Final answer:
A PCL tear is a knee injury caused by a force moving the tibia posteriorly. It presents with symptoms like pain, swelling, and knee instability, often part of a sequence of injuries known as the "terrible triad" injury.
Step-by-step explanation:
A PCL (posterior cruciate ligament) tear is a type of knee injury that typically occurs when a strong force is applied to the knee, causing the tibia (shin bone) to move posteriorly (backward). This can happen, for example, when falling and landing on the tibial tuberosity or being involved in a car accident. The PCL tear usually presents with symptoms such as pain, swelling, and knee instability.
When a PCL tear occurs, it is often part of a sequence of injuries referred to as the "terrible triad" injury, which includes tearing of the tibial collateral ligament, damage to the medial meniscus, and rupture of the anterior cruciate ligament. The medial meniscus is particularly prone to injury when the tibial collateral ligament is torn.
If someone suspects a PCL tear, it is important to seek medical attention to confirm the diagnosis and receive appropriate treatment, which may include rest, physical therapy, bracing, or in some cases, surgery.