ConditionInjuries & poisoning
Posterior Cruciate Ligament (PCL) Injury
A posterior cruciate ligament (PCL) injury is a stretch or tear of the strong ligament inside the knee that stops the shinbone from sliding backward under the thighbone. It usually happens from a direct blow to the front of the shin with the knee bent, such as hitting a dashboard in a car crash or falling onto a bent knee. It is less common and often less disabling than an ACL tear. Most isolated PCL injuries heal well with a brace and physical therapy, while combined ligament injuries often need surgery.
Also called: PCL tear, torn PCL, posterior cruciate ligament tear, PCL sprain
At a glance
- What it is
- A stretch or tear of the ligament that keeps the shinbone from sliding backward.
- Common causes
- Dashboard injuries, falls onto a bent knee, sports contact, knee hyperextension.
- Symptoms
- Knee pain and swelling, pain at the back of the knee, mild instability, pain kneeling.
- Grades
- 1 and 2 (partial), 3 (complete), often combined with other ligament injuries.
- Treatment
- Bracing and quadriceps-focused rehab for most isolated injuries. Surgery for combined injuries or persistent instability.
When to get help
Call 911 or go to the ER
- A knee that looks deformed or dislocated after an injury
- A cold, pale or numb foot after a knee injury, or a weak pulse in the foot (possible artery injury with knee dislocation)
- Bone through the skin
See a doctor within a day or two
- Knee injury with rapid swelling, inability to bear weight, or the knee giving way
- Severe pain or a pop at the time of injury
- Numbness or weakness lifting the foot after a knee injury
Book a routine appointment
- Knee pain, swelling or a sense of instability that persists 1 to 2 weeks after an injury
- Ongoing pain at the front of the knee or difficulty with stairs and squatting months after a PCL injury
Usually safe to manage at home
- A mild knee sprain with modest swelling where you can walk normally: rest, ice, elevation and gentle movement
How the PCL works
The knee has two cruciate ligaments that cross in the middle of the joint. The anterior cruciate ligament (ACL) stops the shinbone (tibia) moving forward, and the posterior cruciate ligament (PCL) stops it moving backward. The PCL is about twice as strong as the ACL, which is why it tears less often.
Causes
- dashboard injury: the bent knee strikes the dashboard in a car crash, pushing the shin backward
- falling onto a bent knee with the foot pointed down
- a blow to the front of the shin during contact sports such as football and soccer
- hyperextension (the knee bending backward)
- knee dislocation, which usually tears several ligaments
Symptoms
- pain, often at the back of the knee, that may be mild
- swelling within hours, usually less than with an ACL tear
- stiffness
- difficulty bearing weight at first
- pain when kneeling
- a feeling of instability or the knee being "wobbly", especially on stairs or uneven ground
- later, pain at the front of the knee or knee cap from abnormal joint mechanics
Many isolated PCL injuries cause surprisingly mild symptoms and may be missed.
Grades
| Grade | Damage | Backward shift of the shinbone |
|---|---|---|
| 1 | Partial tear | Slight |
| 2 | Partial tear, more laxity | Moderate |
| 3 | Complete tear | Marked, often with other ligament injuries |
PCL vs ACL injury
| PCL injury | ACL injury | |
|---|---|---|
| Typical cause | Blow to the front of the bent knee | Pivoting, cutting, landing awkwardly |
| Pop at injury | Less common | Common |
| Swelling | Mild to moderate | Rapid, large |
| Instability | Often mild in isolated tears | Often marked with pivoting |
| Usual treatment | Rehab for isolated tears | Surgery for active people |
Associated injuries
PCL injuries often occur with damage to other knee structures, especially in high-energy injuries:
- posterolateral corner ligaments on the outer back of the knee
- MCL and ACL
- meniscus tears and cartilage damage
- bone bruises and fractures
- in knee dislocations, the popliteal artery and peroneal nerve
Diagnosis
- examination: the posterior drawer test, pushing the shin backward with the knee bent, and the sag sign, where the shin sags back when the knee is bent and the leg supported
- X-rays to look for fractures, including small fragments where the PCL attaches
- MRI to confirm the tear and find other injuries
- stress X-rays to measure laxity
- vascular assessment with pulses, ankle-brachial index or CT angiography if knee dislocation is suspected
Treatment
Nonsurgical treatment
Most isolated grade 1 and 2 PCL injuries, and many isolated grade 3 injuries, are treated without surgery:
- brace: a PCL brace that supports the back of the shin, often for several weeks
- crutches initially if needed
- physical therapy: focused on quadriceps strengthening, which helps hold the shinbone forward, plus range of motion, balance and gradual return to activity
- hamstring exercises are introduced carefully because they pull the shin backward
Surgery
Surgery is considered for:
- combined ligament injuries, especially with the posterolateral corner
- PCL avulsion fractures, where a piece of bone is pulled off
- grade 3 tears with persistent instability despite rehab
Reconstruction uses a tendon graft, from the patient or a donor, placed arthroscopically.
Recovery
- isolated grade 1 to 2: return to sport often in about 6 to 12 weeks
- grade 3 nonsurgical: about 3 months or more
- after reconstruction: often 9 to 12 months before return to sport
Outlook
Most people with isolated PCL injuries return to their previous activities. Long-term, some develop arthritis at the front of the knee and the inner side of the knee, especially with untreated laxity. Keeping the quadriceps strong helps protect the knee.
Frequently asked questions
How do you know if you tore your PCL?
Signs include knee pain, especially at the back, swelling, pain kneeling, and a feeling of instability. Symptoms can be mild. A doctor can check with the posterior drawer test, and an MRI confirms the tear.
Can a torn PCL heal on its own?
The PCL has better healing potential than the ACL. Many partial tears, and some complete isolated tears, heal well enough with a brace and physical therapy to allow a return to normal activities and sports.
How long does a PCL injury take to heal?
Mild to moderate isolated PCL injuries often heal in 6 to 12 weeks with rehab. Complete tears treated without surgery may take 3 months or more. After surgical reconstruction, return to sport can take 9 to 12 months.
Is a PCL tear worse than an ACL tear?
Isolated PCL tears are usually less disabling than ACL tears and more often managed without surgery. However, PCL injuries are frequently combined with other ligament damage, which can be more serious and usually needs surgery.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Orthopaedic Surgeons (OrthoInfo): Posterior Cruciate Ligament Injuries
- American Orthopaedic Society for Sports Medicine: PCL injury patient information
- NHS: Knee ligament surgery and injuries
- MedlinePlus: Knee injuries and disorders
- Journal of the American Academy of Orthopaedic Surgeons: Posterior cruciate ligament injury review