Final answer:
The name of the injury involving the semilunar cartilages in the knee is a torn meniscus. This type of injury can happen due to acute trauma or develop over time and is more likely to affect the medial meniscus due to its attachment to the tibial collateral ligament.
Step-by-step explanation:
The injury involving the semilunar cartilages in the knee is known as a torn meniscus. The semilunar cartilages, more commonly referred to as the menisci, are two C-shaped pieces of fibrocartilage located between the femur and the tibia at the knee joint. Specifically, the medial meniscus is attached to the tibial collateral ligament, making it more susceptible to injury, particularly when a strong blow to the lateral side of the extended knee occurs, potentially resulting in the 'terrible triad' injury sequence of the tibial collateral ligament tear, medial meniscus damage, and rupture of the anterior cruciate ligament. A torn meniscus is a common knee injury that can occur from either acute trauma or gradual degeneration.