A PCL injury is the knee ligament tear most people have never heard of, and in my experience it is the one most likely to be missed. After more than twenty years of treating knees in Franklin, I have met plenty of patients who limped around on a torn posterior cruciate ligament for a month. Nobody had put a name on it. The pain was dull and the knee “just didn’t feel right.”
Here is what the PCL does, how it gets hurt, how it is treated, and the part most articles skip: what it means for your knee 20 years from now.
What is the PCL and what does it do?
The posterior cruciate ligament (PCL) is the strongest ligament in the knee, and its job is to keep the shin bone (tibia) from sliding backward under the thigh bone (femur). It runs from the back of the tibia up into the femur, crossing behind its better-known partner, the anterior cruciate ligament (ACL).
The PCL is about 30 percent thicker than the ACL, so it takes a serious hit to tear it. It works hardest with the knee bent to about 90 degrees, which is why stairs, squatting, and slowing down from a run bother PCL patients most.
What causes a PCL injury?
A PCL injury is almost always caused by a strong force pushing the shin backward while the knee is bent. Three mechanisms cause most of the cases I see:
- Dashboard injury. In a car crash, the bent knee hits the dashboard and drives the tibia backward. This is the classic cause and the one most likely to tear the PCL completely.
- Falling on a bent knee. A football or soccer player lands hard on the front of the shin with the foot pointed down. Athletes are the largest group affected.
- Hyperextension. The knee is forced backward past straight, often from an awkward landing.
The energy of the injury matters. A low-energy fall usually tears the PCL alone. A high-energy dashboard injury rarely stops there: roughly 90 percent of patients with lasting PCL symptoms also have damage to the posterolateral corner, the ACL, or the collateral ligaments.
What does a PCL tear feel like?
A PCL tear usually feels like a deep, dull ache in the knee with mild swelling, not the sharp pop and rapid swelling of an ACL tear. That difference is why so many PCL injuries go undiagnosed. Patients describe a “tearing” feeling, and many finish the game or drive home before the knee stiffens.
Common PCL injury symptoms
- Pain deep in the knee, worse when kneeling or going down stairs
- Mild to moderate swelling within a few hours
- A feeling that the knee is loose, weak, or “not quite right”
- Trouble slowing down, pivoting, or walking on inclines
- Front-of-knee pain that appears one to two weeks after the injury
What are the grades of a PCL injury?
PCL injuries are graded I to III by how far the shin slides backward when the knee is bent to 90 degrees and gently pushed; the grade drives treatment.
- Grade I (mild sprain): Stretched with microscopic tearing. The tibia moves 1 to 5 millimeters more than the healthy knee; the knee stays stable.
- Grade II (partial tear): Partly torn and loose. The tibia moves 6 to 10 millimeters. The knee may give way now and then.
- Grade III (complete tear): Fully torn or pulled off the bone. The tibia moves more than 10 millimeters, and other ligaments are usually torn too.
How is a PCL injury diagnosed?
A PCL injury is diagnosed with a hands-on knee exam first, then confirmed with imaging. The signs are subtle, so the injured knee is always compared with the healthy one.
Exam tests for a PCL injury
The posterior drawer test is the most accurate exam for a PCL injury. With the knee bent to 90 degrees, I push the shin gently backward; if it slides too far, the PCL is loose. I also check for the posterior sag sign (the shin visibly drops back compared with the other leg) and the quadriceps active test (tightening the thigh pulls the shin forward into place).
Imaging for a PCL injury
MRI is the confirming test for a fresh PCL tear and also shows the meniscus, cartilage, and other ligaments. X-rays come first to rule out a fracture or a chip of bone pulled off the tibia. For older injuries I often order kneeling stress X-rays, because a chronically torn PCL can heal stretched out and look normal on MRI. My guide to understanding your knee MRI report walks through the terms you will see.
How is a PCL injury treated without surgery?
Most Grade I and II PCL injuries, and many isolated Grade III tears, are treated without surgery, and most of those patients return to full activity. The PCL heals well if it is protected early. Here’s what I tell my patients the plan looks like:
- Protect it early. Rest, ice, compression, and elevation, plus crutches if walking hurts.
- Brace in extension. A brace holds the knee straight and supports the shin so the ligament heals at the right length, often for four weeks or longer.
- Rebuild the quadriceps. A strong thigh muscle pulls the shin forward and does part of the PCL’s job. We avoid early hamstring curls, which pull the shin backward and stress the healing ligament.
- Return gradually. Grade I and II injuries often return to sport in 2 to 4 weeks. Isolated Grade III tears usually take 6 to 12 weeks.
My post on choosing a knee brace explains the types, and my knee sprain treatment guide covers the recovery steps that apply to any ligament.
When does a PCL injury need surgery?
Surgery is recommended in three situations: the PCL is torn along with other ligaments, a piece of bone has been pulled away, or the knee stays unstable after a proper course of rehab. An isolated PCL tear rarely needs an operation; a combined dashboard injury almost always does.
PCL reconstruction replaces the torn ligament with a graft from your own tendon or from a donor, done arthroscopically through small incisions with a camera. If the ligament pulled a chip of bone off the tibia, the fragment can often be screwed back in place instead. The American Academy of Orthopaedic Surgeons covers both approaches.
To be clear about my role: I am a joint replacement surgeon, and I do not reconstruct ligaments. When a patient from Franklin, Nashville, or Columbia comes to the Bone and Joint Institute of Tennessee with a multi-ligament injury, the fellowship-trained sports medicine surgeons in our practice handle the reconstruction. My job is the exam, the honest conversation, and the long game.
What is PCL surgery recovery like?
PCL surgery recovery takes 6 to 9 months for most patients and up to a year for athletes returning to contact sports. Expect a brace and crutches for about a month and physical therapy for 3 to 6 months. It runs longer than ACL rehab because the graft fights gravity pulling the shin backward.
Can a PCL injury lead to arthritis later?
Yes. A knee that stays loose after a PCL injury wears out faster, and many patients develop osteoarthritis in that knee a decade or more later. This is the reason a joint replacement surgeon is writing about ligament tears.
When the shin sits slightly behind where it belongs, the kneecap and inner compartment carry extra load, and over the years that grinds down cartilage. I regularly meet patients in their fifties with worn-out knees who tell me about a car wreck or a hard fall in college.
The good news: a knee replacement handles a missing PCL by design. In many implant designs the surgeon removes the PCL on purpose and the implant shape supplies that stability, which is one reason a total knee replacement works so well in a knee that lost its ligaments decades ago. Still, the lesson is simple: get a bent-knee injury looked at early, follow the brace-and-rehab plan, and keep your quadriceps strong for life.
When should you see a doctor for a PCL injury?
See an orthopaedic specialist promptly if your knee swells, feels unstable, or hurts after a direct blow, a fall onto a bent knee, or a car accident. Being able to walk on it does not rule out a tear. Go to the emergency department right away if the knee looks deformed or the foot is numb, cold, or discolored; those can signal a dislocated knee and an injured artery.
For an acute knee ligament injury, call the Bone and Joint Institute of Tennessee at (615) 791-2630 and our team will match you with the right specialist. If an old PCL injury has left you with a painful, arthritic knee, you can schedule a consultation with me at 3000 Edward Curd Lane in Franklin. We see patients from Nashville, Brentwood, Columbia, Spring Hill, and across Middle Tennessee, with no referral required.
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Medical disclaimer: This article is for educational purposes only and does not replace an evaluation by a qualified orthopaedic specialist. Treatment for a PCL injury depends on your exam, imaging, activity goals, and overall health. Individual results vary.
References
- Knapik DM, Smith MV, Matava MJ, Brophy RH. Management of Posterior Cruciate Ligament Injury: A Concise Overview of Current Indications, Techniques, and Outcomes. J Am Acad Orthop Surg. 2026;34(4):e515-e526. PubMed
- Bedi A, Musahl V, Cowan JB. Management of Posterior Cruciate Ligament Injuries: An Evidence-Based Review. J Am Acad Orthop Surg. 2016;24(5):277-289. PubMed
- Raj MA, Mabrouk A, Varacallo MA. Posterior Cruciate Ligament Knee Injuries. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023. NCBI Bookshelf
- American Academy of Orthopaedic Surgeons. Posterior Cruciate Ligament (PCL) Injuries. OrthoInfo. Accessed September 2, 2026. OrthoInfo
- Harvard Health Publishing. Posterior Cruciate Ligament (PCL) Injuries. Harvard Medical School. Reviewed May 27, 2025. Harvard Health
