PCL Tear

The posterior cruciate ligament — the PCL — is the strongest ligament in your knee. It sits deep inside the joint and runs from the back of your shin bone up to the inner side of your thigh bone. Its job is to keep your shin bone from sliding backward relative to your thigh. PCL tears most often happen from a direct hit to the front of a bent knee — a dashboard injury in a car wreck, or falling onto a bent knee with the foot pointing down. They're less common than ACL tears, and they more often happen on their own without other ligament injuries.

Compared to an ACL tear, an isolated PCL tear actually does better on its own — many people with a partial (grade I-II) PCL tear get back to full activity with physical therapy alone, no surgery. The story changes when the PCL is torn together with other ligaments — those combined injuries are more disabling and usually need surgical repair.

Swelling and pain at the back of the knee after a direct hit — commonly a dashboard impact or a fall onto a bent knee. Unlike an ACL tear, a PCL tear may not feel dramatic at first; many people walk off the field before realizing something is wrong.

The knee may feel vaguely unstable going downhill or down stairs, and you may notice a dull ache in the back of the knee that worsens with activity. Over time an untreated PCL tear can lead to pain in the front of the knee or on the inner side as other structures compensate for the missing ligament.

Pain and swelling at the back of the knee after a direct blow. On exam, your provider does a posterior drawer test — sitting your knee at 90° and pressing your shin backward — and feels for excess motion compared to the other side. With you lying on your back, knees bent, the shin sometimes visibly sags backward (the posterior sag sign) when the PCL is torn. An MRI confirms the tear and looks for any other ligaments or cartilage that might be hurt at the same time.

We consider surgical reconstruction for complete (grade III) PCL tears, for PCL tears that come together with other ligament injuries (especially the back-outside corner of the knee or the ACL), and for any PCL tear where the knee still feels unstable after a real trial of physical therapy.

External patient-education references and related OSI pages for additional background:

• Britannica — Ligament
• Britannica — Knee (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language