concepts in diagnosis and treatment of posterior cruciate ligament injury. Acta Orthop Belg. 2000;66(3):217-228.
  17. Kopkow C, Freiberg A, Kirschner S, Seidler A, Schmitt J. Physical examination tests for the diagnosis of posterior cruciate ligament rupture: a systematic review. J Orthop Sports Phys Ther. 2013 Nov;43(11):804-13. doi: 10.2519/jospt.2013.4906. Epub 2013 Oct 11.
  18. Cosgarea AJ, Jay PR. Posterior cruciate ligament injuries: evaluation and management. J Am Acad Orthop Surg. 2001;9(5):297-307.
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  20. Allen, D. (2023, May 31). PCL injury. Orthobullets. https://www.orthobullets.com/knee-and-sports/3009/pcl-injury
  21. Laoruengthana A, Jarusriwanna A. Sensitivity and specificity of magnetic resonance imaging for knee injury and clinical application for the Naresuan University Hospital. J Med Assoc Thai. 2012;95 Suppl 10:S151-157.
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  24. Loughran GJ, Vulpis CT, Murphy JP, Weiner DA, Svoboda SJ, Hinton RY, Milzman DP. Incidence of Knee Injuries on Artificial Turf Versus Natural Grass in National Collegiate Athletic Association American Football: 2004-2005 Through 2013-2014 Seasons. Am J Sports Med. 2019 May;47(6):1294-1301. doi: 10.1177/0363546519833925. Epub 2019 Apr 17. 
  25. Raj MA, Mabrouk A, Varacallo M. Posterior Cruciate Ligament Knee Injuries. StatPearls. 2021;1(22).
  26. Kew ME, Cavanaugh JT, Elnemer WG, Marx RG. Return to Play after Posterior Cruciate Ligament Injuries. Curr Rev Musculoskelet Med. 2022 Dec;15(6):606-615. doi: 10.1007/s12178-022-09794-z. Epub 2022 Nov 30. 
  27. MacDonald J, Rodenberg R. (2024). Posterior cruciate ligament injury. In: UpToDate, O’Connor F (Ed). Wolters Kluwer. (Accessed on Oct 5, 2024.)
  28. Hewlett J, Kenney J. Innovations in functional and rehabilitative knee bracing. Ann Transl Med. 2019 Oct;7(Suppl 7):S248. doi: 10.21037/atm.2019.03.34.
  29. Schroven, W., Vles, G., Verhaegen, J. et al. Operative management of isolated posterior cruciate ligament injuries improves stability and reduces the incidence of secondary osteoarthritis: a systematic review. Knee Surg Sports Traumatol Arthrosc 30, 1733–1743 (2022). https://doi.org/10.1007/s00167-021-06723-4
  30. Wang LY, Yang TH, Huang YC, Chou WY, Huang CC, Wang CJ. Evaluating posterior cruciate ligament injury by using two-dimensional ultrasonography and sonoelastography. Knee Surg Sports Traumatol Arthrosc. 2017 Oct;25(10):3108-3115. doi: 10.1007/s00167-016-4139-5. Epub 2016 May 4. 
  31. Messina G, Cataldo P, Mantia F, Iovane EM, Mantia C, Terrasi M, Iovane A. Platelets-rich-plasma in management of non operative post cruciate ligament injury. Eur J Transl Myol. 2023 Dec 18;34(1):11535. doi: 10.4081/ejtm.2023.11535. 

Original Version of the Topic

Steve M. Aydin, DO. Posterior cruciate ligament (PCL) injuries. 1/30/2014

Previous Revision(s) of the Topic

Steve M. Aydin, DO. Posterior cruciate ligament (PCL) injuries. 2/13/2017

Ajay Patel, MD, Katherine Victoria Yao, MD. Posterior Cruciate Ligament (PCL) Injuries. 7/20/2021

Author Disclosure

Marlena Rose Mueller, DO
Nothing to Disclose

Aldo Salgado Hernandez, MD
Nothing to Disclose

Jessica Bailey, DO
Nothing to Disclose

Travis Treml, BS
Nothing to Disclose