Mechanism of Injury

Typically, the ACL is injured in a non-contact, twisting movement involving rapid deceleration on the leg, or a sudden change of direction, such as during side stepping, pivoting or landing from a jump . Injuries are often associated with a popping sensation followed by swelling in the knee over the next few hours due to bleeding from the torn ligament.

Typical scenarios include a footballer or rugby player who catches his foot in the ground as he tries to change direction, a netball player who jumps and lands awkwardly twisting on their bent knee with their foot out to the side, and a skier who catches the ski at slow speed and twists their leg out to the side.

There are many other scenarios of course and depending on the exact mechanism it is also possible to damage the joint surfaces (articular cartilage), or the meniscus (footballer’s cartilage).