What is the difference between a PCL tear and an ACL tear?

Two ligaments, opposite jobs

The two cruciate ligaments cross in the centre of the knee. The anterior cruciate ligament (ACL) resists the tibia moving forwards and rotating, which matters most when you plant and turn. The posterior cruciate ligament (PCL) is thicker and stronger and resists the tibia moving backwards, which matters most when the knee is bent and when you slow down or go downhill.

How each injury usually happens

• ACL: a non-contact twist, sudden change of direction or awkward landing in football, padel or basketball
• PCL: a direct blow to the front of the upper shin, such as a dashboard injury in a road accident, or a fall onto a bent knee
• Both: high-energy injuries can tear both, often with other ligaments, and need urgent specialist care

How they feel

An ACL tear often causes a pop, rapid swelling and a knee that gives way when you turn. A PCL tear tends to cause less swelling, an ache at the back of the knee, and unsteadiness on stairs or when decelerating. Over time, an untreated PCL injury can cause aching at the front and inner side of the knee because the load through the joint changes.

How treatment differs

The ACL heals poorly on its own, so active people who want to return to pivoting sport often choose reconstruction. The PCL has a better capacity to heal, and many isolated PCL tears do well with a specific brace and quadriceps-focused rehabilitation. Surgery for the PCL is usually considered for complete tears with persistent instability, injuries combined with other ligaments, or a bone fragment pulled off with the ligament.

Dr. Gelber examines both ligaments in every injured knee, because the treatment depends on which is torn and what else is involved.