This article is part of our Injury Analysis series.
The biggest disappointment in Week 11 was the nasty left knee injury sustained by the rookie Bengals quarterback. Burrow was carted off the field following the injury and was later diagnosed with multiple injuries to the knee. Medically, it sounds as though Burrow has suffered what is known as the "Unhappy Triad," a trio of injuries that includes damage to the anterior cruciate ligament (ACL), the medial collateral ligament (MCL) and the medial meniscus.
The ACL and MCL are two of the four stabilizing ligaments in the knee. These connective tissues along with two menisci fortify and stabilize the knee joint. Their design and structure allows them to divert and absorb the various stresses placed on and through the knee. However, the ligaments can all fail if the knee is subjected to enough excessive force. Furthermore, an injury to the MCL is often accompanied by medial meniscus damage, because the fibers of the ligament are intertwined with the cartilage disc.
The Unhappy Triad usually occurs when the joint is twisted and an outside load is placed through the knee. Burrow's injury was a classic mechanism of injury for the Unhappy Triad as a his leg was planted as multiple players fell into the lateral portion of the knee.
Multiple NFL players have succumb to the Unhappy Triad including Sean Lee, Adrian Peterson and Rob Gronkowski. For quarterbacks, Tom Brady is the most noteworthy player to suffer the injury. However, several All-Pro quarterbacks appear on the list.