This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bones Joints and Ligaments, Subject name: Anatomy
While playing football, a 19-year-old college student receives a twisting injury to his knee when being tackled from the lateral side. Which of the following conditions most likely has occurred? 
Select and explain. 
A. Tear of the medial meniscus, B. Ruptured fibular collateral ligament, C. Tenderness on pressure along the fibularcollateral ligament, D. Injured posterior cruciate ligament
A: Tear of the medial meniscus
Answer: A: Tear of the medial meniscus 
Explanation: The "unhappy triad" of the knee joint is characterized by: tear of the medial meniscus, rupture of the tibial collateral ligament, and rupture of the anterior cruciate ligament. This injury may occur when a cleated shoe, as worn by football players, is planted firmly in the turf and the knee are struck from the lateral side. Tenderness along the medial collateral ligament and over the medial meniscus and swelling on the front of the joint are due to excessive production of synol fluid, which fills the joint cavity and the suprapatellar bursa.