PCL Injury: Symptoms, Diagnosis and Treatment Course

A PCL injury is a strain, partial tear or complete rupture of the posterior cruciate ligament, which limits backward movement of the shinbone relative to the thighbone. The PCL is one of the four main ligaments that stabilise the knee; it may be injured on its own or alongside damage to the anterior cruciate ligament, collateral ligaments, meniscus, cartilage or blood vessels and nerves.

Summary: Treatment of a PCL injury is planned according to the degree of ligament damage, functional knee laxity, associated injuries and the person's daily and sporting needs. Not every PCL tear requires surgery. A substantial proportion of isolated injuries can be managed with load modification, an appropriate knee brace and individualised rehabilitation. Reconstruction may be considered for marked instability, multiple ligament injuries or persistent loss of function despite appropriate non-surgical treatment. The outcome cannot be predicted solely from MRI images or the time elapsed.

This injury does not always begin with an obvious popping sound. In some people, the first complaint is pain and swelling at the back of the knee; in others, it is a feeling of insecurity when descending stairs, walking downhill or changing direction. Because injury mechanisms and associated damage vary between patient groups, studies may report widely differing rates of PCL injury. This variation in epidemiology, anatomy and diagnostic approaches was discussed in a comprehensive 2021 review (PMID 33201271).

What Is a PCL Injury?

A PCL injury is a strain or tear of the posterior cruciate ligament fibres in the centre of the knee. PCL stands for posterior cruciate ligament; it limits backward movement of the shinbone, particularly when the knee is bent. The clinical significance of the injury depends not only on structural ligament damage but also on the resulting knee laxity and the other structures affected.

The posterior cruciate ligament is one of the knee's four main ligaments. It crosses the anterior cruciate ligament in the centre of the knee, but is a separate structure and controls different movements. While limiting backward displacement of the shinbone relative to the thighbone, it also contributes to rotational control of the knee. Recent reviews provide detailed assessments of PCL anatomy and biomechanics (PMID 29430489; PMID 33201271).

Ligament damage can be described clinically in three grades:

• Grade 1: The ligament fibres are stretched; structural integrity is largely preserved and laxity is limited.
• Grade 2: Some fibres are torn; examination may reveal more pronounced backward displacement.
• Grade 3: Ligament continuity is completely disrupted; backward displacement may increase, and the possibility of other ligament injuries is investigated separately.

Grading alone does not determine treatment. Two injuries that appear to have the same structural grade may affect daily life to different degrees. Episodes of the knee giving way, the person's occupation, sporting needs, muscle control and associated damage are included in decision-making.

PCL injuries can occur in two broad forms:

• Isolated injury: Damage is largely confined to the posterior cruciate ligament.
• Combined injury: The ACL, medial or lateral collateral ligaments, posterolateral corner structures, meniscus or cartilage are also affected.

Combined injuries can compromise knee stability in different directions. The possibility of blood vessel and nerve damage must also be assessed after high-energy trauma. The term ‘PCL tear’ therefore does not describe the full extent of the injury.

How Does a Posterior Cruciate Ligament Injury Occur?

A posterior cruciate ligament injury most often occurs when a force strikes the front of the shinbone while the knee is bent, pushing the bone backwards. Typical examples include the knee hitting the dashboard in a vehicle collision, a fall onto a bent knee and direct blows during contact sports. Hyperextension and rotational forces can also injure the PCL together with other structures.

When the knee is bent close to a right angle, a blow to the front of the upper shinbone can force it backwards relative to the thighbone. However, the degree of ligament damage cannot be determined solely from the knee angle or direction of impact. The force involved, the position of the foot on the ground and any accompanying rotation also matter. Injury mechanisms are described in detail in a current concepts review (PMID 29430489).

Common mechanisms include:

• Vehicle collision: A bent knee striking the dashboard pushes the shinbone backwards. This ‘dashboard injury’ mechanism may involve fractures and damage to multiple ligaments.
• Fall onto a bent knee: The front of the knee hitting the ground during football, handball, skiing or daily activities can produce a similar force.
• Impact during contact sports: Another player striking the front of the knee can affect the collateral ligaments and cartilage surfaces as well as the PCL.
• Hyperextension: Extending the knee beyond its natural limit while the foot is planted can strain ligament fibres.
• Sudden rotation: Rotation alone is not a typical PCL injury mechanism; however, forceful turns with the foot planted can injure several knee structures.
• High-energy trauma: Events such as road traffic accidents or falls from height require assessment for knee dislocation, fractures and blood vessel or nerve injuries.

A low-energy strain may result in partial ligament damage, while a more forceful trauma may cause a combined injury. Nevertheless, an event that appears mild should not be assumed to have caused only minor damage. Pain, swelling, difficulty bearing weight or a feeling of instability requires examination.

Remembering the position of the knee at the time of injury can help the assessment. Tell the doctor where the impact occurred, when swelling was noticed, whether you could walk afterwards and whether the knee felt as though it had dislocated and gone back into place.

What Are the Symptoms of a PCL Injury?

Symptoms of a PCL injury include pain at the back of or throughout the knee, swelling, restricted movement, limping and insecurity when bearing weight. Symptoms may be particularly noticeable when descending stairs or slopes, slowing down or changing direction. Mild symptoms do not mean that the ligament is intact; symptom severity does not always match the degree of structural damage.

Symptoms that may occur after an acute injury include:

• Pain at the back, front or throughout the knee
• Swelling that may become noticeable in the hours after the trauma
• Difficulty fully straightening or bending the knee
• Limping or inability to bear weight confidently on the injured leg
• Worsening symptoms when kneeling or descending stairs
• A feeling that the shinbone is slipping backwards or the knee may give way
• Tenderness or bruising at the front of the knee, particularly over the upper shinbone
• Numbness extending to the foot, colour changes or difficulty moving after severe trauma

Swelling may develop immediately or become more apparent over time. A PCL injury does not always produce an audible pop. Being able to walk after the event does not rule out serious ligament damage. A 2024 review of non-operative assessment of acute knee injuries emphasises the importance of combining examination and imaging (PMID 38095838).

Chronic PCL injuries that were not recognised promptly or in which functional laxity persists may produce a different pattern of symptoms:

• Early knee fatigue during long walks or running
• Difficulty maintaining control on sloping ground
• Insecurity when slowing down or changing direction
• Load-related pain at the front of the knee that becomes more apparent over time
• Recurrent feelings of the knee giving way
• Difficulty with sport-specific jumping, landing or turning movements

These symptoms are not specific to the PCL. Meniscal tears, cartilage damage, fractures or other ligament injuries can cause similar complaints. Locking, catching or sharp pain at a specific point in the knee warrants further assessment of the meniscus and other structures inside the joint.

The course of symptoms over time also matters. If giving way persists despite reduced swelling, or recurs with daily activities, pain relief alone is not a sufficient measure of recovery. Knee control, range of motion and muscle strength should be assessed together.

What Are the Differences Between PCL and ACL Injuries?

PCL and ACL injuries differ in the direction of movement they control and their common mechanisms. The PCL limits backward movement of the shinbone, while the ACL limits forward movement. The PCL is most often injured by a blow to the front of a bent knee; the ACL by sudden deceleration, changes of direction, twisting or an unbalanced landing. Examination and imaging establish the distinction.

Both ligaments lie in the centre of the knee, but their roles are not identical. PCL stands for posterior cruciate ligament; ACL stands for anterior cruciate ligament. Since both ligaments can be affected in the same trauma, the mechanism provides only an initial clue.

Comparison criterion	PCL injury	ACL injury
Ligament name in Turkish	Posterior cruciate ligament	Anterior cruciate ligament
Main function	Limits backward movement of the shinbone	Helps control forward movement and rotation of the shinbone
Common mechanism	Direct blow to the front of a bent knee	Sudden change of direction, deceleration, twisting or an unbalanced landing
Pattern of symptoms	Posterior knee pain, swelling and insecurity on slopes or when slowing down	Rapid swelling, giving way during rotation and sometimes a tearing sensation
Associated injuries	Other ligaments, fractures and posterolateral corner structures after severe trauma	Meniscus, cartilage and other ligaments
Focus of examination	Posterior drawer, posterior sag and posterior laxity	Lachman test, anterior drawer and rotational stability
Factors determining treatment	Functional laxity, combined injury and response to rehabilitation	Functional instability, associated damage and activity requirements

The differential assessment considers the following:

• Direction of impact: A force striking the upper shinbone from the front suggests PCL damage.
• Knee and foot position: Rotation of the body while the foot is planted can affect the ACL and other structures.
• Movement that causes insecurity: Descending slopes or stairs may be more troublesome with PCL insufficiency, while sudden turns may cause greater problems with ACL insufficiency.
• Energy of the trauma: High-energy events should not be assumed to involve only one ligament.
• Examination findings: Pain and muscle spasm can affect the reliability of the initial examination, so assessment may be repeated if needed.
• Loss of function: How the person uses their knee is considered in treatment planning alongside the ligament involved and its MRI appearance.

Although PCL injuries are considered less common than ACL injuries, this does not mean that an individual injury is unimportant. Comprehensive assessment is required, particularly after trauma that may involve multiple ligaments or blood vessels and nerves.

How Is a Posterior Cruciate Ligament Injury Diagnosed?

A posterior cruciate ligament injury is diagnosed by interpreting the mechanism of trauma, a physical examination comparing both knees and any necessary imaging together. X-rays assess bone injuries, MRI shows ligaments and tissues inside the joint, and stress radiographs can help measure backward displacement. Diagnosis does not rest solely on the word ‘tear’ in an MRI report.

The history covers knee position at the time of injury, direction of impact, progression of swelling, ability to bear weight and a feeling of giving way. A knee striking the dashboard in a road traffic accident, a fall onto a bent knee or an impact in contact sports is relevant to the PCL. However, these mechanisms can also cause fractures and multiple ligament injuries.

Which Tests Are Used During the Physical Examination?

The examination covers the entire knee, not only the PCL. The doctor assesses swelling, range of motion, tender areas and the leg's neurovascular status. Comparison with the uninjured side helps distinguish an individual's natural laxity.

Common assessments include:

• Posterior drawer test: The knee is bent close to a right angle; backward displacement of the shinbone under a controlled force is assessed.
• Posterior sag sign: With the hip and knee bent, the examiner checks whether the shinbone sags backwards under gravity.
• Quadriceps active test: The examiner checks whether contraction of the front thigh muscle moves a posteriorly displaced shinbone forwards.
• Rotational and collateral ligament tests: Additional laxity involving the ACL, medial and lateral collateral ligaments and posterolateral corner structures is assessed.
• Neurovascular examination: Foot colour, temperature, pulses, sensation and muscle movements are checked.

PCL anatomy, examination methods and diagnostic approaches were discussed in a 2021 review (PMID 33201271). Pain, swelling or protective muscle guarding can make laxity difficult to assess at the first examination. In that case, assessment may be repeated when considered safe and clinically necessary.

What Do Imaging Methods Add to the Diagnosis?

Method	Area assessed	Diagnostic contribution
X-ray	Bones and joint alignment	Assesses injuries such as fractures, dislocation or a ligament pulling off a fragment of bone
Stress radiograph	Backward displacement of the shinbone	Compares laxity between the two knees under a controlled applied force
MRI	PCL, ACL, meniscus, cartilage and surrounding soft tissues	Shows the site of ligament damage and associated injuries inside the joint
Advanced vascular imaging	Blood vessels of the leg	Used on clinical judgement after trauma with suspected vascular injury

Although valuable, MRI does not measure ligament function on its own. After an old injury, ligament fibres may appear continuous on imaging while the knee remains clinically lax. Conversely, structural damage seen on MRI may have only a limited impact on daily function. Results must be matched with examination findings and symptoms.

What Are the Treatment Options for a PCL Injury?

Treatment planning for a PCL injury starts by assessing whether suitable non-surgical options are adequate and safe for the individual. Load modification, an appropriate brace and rehabilitation may be used for isolated injuries with limited functional laxity. Surgery is considered separately for multiple ligament damage, marked instability or persistent loss of function despite appropriate rehabilitation.

‘Conservative treatment’ does not simply mean waiting. It is a planned process that protects knee tissues, limits muscle loss and gradually restores movement control. Not every patient needs to try every non-surgical method; suitability for the injury, safety and response to previous treatment guide the choice. The goals and natural course of non-operative PCL treatment were assessed in a 2018 review (PMID 29721691).

Non-surgical treatment may include:

• Load modification: The amount of weight-bearing and use of crutches are determined by pain, knee control and associated damage.
• Activity modification: Squatting, sudden changes of direction, running and contact sports may be temporarily restricted.
• PCL-specific brace: Braces designed to reduce backward displacement of the shinbone may be used in selected patients.
• Swelling control: Cold application with skin protection and appropriate elevation of the leg may be recommended.
• Medication: Prescribed by the doctor with regard to the person's conditions and other medicines. Prescription medicines, blood thinners or painkillers should not be started, stopped or changed on one's own initiative.
• Rehabilitation: Range of motion, quadriceps strength, hip and trunk control and balance are trained progressively.
• Return to function: Progression to walking, stairs, running and sport-specific movements follows clinical criteria rather than taking place all at once.

Quadriceps control is important in early rehabilitation. Because some exercises that intensively work the hamstrings can pull the shinbone backwards, the timing and design of the programme should be set by the physiotherapist and doctor. Exercises, assistive device use and stair training should be demonstrated in practice; a walking frame must not be used on standard stairs.

In surgical treatment, the PCL is usually rebuilt with a tendon graft. This is called PCL reconstruction. Different techniques may be used depending on the injury; not all operations use the same tunnel arrangement or graft. Surgical techniques and rehabilitation approaches have been assessed in recent reviews (PMID 33125531; PMID 31895328; PMID 34081174).

Potential surgical risks include infection, bleeding, blood vessel or nerve injury, joint stiffness, persistent pain or laxity, blood clots and the need for further surgery. Inadequate biological incorporation of the graft or reinjury is also possible. Surgery does not guarantee a return to a particular level of function.

Outcomes of any surgical or interventional procedure can vary between individuals. The method is selected by considering examination findings, imaging, associated injuries, general health and the person's functional needs together.

When Is PCL Surgery Considered?

PCL surgery may be considered when instability affecting daily life or sport persists despite appropriate non-surgical treatment, when multiple ligaments are injured or when the ligament is damaged together with an avulsed bone fragment. The decision is not based solely on tear grade; examination, measurable laxity, associated damage and the person's needs are interpreted together.

Rehabilitation is often the initial approach for isolated, low-grade injuries. However, prolonged waiting is not appropriate for every patient. Assessment and timing differ when there is a knee dislocation, neurovascular risk, a bone avulsion that may need repair or multiple ligament injuries.

Situations that may require a surgical opinion include:

• Recurrent giving way or marked insecurity during everyday movements
• Persistent loss of function despite planned, appropriate rehabilitation
• ACL or collateral ligament injury alongside the PCL injury
• Significant damage to the posterolateral corner structures of the knee
• An avulsion fracture in which the ligament pulls away with a fragment of bone
• Multiple ligament injuries associated with knee dislocation
• Associated meniscal or cartilage damage that changes the treatment plan
• Inability to achieve the directional changes and load control required for work or sport

Stress radiographs and examination can help grade backward displacement of the shinbone. However, a particular measured amount of displacement does not, on its own, make surgery mandatory. The measurement technique, difference from the uninjured side, rotational laxity and condition of the other ligaments are assessed together.

In PCL reconstruction, a graft is passed through bone tunnels and secured to take over the ligament's function. The approach may vary according to whether the injury is acute or chronic, bone anatomy, the number of affected ligaments and the surgeon's assessment. When several ligaments are injured, simultaneous or staged procedures are planned according to clinical circumstances.

After surgery, infection, thrombosis or embolism, blood vessel or nerve injury, restricted movement, persistent pain, residual laxity, graft failure and revision surgery are possible. Participation in rehabilitation is important but does not guarantee that adverse outcomes will not occur. Variation in postoperative rehabilitation protocols has been examined in a systematic review (PMID 33972484).

Outcomes of any surgical or interventional procedure can vary between individuals. The need for and timing of surgery require joint assessment of orthopaedic examination and imaging findings.

Rehabilitation and Return to Sport After a PCL Injury

Rehabilitation after a PCL injury aims to gradually improve range of motion, muscle strength, balance and confidence in movement while protecting the ligament or graft. Return to sport is not determined by the calendar alone. Swelling, pain, range of motion, strength, single-leg control and sport-specific movements are assessed together, with stages progressed individually.

The pace of rehabilitation depends on tear grade, whether surgery was performed, the technique used and any associated ligament, meniscal or cartilage procedures. Another patient's programme should therefore not be used as a template. Substantial differences between postoperative protocols have also been reported (PMID 33972484).

The general rehabilitation stages are:

1. Protection and swelling control: Weight-bearing, brace and crutch use are arranged as demonstrated by the doctor and physiotherapist.
2. Regaining range of motion: Knee bending and straightening progress in a controlled manner; movements that place excessive posterior load on the ligament may be restricted early on.
3. Improving muscle activation: Quadriceps, hip and trunk muscles are trained with appropriate resistance.
4. Balance and gait training: Walking without a limp, weight transfer and safe stair use are taught.
5. Preparation for running: Single-leg control, strength, swelling response and walking capacity are assessed.
6. Sport-specific training: Acceleration, deceleration, jumping, landing and changes of direction are added in a controlled setting.
7. Return to training: Limited non-contact activity is planned first, followed by more complex tasks as required.

Sharp pain or marked giving way during exercise, or increased swelling afterwards, requires reassessment of the programme. This should not be interpreted as a need to ‘push harder’. Exercise technique, resistance and progression criteria should be demonstrated by the physiotherapist or doctor.

Everyday movements such as using stairs, walking with an assistive device and getting into a vehicle should also be taught in practice. Crutch placement on steps is demonstrated individually; a walking frame must not be taken onto standard stairs. Before returning to driving, the person must be able to control the vehicle fully, perform an emergency stop and be free of medication effects that cause sleepiness or dizziness. Medicines must not be stopped on one's own initiative in order to drive.

It is important for the strength and function of the two legs to become similar before returning to sport, but a single symmetry value does not guarantee a safe return. Movement quality, psychological readiness, the sport's contact and rotational demands and the knee's response after exercise are assessed together. Assessment of return to sport after PCL injuries is discussed in recent reviews (PMID 36447081). Return after multiple ligament injuries is more complex, and the evidence encompasses different protocols (PMID 39539337).

When Should Healthcare Facilities Be Visited Without Delay?

If one or more of the following emergency signs occur after knee trauma, call 112 or attend an emergency department without delay. They do not all need to be present together. Severe pain, tense swelling, impaired circulation, weakness, altered consciousness or breathing symptoms may indicate a time-critical condition beyond a ligament injury.

Signs requiring an immediate call to 112 or emergency department attendance

One or more of the following is sufficient reason to seek emergency care:

• Sudden difficulty breathing
• Chest pain
• Fainting
• Coughing up blood
• Rapid heartbeat
• Severe pain disproportionate to the injury, persistent or rapidly increasing
• Pain that markedly worsens with passive movement
• Tense swelling
• New numbness or weakness
• Coldness, pallor or a bluish colour in the limb
• New loss of sensation or movement
• New confusion or incoherent speech, with or without fever
• Severe pain, obvious deformity, inability to move the knee or bear weight
• Uncontrolled bleeding
• Bone or deep tissue visible in an open wound

Rapidly increasing pain out of proportion to the injury, marked pain with passive movement, tense swelling, numbness or weakness may occur in compartment syndrome. This is a surgical emergency. Trying a painkiller and waiting for its effect must not delay emergency assessment.

With these symptoms, do not strain the knee, bear weight on it or try to correct a visible deformity yourself. If there is bleeding, direct, controlled pressure may be applied to an open wound; avoid improvised tight binding that could impair circulation.

Conditions requiring assessment on the same day

Same-day medical assessment is needed if one or more of the following occurs:

• One-sided leg or calf swelling
• Calf pain or tightness
• Increasing redness, heat, swelling or discharge at the wound site
• Wound edges opening
• Fever of 38°C or higher
• Persistent fever, chills or general deterioration
• Exceeding the lower fever threshold specified in discharge instructions
• New severe pain or inability to bear weight after a fall or impact
• Markedly increasing knee swelling in the hours after trauma
• Joint locking or markedly restricted movement
• Persistent pain after a road traffic accident, fall from height or forceful direct blow

Wound infection, or infection around a prosthesis if one is present, can develop without fever; wound signs should therefore not be judged by fever alone. One-sided calf swelling and pain require same-day assessment for deep vein thrombosis. If sudden shortness of breath or chest pain develops, emergency help is needed.

A posterior cruciate ligament injury may not completely prevent walking at first. Nevertheless, assessment should not be postponed if pain at the back of the knee, swelling or insecurity persists. Fractures and associated ligament injuries can only be distinguished through appropriate examination and imaging.

Frequently asked questions

Frequently asked questions focus on the PCL's role, the likelihood of a tear healing, treatment choice and return to everyday life. Answers depend on whether the injury is isolated and the loss of knee function it causes. The information below outlines general principles; individual treatment decisions require an examination.

What is a PCL tear?

A PCL tear is a partial or complete rupture of the posterior cruciate ligament fibres in the centre of the knee. The ligament limits backward movement of the shinbone. Injury most often follows a blow to the front of a bent knee, a fall onto the knee or forceful sports trauma. It can cause pain, swelling, restricted movement and insecurity, particularly on sloping ground.

Can a posterior cruciate ligament tear heal?

The likelihood of recovery depends on tear grade, knee laxity, associated injuries and response to rehabilitation. Isolated injuries with limited functional laxity can be managed with an appropriate brace and rehabilitation. Surgery may be considered if several ligaments are damaged or instability persists. No approach guarantees a particular functional outcome.

What does PCL stand for?

PCL stands for ‘Posterior Cruciate Ligament’, known in Turkish as arka çapraz bağ. It is one of the two cruciate ligaments inside the knee. Its main function is to limit excessive backward displacement of the shinbone relative to the thighbone and contribute to joint stability, particularly when the knee is bent.

What does PCL mean in the knee?

In the knee, PCL refers to the posterior cruciate ligament, located behind the anterior cruciate ligament. This strong ligament controls backward movement of the shinbone and contributes to rotational control of the knee. PCL damage on an MRI report does not determine treatment on its own; laxity on examination, symptoms and associated injuries are also assessed.

What happens if the posterior cruciate ligament ruptures?

When the posterior cruciate ligament ruptures completely, backward movement of the shinbone may increase. Swelling, restricted movement and insecurity, particularly when descending stairs or slopes, may develop. Some people can walk on level ground; this does not prove that the ligament is functionally adequate. The condition of the other ligaments, meniscus and cartilage can change the treatment plan.

How long does a PCL injury take to heal?

There is no fixed recovery period for a PCL injury that applies to everyone. Duration varies with the degree of damage, associated injuries, treatment and rehabilitation response. Return to daily life or sport is determined not by the calendar alone, but by swelling, range of motion, strength, balance and the ability to perform sport-specific movements safely.

This information is for educational purposes and does not replace diagnosis and treatment. Please consult your doctor about your symptoms.